Analysis And Application Of The In-situ Stress Characteristics Of Upper Ganchaigou Formation In Zaha Spring

With the increase of the Qaidam basin exploration and evaluation efforts,Zaha springs area appeared a good exploration prospect.Because the Zaha spring area is still in the initial stage of exploration,the basic research and test data are few,especially the rock mechanics parameters,the magnitude and direction of the in situ stress is lack,it is necessary to carefully analyze the characteristics of rock mechanics parameters and stress of Zaha springs are the specific application of stress characteristics comprehensively and effectively evaluate the purpose layer and in the oil and gas well construction,design of oil and gas field development scheme,provides important technical support for further exploration and development of the ganchaigou formation Zaha springs area.This research combines laboratory experiment,logging calculation and finite element numerical simulation method to determine the magnitude and direction of in situ stress in the southwest of Zaha springs(upper Ganchaigou Formation)area section.Firstly,the static mechanical parameters of the target stratum are measured by the rock mechanics experiment,after establishing the shear move out curve,using the rock mechanics calculation model to calculate the dynamic parameters of rock mechanics in this area,the model of dynamic and static parameters is established.Secondly,according to the working condition,characteristics analysis and computation method of several kinds of formation pressure and stress,and the preferred method of equivalent stress and Huang's model to predict reservoir formation pressure and stress,vertical distribution and gives the area wells mechanical parameters for further finite element numerical simulation of stress field and provide basic data.Then,based on the paleomagnetic orientation technique,this study uses the method of the differential strain analysis(DSA)and the wave velocity anisotropy method to confirm the size and direction of the in-situ stress.Thirdly,the actual geological model of the work area is established by using the geological modeling software,and it is introduced into the finite element numerical simulation software.Finally,based on the target strata stress field simulation results and measured results,analyze examples of wellbore stability evaluation,and gives the specific wells three segment suitable safe density window of drilling fluid and drilling method.And the distribution of the stress distribution and the actual distribution of the natural fractures are recognized,and the distribution of the artificial fractures after reservoir fracturing is recognized.In summary,combined with logging experiment method,calculation method and numerical simulation methods of the three not only accurately determine the distribution characteristics of the crustal stress field,but also effectively expand the scope of application of the stress test results.The results obtained in this paper can be applied to the evaluation of wellbore stability,the qualitative evaluation of artificial fractures and the layout of injection and production wells.