In steam injection process, the injection well is subjected to high temperature heating. Heat is conducted from the injection well through metal casing, grout cement annulus, and surrounding geological formation. In low-permeability and water saturated formations such as clay shale, high excess pore pressure can be induced in the formation due to heat-driving mechanism. If the rate of increasing excess pore pressure was higher than that of overburden stresses, the tensile fracturing could occur. Development of such tensile fracturing destroys the hydraulic integrity of the shale formation, thereby resulting in casing impairment and environmental concern. This geomechanical phenomenon can aggravate the heavy oil production performance. This paper mainly focuses on the coupling between thermal-hydro-mechanical aspects of the steam injection, formation deformation, and the resulting collapse/fracture of structure shale. An updated coupled fracture element technique with fully implicit Galerkin finite element methods has been incorporated into this refine simulating process. The numerical results also suggest a strong influence from heating rate and shale permeability on the pore pressure and fracturing development around thermal well. Therefore, the permeability parameters, in-situ stress, and the strength of casing structure, should always be a main concern to complete production scheme.
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