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

Although LRLC pay sands have been recognized for many years, their economic importance has only recently been demonstrated. With the recognition of LRLC zones in clastic basins throughout the world, (e.g., Gulf of Mexico, North Sea, Indonesia, West Africa, Alaska) evaluation and production of these zones has taken on new significance. These not-so-obvious pay zones have proven 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 geological 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.

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