Integrated Stratigraphic Analysis of Turbidite System Reservoirs: East Breaks Block 160 Field, Offshore Texas Pliocene-Pleistocene

John M. Armentrout, Steven J. Malecek, Philip Braithwaite, Charles E. Beeman

Integrating seismic facies and biofacies maps, calibrated by local well data, helps reduce the risk in predicting the probable reservoir geometry and the speculative-reserve volume of exploration leads. This integrated approach is particularly important where lenticular sandstones of turbidite origin must be differentiated from more laterally continuous sandstones reworked by wave-dominated processes.

Four Pliocene to Pleistocene reservoirs of the East Breaks Block 160 field are interpreted as deep-water sand deposits of turbidite origin: the oldest (Globoquadrina altispira) is about 50 mi downslope from its age-equivalent shelf; the youngest (Trimosina A) is only 6-10 mi downslope from its shelf. Electric-log correlations and facies analysis for both reservoirs suggest channel-fed deposition of aggradational lobes with basal sheet sands. Biofacies indicate deposition at middle to upper bathyal water depths (> 600 ft). Seismic facies analysis shows the reservoir interval correlates with discontinuous, variable-amplitude, non-parallel reflection character. This sand-prone seismic facies has a lobate map pattern within the isochron thicks of the Block 160 salt-withdrawal basin. A epositional model for this system includes (1) deposition during a sea level lowstand, (2) sediment supplied from a shelf-edge deltaic system, (3) transport by gravity flow process through physiographic lows on the slope, and (4) deposition as intraslope basin fans consisting of sheet, lobe, and channel deposits.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.