The Effect of Anisotropy on the Borehole Instability in Carbonate Reservoir
Carbonate reservoirs are characterized by extremely heterogeneity full of microcracks and vugs in it. It also presents anisotropic property of water filtration in terms of distribution of microcracks and void space. Incidents are common practice when drilling through carbonate formation such as loss circulation and borehole breakout. In drilling through fractured carbonate formation in North China, excessive volume of cavings accompanied significant volume of mud loss. To better understand the mechanism of this instability, both laboratory experiment and numerical simulation are conducted. The laboratory mechanical testing provides insight for the bearing capacity of carbonate rock and assists calibration for numerical modeling. Discrete element method (DEM) is used in this study to establish wellbore model. To characterize the anisotropy of pore space and microcracks, smooth-joint contact model is used. In addition, hydraulic flow in microcracks and matrix in the model is coupled with mechanical analysis. Discrete element-based hollow wellbore model is validated with analytical solution to gain reliability on the modelling. After running a specified time, the modeling results show that no fracture is induced in this incident, but significant mud loss is observed.
C. Zeng and W. Deng, "The Effect of Anisotropy on the Borehole Instability in Carbonate Reservoir," Proceedings of the 53rd U.S. Rock Mechanics/Geomechanics Symposium (2019, Brooklyn, NY), American Rock Mechanics Association (ARMA), Jun 2019.
53rd U.S. Rock Mechanics/Geomechanics Symposium (2019: Jun. 23-26, Brooklyn, NY)
Civil, Architectural and Environmental Engineering
Keywords and Phrases
Anisotropy; Boreholes; Carbonation; Finite difference method; Infill drilling; Mechanical testing; Numerical models; Oil field equipment; Petroleum reservoirs; Pore pressure; Rock mechanics; Water filtration, Anisotropic property; Borehole instability; Carbonate formations; Carbonate reservoir; Fractured carbonates; Joint contact modeling; Laboratory experiments; Mechanical analysis, Microcracks
Article - Conference proceedings
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01 Jun 2019