Showing papers by "Maurice B. Dusseault published in 2006"

3D Coupled Displacement Discontinuity and Finite Element Analysis of Reservoir Behavior during Production in Semi-infinite Domain

Abstract: In this paper, we apply a DDM-FEM coupling method to reservoir simulation to evaluate the reservoir behavior over a compacting oil reservoir in half space. We use displacement discontinuity methods to account for the reservoir surroundings, and finite element methods in the fully coupled simulation of the reservoir itself.

Simulation of Tectonic Deformation and Large Area Casing Shear Mechanisms----Part B: Geomechanics

Abstract: We present a study on the causes of large-area casing deformation mechanisms in one area experiencing extensive casing shear in the Daqing Oilfield, China. We use stress data and numerical stress simulation experiments under various injection situations. Instead of qualitatively stating the cause of large areas of casing shear, as in most previous work, we carried out a series of analysis of the effect of rock properties, casing displacement experiments under in situ stress changes, and slip mechanism determination. We developed a mathematical model to quantitatively compute the coupled effect between the tectonic stress field and the induced stresses from high-pressure water injection. Our study indicates that large-area casing shear in Daqing Oilfield occurs in weak lithological interfaces within the overburden; the increase of water content in shale formations decreases cohesion and the friction angle (shear resistance degradation); and, variation of injection pressure generates a clear perturbation of the regional stress field. Once the maximum compressive stress parallels or nearly parallels the maximum differential pressure gradient, the stability of strata in shear is severely compromised. Simulation results for various schemes show that so long as the injection pressure and pressure differential between blocks are controlled to be less than 12.7 MPa and 0.86 MPa respectively, formation shear slip along horizontal surfaces will no longer occur. Multi-disciplinary casing shear mitigation methods are recommended. Our method and the results can serve as a reference for other similar oilfield circumstances.