Optimization of Hydraulic Fracture Parameters in Shale Oil Reservoirs Based on Embedded Discrete Fracture Model

The shale oil reservoirs in the Lianggaoshan Formation of the Sichuan Basin exhibit low porosity, low permeability, complex lithological combinations, and localized natural fracture development. The unclear demand for hydraulic fractures in reservoir stimulation leads to suboptimal results and challenges in cost-effective development. To enhance stimulation effectiveness and improve design precision, this study builds a multi-scale fractures flow model using the embedded discrete fracture model (EDFM). This model incorporates lithological combinations,varying natural fracture development. The response surface methodology (RSM) is applied to establish a relationship between cumulative oil production and multiple factors, including sand-shale ratio, natural fracture intensity, cluster spacing, hydraulic fracture length and conductivity. Optimization research on hydraulic fracture parameters under multifactorial influences is conducted. Key findings include: (1) The EDFM-based multi-scale fractures flow model demonstrates fast computation, strong adaptability to complex fracture systems, and high accuracy. It effectively analyzes hydraulic fracture parameter requirements under low-permeability conditions, diverse lithological combinations, and varying natural fracture development; (2) RSM enables comprehensive analysis of complex fracture flow simulation results under multiple variables. It establishes quantitative relationships between various influencing factors and cumulative oil production, clarifies variation patterns in production performance, and ultimately optimizes the selection of the best fracture parameter combinations; (3) In reservoirs with well-developed natural fractures, demand for long hydraulic fractures and small cluster spacing is low. High fracture conductivity is prioritized for fracture-dominated shale reservoirs; (4) In reservoirs with underdeveloped natural fractures (pore-dominated systems), long fractures and small cluster spacing are critical. Conductivity enhancement is secondary. Such reservoirs prioritize extending fracture length and shortening flow distances before improving conductivity; (5) In sand-shale interbedded reservoirs (interlayered shale systems), production is highly sensitive to sand-shale ratio, cluster spacing, fracture length, and conductivity. (6) The fracture parameter combination charts developed based on RSM demonstrate strong adaptability. These charts can effectively guide the optimization of stimulation parameters for different reservoir types, enhance treatment precision, and consequently improve productivity. Optimal development requires targeting high sand-shale ratio zones and constructing small cluster spacing, long and high-conductivity hydraulic fracture systems.