Characterization of hydraulic fracture configuration based on complex in situ stress field of a tight oil reservoir in Junggar Basin, Northwest China.

The Jurassic Badaowan formation of the tight oil reservoir in northwest Xinjiang, China, is featured by a complex in situ stress pattern, leading to an unclear understanding of the orientation and geometry of a propagated hydraulic fracture. In this regard, a three-dimensional (3-D) in situ stress field was first configured based on a detailed mechanical earth model of the region of concern. Secondly, a fluid-solid-damage coupling model was established to explore the influences of the in situ stresses and the engineering parameters on fracture propagation. Finally, a systematic approach was proposed to characterize the updated stress field and the fracture morphology reconfigured by the in situ stress. The findings disclose that the reservoir is mainly controlled by reverse faults that generate horizontal fractures in most parts of the region. The in situ stress follows the strike-slip fault pattern where vertical fractures are dominant in the central and southeastern part of the reservoir, where the vertical fracture tends to be constrained in the oil layer when the interlayer minimum stress difference ∆Sh becomes greater than 4 MPa in the southeast. In addition, as the injection rate increases, the width of a fracture increases, whereas its height decreases. The viscosity has negligible effect on the fracture height, but its increase can enlarge the fracture width and decrease the length. Here, the cross-dipole shear wave logging record in a field well was used to verify the proposed method, showing that the predicted fracture morphology was consistent with the field test result. The research can aid field engineers in predicting fracture morphology for optimizing a fracturing scheme. [ABSTRACT FROM AUTHOR]