Geochemical Characterization and Thermal Maturation of Cerrejón Formation: Implications for the Petroleum System in the Ranchería Sub-Basin, Colombia
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geosciences Article Geochemical Characterization and Thermal Maturation of Cerrejón Formation: Implications for the Petroleum System in the Ranchería Sub-Basin, Colombia 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; mgarciag@uis.edu.co (M.G.-G.); lecruz@uis.edu.co (L.E.C.-G.); gmavesan@correo.uis.edu.co (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: LUIS.CRUZ@correo.uis.edu.co Received: 17 April 2020; Accepted: 19 June 2020; Published: 4 July 2020 Abstract: The Upper Paleocene 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 Cretaceous ? Rio Negro 120 Fm Venezuela Mesozoic 125 Early 130 130 136 Colombia 140 140 145.5 Jurassic La Quinta Fm. 201.6 Ecuador Brazil Triassic 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].