Radiant energy – Geological testing or irradiation – Well testing apparatus and methods
Patent
1996-06-28
1997-09-16
Porta, David P.
Radiant energy
Geological testing or irradiation
Well testing apparatus and methods
250266, G01V 510
Patent
active
056683693
ABSTRACT:
A system and method of determining porosity and water saturation of a formation surrounding a wellbore is disclosed. Well logs are taken to obtain near and far thermal and epithermal neutron log measurements, and to obtain pulsed neutron capture log measurements, at varying depths along the borehole, with the results stored in a computer memory. The computer is then operated, using an assumed porosity value, to calculate the matrix diffusion length according to two independent methods. If the two matrix diffusion lengths do not closely match, the assumed porosity value is adjusted, and the method repeated. Upon convergence of the matrix diffusion lengths, the adjusted assumed porosity value is used to determine the water saturation of the formation. A set of three equations in three unknowns is solved, where the three equations are indicative of the pulsed neutron capture cross-section, and also the near and far thermal neutron absorption. The water saturation of the formation is then determined, without requiring extrinsic data regarding the lithology of the matrix.
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Atlantic Richfield Company
Bruce David Vernon
Porta David P.
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