Gorham Oil Field, Russell County, KansasRobert F. WaltersBulletin 2281991 111 pages, 50 figures, and an index |
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The 1,397 oil wells in the Gorham oil field have produced nearly 100 million barrels of oil (BO) from 1926 to 1986. Wells were drilled on 10-acre (4-hectare) spacing 660 ft (198 m) apart, within the 50 mi2 (130 km2) oil field. The Arbuckle dolomite (Cambrian-Ordovician) and Reagan Sandstone (Cambrian), a unit reservoir with a strong water drive (original oil-water contact near subsea -1,440 ft), has produced 66% of the oil from porosity under the Pennsylvanian unconformity surface near 3,300 ft (990 m). The Lansing-Kansas City (Pennsylvanian) limestone reservoirs have produced 25% of the oil from structural and porosity traps by primary dissolved gas drive and secondary water flooding. A fracture zone in the Topeka limestones (Pennsylvania) provided the reservoir(s) for spectacular oil recovery of 200,000 BO per well from 30 oil wells. A fourth pay zone yielded gassy, stratigraphically trapped oil from the Tarkio (Pennsylvanian) after fracturing. Precambrian granite and quartzite yield small amounts of oil in 15 wells.
The Gorham oil field is localized by a 10-mi (16-km)-long northwest-trending anticline with 400 ft (120 m) of faulting in the Precambrian granite on the southwest flank. Fault relief diminishes upward with 30ft (9 m) of closure present in the near-surface Fence-post limestone (Cretaceous). The anticline was defined by the then-unique method of core drilling which provided the location for the discovery well in 1926.
In the 1920's, 1930's, and early 1940's, holes were drilled by the now-obsolete method of cable-tool drilling, providing excellent samples of well cuttings used by the author for acid insoluble residue studies, permitting subdivision of the Arbuckle dolomites into six mapped units. The drilling and development history and the changing role of the petroleum geologist are reviewed with illustrations of cable-tool rigs, derricks, and historic maps.
The adverse environmental effects of this 60-year-old oil field (444 remaining active oil wells, December 31, 1986) include saline contamination of formerly useful freshwater aquifers and of limited agricultural areas plus slow, long-continued, costly subsidence affecting Interstate Highway 70 (I-70) in three areas. Subsidence rates are diminishing to only one-half foot per year, maximum, in 1986. Subsidence is caused by inadvertent dissolution of the Wellington salt (Permian) at depths of 1,300-1,550 ft (390-465 m) by improperly disposed waste oil-field brines that were unsaturated with regard to salt (halite, NaCl). Stringent regulation by the Kansas Corporation Commission of brine disposal and plugging of abandoned wells is minimizing additional adverse environmental impact.
Regional index map showing the location of the Gorham oil field within Russell County, central Kansas.
Kansas Geological Survey, Public Outreach Section
Placed online Sept. 2, 1998
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