Measuring and testing – Borehole or drilling – Formation logging
Patent
1996-03-25
1998-06-16
Brock, Michael
Measuring and testing
Borehole or drilling
Formation logging
364422, E21B 4902
Patent
active
057673993
ABSTRACT:
A method of assaying the compressive strength of rock comprises testing a primary plurality of rock samples of similar lithology, at least some of which have different porosities, to determine, for each sample respectively, a value corresponding to compressive strength and a value corresponding to porosity. A first series of pairs of electrical compressive strength and porosity signals, the signals of each pair corresponding, respectively, to the compressive strength and porosity values for a respective one of the samples, is generated. These signals are processed by a computer to extrapolate additional such pairs of signals and generate a second series of electrical signals corresponding to compressive strength as a function of porosity. The second series of signals may correspond to unconfined compressive strength, and may be further processed, to generate a cumulative series of signals, using electrical adjustment signals corresponding to other conditions affecting the compressive strength of the rock. Site characteristics of the rock for a wellbore locus, at a plurality of sites along the length of the locus, and as the rock would be addressed by a drill bit, are determined. At least one of these site characteristics is porosity. The site characteristics are used to generate a plurality of site signals, which, upon processing with the second series of signals (or cumulative series, if any), generate in-situ compressive strength signals corresponding to the in-situ compressive strengths of the rock at the respective sites.
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Goldman William A.
Smith Lee Morgan
Brock Michael
Dresser Industries Inc.
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