Experimental Study And Application On Mechanical Properties Of Mud Shale Of No.Five Structure In Lenghu

With the increase of oil field exploration,the great development potential of the northern margin shale of qaidam basin is gradually realized.The structure of LengHu no.5 is one of the large surface structures in the western section of the northern margin,which is rich in mud shale reservoir.However,scholars at home and abroad are not deep enough to study the shale reservoir in the region,especially in the study of physical characteristics of reservoir and the lack of research on rock mechanics.There is not enough effective theoretical basis to support in the later stage of mining and fracturing.Therefore,this text mainly studies the construction of mud shale in LengHu no.5.On the basis of laboratory and rock mechanics experiments,the rock mechanics characteristics and application of this reservoir are analyzed.In the course of this study,the physical and chemical properties of mud shale were analyzed through experiments on porosity,permeability,microstructure,specific surface area,pore size distribution and mineral composition.Through the experimental study of acoustic properties of mud shale,triaxial compressive strength,tensile strength,shear strength and drilling fluid influence on the mechanical parameters of the shale immersion test,to a concrete analysis of mud shale rock mechanics characteristics.In this way,the prediction model of rock mechanics parameters is constructed,and the prediction section of rock mechanics parameters of a well is drawn,which lays a foundation for the study of ground stress and borehole stability.In the study of ground stress,the well circumferential stress analyzed based on fracturing data inversion,and the stress azimuth analyzed based on imaging well logging data.On the basis of borehole wall stability analysis,the collapse and fracture pressure calculation model are selected and the formation pore pressure model-calculated by equivalent depth method-are selected.Using the model the three-pressure profile of two prediction Wells is established.On the basis of the above experimental study,the safety density window considering the increment of collapse pressure is obtained.In this regard,the design proposals of drilling fluid density for new drilling in high spot one?high spot two and high spot four of LengHu no.5 are proposed.The proposed site application has good effect,there are no complicated situations and accidents caused by the instability of borehole wall,so the safe and fast drilling is ensured.By measuring the stratigraphic rocks and mud function before and after the change and the mechanical properties of the impact on the formation collapse pressure and the optimizing drilling scheme,the feasibility and correctness have the further validation in the field test.In the end,the mechanism and stabilization technology of borehole wall instability in the formation of LengHu No.5 are formed,which is applied in the exploration and development of LengHu construction drilling.