Fracturing Spacing Optimization Study of Tight Oil Horizontal Well Based on Induced Stress Field

Abstract

Tight oil reservoirs in the Songliao Basin have characteristics such as poor permeability parameters and undeveloped natural fractures. Reducing the fractural spacing and subdivision cutting the reservoir is to explore the trend and direction of enhancing SRV and recovery. This paper analyzes the induced stress field during the fracture propagation process of horizontal well tight cutting, and then uses XFEM numerical simulation method to study the optimization of fracture spacing. The results show that with the increase of the distance from the fracture, the induced stress difference caused by the pre-fracture in the horizontal well increases first and then decreases. In the effective range where the induced stress difference is greater than 0, turning or even reversal occurs when a new fracture is propagated. Define the corresponding position when the induced stress difference equals the initial geostress field difference as the minimum cluster spacing ΔLmin. During the fracturing construction, arranging fractures larger than ΔLmin can ensure that the cluster spacing is as small as possible and also allow the fractures to expand normally. As a result, multiple parallel effective main fractures are formed to achieve dense cutting of tight oil reservoirs, thereby increasing the SRV. This conclusion can be used as reference for the optimization design of subdivision cutting and fracturing spacing in Daqing Oilfield and other tight oil reservoirs in the future.KeywordsInduced stress fieldHorizontal wellSubdivision cuttingFracture spacing