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 By 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 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.