Study Of Wellbore Stability In Shunbei Block Triassic Ketuer Technology

The stability of borehole wall is a crucial link in oil drilling,and it is the fundamental guarantee that the drilling process can proceed smoothly.The instability of the well wall will have great impact on the project schedule and the project quality,which will increase the difficulty and cost of oil exploration and development.In view of this problem,this paper carried out experimental research on the stability of borehole wall in shunbei block in the tarim basin of xinjiang autonomous region.It is easy to collapse,block and loose in ketuer former of shunbei block.,loose texture,severe borehole wall stability problems,according to the situation,this article selects the suitable north 3 Wells six core sample,respectively,into the mineral composition and the physical and chemical properties analysis,summarizes the formation mechanism of borehole wall instability.Drilling fluid system is presented according to the results from optimization idea,from two directions of improving inhibitory and plugging chose potassium amino polysulfide drilling fluid system,finally through comparative tests to determine the potassium amino optimal formula of polysulfide drilling fluid system.After summary,the root cause of the instability in the area is as follows:Along the north block trias ke puke,stratum clay mineral content was 30%～30%,the rest is mainly composed of quartz,plagioclase,almost does not contain heavy mineral,the clay mineral is given priority to with bent Erie Shi Meng stone mixed layer off,yili Shi Meng off stone relative content was 53%～53%,mixed layer and layer between 45%～80%,and for typical argillaceous sandstone formation,at the same time ke puke,group formation shale inflation and high cation exchange capacity,and shale water recovery rate is extremely low,at around 5%,with strong ability of hydration.To solve above problems,mainly from two aspects of sexual improve sealing,and inhibitory put forward against the borehole wall instability of drilling fluid design train of thought,and through the indoor experiment,combining along the north block drilling design and construction,optimizing the main treating agent amino shale inhibitor HPA and resistance to high temperature and salt resistant polymer RHTP-2,completed the resistance to high temperature potassium amino polysulfide drilling fluid system optimization research.The system formula as follows:4%bentonite+0.2%NaOH+0.2%Na2C03+0.3%K-PAM+0.3%DS-301+1%DS-302+0.5%RHPT-2+1%HPA+2%borehole stabilizer+5%KCl+3%sulfonated asphalt3%+2.5%RHJ-3+SMC+3%SPNHEvaluation results for the system:potassium amino polysulfide film forming drilling fluid system has good rheological properties,API filtration<5 ml,90 ℃HTHP filtration quantity<12 ml,recovery>90%,and can satisfy the ke puke,along the north block,set of borehole wall stability requirements.