Moustafa E Oraby

US Patent:

60723149, Jun 6, 2000

Filed:

Sep 16, 1997

Appl. No.:

8/931539

Inventors:

Moustafa Oraby - Houston TX

Assignee:

Halliburton Energy Services, Inc. - Houston TX

International Classification:

G01V 300

US Classification:

324303

Abstract:

This invention provides improved geological formation evaluation, resulting in a more accurate prediction of the location of hydrocarbon. It also increases the yield at those sites. The disclosed method involves determination by a nuclear magnetic resonance tool of a downhole T2 distribution, determination of T2 cutoff valves at discrete points in the borehole, and deriving a variable T2 cutoff time by either linear or non-linear correlations. Derivation of these variable T2 cutoff times provides the likely location of high irreducible water saturation, even where large quantities of movable water reside nearby.

US Patent:

56683693, Sep 16, 1997

Filed:

Jun 28, 1996

Appl. No.:

8/672318

Inventors:

Moustafa E. Oraby - Houston TX

Assignee:

Atlantic Richfield Company - Los Angeles CA

International Classification:

G01V 510

US Classification:

2502695

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.