Numerical Study on Inter-Well Interference Characteristics During Well-Pad Production of Shale Gas: A Case in Southern Sichuan, China

ABSTRACT: With the development of shale gas horizontal well infill technology, by drilling infill Wells between Wells, the well spacing is continuously reduced, which makes the shale reservoir reconstruction more effective. However, in China's shale gas reservoirs, particularly those in the deep layers of southern Sichuan, the problem of inter-well interference has become increasingly severe. Currently, the process of interference in the production process is unclear. This study addresses the inter-well interference issue in deep shale gas reservoirs. An integrated numerical method combining Discrete Fracture Network, Finite Element Method, and Finite Difference Method is proposed. A comprehensive reservoir numerical model considering production process is proposed. According to the actual reservoir model parameters and operation parameters, a multi-factor analysis model under multiple production conditions is established. The gas production cumulative and inter-well interference were analyzed. Finally, the field model is established and the history matching of formation pressure is carried out. According to the history matching results, the pressure expansion range in the production stage is analyzed. These research results provide scientific basis and practical suggestions for effective management and mitigation of inter-well interference, and are expected to play an important role in practical engineering applications. 1. INTRODUCTION With the development of shale gas horizontal well infill technology, by drilling infill Wells between Wells, the well spacing is continuously reduced, which makes the shale reservoir reconstruction more effective (Ren et al., 2021; Fan, 2020; Yang, 2020 and Yu et al., 2020). In the fracturing process of infill Wells, when well spacing is too small or adjacent Wells are fractured too much, it is often observed that the pressure of existing Wells suddenly increases, the production drops sharply, and it is difficult for new Wells to maintain high net pressure (Zhang et al., 2011 and He et al., 2012). This indicates that there is communication between the mother and child well. This fracturing induced inter-well interference is commonly known as Frac Hit (Guptake et al., 2021). The problem of Inter-well interference in shale gas reservoirs in China is becoming more and more serious. It is mainly reflected in the two stages of fracturing and post-compression mining. The main manifestation is the disturbance of wellbore pressure. Severe Inter-well interference can lead to wellhead damage, compromise well integrity, and even lead to well abandonment (Li et al., 2023 and Kurtoglu and Salman, 2015). Among them, the most serious situation is the occurrence of Inter-well interference response during fracturing and production. At present, there is a lack of research on Inter-well interference, and the process of Inter-well interference in post-pressure production is still unclear. Field practice has shown that inter-well interference caused by fracturing has become a major difficulty faced by the shale industry, which will have many negative impacts on platforms and adjacent platforms (Jacobs, 2017).