Evaluation Method Of Shale Gas Reservoir Fracability Based On Well Logging Data And Hydraulic Fracturing Experiment And Its Applications

Shale gas is a huge global resource with the excellent development prospects.At present,relevant scholars at home and abroad have carried out lots of studies on shale gas enrichment mechanism,reservoir forming conditions and selection of favorable development zones,but there are relatively few studies on the evaluation of hydraulic fracturing fracability of shale gas reservoirs.In this paper,the key factors of hydraulic fracturing fracability of shale gas reservoir are analyzed and studied to construct the index system of hydraulic fracturing fracability of shale gas reservoir.Combining on-site logging data and hydraulic fracturing test results,a fracability evaluation model and method for different types of shale gas reservoirs are proposed from a quantitative point of view.The specific engineering application in the Longmaxi Formation shale reservoir in Jiaoye X well of Chongqing shows that this method can better predict the hydraulic fracturing effect of shale gas reservoirs at different depths The main research work and results are as follows:(1)First,the key factors influencing the shale gas reservoir hydraulic fracturing fracability are analyzed.According to the determined principle of index selection,combined with the simplified analysis of the hydraulic fracturing process,the brittleness index,the coefficient of horizontal stress difference and the rate of liquid injection were selected to construct a fracability evaluation index system for shale gas reservoirs;And based on the previous theoretical research,the corresponding quantitative calculation method for each fracability evaluation index is given.(2)An expert inquiry form is designed for each fracability evaluation index,and relevant experts and researchers are invited to evaluate the importance of each fracability evaluation index,and the weight of each fracability evaluation index is obtained according to the evaluation result;Calculate the weight of each fracability evaluation index through the entropy weight method;The evaluation results of the expert scoring method and the entropy weight method are processed by integrating the optimal weighting method to find the optimal weight of each fracability evaluation index and based on this,a shale gas reservoir fracability evaluation model and evaluation method based on well logging data and hydraulic fracturing test were constructed.(3)The hydraulic fracturing test of the Longmaxi Formation shale specimen was carried out,and the test fitting results were brought into the shale gas reservoir fracability evaluation model to establish the Longmaxi Formation shale gas reservoir fracability evaluation formula;Using the logging data of the developed Jiaoye X well in Jiaoshiba area,the fracability of shale gas reservoir of Longmaxi Formation was evaluated and divided and optimized the fracturing section.The fracability evaluation method was verified using the fracturing reconstruction volume of each fracturing section obtained by microseismic monitoring in the actual fracturing operation of Jiaoye X Well,and combined with the fracturing reconstruction volume,simulation optimizes and adjusts the pump displacement during the fracturing operation to improve its expected fracturing effect.