2 research outputs found
Numerical ModelāSoftware for Predicting Rock Formation FailureāTime Using Fracture Mechanics
Realātime integrated drilling is an important practice for the upstream petroleum industry. Traditional
preādrill models, tend to offset the data gathered from the field since information obtained prior to
spudding and drilling of new wells often become obsolete due to the changes in geology and geomechanics
of reservoirārocks or formations. Estimating the complicated nonālinear failureātime of a rock
formation is a difficult but important task that helps to mitigate the effects of rock failure when drilling
and producing wells from the subsurface. In this study, parameters that have the strongest impact on
rock failure were used to develop a numerical and computational model for evaluating wellbore
instability in terms of collapse, fracture, rock strength and failureātime. This approach presents drilling
and well engineers with a better understanding of the fracture mechanics and rock strength failureprediction
procedure required to reduce stability problems by forecasting the rock/formation failuretime.
The computational technique built into the software, uses the stress distribution around a rock
formation as well as the rockās responses to induced stress as a means of analyzing the failure time of
the rock. The results from simulation show that the applied stress has the most significant influence on
the failureātime of the rock. The software also shows that the failureātime varied over several orders of
magnitude for varying stressāloads. Thus, this will help drilling engineers avoid wellbore failure by
adjusting the stress concentration properly through altering the mud pressure and well orientation with
respect to ināsitu stresses. As observed from the simulation results for the failure time analysis, the
trend shows that the time dependent strength failure is not just a function of the applied stress.
Because, at applied stress of 6000ā6050 psi there was time dependent failure whereas, at higher
applied stress of 6350ā6400 psi there was no time dependent strength failure