Pressure Regimes, Burial History, and Source Rock Maturation of the Morrow Formation in the Western Anadarko Basin and the Hugoton Embayment, Kansas, Oklahoma, and Texas

Lars B. Hubert

The western Anadarko Basin and the Hugoton Embayment have been subject to uplift and erosion during the Tertiary. The flanks have been uplifted more than the deep basin: approximately 5,500 feet of sediment have been removed from the deep basin, and 6,500 from the Hugoton Embayment. The deep Morrowan source rocks have generated both oil and gas. The source rocks in the Oklahoma Panhandle and Kansas are marginally mature, and may have generated some oil, but no gas. Hydrocarbon maturation is now dormant due to reduction of temperatures during uplift.

Three pressure regimes are found in the Morrow Formation in the study area. The shallow reservoirs are water saturated, and follow a hydrostatic gradient. This zone is termed the hydrostatic zone. Below this lies the low-pressure gas zone. This zone is gas-saturated and pressures here are low due to depletion of gas as seals breached during uplift. The deepest zone, termed the high-pressure gas zone, is also gas-saturated and coincides with mature source rocks. The high pressures were initiated during source-rock maturation, as hydro-carbons charged reservoirs.

As all rocks below the hydrostatic zone are gas-saturated, any reservoir rock with sufficient porosity and permeability should be a promising exploration target.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995