Study On Temporary Plugging And Diversion Refracturing Technology Of Shaximiao Formation In Xinchang Gas Field

In this paper,the fracturing engineering geological characteristics of shaximao formation in xinchang gas field are studied,Firstly,the performance of the temporary plugging agent used in refracturing is evaluated by experiments,Secondly,the in-situ stress distribution before refracturing is calculated,Thirdly,the in-situ stress distribution before refracturing is calculated,Finally,combined with extended finite element theory,the expansion trajectory of refracturing fractures is simulated.The refracturing technology of shaximao formation gas reservoir in xinchang gas field has been formed and some research results have been obtained.The main contents are as follows:(1)The reservoir characteristics,physical parameters,petrological characteristics and sensitivity evaluation of shaxi miao reservoir in xinchang gas field are collected and sorted out.According to the national standard GB/T50266-2013 engineering rock mass test method standard,the triaxial rock mechanical property parameter experimental test and the Kaiser effect test in-situ stress experimental study of core sample were carried out.The rock mechanics parameters and in-situ stress parameters of the target area are determined.(2)The principle and performance requirement of temporary plugging agent are analyzed,Comprehensive experimental evaluation was carried out oii the temporary plugging performance of fiber temporary plugging agent,the solubility,temporary plugging and compatibility of granular temporary plugging agents ZDJA and ZDJB.The results show that the effect of using fiber temporary plugging agent alone is limited.However,no matter the particle temporary plugging agent with single particle size or combined particle size,the temporary plugging effect is better with smaller particle size;Combined particle size can achieve single particle size plugging effect and can reduce the amount of temporary plugging agent;The greater the thickness,the better the temporary plugging effect.(3)The mechanism model of production-induced in-situ stress in the target gas reservoir is established based on the principle of effective in-situ stress and the Eclipse numerical simulation software.Based on the characteristic parameters of-shaxi miao reservoir in xinchang gas field,a large number of numerical simulation calculations are carried out on the production dynamics,formation pressure and in-situ stress changes in the production process.The variation of in-situ stress under different permeability was studied.Based on the simulation results of formation pressure and in-situ stress of target reservoirs in two and five years of production,the induced in-situ stress field of refracturing production is determined.(4)The simulated pre-refracturing in-situ stress data are imported into the finite element software of ABAQUS through the Python interface installed in ABAQUS.The research reSLilts of this paper provide certain theoretical basis and technical support for temporary plug refracturing in unconventional gas fields,and provide a correct idea for refracturing technology.According to the equilibrium equation of solid skeleton in porous media and the continuity equation of fluid in porous media,the fluid-solid coupling mathematical model of reservoir is established.Considering the influence of changes in fonnation in-situ stress and pore pressure on refracturing after production,Finally,the finite element solution of ABAQUS was used to simulate the steering trajectory of the old crack after the temporary plugging agent was used to temporarily plug the old crack,and the steering extension of the crack under different influencing factors was studied.(5)Taking well X of xinchang gas field as an example,the optimal design of refracturing is carried out by simulating the steering track of temporary plugging and selecting temporary plugging materials.The comparison of microseismic monitoring shows that the theoretical simulation is in good agreement with the field practice.The correctness of the theory is proved.The research results of this paper provide certain theoretical basis and technical support for temporary plug refracturing in unconventional gas fields,and provide a correct idea for refracturing technology.