Application To In-situ Stress Evaluation Based On Cross-dipole Logging Data In Southeast Sichuan Block

In recent years,with the rapid development of petroleum exploration,the application of the corss-dipole acoustic logging in stress evaluation is becoming more mature.Lots of field experiments prove that the types of anisotropy can be identified,even in the monopole acoustic log.The polarization direction of fast shear wave(S-wave)is consistent with the maximum horizontal principal stress azimuth,which can be further determined.In-situ stress analysis calculation is the emphasis and difficulty of my research in well logging evaluation.Based on the current hydraulic fracturing,wall caving method is restricted,the corss-dipole logging shows good prospect.The corss-dipole logging data of our company are not widely used and applied and its application is still immature,especially some large-scale developing new block.Using existing well data from four Sichuan Blocks,we study the direction of the horizontal maximum of in-situ stress and size under the incomplete geological information.Firstly,the general process of corss-dipole acoustic data and anisotropy evaluation is analyzed.Secondly,the processing workflow of both logging softwares is compared.Moreover,the fast and slow flexural-wave dispersion curves are obtained,in order to distinguish the in-situ stress caused by the anisotropy.Then,the stress direction and size in Southeast Sichuan block are estimated by combination with other well data.Well logging data has usually good continuity,high vertical resolution and reliability,and low cost.In view of East China branch in shale-gas well in Pengshui areas of Southeast Sichuan,the evaluation method for borehole-wall stability is investigated based on the rock mechanics perspective.In addition,the mathematical model of in-situ stress,formation pore pressure,and rock mechanicsand are establishd.The stability software is also developed.The results show that the borehole stability analysis can provides reliable data support for drilling engineering,optimization of drilling parameter,and fracturing design.More than 50% contribution of the current national shale gas production is coming from Southeast Sichuan blocks besides Jiaoshiba Jianghan Oilfield.