ABSTRACT: Production of Low-Resistivity, Low-Contrast Reservoirs, Offshore Gulf of Mexico Basin

DARLING, HAROLD L., Schlumberger Well Services, Houston, TX, and ROBERT M. SNEIDER, R. M. Sneider Exploration, Inc., Houston, TX

Low-resistivity, low-contrast (LRLC) pay sands in the Gulf of Mexico Basin are being found and produced now. In the past, these intervals were commonly overlooked, or considered wet or tight. These LRLC intervals, which contain significant reserves, can be recognized today through proper identification and evaluation techniques using well logs, samples, and cores.

Low-resistivity, low-contrast pay sands in the Gulf of Mexico Basin have been recognized for many years. However, their economic importance has only recently been demonstrated. With the finding of other LRLC zones in clastic basins throughout the world, (e.g., North Sea, Indonesia, West Africa, Alaska) evaluation and production of these zones has taken new importance. These not-so-obvious pay zones have shown to be of large areal extent and contain many thousands of barrels of hydrocarbons. Thus, proper evaluation and understanding of these zones has become essential.

The principal geologic causes of LRLC are (1) laminated intervals, (2) dispersed clay, (3) structural clay, (4) altered framework grains, (5) grain size, (6) other.

The major depositional systems containing LRLC reservoirs are (1) channel fills, (2) delta front and toe deposits, (3) shingled turbidites, (4) deep water fans including levee-channel complexes.

This knowledge, along with knowledge of wireline tools and responses, can be used to build petrophysical models that can evaluate these LRLC reservoirs.

AAPG Search and Discovery Article #91014©1992 AAPG GCAGS and GC-SEPM Meeting, Jackson, Mississippi, October 21-23, 1992 (2009)