关键词: 深层页岩, 数值模拟, 裂缝形态, SRV, 主控因素

Abstract: There are abundant deep shale gas resources in China. For deep shale gas wells,the casing pressure is usually very high and it is difficult to pump proppants during hydraulic fracturing treatment,however,the production is low as well. How to generate effective fracture system remains an urgent and unresolved issue in deep shale gas wells. Thus,based on lab experiments together with microseismic monitoring data,a fracture propagation model was established using discrete fracture network model of Meyer,especially for deep shale gas wells in southeast Sichuan Basin,and the simulation accuracy is above 85%. Through orthogonal design and variance analysis,it is defined that fracturing fluid viscosity is the main controlling factor affecting fracture geometry especially for fracture width and SRV in deep shale gas wells,and there are two stages for the fracture propagation progress:the rapid growth stage in the early 1/5-1/4 pump time,and the following moderate growth stage. The fracturing design principle was put forward for the target block:fine field control with larger fluid displacement and moderate operation scale,hybrid hydraulic fluid with various viscosity to achieve fully fracture propagation, and continuous smaller proppant loading mode with lower concentration to prop fracture effectively. The fracturing parameters were optimized such as fracturing fluid volume,proppant volume and fluid displacement. A sample horizontal well buried more than 3 900 m was fractured with comprehensive sand-liquid ratio up to 3.51% and maximum sand volume per stage up to 80.6 m³,and the testing production was 11.4×10⁴m³. The research could provide fracturing references for similar horizontal wells in deep shale gas play.

Key words: deep shale, numerical simulation, fracture geometry, SRV, main controlling factors