Distribution, Thickness, Reservoir Properties, and Production Characteristics of the Tonkawa Sandstone in Northwestern Roger Mills and Southwestern Ellis Counties, Oklahoma
Alex Fitzjarrald and James Puckette
The Tonkawa Sandstone is an important horizontal drilling objective on the northern shelf of the Anadarko Basin. Cores of the Tonkawa interval from the Bishop and Northwest Crawford fields were integrated with wireline log and production data to ascertain depositional features, interpret the depositional setting and environments, and determine rock properties and reservoir characteristics. The lithofacies, current-induced structures and biogenic features observed in core, mapped distribution patterns, and sandstone geometry from wireline logs support the interpretation that the Tonkawa Sandstone in the study area represents a prograding deltaic complex. Observed depositional facies include distributary channel, distributary mouth bar, distal bar, prodelta, interdistributary bay and crevasse splay deposits. The distribution and minor reworking of sandstone bodies are indicative of a fluvial-dominated system that was influenced by destructive marine processes. Thickness maps of genetic units revealed shifting of the primary depocenters in response to available accommodation. The sandstone is dominantly very fined grained sublitharenite that is glauconitic. Primary porosity is almost totally occluded by syntaxial quartz overgrowths and pore-filling calcite cements. Secondary porosity is the principal type in the Tonkawa Sandstone and consists of partially dissolved grains, grain molds, oversized pores and elongate pores. Porosity and permeability measurements indicate a range in porosity of 3.7 to 15.4 percent and 0.16 to 4.86 millidarcies permeability. Porosity and permeability display a positive linear relationship to each other. Net-sandstone thickness, porosity and depositional facies are strongly linked to cumulative production volumes of oil and gas from the Tonkawa Sandstone reservoirs.
AAPG Search and Discovery Article #90176©AAPG Mid-Continent Meeting, Wichita, Kansas, October 12-15, 2013