geosciences

Article Geochemical Characterization and Thermal Maturation of Cerrejón Formation: Implications for the Petroleum System in the Ranchería Sub-Basin,

Luis Felipe Cruz-Ceballos 1,2,* , Mario García-González 1,3 , Luis Enrique Cruz-Guevara 1,3 and Gladys Marcela Avendaño-Sánchez 1,2

1 Geology School, Universidad Industrial de Santander (UIS), Carrera 27 Calle 9 Ciudad Universitaria, Bucaramanga 680002, Colombia; [email protected] (M.G.-G.); [email protected] (L.E.C.-G.); [email protected] (G.M.A.-S.) 2 Grupo de Investigación en Geología Básica y Aplicada (GIGBA), UIS Guatiguará, Piedecuesta 681011, Colombia 3 Energy and Other Non-Renewable Resources Research Group (EONr3g), UIS Guatiguará, Piedecuesta 681011, Colombia * Correspondence: [email protected]

 Received: 17 April 2020; Accepted: 19 June 2020; Published: 4 July 2020 

Abstract: The Upper Cerrejón Formation is a great source of coal in Colombia. The northeastern part of the Ranchería Sub-Basin sees the most intense mining activity. As a consequence, all geological studies have been concentrated on this region. Consequently, neither the distribution of the Cerrejón Formation, nor the quality and quantity of organic matter in the rest of the sub-basin is clear. In this study, we analyzed new geochemical data from Rock–Eval pyrolysis analyses and vitrinite reflectance using core samples from the ANH-CAÑABOBA-1 and ANH-CARRETALITO-1 wells. Based on this information, it was possible to classify the geochemical characteristics of the Cerrejón Formation as a source rock, particularly in the central area of the sub-basin, which had not been extensively studied before. Additionally, based on the interpretation of seismic reflection data, the numerical burial history models were reconstructed using PetroMod software, in order to understand the evolution of the petroleum system in the sub-basin. The models were calibrated with the data of maximum pyrolysis temperature (Tmax), vitrinite reflectance (%Ro), and bottom hole temperature (BHT). We infer the potential times of the generation and expulsion of hydrocarbon from the source rock.

Keywords: Cerrejón Formation; Cesar–Ranchería Basin; Ranchería Sub-Basin; source rock characterization; source rock modeling; coal; coal mining industry in Colombia

1. Introduction Geochemical studies have been insufficient in relation to the Ranchería Sub-Basin [1]. Previous works have focused on data acquired in the northern part of the sub-basin, where the Cerrejón Mine is located (Figure1). However, the southern part has only one well drilled and there are little data regarding it [2], and the central part has not been explored/studied at all. This study provides new geochemical data for the central part of the sub-basin. The Cerrejón Formation is an excellent source of coal in Colombia, with a potential 3000 million tons [3]. The Cerrejón Formation in the Ranchería Sub-Basin has an area distribution of 2500 km2 [4], with a net thickness of 360 ft (109.7 m) of coal, ranging from bituminous to sub-bituminous, with a variation in vitrinite reflectance (%Ro) from 0.4 to

Geosciences 2020, 10, 258; doi:10.3390/geosciences10070258 www.mdpi.com/journal/geosciences Geosciences 2020, 10, 258 2 of 18 Geosciences 2020, 10, x FOR PEER REVIEW 2 of 18

ranging from bituminous to sub-bituminous, with a variation in vitrinite reflectance (%Ro) from 0.4 0.8, which could potentially generate on-site gas reserves associated with more than six trillion cubic to 0.8, which could potentially generate on-site gas reserves associated with more than six trillion feet (TCF) of coal. The study of the evolution of the oil system in this sub-basin is under discussion cubic feet (TCF) of coal. The study of the evolution of the oil system in this sub-basin is under duediscussion to its high due structural to its high complexity structural complexity [5] and the [5 lack] and of the data lack from of data paleo from geothermometers paleo geothermometers (%Ro and maximum(%Ro and pyrolysis maximum temperature pyrolysis temperature (Tmax)). (Tmax)). This is proven This is proven by the resultsby the results obtained obtained by [6 ,by7], [6,7], whose proposalswhose regardingproposals theregarding basin’s evolutionthe basin’s are radicallyevolution contrasting. are radically The Nationalcontrasting. Hydrocarbon The National Agency (ANH),Hydrocarbon a public Agency institution (ANH), which a overseespublic institution the economic which activity oversees of hydrocarbons the economic in activity Colombia, of is interestedhydrocarbons in investigating in Colombia, this is interested sub-basin in in investig the shortating and this long sub-basin term in in order the short to increase and long knowledge term in aboutorder its to hydrocarbon increase knowledge production about potential. its hydrocarbon production potential.

Lithology Age Picks Thickness (My) Era (My) (meters) Units Grain size

Period Epoch Sand Gravel Clay Silt B vf f mc vc gr pb cb bl 0 Holoc 0.01 QuatPleis 2.6 Plioc A 5.3 ’’Conjunto 360 - 610 Conglomeratico’’ 10 11.6

16

20 Miocene 23 75 - 270 ’’Conjunto calcareo’’ 28.4 30 Oligoce 33.9 37.2 Cenozoic 40 Aguas Nuevas Fm.

48.6

50 Eocene Paleogene Neogene

55.8 Palmito Fm. 58.7 100 - 1000 Tabaco F m. 60 Cerrejon F m. 61.7 150 - 200 Manantial Fm. Paleoc. 65.5 175 - 375 Hato Nuevo Fm.

70 70.6 Molino 500 Fm.

80 83.5 La Luna

Late 85.8 40 - 120 Fm. 90 89.3 93.5

235 - 280 Aguas Blanca 100 99.6 Fm.

Lagunitas 110 260 - 350 Fm. 112

? Rio Negro 120 Fm

Venezuela Mesozoic 125 Early

130 130

136 Colombia 140 140 145.5 La Quinta Fm.

201.6 Ecuador Brazil Peru 251

Paleozoic Basement

Coal Volcanic rock Continental mudstone Chert Marine/littoral mudstone Limestone Marine/littoral sandstone Crystalline basement Continental conglomerate

FigureFigure 1. 1.(A (A) Map) Map with with the the location location ofof thethe RancherRancheríaía Basin,Basin, Colombia Colombia (yellow (yellow area). area). Locations Locations of ofthe the RancherRancheríaía Sub-Basin Sub-Basin (red (red bold bold lines), lines), studiedstudied wells ANH-CARRETALITO-1 and and ANH-CAÑABOBA- ANH-CAÑABOBA-1 (red1 (red dots), dots), and and seismic seismic lines lines (bold (bold blue blue lines) lines) are are present, present, with the major major fault fault system system and and the the Cerrejón Cerrej ón miningmining activity activity area. area. ( B)) The The generalized generalized stratigraphic stratigraphic column column of the of Ranchería the Rancher Sub-Basinía Sub-Basin is taken isfrom taken fromMesa Mesa and and Rengifo Rengifo [1]. [1].

ThisThis study study presents presents new new geochemicalgeochemical data, including the the Rock–Eval Rock–Eval pyrolysis pyrolysis of of127 127 samples, samples, thethe total total organic organic carbon carbon (TOC) (TOC) of of 58 58 samples, samples, and and the the vitrinite vitrinite reflectance reflectance (%Ro) (%Ro) of of 58 58 samples. samples. The The core samplescore samples were acquired were acquired from the from ANH-CAÑABOBA-1 the ANH-CAÑABOBA-1 and ANH-CARRETALITO-1 and ANH-CARRETALITO-1 wells (Figures wells 1 and(Figures2). This 1 studyand 2). aims This to study establish aims theto establish current maturitythe current state maturity and the state potential and the for potential hydrocarbon for generationhydrocarbon (quality generation and quantity) (quality and of thequantity) rocks inof th thee rocks Cerrej inó nthe Formation. Cerrejón Fo Furthermore,rmation. Furthermore, we would likewe to would recreate like the to recreate burial history the burial scenario history through scenario numerical through numerical modeling modeling with the with PetroMod the PetroMod software. software. The modeling is based on geochemical data, the stratigraphic/structural architecture as The modeling is based on geochemical data, the stratigraphic/structural architecture as interpreted interpreted by 2D seismic reflection data, and the several uplift events of the Perijá Range (PR) that by 2D seismic reflection data, and the several uplift events of the Perijá Range (PR) that affected the affected the burial history. It also provides insights which may help to understand the current state burial history. It also provides insights which may help to understand the current state of maturity, of maturity, as well as the organic transformation ratios (TR) of the cretaceous formations underneath as well as the organic transformation ratios (TR) of the cretaceous formations underneath the Cerrejón the Cerrejón Formation, which is fundamental for any understanding of the organic geochemical Formation, which is fundamental for any understanding of the organic geochemical characteristics of characteristics of the Cerrejón Formation, as well as how the basin was filled with sediments. It has the Cerrejón Formation, as well as how the basin was filled with sediments. It has direct implications regarding the maturation of organic matter of the units as well as the generation of hydrocarbons. Geosciences 2020, 10, x FOR PEER REVIEW 3 of 18 directGeosciences implications2020, 10, 258 regarding the maturation of organic matter of the units as well as the generation3 of 18 of hydrocarbons.

Figure 2. 2. InterpretedInterpreted 2D 2D seismic seismic lines lines in in two-way two-way ti timeme (TWT) with location of ANH-CARRETALITO-1ANH-CARRETALITO- 1and and ANH-CAÑABOBA-1 ANH-CAÑABOBA-1 wells. wells. Seismic Seismic lines lines (A) CV-1989–2200; (A) CV-1989–2200; (B) CV-1989–1885; (B) CV-1989–1885; and (C) CV-1959–1100.and (C) CV- 1959–1100.Line locations Line are locations shown inare Figure shown1A. in Figure 1A.

2. Study Study Area Area The Cerrejón Cerrejón Formation belongs belongs to to the the stratigrap stratigraphichic section section of of the the Ranchería Ranchería Sub-Basin Sub-Basin [8]. [8]. Based onon palynologicalpalynological analysis, analysis, it it is datedis dated to theto the Late Late Paleocene, Paleocene, which which formed formed in a period in a period of 2 million of 2 millionyears (my) years [9]. (my) The progression[9]. The progression of the depositional of the de systempositional to the system east during to the the east Late during Paleocene the Late was Paleocenesuggested was by Bayona suggested et al. by [10 Bayona]. Furthermore, et al. [10]. Mor Furtheón etrmore, al. [11 Morón] stated et that al. [11] the Cerrejstatedó thatn Formation the Cerrejón was Formationdeposited inwas tectonic deposited subsidence in tectonic with constantsubsidence sedimentation with constant rates sedimentatio and a rhythmicn rates variation and a inrhythmic the base variationlevel of erosion, in the base which level generated of erosion, repetitive which and generated monotonous repetitive sedimentation and monotonous patterns. sedimentation The Cerrejón patterns.Formation The was Cerrejón described Formation by Ingeominas was [12described] as a sequence by Ingeominas with a predominance [12] as a ofsequence mudstones with with a predominancesome quartz-feldspar of mudstones sandstones. with Numerous some quartz coal layers-feldspar distributed sandstones. regularly Numerous throughout coal the layers entire distributedstratigraphic regularly column. Thethroughout Cerrejón the Formation entire st wasratigraphic deposited column. in a fluvial–estuarine The Cerrejón environment Formation was [13]. depositedIt was in a tropicalin a fluvial–estuarine lowland coastal environment humid forest [13]. based It onwas in a megaflora tropical lowland [14], which coastal had characteristicshumid forest basedof a multi-layered on fossil megaflora tropical [14], forest which environment had characterist in the Neotropicsics of a multi-layered [15], with atropical mean annualforest environment temperature in(MAT) the Neotropics of 32 to 33 [15],◦C estimated with a mean from annual the 13-m temperature size , (MAT)Titanoboa of 32 to cerrejonensis, 33 °C estimatedrecovered from the from 13-m the sizeCerrej snake,ón Mine Titanoboa [16]. Regardingcerrejonensis, the recovered Cerrejón Formation,from the Cerrejón Wilf et al.Mine [17 ][16]. calculated Regarding the meanthe Cerrejón annual precipitation (MAP) as around 3240 mm (ranging from 2260 to 4640 mm) using correlations of the

Geosciences 2020, 10, 258 4 of 18 paleo-leaf size and the precipitation observed in live vegetation. The Cerrejón Formation presents 1000 m in total thickness and contains 80 layers of coal [11]. Bayona et al. [10] proposed that the presence of intercalation of siliciclastic materials in the Cerrejón Formation, not only in the Maracaibo Basin (Diablo Mine), but also in the Ranchería Sub-Basin (Cerrejón Mine), may have been due to significant uplift from the Perijá Range (PR) in the late Paleocene to Middle Eocene, between 66 to 41 million years ago (mya). This fact is consistent with the lack of stratigraphic records in the Eocene–Oligocene in the Ranchería Sub-Basin as mentioned by Mesa and Rengifo [1], indicating several tectonic pulses during the Andean Orogeny. Some sediments assigned to this period in the supergiant Maracaibo Basin were from alluvial fan and fluvial deposits (conglomerates and sandstones) [18]. Hernandez and Jaramillo [19] studied the Apatite Fission-Track (AFT) on the Lower Cretaceous rocks present in the PR, asserting that the last uplift event began in the Late Miocene (11 mya). These data were consistent with the studies carried out by Bermudez [20]: AFT established the orogeny of the Andes de Mérida, which had a rapid cooling in the Miocene–Pliocene, indicating its exhumation. This orogeny also occurred in the Merida Block which includes the PR [21]. Previous studies have determined the characteristics of the coal from the Cerrejón Mine to the north of the Ranchería Sub-Basin. They established that the coal is bituminous, high in volatiles A and B[22]. From the analysis of 196 samples of Cerrejón coals, Departamento Nacional de Planeacion [22] obtained an average of 31.19 MJ/kg of calorific value and 37% volatile materials. The analysis by Piñeres et al. [23] of the coal from the mine showed a calorific value of 23.75 MJ/kg with an average of 1.41% sulfur, and were high in volatiles, which were classified as a sub-bituminous B coal [24]. Rincon et al. [25] presented data of 34% volatile material with values of 0.66% sulfur in the coal of the Cerrejón Central Mine and 33.4% volatile material with 0.7% in the coal of the Cerrejón Norte Mine. According to Henao [26], coals of the WRV-04752 and WRV-04774 wells were high in volatiles as well, between 34.09 to 37.2%, with sulfur values from 0.22 to 0.41%. Layton [27] analyzed 25 coal samples from the WRV-04752 Well, establishing an average of 34.91% volatile material with an average of 0.56% sulfur content. Layton [27] also analyzed 28 coal samples from the WRV-04774 Well, determining that volatile material was on average 34.479%, with an average of 0.81% sulfur content.

3. Data and Methods Geochemical analysis was used to establish the type and quality of organic carbon and other geochemical properties of rocks, which contributed to evaluating the potential production of conventional or unconventional hydrocarbons in a prospective play. Geochemical data were obtained using core samples from the Cerrejón Formation of two wells, ANH-CARRETALITO-1 and ANH-CAÑABOBA-1. Vertical sampling was not performed with symmetrical length values (Figure3). The selection criterion was based on the visible presence of organic matter using an ultraviolet lamp. Geochemical analysis of Rock–Eval pyrolysis, TOC, and total sulfur (TS) were carried out for 108 samples of the ANH-CARRETALITO-1 Well and 19 samples of the ANH-CAÑABOBA-1 Well. Vitrinite reflectance analyses on 58 samples were obtained through organic petrography. Additional geochemical data used in this study were obtained from [2,28,29], and corresponded to 356 samples of the hydrogen index (HI) and oxygen index (OI), and 332 samples of TOC belonging to lithological formation where geochemical analyses were performed. The TOC analysis was carried out with the intention of quantifying the amount of organic matter present in the sample using the Leco SC-144DR automated analyzer. It also allowed us to calculate the TS as well as the carbonate content. Likewise, to evaluate the quality of this organic matter, a Rock–Eval pyrolysis analysis was performed in each of the samples with Rock–Eval 6 technology equipment. This technique presented by Barker [30] and Behar [31] uses programmed heating of a small amount of rock (70 mg) or coal (30–50 mg) in an inert atmosphere (helium or nitrogen) in order to determine the quantity of free hydrocarbons present in the sample (S1 peak), as well as those that potentially can be released after maturation (S2 peak). This procedure permitted us to know the Tmax and the current state of thermal maturation. The TOC had to be determined along with the mineral carbon content (MinC), the volume of free hydrocarbon generated GeosciencesGeosciences2020 2020, 10, ,10 258, x FOR PEER REVIEW 5 of5 18 of 18

to be determined along with the mineral carbon content (MinC), the volume of free hydrocarbon beforegenerated pyrolysis before (S1), pyrolysis the amount (S1), of the hydrocarbon amount of generated hydrocarbon during generated pyrolysis during (S2), the pyrolysis amount (S2), of emitted the carbonamount dioxide of emitted (S3), the carbon hydrogen dioxide index (S3), (HI the =hydrogS2/TOCen index100), (HI the = index S2/TOC of oxygen× 100), the (OI index= S3 /ofTOC oxygen100 ), × × the(OI production = S3/TOC yield× 100), (PY the= productionS1 + S2),and yield the (PY production = S1 + S2), indexand the (PI production= S1/(S1 + indexS2). (PI = S1/(S1 + S2).

ANH CARRETALITO -1 well ANH CAÑABOBA-1 well Total Total Sulfur organic Sulfur organic Fm. m Lithologies Fm. m Lithologies content carbon content carbon (TOC) (TOC) Geochemistry Geochemistry 100 0.01 0.01 100 0.10 1.00 10.0 0.10 1.00 10.0 0.10 1.00 10.0 0.10 1.00 10.0 Type of analysis of Type analysis of Type 0 0

100 100 Cuesta

200 200

300 300 Cuesta

400 400 Cerrejon

500 500

600 600 Cerrejon

700 700 Lithologies mudstonesandstone coal conglomerate limestone

Poorly consolidated mudstone Poorly consolidated sandstone Poorly consolidated conglomerate

Figure 3. Lithologies, sample site (+), and variation of sulfur content and total organic carbon Figure 3. Lithologies, sample site (+), and variation of sulfur content and total organic carbon (TOC) (TOC) of the rock samples of the Cerrejón Formation in the ANH-CARRETALITO-1 and ANH- of the rock samples of the Cerrejón Formation in the ANH-CARRETALITO-1 and ANH- CAÑABOBA-1CAÑABOBA-1 wells. wells. The vitrinite reflectance (%Ro) was measured using Zeiss imager microscopy. Sample chips or The vitrinite reflectance (%Ro) was measured using Zeiss imager microscopy. Sample chips or sidewallsidewall core core samples samples were were cleaned cleaned toto removeremove drillingdrilling mud mud or or mud mud cake cake and and then then crushed crushed using using a a mortar and pestle to a grain-size of less than 3 mm. These samples were mounted in cold-setting resin and polished “as received”, so that whole-rock samples were examined, excluding concentrates Geosciences 2020, 10, 258 6 of 18 of organic matter. The core samples were mounted and sectioned perpendicularly to the bedding. Vitrinite reflectance measurements were made using immersion oil of refractive index 1.518 at 546 nm at 23 ◦C and at spinel and garnet standards of 0.42, 0.917, as well as 1.726% reflectance for calibration. Fluorescence-mode observations were made on all samples, providing supplementary evidence concerning organic matter type, exinite abundance, and maturity. For fluorescence-mode, a 3-mm BG-3 excitation filter was used with a TK400 dichroic mirror and a K490 barrier filter. Geochemical information was plotted to visualize its distribution on profiles using free software PanPlot2 as described by Sieger and Grobe [32]. The 2D seismic lines in two-way time (TWT) used in this research were CV-1989–2200, CV-1989–1885, and CV-1959–1100; the interpretation of the lines was used for the purpose of defining the cutting relationships between lithological units present in the basin. Additionally, they had the geographic and stratigraphic positions of the wells used for this study. One-dimensional modeling was carried out with the PetroMod software (2012 version) in order to reconstruct the burial history and thermal maturation of the geological units present in the wells. This modeling used the vitrinite thermal maturation model (EASY %Ro) proposed by Sweeney and Burnham [33], based on the Arrhenius first-order parallel-reaction approach with a distribution of activation energies. EASY %Ro were calibrated to a more rigorous model of vitrinite maturation based on the chemical properties of coal vitrinite. Previous studies such as Mesa and Rengifo [1] were also considered, which provided the deposition ages of each unit, and the maximum and minimum thicknesses of those units. The eroded thickness input for the modeling was inferred by the relation to the maximum thickness reported plus those found in the wells. The heat flow evolution was established by Petromod software using the Mackenzie method, and based on the sub-basin evolution proposed by Mesa and Rengifo [1]. Paleo-water depths were estimated with biostratigraphic studies (e.g., [34]). Sediment water interface temperatures (SWIT) were estimated using PetroMod software (e.g., [35]), which assumed that the current position of the study area is 11 degrees north latitude in the northernmost part of . To determine the evolution of the source rock units, the multiple kinetics were used; IES_TII_Toarcian_Shale_2C, IES_TIII_Tertiary_Coal_2C, and IES_TII_Brown_Limestone_2C, based on lithologies.

4. Results and Discussion

4.1. TOC and Rock Eval Pyrolysis Results The values of the S1 peak indicated the volume of hydrocarbon generated before the pyrolysis. In this study, S1 values from the ANH-CARRETALITO-1 Well and ANH-CAÑABOBA-1 Well samples varied from 0.05 to 4 and from 0.05 to 1.36 mg HC/g rock, respectively. S2 values, indicating the amount of hydrocarbon generated during pyrolysis, showed variations from 0.13 to 166.96 and from 0.50 to 124.02 mg HC/g rock, respectively, and the S3 peak of the amount of carbon dioxide emission showed variations from 0.10 to 19.61 and from 0.32 to 17.93 mg CO2/g rock, respectively. The accumulated thickness of coals in the Cerrejón Formation were: 63.94 m in the ANH- CARRETALITO-1 Well samples and 9.63 m in the ANH-CAÑABOBA-1 Well samples. The accumulated thicknesses of the mudstone were 291.19 and 107.60 m, respectively. The organic richness of the Cerrejón Formation ranged from poor to excellent, according to Lewan [36]. The Cerrejón Formation rocks (Paleocene age) showed variations in TOC from 0.3 to 72.5%, and from 0.74 to 65.46%, respectively. The OI and HI were the most important parameters, of which the correlation indicated the kerogen type of source rocks. The OI value, as calculated, varied from 7.68 to 64.18 mg CO2/g TOC in the ANH-CARRETALITO-1 Well, and from 19.59 to 52.22 in ANH-CAÑABOBA-1 Well. The HI value, as calculated, varied from 10.53 to 330.64 and from 67.40 to 215.96 mg HC/g TOC, respectively. Total sulfur (TS) is an important consideration in coal utilization. The TS obtained varied from 0.001 to 16.233% w/w of the coal in the ANH-CARRETALITO-1 Well samples (the last value being the only one higher than 10%), and from 0.29 to 0.37% w/w of the coal in ANH-CAÑABOBA-1 Well samples. Geosciences 2020, 10, x FOR PEER REVIEW 7 of 18 Geosciences 2020, 10, 258 7 of 18 the only one higher than 10%), and from 0.29 to 0.37% w/w of the coal in ANH-CAÑABOBA-1 Well samples. The PY was the total amount of hydrocarbon generated/liberated under the pyrolysis S1 and S2 The PY was the total amount of hydrocarbon generated/liberated under the pyrolysis S1 and S2 curves [37]. This index helped to categorize the target horizon in terms of total petroleum-generation curves [37]. This index helped to categorize the target horizon in terms of total petroleum-generation potential [38]. The PY values, as calculated, varied from 0.2 to 168.6 mg HC/g rock and from 0.6 to potential [38]. The PY values, as calculated, varied from 0.2 to 168.6 mg HC/g rock and from 0.6 to 124.9 mg HC/g rock in the ANH-CARRETALITO-1 and ANH-CAÑABOBA-1 wells, respectively. 124.9 mg HC/g rock in the ANH-CARRETALITO-1 and ANH-CAÑABOBA-1 wells, respectively. The PI value was taken from a ratio between S1 and S2, which indicated the relationship between The PI value was taken from a ratio between S1 and S2, which indicated the relationship between the amounts of free hydrocarbon before pyrolysis with respect to the amount of hydrocarbon generated the amounts of free hydrocarbon before pyrolysis with respect to the amount of hydrocarbon during pyrolysis, similar to Rock–Eval and Tmax. PI was used as a maturity proxy [38]. The PI values, generated during pyrolysis, similar to Rock–Eval and Tmax. PI was used as a maturity proxy [38]. calculated in ANH-CARRETALITO-1 Well, varied from 0.01 to 0.32 TOC. Only 13 data were higher The PI values, calculated in ANH-CARRETALITO-1 Well, varied from 0.01 to 0.32 TOC. Only 13 data than 0.1 and had an average of 1.1% TOC, indicating that the value could have been affected; while were higher than 0.1 and had an average of 1.1% TOC, indicating that the value could have been in the ANH-CAÑABOBA-1 Well, the calculated values ranged from 0.01 to 0.09 TOC. According to affected; while in the ANH-CAÑABOBA-1 Well, the calculated values ranged from 0.01 to 0.09 TOC. PetersAccording [39], sourceto Peters rocks [39], with source PI values rocks of lesswith than PI values 0.1 are consideredof less than thermally 0.1 are considered immature, whilethermally those fromimmature, 0.1 to 0.4while are those considered from 0.1 thermally to 0.4 are mature. considered According thermally to Nuñezmature. and According Baceta [ 40to ],Nuñez there isand no depletionBaceta [40], in thethere values is no ofdepletio these twon in pyrolysisthe values peaks of these since two the pyrolysis samples peaks were takensince the from samples the core were and hadtaken not from been the exposed core and to weathering.had not been exposed to weathering. TheThe Tmax Tmax values values correspond correspond to theto maximumthe maximum hydrocarbon hydrocarbon generation generation point during point theduring pyrolysis the (S2),pyrolysis which (S2), is widely which used is widely as a thermal used as maturitya thermal indicator maturity [ 38indicator]. According [38]. According to Peters and to Peters Cassa and [41], anyCassa value [41], of Tmaxany value that isof lessTmax than that 435 is◦ lessC is than considered 435 °C thermally is considered immature. thermally The immature. Tmax values The obtained Tmax rangedvalues fromobtained 414 toranged 440 ◦C from in the 414 ANH-CARRETALITO-1 to 440 °C in the ANH-CARRETALITO-1 Well, with only two Well, samples with higher only two than 435samples◦C (Figure higher4). than Likewise, 435 °C in(Figure the ANH-CAÑABOBA-1 4). Likewise, in the ANH-CAÑABOBA-1 Well, the values ranged Well, from the values 414 to ranged 433 ◦C (Figurefrom 4145). to Thus, 433 °C it can(Figure be concluded5). Thus, it can that be the concluded data showed that the the data Cerrej showedón Formation the Cerrejón in theFormation wells is thermallyin the wells immature, is thermally bordering immature, on the bordering limit of 435on the◦C. limit of 435 °C.

FigureFigure 4. 4.Results Results ofof thethe geochemicalgeochemical analyzes.analyzes. Total orga organicnic carbon (TOC), (TOC), total total carbon carbon (TC), (TC), total total sulfursulfur (TS), (TS), and and Rock–Eval Rock–Eval pyrolysispyrolysis ofof thethe CerrejCerrejónón Formation rocks in in the the ANH-CARRETALITO-1 ANH-CARRETALITO-1 Well,Well, see see Supplementary Supplementary Materials Materials Table Table S1. S1.

Finally,Finally, %Ro %Ro analysis analysis functionedfunctioned asas anan indicatorindicator of level of organic maturity (LOM). (LOM). Jarvie Jarvie and and PollastroPollastro [42 [42]] provided provided the thermalthe thermal maturity-profiling maturity-profiling states: Immature,states: Immature, oil-window oil-window mature, condensate mature, wet-gascondensate mature, wet-gas dry-gas mature, mature dry-gas shales, mature with shales, %Ro values with %Ro of < 0.55,values 0.55–1.15, of <0.55, 1.15–1.40,0.55–1.15, and1.15–1.40,>1.40, respectively. The average of %Ro values were from 0.45 to 0.57 in the ANH-CARRETALITO-1 Well, with

Geosciences 2020, 10, x FOR PEER REVIEW 8 of 18 Geosciences 2020, 10, x FOR PEER REVIEW 8 of 18 Geosciences 2020, 10, 258 8 of 18 andand >1.40,>1.40, respectively.respectively. TheThe averageaverage of %Ro values were fromfrom 0.450.45 toto 0.570.57 inin thethe ANH-ANH- CARRETALITO-1CARRETALITO-1 Well, Well, withwith aa meanmean ofof 33.55 measurements perper analysisanalysis (Figure(Figure 6), 6), and and from from 0.37 0.37 to to a mean of 33.55 measurements per analysis (Figure6), and from 0.37 to 0.43 in the ANH-CAÑABOBA-1 0.430.43 in in the the ANH-CAÑABOBA-1 ANH-CAÑABOBA-1 Well,Well, with a mean of 40.32 measurementsmeasurements perper analysisanalysis (Figure (Figure 7). 7). Well, with a mean of 40.32 measurements per analysis (Figure7). Vitrinite reflectance could also be VitriniteVitrinite reflectance reflectance could could alsoalso bebe plottedplotted with Tmax to identifyidentify thethe statestate ofof thermalthermal maturity maturity for for the the plotted with Tmax to identify the state of thermal maturity for the organic matter [43]. The data organicorganic matter matter [43]. [43]. The The datadata correlationcorrelation of the average %Ro versus TmaxTmax isis presentedpresented in in Figure Figure 8 8 to to correlation of the average %Ro versus Tmax is presented in Figure8 to show the change in thermal showshow the the change change in in thermalthermal maturitymaturity ofof the Cerrejón Formation inin thethe ANH-CARRETALITO-1ANH-CARRETALITO-1 and and maturityANH-CAÑABOBA-1ANH-CAÑABOBA-1 of the Cerrejó nwells. wells. Formation in the ANH-CARRETALITO-1 and ANH-CAÑABOBA-1 wells.

FigureFigureFigure 5. 5. 5.Results Results Results of of of geochemical geochemical geochemical analyses. analyses.analyses. TotalTotal organic ca carbonrbon (TOC),(TOC), (TOC), totaltotal total carboncarbon carbon (TC), (TC), (TC), total total total sulfur sulfur sulfur (TS),(TS),(TS), and and and Rock–Eval Rock–Eval Rock–Eval pyrolysispyrolysis pyrolysis ofof thethe the CerrejónCerrejón Cerrejó nFormation Formation rocks rocks inin thethe in ANH-CAÑABOBA-1 theANH-CAÑABOBA-1 ANH-CAÑABOBA-1 Well, Well, see Well,see seeSupplementarySupplementary Supplementary Materials Materials Materials TableTable Table S2.S2. S2.

Standard Standarddeviation deviation

Figure 6. Graphic distribution of vitrinite reflectance analysis (%Ro), total organic carbon (TOC), total sulfur (TS), and hydrogen index (HI) of the Cerrejón Formation in the ANH-CARRETALITO-1 Well,

see Supplementary Materials Table S3. Geosciences 2020, 10, x FOR PEER REVIEW 9 of 18

GeosciencesFigure 20206. Graphic, 10, x FOR distribution PEER REVIEW of vitrinit e reflectance analysis (%Ro), total organic carbon (TOC), total9 of 18 sulfur (TS), and hydrogen index (HI) of the Cerrejón Formation in the ANH-CARRETALITO-1 Well, seeFigure Supplementary 6. Graphic distributionMaterials Table of vitrinit S3. e reflectance analysis (%Ro), total organic carbon (TOC), total Geosciencessulfur2020 ,(TS),10, 258 and hydrogen index (HI) of the Cerrejón Formation in the ANH-CARRETALITO-1 Well, 9 of 18 see Supplementary Materials Table S3. Standard deviation Standard deviation

Figure 7. Graphic distribution of vitrinit vitrinitee reflectance reflectance analysis (%Ro), totaltotal organic carbon (TOC), total Figure 7. Graphic distribution of vitrinite reflectance analysis (%Ro), total organic carbon (TOC), total sulfur (TS), and hydrogen index (HI) of the Ce Cerrejrrejónón Formation in the ANH-CAÑABOBA-1 Well, see sulfur (TS), and hydrogen index (HI) of the Cerrejón Formation in the ANH-CAÑABOBA-1 Well, see Supplementary Materials TableTable S4.S4. Supplementary Materials Table S4.

480 480

470 470

460 460 Thermal Mature Thermal Mature 450 (Oil Window) 450 (Oil Window) ( ) ( )

Tmax °C 440 Tmax °C 440

430430

420420 Thermal Immature 410410 0.20.2 0.4 0.4 0.6 0.6 0.8 1.0 1.0 1.2 1.2 1.4 1.4 VitriniteVitrinite Reflectance (Ro%)(Ro%) CarretalitoCarretalito wellwell data CañabobaCañaboba well well data data FigureFigure 8.8. 8.Data Data correlation correlation of of maximummaximum pyrolysispyrolysis temperature (Tmax) (Tmax) versus versus vitrinite vitrinite reflectance reflectancereflectance (%Ro)(%Ro)(%Ro) average average average to toto indicate indicate source source source rockrock rock thermalthermal thermal maturity maturity inin thethe in CerrejónCerrejón the Cerrej Formation Formationón Formation of of the the ANH- ofANH- the ANH-CARRETALITO-1CARRETALITO-1CARRETALITO-1 and and ANH-CAÑABOBA-1 andANH-CAÑABOBA-1 ANH-CAÑABOBA-1 wells.wells. wells.

4.2.4.2. Quality Quality of of Organic Organic Matter Matter 4.2. Quality of Organic Matter TheThe cross cross plot plot of of S1 S1 versus versus TOC TOC (Figure (Figure9) 9) was was used used to to evaluate evaluate the the origin origin of of the the hydrocarbons hydrocarbons in The cross plot of S1 versus TOC (Figure 9) was used to evaluate the origin of the hydrocarbons thein Cerrej the Cerrejónón Formation Formation at the at Rancherthe Rancheríaía Sub-Basin, Sub-Basin, using using samples samples of theof the ANH-CARRETALITO-1 ANH-CARRETALITO-1 and in the Cerrejón Formation at the Ranchería Sub-Basin, using samples of the ANH-CARRETALITO-1 ANH-CAÑABOBA-1and ANH-CAÑABOBA-1 wells, basedwells, onbased the on methodology the methodol ofogy Fakhri of Fakhri et al. [44et ].al. It [44]. was It established was established that the and ANH-CAÑABOBA-1 wells, based on the methodology of Fakhri et al. [44]. It was established Cerrejtható then Formation Cerrejón Formation was not contaminated was not contaminated with migrated with hydrocarbon.migrated hydrocarbon. The hydrocarbon The hydrocarbon generation that the Cerrejón Formation was not contaminated with migrated hydrocarbon. The hydrocarbon potentialgeneration was potential proven using was proven the cross using plot the of PYcross versus plot TOCof PY (Figureversus 10TOC), based (Figure on 10), the based proposition on the by generation potential was proven using the cross plot of PY versus TOC (Figure 10), based on the Ghoriproposition and Haines by Ghori [45]. Itand concludes Haines that[45]. theIt concludes coals of this that formation the coals hadof this excellent formation potential, had excellent while the proposition by Ghori and Haines [45]. It concludes that the coals of this formation had excellent mudstonespotential, hadwhile a widethe mudstones spectrum had of potential a wide spectrum that ranged of potential from poor that to ranged excellent. from poor to excellent. potential, while the mudstones had a wide spectrum of potential that ranged from poor to excellent.

Geosciences 2020, 10, x FOR PEER REVIEW 10 of 18

1000 1000 Paleocene Paleocene Mudstone Mudstone Paleocene Paleocene 100 Coal 100 Coal Contaminated Contaminated

10 10 Geosciences 2020, 10, 258 10 of 18 Geosciences 2020, 10, x FOR PEER REVIEW 10 of 18 Geosciences 2020, 10, x FOR PEER REVIEW 10 of 18 1 1 1000 1000 S1 HC/g (mg roca) S1 HC/g (mg roca) 1000 Paleocene 1000 Paleocene PaleoceneMudstone PaleoceneMudstone 0.1 Mudstone 0.1 Mudstone Paleocene Paleocene 100 PaleoceneCoal Uncontaminated 100 PaleoceneCoal Uncontaminated 100 Coal 100 Coal A Contaminated B Contaminated 0.01 0.01 0.1Contaminated 1 10 100 0.1Contaminated 1 10 100 10 10 10 TOC (wt.%) 10 TOC (wt.%)

Figure1 9. Cross plot of S1 versus TOC to indicate the origin1 of hydrocarbon in the Cerrejón Formation 1 1 S1 HC/g (mg roca) of the (A) ANH-CARRETALITO-1 and (B) ANH-CAÑABOBA-1S1 HC/g (mg roca) wells. S1 HC/g (mg roca) S1 HC/g (mg roca) 0.1 0.1 0.1 0.1 1000 Uncontaminated 1000 Uncontaminated Paleocene Uncontaminated Paleocene Uncontaminated A Mudstone Excellent BMudstone Excellent 0.01 A 0.01 B 0.010.1Paleocene 1 10 100 0.010.1Paleocene 1 10 100 0.1Coal 1 10 100 0.1Coal 1 10 100 TOC (wt.%) TOC (wt.%) 100 100 TOC (wt.%) TOC (wt.%)

eld Figure 9. Cross plot of S1 versus TOC to indicate the origin of hydrocarbon in the Cerrejón Formation i

y Figure 9. Figure 9. CrossCross plot of S1 S1 versus versus TOC TOC to indicate indicate the origin origin of of hydrocarbon hydrocarbon in the Cerrejón Cerrejón Formation

n Very good Very good o i t of10 the (A) ANH-CARRETALITO-1 and (B) ANH-CAÑABOBA-110 wells. c of the (A) ANH-CARRETALITO-1 andand ((BB)) ANH-CAÑABOBA-1ANH-CAÑABOBA-1 wells.wells. Good Good odu r P Production yield 1000 Fair 1000 Fair Paleocene Paleocene 1000 1000 PaleoceneMudstone Excellent PaleoceneMudstone Excellent 1 Poor 1 Poor Mudstone Excellent Mudstone Paleocene Paleocene Excellent PaleoceneCoal PaleoceneCoal 100 Coal 100 Coal 100 A 100 B 0.1 0.1 0.1 1 10 100 0.1 1 10 100 eld i

y TOC (wt.%) TOC (wt.%)

eld i n Very good Very good

y

o i t n 10 Very good 10 Very good c o i t 10 Good 10 c Good

odu Figure 10. Cross plot of production yield versus TOC to exhibit the generating potential of the r Good Good P Production yield odu r Fair Fair P Production yield Cerrejón Formation in the (A) ANH-CARRETALITO-1Fair and (B) ANH-CAÑABOBA-1 wells. Fair 1 Poor 1 Poor 1 Poor 1 Poor TheA diagram of S2 versus TOC proposed by LangfordB and Blanc [46] was used to classify the type of organic0.1 A matter (Figure 11). It was established that the0.1 Bhydrocarbons of the Cerrejón Formation were 0.10.1 1 10 100 0.10.1 1 10 100 mainly0.1 the type III kerogen,1 TOC which (wt.%) is10 conducive to 100 gas generation.0.1 However,1 TOC they (wt.%) were10 present in 100small TOC (wt.%) TOC (wt.%) quantities,Figure showing 10.10. CrossCross that plot plot ofthis of production formationproduction yield also yield versus contai versus TOCned TOC to type exhibit to II/III exhibit the kerogen, generating the generating which potential can potential produce of the Cerrej of a mixturetheón Figure 10. Cross plot of production yield versus TOC to exhibit the generating potential of the of oilFormationCerrejón and gas. Formation in the (A) in ANH-CARRETALITO-1 the (A) ANH-CARRETALITO-1 and (B) ANH-CAÑABOBA-1 and (B) ANH-CAÑABOBA-1 wells. wells. CerrejónTo assess Formation the maturity in the and (A) ANH-CARRETALITO-1kerogen type, the obtained and ( Bdata) ANH-CAÑABOBA-1 were plotted on an wells. HI versus Tmax diagramThe diagram(e.g., [41,47,48]) of S2 versus (Figure TOC 12). proposedprop Thisosed concluded by Langford that andthe Cerrejón BlancBlanc [[46]46 ]Formation was used toin classifythe central the typearea The diagram of S2 versus TOC proposed by Langford and Blanc [46] was used to classify the type of the organic Ranchería matter Sub-Basin (Figure 1111). has). It notwas reached established the oilthat generation the hydrocarbons window, of but the it Cerrejón Cerrejwouldó nhave Formation the capacity were of organic matter (Figure 11). It was established that the hydrocarbons of the Cerrejón Formation were mainlyto generate the the type typemainly III III kerogen, gas-type kerogen, which hydrocarbons which is isconducive conducive due toto gas toits gas organicgeneration. generation. matter However, type However, III they kerogen. theywere werepresentAdditionally, present in small init mainly the type III kerogen, which is conducive to gas generation. However, they were present in small smallmayquantities, also quantities, have showing the showing capacity that this that toformation generate this formation also oil-type contai also hyned containeddrocarbons type II/III type kerogen,to IIa /lesserIII kerogen, which quantity can which producedue can to its producea mixtureorganic a quantities, showing that this formation also contained type II/III kerogen, which can produce a mixture mixturematterof oil and type of gas. oil II/III and kerogen. gas. of oil and gas. To assess the maturity and kerogen type, the obtained data were plotted on an HI versus Tmax 300To assess the maturity and kerogen type, the obtained300 data were plotted on an HI versus Tmax diagram (e.g.,Paleocene [41,47,48]) (Figure 12). This concluded that Paleocenethe Cerrejón Formation in the central area diagram (e.g.,Mudstone [41,47,48])A (Figure 12). This concluded that Mudstonethe CerrejónB Formation in the central area 250 Paleocene 250 Paleocene of the RancheríaCoal Sub-Basin hasType IInot reached the oil generationCoal window, but it wouldType II have the capacity of the Ranchería Sub-Basin hasOil prone not reachedType the II/III oil generation window, but it Oilwould prone have theType capacity II/III to generate mainly gas-type hydrocarbons Mixeddue to its organic matter type III kerogen. Additionally,Mixed it to generate200 mainly gas-type hydrocarbons due to its 200organicType I matter type III kerogen. Additionally, it may alsoType have I the capacity to generate oil-type hydrocarbonsOil prone to a lesser quantity due to its organic may alsoOil haveprone the capacity to generate oil-type hydrocarbons to a lesser quantity due to its organic matter type II/III kerogen. matter150 type II/III kerogen. 150 Type III Type III 300 300 S2 (mg HC/g rock) 100 Gas prone S2 (mg HC/g rock) 100 Gas prone 300 Paleocene 300 Paleocene PaleoceneMudstone PaleoceneMudstone Mudstone A Mudstone B Paleocene Paleocene 25050 A Type II 25050 B Type II 250 PaleoceneCoal 250 PaleoceneCoal Coal OilType prone II Type II/III Coal OilType prone II Type II/III Dry gas prone Dry gas prone Oil prone TypeMixed II/III Oil prone TypeMixed II/III 200 Mixed 200 Type I Mixed 0 Type I 0 Type I 200 0204060 80 100 200 02040Oil prone 60 80 100 OilType prone I Oil prone Oil prone TOC(wt.%) TOC(wt.%) 150 150 150 150 Figure 11. Cross plot of S2 versus total organicType III carbon (TOC) to exhibit the generating potentialType of theIII

S2 (mg HC/g rock) 100 GasType prone III S2 (mg HC/g rock) 100 GasType prone III S2 (mg HC/g rock) 100Cerrejón Formation in the (A) ANH-CARRETALITO-1Gas prone S2 (mg HC/g rock) 100 and (B) ANH-CAÑABOBA-1 wells. Gas prone

50 50 50 50 To assess the maturity and kerogenDry gas type, prone the obtained data were plotted on an HIDry versus gas prone Tmax Dry gas prone Dry gas prone 0 0 diagram0 02040 (e.g., [41,47,48]) (Figure60 12). This 80 concluded100 that0 02040 the Cerrejón Formation60 in the central 80 area100 of 0204060 80 100 0204060 80 100 the Ranchería Sub-Basin hasTOC(wt.%) not reached the oil generation window, but itTOC(wt.%) would have the capacity to TOC(wt.%) TOC(wt.%)

Geosciences 2020, 10, 258 11 of 18

Geosciences 2020, 10, x FOR PEER REVIEW 11 of 18 generate mainly gas-type hydrocarbons due to its organic matter type III kerogen. Additionally, it may also have the capacity to generate oil-type hydrocarbons to a lesser quantity due to its organic matter Figure 11. Cross plot of S2 versus total organic carbon (TOC) to exhibit the generating potential of the type IICerrejón/III kerogen. Formation in the (A) ANH-CARRETALITO-1 and (B) ANH-CAÑABOBA-1 wells.

1000 Condensate WetgasZone 1000 Condensate WetgasZone Immature Mature Post Mature Immature Mature Post Mature

Type I Type I 900 900 Oil Prone Oil Prone

800 800

700 700 Type II Type II Oil Prone Oil Prone 600 600

500 500

400 Type II-III 400 Type II-III Oil/Gas Oil/Gas Prone Prone Hydrogen Index (mg HC/g TOC) HC/g Index (mg Hydrogen TOC) HC/g Index (mg Hydrogen 300 300 Paleocene Paleocene Mudstone Mudstone 200 Paleocene 200 Paleocene Coal Coal Type III Gas Type III Prone 100 Gas 100 Prone A B

0 0 400425 450 475 500 400 425 450 475 500 Tmax (ºC) Tmax (ºC) FigureFigure 12.12. Cross plot between hydrogen index index (HI) (HI) (mgHC/g (mgHC/g TOC) TOC) versus versus maximum maximum pyrolysis pyrolysis temperaturetemperature (Tmax) to to indicate indicate source source rock rock maturity maturity in the in Cerrejón the Cerrej Formationón Formation of the ( ofA) theANH- (A) ANH-CARRETALITO-1CARRETALITO-1 and (B and) ANH-CAÑABOBA-1 (B) ANH-CAÑABOBA-1 wells. wells.

TheThe organicorganic mattermatter valuesvalues fromfrom thethe mudstonesmudstones andand the coals were fairly high. high. They They did did not not presentpresent anan HIHI higherhigher than 300, and and the the characteri characterizationzation of of the the kerogen kerogen was was mainly mainly type type III, III,which which is isclosely closely related related to toterrestrial terrestrial plant plant remains, remains, with withaverage average TS values TS values for coals for of coals 0.60% of in 0.60% the ANH- in the ANH-CARRETALITO-1CARRETALITO-1 Well Welland 1.11% and 1.11% in ANH-CAÑABOBA-1 in ANH-CAÑABOBA-1 Well. Well.These These findings findings correlate correlate with withthe thepaleontological paleontological findings findings of of[14,16,49], [14,16,49 and], and with with the the analysis analysis of oforganic organic geochemistry geochemistry carried carried out out in in thethe Cerrej Cerrejónón Formation Formation at theat the Cerrej Cerrejónón Mine, Mine, similar simi to Piñereslar to Piñeres et al. [23 et], whichal. [23], presents which a presents distribution a ofdistribution 77.3% vitrinite, of 77.3% 15.7% vitrinite, inertinite, 15.7% and inertinite, 6.9% liptinite and 6.9% on liptinite average on for average the di forfferent the different sizes of particlessizes of percentages,particles percentages, using a petrographic using a petrographic analysis freeanalysis of mineral free of material.mineral material. This study This concurs study concurs with those with by Laytonthose by [27 Layton], giving [27], the giving distribution the distribution as 80% vitrinite, as 80% 12.5% vitrinite, inertinite, 12.5% 7.5%inertinite, liptinite 7.5% for liptinite the WRV-04752 for the Well,WRV-04752 and 77% Well, vitrinite and 77% for thevitrinite WRV-04774 for the WRV-04774 Well, as well Well, as 15% as well inertinite as 15% and inertinite 8% liptinite. and 8% liptinite. TheThe diagramdiagram crosscross plotplot ofof TmaxTmax ((°C)◦C) with respect to to the the PI PI proposed proposed by by Katz Katz [3] [3 ]was was used used to to assessassess the the maturation maturation condition condition of theof Cerrejthe Cerrejónón Formation Formation (Figure (Figure 13). It 13). can beIt seencan be that seen the mudstonethat the andmudstone coal samples and coal occupy samples the occupy immature the area, immature which ar reinforceea, which the reinforce immaturity the immaturity of the rocks of of the the rocks basin; aof condition the basin; also a condition found when also found comparing when Tmax comparing versus Tmax %Ro. versus Three %Ro. examples Three of examples mudstone of didmudstone not fall indid the not immaturity fall in the area,immaturity one of area, them one was of in them the areawas ofin inertthe area coal, of the inert other coal, in the the other area in of the indigenous area of hydrocarbonindigenous hydrocarbon generation, andgeneration, the last and one the in thelastmigrated one in the hydrocarbon migrated hydrocarbon field. These field. three These data three were inconclusivedata were inconclusive and corresponded and corresponded to samples to with samples low TOC with values. low TOC values. Tmax data versus depth (Figure 14) as done by Peters and Cassa [41], showed that there was no repetition of the sedimentary sequences in the wells and that there was no presence of displacement due to geological faults; a situation confirmed with the information obtained from the seismic interpretation, as well as from the drilling report. Based on the data, the Cerrejón formation is immature in the central zone of the Ranchería Sub- Basin. However, as determined by organic petrography [50], the thermal maturation of the coals and shales of the Cerrejón Formation in the Cerrejón Mine established that the Cerrejón Formation is in

Geosciences 2020, 10, x FOR PEER REVIEW 12 of 18

the oil generation window. Arango and Blandon [51] also established that the appearance of different forms of inertinite present in these coals may be due to hydrocarbon expulsion processes at moderate pressures and temperatures. This information coincides with the study carried out by Martinez [52], Geosciences 2020, 10, x FOR PEER REVIEW 12 of 18 Geoscienceswhich 2020determined, 10, 258 by chromatography the existence of gases such as methane, hexane, and heptane,12 of 18 associated with coal mantles in the Cerrejón mine area. the oil generation window. Arango and Blandon [51] also established that the appearance of different

490 490 forms of inertinite present in these coals mayPaleocene be due to hydrocarbon expulsion processes at Paleocenemoderate Mudstone Mudstone pressures480 and temperatures. This information coincides480 with the study carried out by Martinez [52], Paleocene Paleocene Inert Carbon Post mature Coal Inert Carbon Post mature Coal which470 determined by chromatography the existence 470of gases such as methane, hexane, and heptane, associated with coal mantles in the Cerrejón mine area. 460 460

490450 Hydrocarbon 450490 Hydrocarbon generation Paleocene generation Paleocene Tmax (°C) Tmax (°C) Tmax (Indigenous) Mudstone (Indigenous) Mudstone 480440 440480 Non-Indigenous Paleocene Non-Indigenous Paleocene Inert Carbon Post matureHydrocarbon Coal Inert Carbon PostHydrocarbon mature Coal 470430 430470 460420 Immature A 420460 Immature B 410 410 450 Hydrocarbon 450 Hydrocarbon 0 0.2generation 0.4 0.6 0.8 1 0 0.2generation 0.4 0.6 0.8 1 Tmax (°C) Tmax (°C) Tmax (Indigenous) Production Index (PI) (Indigenous)Production Index (PI) 440 440 Non-Indigenous Non-Indigenous Hydrocarbon ℃ Hydrocarbon 430FigureFigure 13. 13.Cross Cross plot plot of of production production index index (PI) (PI) versus versus Tmax 430Tmax (°C ( ) to) to identify identify source source rock rock maturity maturity in in the Cerrejthe óCerrejónn Formation Formation of the of (A the) ANH-CARRETALITO-1 (A) ANH-CARRETALITO-1 and and (B) ANH-CAÑABOBA-1(B) ANH-CAÑABOBA-1 wells. wells. 420 Immature 420 Immature 0 A 0 B 410Tmax data versus depth (Figure 14) as done by Peters410 and Cassa [41], showed that there was no 0 0.2 0.4 0.6 0.8A 1 0 0.2 0.4 0.6 0.8B 1 repetition of the sedimentaryProduction Index sequences (PI) in the wells and that there was no presenceProduction Index of (PI) displacement due Condensate Condensate to geological100 Immature faults; a situation Oil window confirmed with the information100 Immature obtained Oilfrom window the seismic interpretation, Figure 13. Cross plot of productiongas window index (PI) versus Tmax (℃) to identify sourcegas rock window maturity in as well as from the drilling report. the Cerrejón Formation of the (A) ANH-CARRETALITO-1 and (B) ANH-CAÑABOBA-1 wells.

200 200 0 0 A B 300 300 Condensate Condensate 100 Immature Oil window gas window 100 Immature Oil window gas window

400 400 Depth (meters) Depth (meters) 200 200

500 500 Paleocene Paleocene Mudstone 300 Mudstone 300 Paleocene Paleocene Coal Coal 600 600

400 400 Depth (meters) Depth (meters)

700 700 410 420 430 440 450 460 470 480 490 410 420 430 440 450 460 470 480 490 Tmax (ºC) Tmax (ºC) 500 500 Paleocene Paleocene Mudstone Figure 14. Cross plot of Tmax (℃) versusMudstone depths (m) to demonstrate the distribution of the parameter Paleocene Paleocene Coal with increasing depth in the Cerrejón FormationCoal of the (A) ANH-CARRETALITO-1 and (B) ANH- 600 600 CAÑABOBA-1 wells.

4.3.700 Geochemical Modeling 700 410 420 430 440 450 460 470 480 490 410 420 430 440 450 460 470 480 490 A one-dimensionalTmax model (ºC) of burial history was performed in theTmax location (ºC) of the ANH- CARRETALITO-1FigureFigure 14. CrossCross plotand plot of ANH-CAÑABOBA-1Tmax of Tmax (℃) (versus°C) versus depths depthswells, (m) to (m)demonstrateusing to demonstratethe information the distribution the distributionobtained of the parameter from of the the interpretationparameterwith increasing with of the increasing depth seismic in the depth lines Cerrejón inin thetime, CerrejFormation theó bounn Formation ofdary the conditions (A of) ANH-CARRETALITO-1 the (A) heat ANH-CARRETALITO-1 flow, the paleo-water and (B) and ANH- depth, (B) the SWIT (Figure 15), and the bottom hole temperature (BHT) of the wells (Figure 16, right side). The ANH-CAÑABOBA-1CAÑABOBA-1 wells. wells. heat flow, considering the sin-rift stage and the post-rift stage in this sub-basin, was established from 4.3.200 GeochemicalBased to 116 on mya the Modeling and data, from the 116 Cerrej to 20 ómya,n formation respectively. is immature The paleo-water in the depth central used zone for of the the simulation Rancher ía Sub-Basin. However, as determined by organic petrography [50], the thermal maturation of the coals and shalesA one-dimensional of the Cerrejón Formationmodel of inburial the Cerrej historyón Minewas establishedperformed thatin thethe Cerrejlocationón Formationof the ANH- is in theCARRETALITO-1 oil generation window. and ANH-CAÑABOBA-1 Arango and Blandon wells, [51] also using established the information that the appearance obtained of from different the formsinterpretation of inertinite of the present seismic in theselines in coals time, may the be boun duedary to hydrocarbon conditions heat expulsion flow, the processes paleo-water at moderate depth, pressuresthe SWIT and(Figure temperatures. 15), and the This bottom information hole temperature coincides (BHT) withthe of the study wells carried (Figure out 16, by right Martinez side). [ 52The], whichheat flow, determined considering by chromatography the sin-rift stage theand existence the post-rift of gases stage such in this as sub-basin, methane, hexane,was established and heptane, from associated200 to 116 withmya and coal from mantles 116 in to the 20 Cerrejmya, respectively.ón mine area. The paleo-water depth used for the simulation

Geosciences 2020, 10, 258 13 of 18

4.3. Geochemical Modeling A one-dimensional model of burial history was performed in the location of the ANH- CARRETALITO-1 and ANH-CAÑABOBA-1 wells, using the information obtained from the interpretation of the seismic lines in time, the boundary conditions heat flow, the paleo-water depth, the SWIT (Figure 15), and the bottom hole temperature (BHT) of the wells (Figure 16, right side). The heat flow, considering the sin-rift stage and the post-rift stage in this sub-basin, was

GeosciencesestablishedGeosciences 2020 2020 from, 10,, 10x 200FOR, x FOR toPEER PEER 116 REVIEW myaREVIEW and from 116 to 20 mya, respectively. The paleo-water depth1313 of used of18 18 for the simulation was proposed by [34], 50 m from 126 to 103 mya, subsequently, increasing to 200 wasm inwas proposed 92 proposed mya and by by gradually[34], [34], 50 50 m m decreasingfrom from 126 126 to to 103 100103 mya, mya, m in subsequently, 79subsequently, mya, then 15increasing m in 70 to mya,to 200 200 and,m m in in finally,92 92 mya mya 0and mand to graduallythegradually present. decreasing decreasing to to100 100 m m in in 79 79 mya, mya, then then 15 15 m m in in 7070 mya,mya, and, finally,finally, 0 0 m m to to the the present. present.

80 80 3232 0 0

3030 60 60 100100

28 28 40 200

40 (°C) Temperature 200 Heat flow (mW/m^2) Temperature (°C) Temperature

Heat flow Paleo water depth Paleo water depth (m) Heat flow (mW/m^2) Heat flow 26 SWI-TemperaturePaleo water depth Paleo water depth (m) 26 SWI-Temperature 20 300 20 200 150100 50 100 50 300 200 150Time (Ma)100 50 100 Time (Ma) 50 Time (Ma) Time (Ma) Figure 15. Boundary conditions used for 1D modeling of burial history of the lithological units in the Figure 15. Boundary conditions used for 1D modeling of burial history of the lithological units in the ANH-CARRETALITO-1 and ANH-CAÑABOBA-1 wells. ANH-CARRETALITO-1 andand ANH-CAÑABOBA-1ANH-CAÑABOBA-1 wells.wells.

Burial history with %Ro variations, ANH-CARRETALITO-1 well Modeled temperature ANH-CARRETALITO-1 well Modeled temperature A Burial Cretaceoushistory with %Ro variations, ANH-CARRETALITO-1Paleogene wellNeogene vs BHT ANH-CARRETALITO-1 well ANH-CARRETALITO-1 well Lwr Cretaceous Upper Cretaceous Plc. Eocene Oligocene Miocene vs BHT40 ANH-CARRETALITO-160 80 100 120 well A 0 Cretaceous Paleogene Neogene 0 Conjunto Conglomeratico Lwr Cretaceous Upper Cretaceous Plc. Eocene Oligocene Miocene Cerrejon Fm 4060 80 100 120 0 0 ManantialConjunto Conglomeratico Fm 1000 MolinoCerrejon Fm Fm 500 LaManantial Luna Fm Fm 1000 AguasMolino Blancas Fm Fm 500 Lagunitas Fm 2000 La Luna Fm AguasRio Negro Blancas Fm Fm 1000 Sweeney and Burnham LaLagunitas Quinta FmFm 2000 (1990) Easy %Ro : Rio Negro Fm 1000 3000 SweeneyImmature and (0.25Burnham - 0.55) La Quinta Fm Depth [m] (1990)Early Easy Oil (0.55 %Ro - : 0.7) 1500 Main Oil (0.7 - 1.0) 3000 ImmatureLate (0.25 Oil -(1.0 0.55) - 1.3) Depth [m] Early OilWet (0.55 gas (1.3- 0.7) - 2.0) 1500 4000 Main OilDry (0.7 gas - (2.0 1.0) - 4.0) Late OilOvermature (1.0 - 1.3) > 4 2000 Wet gas (1.3 - 2.0) 4000 Dry gas (2.0 - 4.0) 5000 Overmature > 4 2000

BHT ANH-CARRETALITO-1WELL (°C) 5000 100 50 0 Modeled Temperature (°C) Time [Ma] BHT ANH-CARRETALITO-1WELL (°C) Modeled temperature 100Burial history with %Ro variations, 50 ANH-CAÑABOBA-1 well 0 Modeled Temperature (°C) Time [Ma] ANH-CAÑABOBA-1 well B Cretaceous Paleogene Neogene vs BHT ANH-CAÑABOBA-1 well Lwr CretaceousBurial historyUpper Cretaceouswith %Ro variations,Plc. ANH-CAÑABOBA-1Eocene Oligocene wellMiocene 20 40Modeled60 temperature 80 100 120 0 0 ANH-CAÑABOBA-1 well B Cretaceous Paleogene Neogene Conjunto Conglomeratico vs BHT ANH-CAÑABOBA-1 well Lwr Cretaceous Upper Cretaceous Plc. Eocene Oligocene Miocene Cuervos Fm 20 4060 80 100 120 0 1000 0 ManantialConjunto Conglomeratico Fm 500 Molino Fm LaCuervos Luna Fm Fm Aguas Blancas Fm 1000 2000 Manantial Fm 500 Lagunitas Fm 1000 Sweeney and Burnham Molino Fm (1990) Easy %Ro : Rio Negro Fm La QuintaLuna Fm Fm 3000 Immature (0.25 - 0.55) Aguas Blancas Fm

2000Depth [m] Early Oil (0.55 - 0.7) 15001000 SweeneyMain and Oil Burnham(0.7 - 1.0) Lagunitas Fm (1990)Late Easy Oil (1.0 %Ro - 1.3) : Rio Negro Fm Wet gas (1.3 - 2.0) La Quinta Fm 3000 4000 ImmatureDry (0.25 gas (2.0- 0.55) - 4.0) Depth [m] Early OilOvermature (0.55 - 0.7) > 4 20001500 Main Oil (0.7 - 1.0) Late Oil (1.0 - 1.3) 5000 Wet gas (1.3 - 2.0) 4000 Dry gas (2.0 - 4.0) 25002000 Overmature > 4 BHT ANH-CAÑABOBA-1WELL (°C) 100 50 0 Modeled Temperature (°C) 5000 Time [Ma] 2500 BHT ANH-CAÑABOBA-1WELL (°C) FigureFigure 16. 16.Burial100 Burial history history using using modeled modeled50 temperature temperature variation variation for0 for (A ()A ANH-CARRETALITO-1) ANH-CARRETALITO-1Modeled Temperature and and ((°C)B ) Time [Ma] ANH-CAÑABOBA-1(B) ANH-CAÑABOBA-1 wells. wells. Figure 16. Burial history using modeled temperature variation for (A) ANH-CARRETALITO-1 and (B) TheANH-CAÑABOBA-1 model of burial history wells. (Figure 16), with overlapping values and the different hydrocarbon generation windows were colored as proposed by Sweeney and Burnham [33]. The current temperatureThe model model of burial was history calibrated (Figure with 16),BHT. with Likewise, overlapping it was possible values toand calibrate the different the model hydrocarbon of EASY generation%Ro with windows paleo-geothermometer were colored data as (%Ro) proposed from samplesby Sweeney from theand Cerrejón Burnham Formation [33]. (FigureThe current 17). temperatureThe resulting model was model calibrated predicts with that BHT. the Likewise, Upper Cretaceous it was possible formations, to calibrate Molino the andmodel La ofLuna, EASY %Roentered with paleo-geothermometer in the early oil window data at (%Ro)the Late from Paleocene, samples frombefore the the Cerrejón Middle FormationEocene uplift (Figure event. 17). Likewise,The resulting the Lower model Cretaceous predicts thatformations the Upper would Cretaceous be in the formations,main oil window Molino since and theLa LateLuna, Paleocene; after this time, it is expected that its thermal maturation did not progress any further, and entered in the early oil window at the Late Paleocene, before the Middle Eocene uplift event. the Cerrejón Formation is immature in both wells. The higher maturation levels might have reached Likewise, the Lower Cretaceous formations would be in the main oil window since the Late for the other source rock of Cretaceous formations in the ANH-CARRETALITO-1 Well. Paleocene; after this time, it is expected that its thermal maturation did not progress any further, and the Cerrejón Formation is immature in both wells. The higher maturation levels might have reached for the other source rock of Cretaceous formations in the ANH-CARRETALITO-1 Well.

Geosciences 2020, 10, 258 14 of 18

The model of burial history (Figure 16), with overlapping values and the different hydrocarbon generation windows were colored as proposed by Sweeney and Burnham [33]. The current temperature model was calibrated with BHT. Likewise, it was possible to calibrate the model of EASY %Ro with paleo-geothermometerGeosciences 2020, 10, x FOR PEER data REVIEW (%Ro) from samples from the Cerrejón Formation (Figure 17). 14 of 18 A B 0.20 0.40 0.60 0.80 1.00 Ro(%) 0.20 0.40 0.60 0.80 1.00 Ro(%)

Quaternary 0 0 Quaternary Conjunto conglomeratico

200 200 Conjunto conglomeratico

400 Cerrejon Fm 400 Depth (m) Depth (m)

600 600 Cerrejon Fm

Manantial Fm 800 800

Measured %Ro Measured %Ro (min, mean,max) (min, mean,max) Modelled %Ro Modelled %Ro Figure 17.17. CalibrationCalibration ofof vitrinite vitrinite reflectance reflectance (%Ro) (%Ro) with with depth depth for for the the (A) ( ANH-CARRETALITO-1A) ANH-CARRETALITO-1 and (andB) ANH-CAÑABOBA-1 (B) ANH-CAÑABOBA-1 wells. wells.

The resultingthermal stress model can predicts be measured that the by Upper taking Cretaceous into account formations, the Tmax Molino and %Ro and Lavalues, Luna, which entered is innecessary the early to oilevaluate window the amount at the Late of organic Paleocene, matter before that has the been Middle transformed Eocene uplift into hydrocarbon event. Likewise, [53]. theThis Lower is the reason Cretaceous for the formations variation wouldin the transformation be in the main rates oil window (TR) in sinceFigure the 18. Late As a Paleocene; result, TR afterwas thisnot time,expected it is in expected the study that area its thermal for Cenozoic maturation formations. did not progressThe TR estimated any further, for and the the Cretaceous Cerrejón FormationLagunitas, isAguas immature Blancas, in bothLa Luna, wells. and The Molino higher formations maturation in levels the ANH-CARRETALITO-1 might have reached for Well the other had sourcevalues rockof 90, of 85, Cretaceous 67, and 29%, formations respectively. in the ANH-CARRETALITO-1The TR expected for the Well. Cretaceous Lagunitas, Aguas Blancas,The La thermal Luna, stress and Molino can be measuredformations by in taking the ANH-CAÑABOBA-1 into account the Tmax Well and did %Ro not values, seem whichto be of is necessarygreater importance, to evaluate as the evidenced amount ofin organicFigure 18B. matter The that TR hasoccurred been transformedmainly in the into Paleocene hydrocarbon and Early [53]. ThisEocene, is the with reason values for theof 70, variation 45, 26, inand the 8%, transformation respectively. rates It should (TR) inbe Figure noted 18 that. As the a result, Cretaceous TR was units not expectedreached their in the maximum study area TR for value Cenozoic in the Middle formations. Eocene. The However, TR estimated only in for the the ANH-CARRETALITO- Cretaceous Lagunitas, Aguas1 Well Blancas,did the LaLower Luna, Cretaceous and Molino formations formations have in the a greater ANH-CARRETALITO-1 advance in their WellTR at had the values end of of the 90, 85,Paleocene, 67, and 29%,while respectively. the Upper Cretaceous The TR expected units forhad the almost Cretaceous all their Lagunitas, increase Aguas in their Blancas, TR during La Luna, the andEocene. Molino This formations establishes in two the pulses ANH-CAÑABOBA-1 of hydrocarbon Well generation did not in seem the toPaleocene be of greater and importance,the Eocene, asrespectively. evidenced in Figure 18B. The TR occurred mainly in the Paleocene and Early Eocene, with values of 70, 45, 26, and 8%, respectively. It should be noted that the Cretaceous units reached their maximum

TR value in the Middle Eocene.Cretaceous However, only in thePaleogene ANH-CARRETALITO-1Neogene Well did the Lower Upper Cretaceous Paleocene Eocene Oligocene Miocene Plio. 100.0 Cretaceous formationsTR-ALL have at Middle a greater of Cerrejon Fm. advance in their TR at the end of the Paleocene, while the Upper Cretaceous units hadTR-ALL almost at Middle all of Molino their Fm. increase in their TR during the Eocene. This establishes two TR-ALL at Middle of La Luna Fm. pulses of hydrocarbonTR-ALL generation at Middle of Aguas in Blancas the Fm. Paleocene and the Eocene, respectively. This shows thatTR-ALL the at Cerrej Middle of Lagunitasón Formation Fm. in the study area is not in the oil window. A trend of higher levels50.0 of thermal maturation towards the north of the Ranchería Sub-Basin is expected, Fraction[%] as corroborated by Sanchez and Mann [6], who proposed that in general the thermal maturation of the generating units isA increasing towards the northeast of the sub-basin. This is caused by the increase in sedimentary coverage and does not coincide with the study by Martinez et al. [7], which suggested 0.0 that there are thermal100 maturation bands generated by50 the uplift of PR. These bands are oriented0 in Time [Ma] parallel to the reverse faultCretaceous trace of Cerrejón-Villanueva,Paleogene where the displacementNeogene of the PR developed, Upper Cretaceous Paleocene Eocene Oligocene Miocene Plio. whereas the100.0 areas of greater maturation are those close to the PR. TR-ALL at Middle of Cerrejon Fm. TR-ALL at Middle of Molino Fm. TR-ALL at Middle of La Luna Fm. TR-ALL at Middle of Aguas Blancas Fm. TR-ALL at Middle of Lagunitas Fm. 50.0 Fraction[%] B

0.0 100 50 0 Time [Ma]

Geosciences 2020, 10, x FOR PEER REVIEW 14 of 18

A B 0.20 0.40 0.60 0.80 1.00 Ro(%) 0.20 0.40 0.60 0.80 1.00 Ro(%)

Quaternary 0 0 Quaternary Conjunto conglomeratico

200 200 Conjunto conglomeratico

400 Cerrejon Fm 400 Depth (m) Depth (m)

600 600 Cerrejon Fm

Manantial Fm 800 800

Measured %Ro Measured %Ro (min, mean,max) (min, mean,max) Modelled %Ro Modelled %Ro Figure 17. Calibration of vitrinite reflectance (%Ro) with depth for the (A) ANH-CARRETALITO-1 and (B) ANH-CAÑABOBA-1 wells.

The thermal stress can be measured by taking into account the Tmax and %Ro values, which is necessary to evaluate the amount of organic matter that has been transformed into hydrocarbon [53]. This is the reason for the variation in the transformation rates (TR) in Figure 18. As a result, TR was not expected in the study area for Cenozoic formations. The TR estimated for the Cretaceous Lagunitas, Aguas Blancas, La Luna, and Molino formations in the ANH-CARRETALITO-1 Well had values of 90, 85, 67, and 29%, respectively. The TR expected for the Cretaceous Lagunitas, Aguas Blancas, La Luna, and Molino formations in the ANH-CAÑABOBA-1 Well did not seem to be of greater importance, as evidenced in Figure 18B. The TR occurred mainly in the Paleocene and Early Eocene, with values of 70, 45, 26, and 8%, respectively. It should be noted that the Cretaceous units reached their maximum TR value in the Middle Eocene. However, only in the ANH-CARRETALITO- 1 Well did the Lower Cretaceous formations have a greater advance in their TR at the end of the Paleocene, while the Upper Cretaceous units had almost all their increase in their TR during the

GeosciencesEocene. This2020, 10establishes, 258 two pulses of hydrocarbon generation in the Paleocene and the Eocene,15 of 18 respectively.

Cretaceous Paleogene Neogene Upper Cretaceous Paleocene Eocene Oligocene Miocene Plio. 100.0 TR-ALL at Middle of Cerrejon Fm. TR-ALL at Middle of Molino Fm. TR-ALL at Middle of La Luna Fm. TR-ALL at Middle of Aguas Blancas Fm. TR-ALL at Middle of Lagunitas Fm. 50.0 Fraction[%] A

0.0 100 50 0 Time [Ma] Cretaceous Paleogene Neogene Upper Cretaceous Paleocene Eocene Oligocene Miocene Plio. 100.0 TR-ALL at Middle of Cerrejon Fm. TR-ALL at Middle of Molino Fm. TR-ALL at Middle of La Luna Fm. TR-ALL at Middle of Aguas Blancas Fm. TR-ALL at Middle of Lagunitas Fm. 50.0 Fraction[%] B

0.0 100 50 0 Time [Ma] Figure 18. Hydrocarbon middle-component and transformation ratios (TR) for the Cretaceous and Paleogene formations in the (A) ANH-CARRETALITO-1 and (B) ANH-CAÑABOBA-1 wells.

5. Conclusions The mudstones of the Cerrejón Formation showed 10.68% TOC value on average, which indicated • the presence of organic matter consisting of mixed type II/III kerogen. It supported a good source rock potential to produce oil/gas type hydrocarbons. The coals of the Cerrejón Formation presented ~64% TOC value and the presence of organic • matter consisting of mixed type III kerogen. Evidence of excellent gas-generating hydrocarbon were indicated in the intervals. The Cerrejón Formation in the central area of the Ranchería Sub-Basin is in the immature stage, • but close to the oil window. The high values of Tmax and %Ro obtained in the rocks of the Cerrejón Formation revealed • a possible great tectonic event in the Middle Eocene as the cause of the highest loss of the stratigraphic record in the Ranchería Sub-Basin. Based on the burial history diagrams calibrated with %Ro data, the loss of sedimentary coverage • in the Middle Eocene was estimated as 2600 m in the ANH-CARRETALITO-1 Well and 500 m in the ANH-CAÑABOBA-1 Well. Two peaks of increase in the organic matter transformation were recognized in the Paleocene and • Middle Eocene intervals. They showed distinct characteristics in hydrocarbon generation and migration patterns. This corresponded better to the northern part of the sub-basin.

Supplementary Materials: The following are available online at http://www.mdpi.com/2076-3263/10/7/258/s1, Table S1: ANH-Carretalito-1 Well, Rock Eval pyrolysis data. Table S2: ANH-Cañaboba-1 Well, Rock Eval pyrolysis data. Table S3: ANH-Carretalito-1 Well, vitrinite reflectance data. Table S4: ANH-Cañaboba-1 Well, vitrinite reflectance data. Author Contributions: Conceptualization, L.F.C.-C., M.G.-G., L.E.C.-G., G.M.A.-S.; investigation, L.F.C.-C., G.M.A.-S.; writing—original draft preparation, L.F.C.-C., G.M.A.-S.; writing—review and editing, L.F.C.-C., M.G.-G., L.E.C.-G., G.M.A.-S.; visualization, L.F.C.-C.; supervision, M.G.-G., L.E.C.-G. All authors have read and agreed to the published version of the manuscript. Geosciences 2020, 10, 258 16 of 18

Funding: We would like to thank the Agencia Nacional de Hidrocarburos (ANH) for financing the project entitled: “Thermal and geochemical modeling under subsidence and thrust of the Perijá Range, Ranchería Sub-Basin, Colombia, South America” (project carried out under the contract No FP44842-454-2017). The Universidad Industrial de Santander (UIS) provided lab and computing facilities. Acknowledgments: Special thanks to the Agencia Nacional de Hidrocarburos (ANH), and the Departamento Administrativo de Ciencia, Tecnología e Innovación (COLCIENCIAS), which allowed access to the information published in this article. The geochemical analysis was performed by personnel of the Laboratorio de Geología del Petróleo (LGP) at the headquarters of Guatiguará-UIS. Thanks to the style-writer corrector, German Morales. We thank the anonymous reviewers for their valuable contributions, allowing the document to improve substantially. Conflicts of Interest: The authors declare no conflict of interest.

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