Cluster spacing optimization of deep shale gas fracturing with non-uniform geostress

Abstract

Cluster spacing optimization in non-uniform stress field, with the optimal stimulated reservoir volume (SRV) as target, which is critical for deep shale gas fracturing performance. A non-uniform stress field characterization model and a fracture network propagation model were constructed. The diagrams of the optimal cluster spacing were drawn based on the fault development in the Y1-01 well area. The results showed that the horizontal well should be deployed at a distance of between 2,000 and 4,000 m from the first-level fault, 1,500 and 2,500 m from the second-level fault, 700 and 1,200 m from the third-level fault, and an acceptable distance from the fourth-level fault. The shorter the distance to the fault for first-level faults, the bigger difference in horizontal stress, which was not conducive for fracture network propagation, and the smaller the optimal cluster spacing. For second-level, third-level, and fourth-level faults, when the fault strike was less than 50°, the closer to the fault, the bigger the difference in horizontal stress and the smaller the optimal cluster spacing. When the fault strike was greater than 50°, the farther away from the fault, the bigger the difference in horizontal stress, and the smaller the optimal cluster spacing.