Optimization of Fracturing Parameters for Channelized Tight Sandstone Gas Reservoir Development with Surrogate Models

Abstract

ABSTRACT: The channelized tight sandstone gas reservoir in Jinqiu gas field, China, is mainly produced with hydraulic fractured horizontal wells. Currently, the fracturing parameters (e.g, cluster spacing and injection volume) are optimized with given sand body shape, which has strong limitations when applied to complex sand body geometries in practice. In this work, we try to construct a method to find the optimal parameters for arbitrarily shaped sand. First, a surrogate model for fracture geometry prediction based on numerical simulation results is built using a deep neural network (DNN). Then, the embedded discrete fracture model (EDFM) is used to characterize the fractures and evaluate the effectiveness of different fracturing designs. With the above models, we first find the optimal designs of fluid injection volume and fracture spacing for difference reservoir types and sand height/length. Optimization for horizontally and vertically curved sand bodies are then conducted to show the impact of sand geometries on fracturing parameter designs. The surrogate model proposed in this work helps to quickly predict the fracture geometries, which makes it possible to optimize fracturing parameters with optimization algorithms. 1. INTRODUCTION Tight gas, due to its advantages such as widespread distribution and abundant reserves, has occupied a key position in the development of unconventional natural gas in China (Zeng et al., 2024). Compared with conventional gas reservoirs, tight gas reservoirs usually have characteristics such as low porosity, high water saturation, and low permeability, making the optimization of fracturing parameters more complex (Zhang et al., 2022). The Shaximiao reservoir in the Jinqiu gas field is a typical tight gas reservoir, with porosity ranging from 8% to 16%, averaging 12.31%, and permeability ranging from 0.01 mD to 1 mD. The channel width is 200 – 4800 m and the sand thickness is 5 – 40 m (Fig. 1 and Fig. 2). The Jinqiu gas field is a typical narrow channelized sandstone gas reservoir, which is mainly produced with hydraulic fractured horizontal wells. To further increase the production, it is necessary to optimize the fracturing parameters considering the sand body geometries.