Patent ID: 6353799
Filing Date: 2002-03-05
Classification: E21B

Abstract:
A method of providing an indicator of potential for abrupt changes in rock strength in a particular wellbore, comprising:(a) obtaining forensic wellbore data from at least one previously drilled wellbore which is determined to be comparable to said particular wellbore; (b) providing an interfacial severity computer program consisting of executable program instructions, and adapted to utilize said forensic wellbore data; (c) loading said interfacial severity computer program on to a data processing system; (d) supplying as an input to said interfacial severity computer program said forensic wellbore data; and (e) utilizing said data processing system to execute program instructions of said interfacial severity computer program to apply said input to said interfacial severity computer program and to produce as an output for a particular predefined interval an indicator of potential for abrupt changes in rock strength in said particular wellbore which utilizes at least one of the following types of measures of rock strength: (1) a measure of relative magnitudes of changes in rock strength over said predefined interval; (2) a measure of rock strength for each rock forming an interface of differing rocks over said predefined interval; and (3) a measure of frequency of changes of rock strength over said predefined interval.