Integrated Quantitative Seismic Sequence Stratigraphic Characterization of Leonardian Carbonate Depositional Architecture on the Eastern Shelf of Midland Basin, West Texas

Abstract

The Leonardian series in the Eastern Shelf of Midland Basin is comprised of a thick succession of carbonate and siliciclastic deposition that accumulated on shallow to deep water platforms and shelves, displaying a wide range of complex geological features. Despite decades of exploration, precise stratigraphic correlations continue to be challenging. Many academic and practical problems remain in the understanding of the stratal progradation and retrogradation which occur in response to depositional and erosional processes associated with sea-level changes.

Sequence stratigraphic architecture and depositional systems of Leonardian carbonate buildups on the Eastern Shelf of Midland basin are characterized by integrating multiple 3-D seismic volumetric attributes, spectral decomposition, and acoustic impedance inversion that cover 30 square miles with 50 wells. First, the smallest seismic sequence stratigraphic units are constructed and assigned stratigraphic ages. Second, the control of sea-level upon stratigraphic architecture are analyzed in accordance with the variation of relative base-level and accommodation. Third, major depositional systems are characterized, which directly record the platform responds to sea-level changes.

Quantitative stratigraphic analysis indicates the Leonardian series on the Eastern Shelf is separated into four parasequence sets (PPS): transgressive system track (TST) of PSS-1 equivalent to Wichita Group, Highstand systems track (HST) and regressive systems track (RST). of PSS-2 equivalent to Lower Clear Fork, Lower TST of PSS-2 equivalent to Tubb formation, Upper part of TST, HST, and RST of PSS-2 constitute Middle Clear Fork, PSS-3 and PSS-4 constitute Upper Clear Fork. The Wichita group consists a thick succession of retrogradational and aggradational shelf carbonate buildups. The Lower Clear Fork only consists of rimmed shelf carbonate platform deposition, the Middle and upper Clear Fork comprise thick rimmed shelf and ramp carbonate deposition, recording platform catch-up and keep-up buildups. The Clear Fork carbonate platform margin gradually changes from a rimmed shelf to ramp; the dip angles of slopes are 7°,5°, and 9°. In sequence stratigraphic framework, multiple 3-D seismic provide important information for the characterization of rimmed shelf edge carbonate buildups, slope failure, and sandstone facies of varying geometry, pattern, and dynamic nature during HST, RST, LST, and TST episodes of carbonate deposition.

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