Study On Optimal Proppant Injection Intensity Of Shale Gas Reservoir

In 2020,China’s shale gas production has reached 20 billion cubic meters,accounting for 10.4% of China’s total natural gas production,and shale gas has become an important part of China’s energy market.The effective development of shale gas is attributed to the great progress and development of volumetric stimulation technology of horizontal wells with long-stage and multi-cluster fracturing,among which,proppant injection intensity is an important factor affecting the volumetric stimulation of shale gas.High-intensity proppant injection fracturing technology can better fracture shale gas reservoirs and achieve higher production,however,high-intensity proppant injection can lead to higher fracturing costs.Therefore,it is important to study the optimal proppant injection intensity for shale gas development.In this thesis,it is found that the proppant injection intensity mainly affects the fracture conductivity.Therefore,this thesis investigates the optimal dimensionless fracture conductivity of single-stage 5-,7-and 15-clusters fracturing models for horizontal shale gas wells with the objective of optimal cumulative production,and considers the effects of four scenarios,namely,no natural fractures and natural fracture spacing of 0.1 m,10 m and 50 m,on the optimal dimensionless fracture conductivity.Using CMG numerical simulation software,it is found that the cumulative production increase in the short term exceeds 20% when the number of clusters exceeds 5 and the fracture half length exceeds 85 m compared to conventional 3-cluster fracturing.Moreover,the smaller the natural fracture spacing is,the more developed the fracture network system is and the higher the development potential is,so it can increase the production rapidly in a short period of time and the required dimensionless fracture conductivity is higher.And it is found that the optimal dimensionless fracture conductivity for single-stage 5-,7-and 15-cluster fracturing models is 200-320 for shortterm payout criteria and 90-150 for long-term payout criteria,the former is much higher than the latter.Finally,the optimal fracture conductivity of the short-term and long-term fracture performance criteria are used to numerically simulate the optimal proppant injection volumes of 40/70 mesh quartz sand and 70/140 mesh quartz sand for fracturing 5-,7-and15-cluster in a single stage.The numerical model results are compared with the proppant injection process parameters of the fracturing experimental wells to improve and refine the optimal proppant injection optimization model for shale gas in the target block,and to provide a basis and reference for the determination of the proppant injection process for future fracturing in the target block.