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Finite Difference Modeling for Wellbore Stability Analysis in Various Fluid Flow Scenarios

Nordin, Noor Azree

Engineering Honours Degree, 2006

University of Adelaide

Executive Summary

The purpose of this honours project is to summarize the wellbore stability analysis in various fluid flow analyses. The analyses are based on parameters extracted from the modelling such as flow vectors, pore pressure changes, displacements of the formation, and principal stresses around the wellbore. In order to obtain these results, fluid flow models have been done and results from these models are presented in this summary.

Model 1 shows that the flow vector is decreasing with time. Moreover, Model 1 proves that normal faulting regime gives less displacement of formation and yields the lowest principal stresses around wellbore compared to strike slip and reverse faulting regimes.

Model 2 successfully establishes the fact that mud pressure applied on the wellbore exerts sufficient hydrostatic pressure against the wellbore preventing failure and flow of formation fluids into the well thus yields a low value of principal stress.

In the cased and cemented borehole, values of flow vector and principal stresses around the wellbore are three times lower than the values obtained from Model 1 which is the basecase for this experiment.

In the final analysis, which is half cased and cemented borehole, linear relationship between permeability of the formation with flow vectors has been established. The experiment also shows that permeability changes will not affect the displacement of the formation.

Further work and studies in fluid flow analysis around wellbore should be done rigorously in order to establish good understanding in wellbore stability analysis. Fluid flow contributes significant impact to the stability of the wellbore because it can effects the displacement of the formation and principal stresses around the borehole. For this reason, more attention should be placed on analysing fluid flow behaviour around the wellbore.

Australian School of Petroleum



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