The Nigger Creek oil field is worthy of description because it is the first commercial pool to produce Woodbine sand oil from a fault structure up-dip from the prolific Woodbine fields in the Mexia-Powell fault zone of east-central Texas. The field is located in the graben between the Mexia-Powell fault and the Balcones fault. It contains 170 productive acres, 79 producing wells, and in two years, since discovery, has produced 2,690,000 barrels of oil, or 15,823 barrels per acre, from a fine-grained soft sand having a maximum thickness of 27 feet and an average pay thickness of about 16 feet. The depth of oil sand ranges from 2,800 to 2,850 feet below the surface. The subsurface structural relief is 35 feet, and the oil-water contact was 2,360 feet below sea-level. The fault plane dips 430 from the surface to the Austin chalk, flattens as it passes through the chalk, and in some parts of the field it dips as low as 150 where it cuts the Woodbine sand. The surface displacement of the fault is 260 feet, and the displacement in the Woodbine sand exceeds 500 feet. The drainage area tributary to this field is limited by the Mexia and other faults located within 2f miles toward the east (down-dip). Probably upward migration along the fault zone, horizontal migration across the fault, and migration up-dip, all contributed to the accumulation in this structure. The oil has a gravity of 40° API., contains 0.27 per cent sulphur and 39.9 per cent gasoline. Although the field was overdrilled, it returned the cost of leases, development, and operating expense plus 37 per cent profit in two years.
Figures & Tables
Modern petroleum geology in the United States had its beginning in the first decade of the 20th Century when the U.S. Geological Survey began mapping the structure of the rocks in and near old fields in order to discover the various types of structural conditions under which oil and gas are trapped. Structural geology has evolved as a branch of the broader science far more rapidly than have methods of mapping the attitude of rocks at the surface. This volume, published in the late 1920s, was designed to afford authoritative and modern descriptions of the structure of typical oil fields in the United States. Each of the 30 fields contained here is described by an author who is intimately familiar with the available data. The relationship of structure at the surface and at depth for different terranes is clearly set forth wherever the strata are not parallel. Fields include: McKittrick, California; Fairport, Kansas; Urania, Louisiana; Artesia, New Mexico; Burbank, Oklahoma; Cabin Creek, West Virginia; and Luling, Texas.