Study On Optimization Of Fracturing And Energy Supplement For Infill Horizontal Wells In Tight Reservoir In Well District M

Among the recoverable petroleum resources in China,tight reservoirs are rich in reserves,widely distributed and have broad development prospects.However,due to low reservoir permeability and complex pore throat structure,conventional fracturing can not improve tight oil production.With the development of horizontal well technology,the application of horizontal well technology in the development of low permeability reservoirs has broad prospects.However,since the formation pressure of low-permeability oil field decreases greatly after long-term exploitation,the degree of pressure drop varies in different well areas due to the influence of well pattern development,so it is difficult to establish an effective displacement system.Therefore,energy supplement optimization is required before fracturing.Through the coupling mechanism simulation method of in-situ stress field and seepage field,this paper combines the traditional reservoir seepage simulation with geomechanical simulation to study the pressure,stress field and artificial fracture propagation law in the development process,which provides a strong support for the optimization of energy supplement and fracturing parameters of infill horizontal wells.Based on well logging data,seismic data and reservoir research data in well district M,a three-dimensional geological model of reservoir is constructed in this paper.Combined with the rock mechanics parameters,the rock mechanics model is established,and the in-situ stress in the well area is simulated.Through the finite element simulation of the original in-situ stress field and the development performance data,the formation pressure and in-situ stress field models are established.By analyzing the variation law of the formation pressure and in-situ stress,the reference is provided for the next step of energy supplement optimization before fracturing.The design schemes of different energy supplement methods in well district M are explored.For different energy supplement media,taking gas medium and water medium as examples,the changes of formation pressure and ground stress of adjacent old wells under different conditions are simulated.At the same time,the expansion of artificial fractures is explored,the reservoir reconstruction volume under different energy supplement media is analyzed,and the water medium is determined as the optimal energy supplement medium;For different infill well spacing,the corresponding well spacing of 1-3 infill wells is simulated to be 600m,400m and 300m respectively.Based on the understanding of the changes of formation pressure and geostress of infill wells and surrounding old wells,and the analysis of the propagation law of artificial fractures,300m well spacing is determined as the optimal infill well spacing;Based on the relationship curve between formation pressure and single well fluid replenishment energy,the reasonable fluid replenishment energy of old wells and infill wells is studied respectively,and the relationship curve between single well formation pressure and single well fluid replenishment energy is analyzed.Combined with the comparative study of pressure and stress field and artificial fracture expansion law,the transformation volume under each fluid replenishment energy is determined,and it is obtained that the optimal fluid replenishment energy of old wells and infill wells is 20000m~3 and 15000m~3 respectively.Finally,the fracturing process design and optimization of well district M are studied,and the fracturing parameters are optimized according to the half fracture length,fracturing section length,number of fracturing clusters,fracturing fluid volume and sand addition volume.The results show that the half fracture length of the fracture is 120-140m,the length of the fracturing section is 90-100m,each section has 4-6 clusters,the amount of fracturing fluid in a single section is 1600m~3,and the amount of sand added is 180m~3.According to the optimization results of fracturing parameters,the artificial fractures of infill wells are simulated.The designed fracturing optimization parameters have good adaptability to the actual production data of infill wells.The optimized M well area is analyzed for the post fracturing effect of single well and the whole area.It provides guidance and basis for optimization of fracturing and energy replenishment of infill horizontal wells in M tight reservoirs.