Ordovician Oil in Sedgwick Embayment: ABSTRACT

Abstract

The Sedgwick embayment occupies approximately 8,000 sq mi in south-central Kansas. The area is bounded on the west and northwest by the Pratt anticline and the Central Kansas uplift. The Nemaha ridge limits the embayment on the east. Late Mississippian and Early Pennsylvanian movements were primarily responsible for the development of the embayment. The most important reservoir of the Ordovician oil is the Simpson sandstone. Other reservoirs contributing significant recoveries are the Viola and Arbuckle. Simpson sandstone of the area was laid down by transgressive seas, with locally regressive phases, which invaded from a subsiding basin on the south. Source of the sand was on the north and northeast. The Sedgwick embayment has undergone two phases of exploratory activity. In the late 1920s and early 1930s the large features were found through core-drilling operations. Subsequent to World War II many new fields were found by subsurface studies and seismic activities. Fields in the Sedgwick embayment have produced approximately 303,000,000 bbls of oil. Of this total, 108,000,000 bbls, or approximately 30%, has come from Ordovician rocks. Most of the oil fields of the area which produce from the Ordovician exhibit similar geologic characteristics. Among the more important factors governing Ordovician accumulation are thinning of the Mississippian, existence of adequate reservoir rocks, and Permian structure. Proper geological application of the known factors which control Ordovician oil accumulation will result in many future Sedgwick embayment discoveries. End_of_Article - Last_Page 1689------------