Regional Stratigraphy and Organic Richness of Meramecian and Equivalent Strata, Anadarko Basin, Central Oklahoma

Abstract

Mississippian-age strata of the STACK, Merge, and SCOOP trends in Oklahoma form premier unconventional reservoirs that overlie the Devonian Woodford Shale. Meramec siltstones of the STACK play are correlative with silty mudrocks of the lower Caney Formation in the Merge and SCOOP. Quartz-rich silty detrital carbonates of the Sycamore Formation in the Merge and SCOOP are basinal time-equivalents of the Osagean intervals to the north. The Meramec and Caney systems, which overlie the carbonate-rich Osage and Sycamore, have elevated total organic carbon (TOC) and good source-rock characteristics. Core, well-log, and outcrop data are integrated to develop a stratigraphic framework and explore the spatial distribution of TOC for the Meramec/Sycamore and Caney.

Stratigraphic correlation through the STACK, SCOOP, and Merge demonstrate that the Osage is correlative downdip to the Sycamore, and the Meramec is correlative to the lower Caney. The depositional environment and paleogeography of Meramec and equivalent strata are determined using high-resolution (cm-scale) descriptions of 3 cores. Meramecian sediments are predominantly mixed argillaceous and calcareous siltstones deposited as prograding clinoforms with proximal facies being above storm wave base. Outcrop gamma-ray measurements of a Sycamore/Caney outcrop in the Arbuckle Mountains are correlated to the subsurface. Lithofacies cycles and key stratigraphic surfaces observed in core and outcrop are compared to their log responses and correlated in non-cored wells to construct a sequence-stratigraphic framework. Parasequence stacking patterns show that the Mississippian strata were deposited during an overall sea-level rise and establish the downdip transition from progradational clinoforms of the Meramec over the Osage carbonate shelf to aggradation of the Sycamore and Caney formations.

The Δlog R technique is used to estimate TOC in 357 Anadarko basin wells, baselined against pyrolysis-based TOC measurements of core samples. A 3-D model of TOC illustrates the stratigraphic controls on the spatial distributions of organic-rich intervals. Paleogeographic reconstructions identify potential relationships between organic richness, sea level, and paleogeography.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018