G SOCIETY OF PETROLEUM ENGINEERS OF AIME 62oO North Central Expressway ‘&RWE 2~83 Dallas, Texas 75206
THIS IS A PREPRINT -— SUBJECT TO CORRECTION Geologic Factors Which May Affect the Occurrence of Natural Gas in the Oklahoma Panhandle; with Notes on Gas Analyses in Uinta Basin, Utah
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Carl A. Moore, Member AIME, The U. of Oklahoma @ Copyright 1970 American Institute of Mining, Metallurgical, and Fetrdetifi, Ew#neer% ~n~. This paper was prepared for the Third &ier.ndalGas Industry Symposium, to be held in Omaha, Nebr., May 21-22, 1970. Permission to copy is restricted to an abstract of not more than 300 words. Illustrationsmay not be copied. The abstract should contain conspicuousaclmowledgmentof where and by whom the paper is presented. Publication elsewhere after publicationin the JOURNAL OF PETROLEUM ENGINEERINGor the SOCIETY OF PETRILEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.
Discussion of tinispaper is invited. ~.ree ~~pies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.
INTRODUCTION expected to provide additionalinformation. Keyes Dome is situated within the closing The Oklahoma Panhandle has produced major contour““’ m tne no~rtheaste.rn.~n~ev...... Qf the amounts of gas for 50 years. Initial produc- County, ,. Lion Came frm D.,-*”...-h.11.w rQ&~ Qt Permian age— the Herington, Krider and Winfield porous Across Texas County, the middle Co’u.?.?tyi limestones located on the northwest flank of subsurfaceelevations range from 1,000 to the Anadarko basin. 4,000 ft below sea level. Most of this difference in elevation is related to the Beginning in the early 1950’s, additional prominent faults along the western county line. reserves of gas have been proved in the East of these faults the shelf area of the Panhandle from deeper horizons in Pennsylvanian Anadarko basin dips fairly uniformly basinward. and Mississippianage rocks. Of these newer horizons, the Morrow ssnds are by far the most Beaver County, the eastern county, lies important, followed in importance by the Chester on the hinge line between the shelf area of (Mississippian),then the Hoover, Tonkawa and Texas County and the steep basin flank that Topeka in approximate equal proportions. This drops southeastwardinto the Anadarko basin newer production has added significantreserves trough. In the basin, each formation is tQ the earlier reserves, making the Oklahoma expected to be found in full or maximum thick- Panhandle a major segment of the Amariiio- ness. !=!e’whgout of the basin, past the hinge Hugoton gas fieid. line and onto the shelf, each individual forma- tion becomes thinner either by oniap or by REGIONAL GEOLOGY erosion. Along the hinge line, environmental conditionsare in optimal.development for the The subsurface structure at the base of deposition of porous/permeablebeds. Thus, the Pennsylvaniansystem of rocks across the Beaver County contains a large number of Oklahoma Panhandle is illustratedin Fig. 1. In multiple stratigraphicpinch-outs or traps, any Cimarron Cou@, the western of the three of which are potential reservoir beds, and Panhandle counties, depths to the pre- hence capable of becoming a producing field. Pennsylvanian sequence of rocks average about 1,000 ft below sea level. Much of this county FACTORS OF DEPOSITION is not well recognized because of the lack of well control. Recent tests near Boise City are Deposition of rocks in the Oklahoma Pti~dle was on the shelf or flank of the References end illustrationsat end of paper. GFKLOGIC FACTORS WHICH MAY AFFECT THE OCCURRENCE OF NATURAL GAS IN THE OKLAHOMA PANHAN~LE W17H INITIAL FWSL!TS OF STUDIES OF GAS 2 AnlA1-vc!r5 l-nT TTrnT1-rlA DAc-rn? TMIAU ru~ CDT 9QQQ
Anadarko basin where ltiestones make up to 50 while the upper Morrow sand may be a channel? percent and more of the total depositim in th or a ?-h&et Qpe. Variable conditions are to Pennsylvanian and pre-Pennsylvaniansystems of be anticipatedin this upper sand zone. rocks.4 Shelf limestoneswill be light color- ed, coarsely crystalline,fossiliferousand GEOLOGICAL CONTROL OF NATURAL GAS ANLLYSES porous. These drill at a rapid rate, and be- cause of high porosity, loss of circulation NitroKen Content problems are common. 1 Of the number of variables in the 400 Basinward, these thick limestones will natural gas analyses from the Ol&&oma Fanhandie grade into normal marine shales with few thin four factors have been studied with respect to beds of ltiestones. The limestoneswill be variations with depth of production. In Fig. 4, thin bedded, dark colored, finely crystalline, nitrogen percentages are high above 5,000 ft essentially nonfossiliferousand will exhibit (drilled depth). The 30-percent values at the minimal porosity. They will be hard and 3,000-ft depth are from the Hugoton-Permian Downloaded from http://onepetro.org/spegis/proceedings-pdf/70GIS/All-70GIS/SPE-2883-MS/2069836/spe-2883-ms.pdf by guest on 01 October 2021 siliceous, indicating “shale and shells” to the horizons. Between 4,500 snd 4,900 ft are the driller. high nitrogen values from the Keyes (Morrow age) sand in Keyes field, Cimarron County. Oil and gas in the shelf limestones could originate from the dark shales in the basin High values at 5,70C-7,30&and 7,50Qft and migrate into the porous limestone traps. depths are the average of a limited number of armlyaes in which there is at least one abnor- Sandstone deposition is also governed by reallyhigh value. Otherwise the values average environments of deposition,whether shallow or no more than 2 percent nitrogen. deep water, above or below wave base, nonshaly (clean) sands, or shaly (dirty) types. Sand High percentages of nitrogen, as much as will accumulate on the shelf of the basin in 25 percent and higher, are locelized in the lenses, or over a broad area as a blanket-type Keyes field. This happens to correspondwith deposit. Above the wave base, the sands will the 4,500 to 4,900-ft depth at which the highest be clean and nonshaly, while below wave base nitrogen values are recorded. the waves will not have winnowed out the shale particles and the sand will be shaly or dirty. Moving eastward across Texas County, there is a rapid decrease in nitrogen values that Across the Oklahoma Panhandle, the Morrow correspondwith the depth factors of Fig. f+. formation consists of a number of individual All nitrogen values in the Morrow sands of sand beds, some being fairly uniform blanket- Beaver County are less than 5 percent. types, while others appear to be irregular channel fillings. Fig. 2 shows at least four When these high nitrogen values are plotted discrete sand bodies in the Morrow, most of geographicallyacross the Panhandle, the Btu which are bisected by shale interbeds, and value of the natural gases decreases as the there is a prominent channel Sand A. nitrogen percentage increases. The most val- uablegases in the Oklahoma Penhandle are shown The flan.!of the basin is a fortuitous to be produced in Beaver County where nitrogen location for channel sands since these are values are low, hydrocarbon Pereerlhgm are sensitive to fluctuationsof the sea. The high, and there is usually an increase in the channel sands may be mutually connected through higher hydrocarbonfractions. multiple channel sand fingers over which a porous/permeableblanket-type sand may be de- Helium Content posited. This will provide a carrier bed for the free movement of fluids throughout an area Panhandle gases contain an unusually high or a county. percentage of helium at shallow drilled depths (Fig. 4). Above 3,000ft arethe Hugoton- ~.Aan isolatedA.------c~~~l- it is possible to Permian horizons, and an average helium value have an individual reservoir rock &th its own of 0.5- percent lS reeorded UUWAAa-.- +-Vv ,,,VW2 .mn .f+.. fr~~ geometry and fluid content. Gas analyses may a small number of widely scattered analyses. -..-..+ +- m. ~emtau~~ of each hydro- vary ‘~ithlL-GSpGbU w p“)? ...... carbon fraction, percentages of nitrogen and Between 4,500 and 4,900 ft are the large helium, oxygen and carbon dioxide, and may number of gas analyses from the Keyes (Morrow) exhibit subnormal bottom-hole pressures. Btu sand in Keyes field. This field is a major values appear to be related to the analysis of source of helium in the country. Average value: the gas rather than the depth of production. as high as 2.0 percent are recorded. Below Fig. 3 illustrates the Morrow zone in a 4,900 ft, aveoragehelium content is 0.1 percent DG&Gtiu.u..l..+.~ w.11“.+-. —.in c~~a_rron COUnty. The Keyes with single values of 0.2 and 0.3 percent being blanket-type sand is at the base of the Morrow, shown.
— SPE 2883 CARL A mom 3
Workers have contended that the helium drilled depth. Greater depths show only content of a gas depends on its nitrogen con- minimal values, averaging less than 0.1 per- tent. The two curves, plotted against depth in cent. If helium were generated solely from tht Fig. 4, indicate considerablecorrelation,and deep Precambrian basement rocks, the deeper high helium values are associatedwith high horizons should contain greater amounts of nitrogen values. The converse is not as ap- heiium. parent - moderately high nitrogen values do not always indicate correspondinglyhigh helium It is believed that some helium has come values. from basement rocks, but by far the major portion appears to have been generated from WEIUIEADPmsums sediments that today serve as resezwoir rocks for the helium-richgases. The Morrow sands Fig. 5 shows the average pressures as re- may contain clastic fragments of pre-existing ported by the USBM for he gas analyses from igneous rocks that contain measurable quanti- t the Oklahoma Panhandle. These wellhead pres- ties of uranium and thorium. These two ele- Downloaded from http://onepetro.org/spegis/proceedings-pdf/70GIS/All-70GIS/SPE-2883-MS/2069836/spe-2883-ms.pdf by guest on 01 October 2021 sures have not been adjusted for bottom-hole ments are alpha emitters and continue to pro- pressures using the analyses of the produced duce radiogenic helium over a long period of gases. Again, the Hugoton-Pemian horizons to time. a depth of 3,500 ft indicate abnormallylow, or subnormal pressures, averaging less than 400 As $38 decays radioactivelythrough the psi where the normal calculatedpressures shoul more than 14 stages to Pb206, each stage and be three times higher. most of the daughter products emit alpha particles. Whether these molecules are con- Between 4,500 and i+900 f% drilled depth tained in a solid granite or have been up- through the Keyes (Morrow!lsand of Cimarron lifted to form a mountain range that is being County, the pressures average less than 900 eroded, helium is generated as the molecules psi with two values going as high as 1,100 and decay and pass through the normal rock cycle a: 1,300 psi. The high value at 4,900 ft is a shown in Fig. 9. single analysis. Below 5,300 ft, average value increase from 1,500 psi to almost 1,800 psi Thus an igneous rock can act as a source without regafi for increasingdepths. But what of helium without regard to its position in thf d~ you do with two analyses that average only rock cycle or its position in time and space. 575 psi at a depth of 7,800 ft? And deeper T& major problem seems t~ be concernedwith there is an increase in pressures to 2,600 psi. the trapping mechanism that will hold the helium. A typical l~heliumholder” can be a Pressure variations appear to be dependen dense, impervious shale that will trsnsmit a on the nature of the reservoir rock and the gas minimum amount of helium by diffusion or by that this rock produces. There is a minimal migration in a fluid medium. correlationwith the so-callednormsl increase of pressure with depth. This raises a question Although unusually insoluble, helium does of what is a “normal”pressure gradient in a occur in a number of natural gases where it is gas field — does this depend on the rock type, held by the helium holders in sedimentary pore geometry, fluid content, basin position, ~o~k~, It is stcred in the natural gases in depth, overburdenpressure? Cliffside field near Amafllo, Tex., under anhydrite (C5S04). Over a long period of time! BreezeL is [email protected] subnormalpressures i a given percentage of helium will diffuse from western Oklahoma including the Panhandle based a reservoir. Any change in the geometry of th[ on analyses of electric log diagrams and re- reservoir rock, or a change in its environment corded pressure data. He hopes to relate the that will alter the diffusivityfactor with pressures to rock characteristics,and pressure respect to heat, pressure, and vapor pressure, gradients to adjacent shale beds. will be related to geologic factors, such as structural.movements or displacements,re- SOURCES OF HELIUM FROM SEDIMENTS cementationby moving subsurfacewaters, and natural processes of fracturing. The origin, migration and accumulationof helium were tivestigatedby Esfandiari.2 An Porosity and permeability can be increase( original notion that all helium was derived or decreased through natural processes of from the Precambrian basement rocks lying belo microfracturingor re-cementation. Ibcks de- a helium-producingfield5 does not adequately pressed to great depths by structuraldownwarp account for the occurrence of helium in the due to basin filling will undergo tensional OWahoma Panhandle gases. fracturing, as well as being subjected to an increase in heat and pressure. These factors In this study, the percentages of helium will enhance the ability of any entrapped are at a maximum between 4,500 and 4,900 ft helium to escape to be trapped by overlying GFKXOCIC-—.——— FACTORS WHICH MAY AFFECT THE OCCURRENCE OF NATURAL GAS IN -LRE3ULTS OF STUDIES OF GAS THE OKLAHOMA PANHANDLE WITH INIll spFF28& < impermeable barriers where a helium-rich gas could be accumulated. better quality gases (Fig. 8). Again, with th( exception of three analyses, the wellhead Minerals with close-packedmolecular pressures are below the normal gradient. Btu structures, as is common in many of the values are high because of the higher hydro- *..wamaanesi ~ ~~erals~ tend to retain carbon content; nitrogen values are quite low; .LGA.“.!.------., s.-..
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m._.rig. L - LJL4”L.L4..”-..C..-q,+$npapa L-.-~t,ruct,ure.... on the base of the Pennsylvaniansystem of rocks acrossthe Oklshoma z -- ~ . 1-*+ (wQs+.)with Texas Panhandle. Contour interval200 ft. CimarronCounty is iocatea UIL bh= ~=.. ,..--., County in the middle and ~eaver @W3tij C= +.h....---”riaht (east) side of the Panhandle. Note the small domal closure in centralCimarronCounty,the broad Keyes”fielddomal closwe> the major f’a~t:~g in westernTexas County and the uniform basin-warddip across Texas and Beaver Counties. This is the flank of the Anadarko basin. AN IMISS. PEN NSYLV ‘N: [cHEsTER .R R w 1~TOKA M o I II IL I II I 1 Downloaded from http://onepetro.org/spegis/proceedings-pdf/70GIS/All-70GIS/SPE-2883-MS/2069836/spe-2883-ms.pdf by guest on 01 October 2021
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Fig. 3 - Electric log of I’hbil.2 Gladen in T. 5 N., R. 13 ECM. This illustratesthe Morrow formation includingthe upper sandstone zone and the basal, Keyes sandstones,the well developed Thirteen-Fingerlime zone of Atoka age and the four well marked members of the upper few feet of the Chester formation. i Downloaded from http://onepetro.org/spegis/proceedings-pdf/70GIS/All-70GIS/SPE-2883-MS/2069836/spe-2883-ms.pdf by guest on 01 October 2021 I , 1 1 I I &o I I 0 0 o ) o 0 0 0 0 0 ) 0 0 ~ o 0 g ) o 0 @ b J W) * lj-Hld3a
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Average Analyses of Gas in each Formation
TOTAL PRESSURE BTU METHANE HYDROCARBONS N FORMATION DEPTH 02 c02 ‘e
Was atch 1097 342 1058 95 99.2 0.26 .07 .13 -
Tertiary -Eocene 4352 1412 1034 ~i ‘$%.b 0.1 .45 2.1 tr
Paleocene- upper Cretaceous 4357 1300 1150 81 90 4.4 .38 5.8 .13
~o,h,~~ Cretaceous 4074 1074 805 ‘n 75 10.0 .08 14.5 .55
Jurassic 4834 1217 809 65 70 14.0 .09 16 .49
Pennsylvanian5930 1600 1211 22 78 19.6 .36 1.03 .40
Fig. 6 - Chart of ths producing horizons in Uinta basin, Utah, comparing the average depths, pressures, Btu values, hydrocarbon content, ni~r~~ea, carbon dioxide and helium percentages. The lower Cretaceous and Jurassic values appear to be similar, perhaps indicating essentially equivalent geological environments. o 100 2000 I ? I /’ J’ 3000 - \\ \\ ●\“0 F \ + 400 0- \ \\ z \
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0,1 6000 - ●“ 4,%, <\ 1 A I 1 ) 700 00 2000 ~ 01 xza~ % lie PRESSURE - PSI
Fig. 7 - pre~Sure~al~es(hydrocarbon, nitrogen,carbondioxide~d helium percentages)in the J~~a$sic Morrison-Entrade horizonsplottedagainst drilleddepths. Theseill~stratethetypeof gasthatmaYbe emected‘0 be encountered in these beds.
% % o 100 o 100 : 100oh \ \ 1 \ PAHI
7000 I , I 1 I I I I , I I 1 I 2000 yggo 10 8000~ 2000 ~ ; f 0%Lo :RESS”RE . Psl ~ %* PRESSURE-PSI
~es~urevalues(hydrocarbon,nitrogen,carbondioxideandheliumPercentages)&illed depths.in the Fig. 8 - Dakota,~nco~ ad MeS8 VerdehorizonsP?ottedaga‘nst upperCretaceous- Thebetterqualitygasis clearlyind~cated. \ Downloaded from http://onepetro.org/spegis/proceedings-pdf/70GIS/All-70GIS/SPE-2883-MS/2069836/spe-2883-ms.pdf by guest on 01 October 2021 ti original igneous rock erosion (molten state) containing uranium and thorium k clastic sediments ~–--”- “ -’-ail transportation
deposition1 ——-——----> induration
> ,..... ------’-....—— ,_ ...... , .- _~-” ‘““ ;~ .,...... -.- ~ re-uplift and a second cycle of ~~ weathering
\ erosion
/ clastic sediments L.- -?v transportation
\ A /’ deposition —-----+~nduratio~
Fig. 9