NSWE. BAS: BASIC program for determining effective water saturation in shaly sands using percentage of clay-bound water-filled microporosity

Journal Article · Fri Jun 01 04:00:00 EDT 1990 · Geobyte; (United States)

OSTI ID:5981614

Asquith, G B ^[1]

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1. Texas Tech University, Lubbock (United States)

Reservoirs with microporosity present significant exploration opportunities as well as new exploitation potential. In sandstones with clay or shale, clay microporosity may distort a number of log-calculated parameters that form the basis for estimating producible reserves. Since reservoirs with microporosity often appear water-productive, the author concludes that producible hydrocarbons in such zones often may be overlooked. Standard formation evaluation approaches that correct for the presence of shale or clay are hampered by the lack of accurate methods for determining volume of clay (Vcl), total shale porosity ({phi}tsh), bound water resistivity (Rb), and resistivity of dispersed clay (Rcl) or by the lack of laboratory-determined values for cation exchange capacity (CEC). In addition some shaly sand corrections (Fertl and Dispersed Clay) can be unreliable in shaly sands with large formation water resistivities (Rw). This paper proposes a microporosity approach which does not require values for Vcl, {phi}tsh, Rcl, Rb, or CEC, and is based on the observation that CEC is related to specific surface area of clays, and specific surface area is related to the amount of clay-bound water-filled microporosity. Without the limitations imposed on other approaches the microporosity method has broad application.

• OSTI ID: 5981614
• Journal Information: Geobyte; (United States), Journal Name: Geobyte; (United States) Vol. 5:3; ISSN 0885-6362; ISSN GEOBE
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
COMPUTER CALCULATIONS
COMPUTER CODES
EXPLORATION
GEOLOGIC DEPOSITS
MATHEMATICAL MODELS
MINERAL RESOURCES
PETROLEUM DEPOSITS
POROSITY
RESERVOIR ROCK
RESOURCES
ROCKS
SATURATION
SEDIMENTARY ROCKS
SHALES
WATER SATURATION