Experimental Investigation of the Growth Law of Multi-Fracture during Temporary Plugging Fracturing within a Stage of Multi-Cluster in a Horizontal Well

Abstract

Temporary plugging fracturing in a horizontal well with multi-stages and multi-clusters is usually used to improve stimulation efficiency and increase the gas production from shale gas reservoirs. However, the fracture propagation geometry and the mechanism of temporary plugging are still unclear, which restricts the further optimization of temporary plugging fracturing scheme. In this study, taking the Longmaxi shale as the research object and considering the intrafracture and intrastage temporary plugging, the true tri-axial hydraulic fracturing system was used to put forward an experimental method for simulating the temporary plugging fracturing in a horizontal well with multi-stages and multi-clusters. Afterward, the effects of the size combination and concentration of temporary plugging agents and the cluster number in a stage on the fracture geometry created in the secondary fracturing were investigated in detail. The results show that an optimal fracture propagation geometry tends to be obtained by using the combinations of 100 to 20/70 mesh, and 20/70 to 10~18 mesh temporary plugging agents for the intrafracture and intrastage temporary plugging, respectively. Increasing the proportion of the temporary plugging agent of a larger particle size can improve the effectiveness of intrafracture and intrastage temporary plugging fracturing, and tends to open new fractures. With the increase in temporary plugging agent concentration and the cluster number within a stage, both the number of diverting fractures formed and the overall complexity of fractures tend to increase. After fracturing, the rock specimen with a high peak in the temporary plugging pressure curve has more transverse fractures, indicating a desirable diversion effect. By contrast, the fractured rock specimen with a low peak pressure has no transverse fracture, generally with fewer fractures and poor diversion effect.

Special Issue “Petroleum Engineering: Reservoir Fracturing Technology and Numerical Simulation”

“…They found that effective temporary plugging can be achieved by using a temporary plugging agent with the proper size and concentration. Li et al [2] also studied the fracture growth mechanism of diverting fracturing. They found that increasing the proportion of the temporary plugging agent of larger particle size can improve the effectiveness of intra-fracture and intra-stage temporary plugging fracturing, and tends to open new fractures.…”

Numerical Simulation of the Transport and Sealing Law of Temporary Plugging Particles in Complex Fractures of Carbonate-Type Thermal Storage

“…Li et al [16] conducted indoor multi-cluster temporary plugging fracturing experiments in horizontal shale wells; investigated in detail the effects of fracture spacing, the number of fractures, ground stress, and the type of injected fluids on the initiation of multi-cluster fractures; and quantitatively investigated the expansion pattern of multi-cluster fractures during the TPDF process. Li et al [17] proposed a new method of multi-stage and multi-cluster temporary plugging experiments in horizontal wells that considered fracture temporary plugging and segmented temporary plugging and investigated the effects of the particle size combinations of the plugging agent, its concentration, and the number of clusters at a certain stage on the geometry of fractures. Chen et al [18] developed a new thermo-responsive temporary plugging agent by conducting indoor tests that were successfully applied in the field, and the production and injection data in the field proved that the effect of production increase was remarkable.…”

Multi-Fracture Growth Law for Temporary Plugging and Diversion Fracturing of Horizontal Well with Multiple Clusters in Shale Reservoir

“…To gain insights into the growth behavior of multi-fracture during TPDF, numerous studies have been conducted by scholars. These studies have revealed that the effectiveness of temporary plugging is influenced by factors such as geological conditions (e.g., horizontal differential principal stress ∆σ h , temperature, BPs, natural fractures, and induced stress of primary fractures) and operational parameters (e.g., type, particle size, concentration, and viscosity of plugging agents, as well as displacement of fracturing fluid) [1][2][3][4][5][6][7]. Different plugging positions result in different diversion fracture patterns.…”