Optimization of Fracture Spacing in Horizontal Well of Intermediate-Basic Volcanic Gas Reservoir

Horizontal Wells of intermediate-basic volcanic gas reservoir in Songliao Basin have low production after fracturing and weak stable production ability. How to set fracture spacing reasonably and improve recovery percent is the key to increase production. Based on the seepage theory, three methods of productivity maximization, orthogonal factor Z-value maximization and seepage interference theory are used to study and analyze the reasonable fracture spacing matching relationship between reservoirs with different permeability conditions.The results show that, with the decrease of fracture spacing, the recovery percent increases, but the growth is getting smaller and smaller. When the fracture spacing decreases to a certain value, the recovery percent is very small with the increase of fracture spacing, which is called the critical fracture spacing (90% of the maximum recovery percent), and the smaller the reservoir permeability, the smaller the critical fracture spacing. In a certain permeability level, there is an optimal fracture spacing value, the best fracturing effect. The optimal fracture spacing chart of intermediate-basic volcanic rocks was established and the functional relationship between the optimal fracture spacing, corresponding optimal recovery percentand reservoir permeability was fitted, which can provide reference for the optimization design of fracturing process parameters of similar reservoir.