Method of determining redox potential

Claim 1

A method of determining the redox potential of a fluid system comprising: a. contacting said fluid system with a two electrode redox potential measuring system, b. observing the redox potential values after the measuring system is in contact with the fluid system for four minutes and for 5 minutes, c. plotting on linear graph paper the observed redox potential versus the time factor 1/time, and d. drawing a straight line through the plotted redox potential values and extrapolating to infinite time to give the desired infinite time value of the redox potential.

Claim 2

A method of determining the redox potential of a fluid system comprising: a. contacting said fluid system with a two electrode redox potential measuring system, b. observing the redox potential values after the measuring system is in contact with the fluid system for four minutes and for 5 minutes, c. plotting on linear graph paper the observed redox potential versus the time factor 1/time, and d. drawing a straight line through the plotted redox potential values and extrapolating to infinite time to give the desired infinite time value of the redox potential.

Claim 4

A method for detecting the approach of an underlying abnormally pressured zone while drilling normally pressured zones of a subterranean strata comprising: a. drilling the normally pressured zones with a drilling fluid whose pressure is balanced against the subterranean strata pressure, b. periodically preparing an aqueous slurry of cuttings removed from the well, c. contacting said aqueous slurry with a two electrode redox potential measuring system, d. observing the redox potential value 4 minutes and five minutes after the measuring system is in contact with the aqueous slurry, e. making a first plot on linear graph paper of the observed redox potential values versus the time factor 1/time, f. drawing a straight line through the plotted redox potential values and extrapolating to infinite time to give the desired infinite time value of the redox potential, g. making a second plot on linear graph paper of the extrapolated redox potential value versus depth from which the cuttings in the aqueous slurry came, h. when the rate of change of extraploated redox potential with depth begins to change greatly, instituting controlled drilling procedures, and i. when the abnormally pressured zone is penetrated, adjusting the drilling fluid pressure to balance the same againSt the pressure in the abnormally pressured zone.

Claim 5

A method for detecting the approach of an underlying abnormally pressured zone while drilling normally pressured zones of a subterranean strata comprising: a. drilling the normally pressured zones with a drilling fluid whose pressure is balanced against the subterranean strata pressure, b. periodically preparing an aqueous slurry of cuttings removed from the well, c. contacting said aqueous slurry with a two electrode redox potential measuring system, d. observing the redox potential value 4 minutes and five minutes after the measuring system is in contact with the aqueous slurry, e. making a first plot on linear graph paper of the observed redox potential values versus the time factor 1/time, f. drawing a straight line through the plotted redox potential values and extrapolating to infinite time to give the desired infinite time value of the redox potential, g. making a second plot on linear graph paper of the extrapolated redox potential value versus depth from which the cuttings in the aqueous slurry came, h. when the rate of change of extraploated redox potential with depth begins to change greatly, instituting controlled drilling procedures, and i. when the abnormally pressured zone is penetrated, adjusting the drilling fluid pressure to balance the same againSt the pressure in the abnormally pressured zone.