Abstract
A tight oil reservoir is characterized by developed natural fractures, strong heterogeneity, and anisotropy. During long-term production, the geomechanical parameters change accordingly, which results in the difference in hydraulic complex fracture propagation between the infill well and the parent well. The difference is the key factor for infill well placement and hydraulic fracturing treatment. In this paper, a numerical modeling method was proposed to investigate the infill well complex fractures propagation based on four-dimensional stress evolution during parent wells production. This method integrates with heterogeneity and anisotropy of geomechanical parameters and natural fractures, as well as the flow-geomechanics coupling process during parent wells production. The field data, including well-test data, fracturing injection data, and numerical simulation data, were involved in verifying the method. A modelling case of the Da13 region in the Junggar Basin tight oil reservoir was involved in studying the four-dimensional in-situ stress evolution and its impact on the propagation law of infill well complex fractures propagation. It can be drawn from the result that all the principal stresses decrease after long-term production, but the stress difference increases. The increase of stress difference is the largest in the region nearby the wellbore. On the basis of the 3D geomechanical modeling, with the consideration of the stress shadow, proppant settlement, and migration, the full 3D coupling simulation of artificial fractures was realized to provide support for the numerical simulation of the post-horizontal well pressure productivity. Based on the actual segmentation of Well Da 136_ H, additional productivity numerical simulation was conducted for seven segment length schemes. The EUR of the 10-year single well ranged from 25100 to 44200 tons. Case 8 provides the best development effect. However, when the fracturing segment length is less than 75 meters, the EUR increases little, and the fracturing cost increases significantly. The recommended single fracturing segment length is 75 meters.
