| Paralleling the uplift to the northeast is the Anadarko Basin, a relatively deep syncline. The dip of the sedimentaries from the uplift into this basin is exceptionally steep in the eastern part of the Panhandle, so much so, as to suggest faulting. To the westward the dip flattens out and, in general, is more gradual near the western end of the Anadarko Basin which ends at approximately the western boundary of Hutchinson and Hansford counties.
The dip of the beds off the structure into the West Texas Permian Basin to the south, in general, is gentler in the eastern part of the Panhandle and becomes steeper to the west. In several places faulting is suggested and in Potter County, a northwestsoutheast trending fault with approximately 700 feet of displacement, separates two closed structures known as the John Ray Dome and the Bush Dome. The latter, which is located on the south and downthrown side of the fault, has produced no oil to date but is known chiefly as a reservoir for the gas from which helium is extracted at the Bureau of Mines west of Amarillo. It is of interest to note that the rock pressure of the gas in this area is approximately 720 pounds as compared to a virgin pressure of 430 pounds over the rest of the producing area in the Panhandle. Production is also found much lower on structure in this area than elsewhere in the Panhandle so the fault is evidently an effective seal.
Numerous structural irregularities are present throughout the extent of the uplift, there being numerous noses and reentrants along the flanks and large and small closed anticlines superimposed on the regional structure along with several closed syndines.
Recent caliche or "Cap Rock" is present on the surface over a large portion of the Panhandle. However, in the valley of the Canadian River and the drainage area of other streams, beds of Triassic and Permian age are exposed. Permian beds of salt, red shale, sand, and gypsum compose the major part of the section down to the top of the "Big Lime" which is the most prominent marker used in determining structure.
The average section in the Borger pool of Hutchinson County is as follows:
Surface to 400 ft.--sand and red shale
The average section in the main producing area of Wheeler County is as follows:
Surface to 200 ft.--sand and red shale
Top of the "Big Lime" is found at varying depths; the highest points being in Wheeler County where it is found as high as 1,300 feet above sea level and at a hole depth of 1,250 feet, and in northern Potter County, where it is approximately 1,600 feet above sea level and 1,700 feet below the surface.
The upper part of the Permian "Big Lime" is composed chiefly of anhydrite, gray to dark shale, and dolomite and has a thickness of 400-500 feet throughout most of the oil producing area although it becomes much thicker farther down on the flank of the structure. On a few of the highest granite peaks it is entirely cut out.
The dolomite series, which is found immediately below the anhydrite and shale section of the Big Lime, is present over most of the Panhandle with the exception of a few extremely high points in Potter and Wheeler counties, and, while it is thinner in Wheeler and eastern Gray, it is usually 200 feet or more in thickness. The lower part of this series may be sandy or arkosic, depending on its distance from and relationship to the buried granite ridge. This dolomite series is probably Permian in age.
The dolomite is the most consistent producing formation in the Panhandle, producing gas over almost all of the higher part of the structure and oil on the north flank. It is usually referred to as the "Big Gas" horizon.
Below the dolomite series is a limestone section, probably of Pennsylvanian age, which is not present on the higher parts of the structure but thickens rapidly down dip. While it has furnished an occasional large well, it is extremely erratic as a producing formation and, to date, has been of only minor importance.
The granite wash, which may underlie either the dolomite or limestone sections was derived from the weathering of the granite of the buried mountains and deposited as a mantle over it and along the flanks, mainly during Permian and Pennsylvania times. Its thickness and other characteristics are extremely variable as it is often cemented with calcium carbonate or clay and interbedded with red shale. It is very lenticular and crossbedded, especially near the ridge. It produces gas on the higher parts of the structure and both gas and oil on the flanks. As a producing zone it is very erratic, but under favorable conditions is extremely prolific.
A number of wells are producing from faults or fracture zones in the granite. This type of production is erratic and usually shortlived and cannot be compared to the dolomite and granite wash in importance.
Sands in the "Red Cave" section are productive of gas on the higher parts of the structure in northern Potter and portions of the adjacent counties.
Several tests on the north flank of the uplift have encountered beds of Ordovician age. Our present information, however, is still too meager to warrant any prediction as to the oil possibilities.
Gas is found in all of the producing formations where present on the higher parts of the regional structure, oil being present on the north flank and maintaining a general level between sea level and 200 feet above. Each formation, the granite wash, limestone, and dolomite, carries progressively gas, oil, and water as it becomes lower on the structure. The water level approximates sea level although there are localities where it is found 100 feet or more above and also places where it is considerably below. Several pools have production from all three horizons and in a number of cases individual wells are producing from two.
The width of the oil producing area depends on the steepness of the dip and the best production is usually found where there is a flattening in dip at the proper position on structure to place a good porous horizon at the producing level, that is, somewhere near sea level. Oil production is usually confined to the area between the plus 600 and plus 1,200 foot contours on the top of the Big Lime although there are numerous exceptions. The areas of most intensive development have been designated by pool names but, as drilling continues, these areas will be joined by production and, in all probability, there will eventually be an almost continuous strip of production from Moore County to the eastern extremity of Wheeler, along the north flank. At the present time, production has been developed along the north flank approximately 110 miles in length and varying from one-half to seven miles in width. In one area south of the axis in Carson County, three granite wash wells have been completed.
Gas occurs in the higher parts of the structure and is also found to some extent in the oil producing area, the volume generally decreasing down the dip. On the higher parts of the structure the gas is sweet while that found in and adjacent to the oil producing area from Gray County westward is usually sour, that is, relatively high in hydrogen sulfide content.
The total area proven for gas, including acreage capable of making enough casinghead gas to warrant connection with a casinghead plant, is approximately 1,400,000 acres. Of this total approximately eighty percent is classified as sweet gas land and twenty percent as sour.
There has been a total of approximately 4,000 producing wells, both oil and gas, and 400 dry holes drilled in the entire Panhandle area.
The Panhandle has produced to January 1, 1935, in excess of 240 million barrels of oil and more than four trillion cubic feet of gas.
During the month of February, 1935, the average daily production was 61,544 barrels divided as follows: Carson County 4,821, Gray County 33,465, Hutchinson County 12,409, Moore County 1,580, and Wheeler County 9,269. The proration factor for this month was 8.42 percent.
The total gas open flow capacity of the field is approximately nineteen billion cubic feet, exclusive of casinghead gas. Operating on both dry and casinphead gas are forty-nine natural gasoline extraction plants with a total daily capacity of 2,287,500,000 cubic feet. These plants processed an average of 1,577,257,939 cubic feet of gas per day during 1934. Operating on dry gas are seventeen natural gas pipelines, eight of which are local, nine interstate, having an estimated capacity of 740 million cubic feet per day. During the Year 1934, they withdrew a daily average of 376,381,912 cubic feet.
There are twenty-seven carbon black plants, twenty-six of which operated throughout the past year, consuming a total of 163,983,709,000 cubic feet, or a daily average of 449,270,435 cubic feet.
There are nine refineries in the district with a total daily capacity of 78,250 barrels, seven of which are in operation. During the year 1934, they ran a total of 11,000,730 barrels.
At the present time there are about 200 active operations in this district.
This concludes the paper as written by the Panhandle Geological Society. I think the men attending the American Petroleum Institute convention are interested in what can be expected from this field in the future. As these data are of a controversial nature, I am presenting them as my own, rather than the joint opinion of the Society.
The total acreage proven for oil production is approximately 120,000 acres, which is comparable in size to the East Texas field. The recoveries per acre are extremely variable but some of the richer areas will undoubtedly produce 25,000 barrels per acre. The field has already produced more than 240 million barrels and it is estimated that the total amount from present proven areas will be between 750 million and one billion barrels.
Of the total gas area of 1,400,000 acres, approximately 1,300,000 acres will have wells with open flow capacities of ten million cubic feet per day, or better. A number of wells having an initial production of 100 million cubic feet per day have been completed and fifty million cubic foot wells are common. This area is conceded to be the largest known gas reserve in the world and it is expected to produce ultimately between twenty-five and thirty trillion cubic feet.