Numerical Simulation Study On Staged Fracturing Effect Of Horizontal Wells In Shale Gas Reservoirs

With the progress of science and technology in the field of oil and gas development,the last part of twentieth Century has entered the industrial exploitation of gas,and it is known as another "gold mine" buried underground.However,because of its nanoscale porosity and ultra-low permeability,the shale gas reservoirs mostly use the high efficiency mining method of horizontal well section fracturing,and the fracture is formed by fracturing,and the maximum increase of reservoir moving rate is achieved.Therefore,the evaluation of fracturing effect is very important for shale gas development.At present,the fracturing effect is evaluated mainly by means of micro seismic monitoring and numerical simulation.This paper introduces four monitoring methods:micro seismic monitoring,fracture tomography monitoring,inclinometer crack monitoring and tracer monitoring.By implementing monitoring measures,we can improve the understanding of underground reservoirs and find more "sweets" accurately,that is,the areas where shale gas is more.Researchers can clearly identify the distribution and direction of artificial cracks and natural cracks in underground,but the construction of monitoring technology is difficult,high cost and a certain risk.Therefore,sensitivity analysis of fracture parameters and adsorption capacity is carried out by numerical simulation,and the effect of different parameters on yield is studied.In this paper,the characteristics of shale gas reservoir are analyzed and analyzed by the method of isothermal adsorption by weight.The relationship between adsorption gas and pressure and temperature is obtained,and the Langmuir equation suitable for the geological and rock characteristics of the target area is established.The calculated adsorption gas content is compared with the measured core isothermal adsorption gas volume(simulated to the gas reservoir state),and the correlation and accuracy of the two are evaluated.The fracture parameters of fractured shale gas are analyzed theoretically from the angle of stress,and the relationship between the length and width of the fracture and the distance between the main cracks and the law of fracture extension are obtained,which provides a reliable basis for the setting of the geological reserves and the parameters of the fracture in the subsequent numerical simulation study.The equivalent geological model of shale gas reservoir is established based on fracture tomography data.Based on PEBI grid,the influence factors of single well fracturing effect in target block were numerically simulated by using commercial software ECLIPSE.The influence of the content of adsorbed gas,the half length of the crack,the number of cracks in the cluster,the interval between the segments,the permeability of natural fracture and the mode of distribution of the fracture are studied and analyzed.