Method for making measurements of the chemical swelling effect of a fluid on a shale
AssigneeShell Oil Company
InventorsThomas R. Bates, Richard B. Bonner, Ronald K. Clark
Life of this patent
Estimating the term…
Abstract
The drilling or treating of subterranean shale-containing earth formations is improved by adjusting the composition of the fluid used to reduce the positive shale swelling strain it causes when a shale sample is first equilibrated with fluid under conditions simulating those in the earth formation and the equilibrating fluid is replaced by the fluid being tested without otherwise significantly altering the conditions of the equilibration.
Claims5
A process for measuring a chemical swelling effect of a fluid on a sample of a shale-containing subterranean earth formation, comprising:
- contacting a sample of shale obtained from said earth formation with a fluid which is, or is substantially equivalent to, the interstitial water contained in said earth formation;
- at least substantially equilibrating the so-contacted shale at pressures at least substantially equivalent to those existing in said earth formation;
- contacting the shale with the fluid to be tested at substantially the pressures used in said equilibration;
- and
- detecting any resultant positive or negative change in the shale swelling strain that was exhibited during said equilibration.
A process for determining whether, and to what extent, an apparent borehole instability within a subterranean shale-containing earth formation is due to a chemically induced swelling, comprising:
- contacting a portion of shale obtained from said earth formation with a fluid which is, or is substantially equivalent to, the interstitial water contained within said earth formation;
- at least substantially equilibrating the so contacted shale at pressure conditions at least substantially equivalent to those existing in said earth formation;
- contacting said shale with a substantially solids-free sample of the fluid with which said earth formation was being contacted when said borehole instability became apparent at substantially the same pressure conditions at which said shale was equilibrated;
- and,
- detecting whether a significant extent of resultant positive change in the shale swelling strain was exhibited during said contacting of the shale with said fluid sample.
A process for measuring the chemical swelling effect of a fluid on a shale obtained from a subterranean earth formation comprising:
- contacting the shale with a fluid that is or is substantially equivalent to the interstitial water contained in said subterranean formation while said shale and fluid are subjected to a pore pressure and a confining pressure at least substantially equalling those within said subterranean formation;
- replacing the shale-contacting fluid with the fluid to be tested without significantly altering any other conditions of said equilibration;
- and,
- detecting any resultant change in the shale swelling strain which existed during said equilibration.
Dependencies are inferred from the claim text.