Local structural conditions seem to have had little influence on the concentration of oil in this field. The area is an undulating monocline with a general westward dip of about 35 feet to the mile. On the north and east sides of the field the oil-bearing sand grades in a short distance into an impervious shale, and this impervious shale prevents the oil from traveling farther up the dip. On the west and lower side of the field the oil is in contact with salt water. The oil production from each well also seems to be in proportion to the porosity of the sand in the immediate vicinity of the well, and has little if any relation to rock deformation. The shale barrier north and east of the field, therefore, has been the medium which retained the oil in its present position, and the porosity of the reservoir rock in the vicinity of each well has regulated that well's daily and ultimate production.
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.