The Research Of Sand-shale Wellbore Stability And Related Software Development

The sidewall stability has been a significant subject in petroleum engineering for a long time, which exists widely around the world. In drilling engineering, sidewall instability will cause complicated conditions and time losses in downhole lead to a huge financial loss. The instability also influences the perforation and sand production, ECT in the reservoir development.As a result, research on sidewall stability has the vital significance in drilling engineering and oilfield development, sidewall instability resulted from the interaction of the rock mechanics and drill fluid chemistry.Considering the complexity, this paper will analyze the affection of the rock mechanics to sidewall stability, from the point of mechanics, when the wellbore was broached, the fluid column pressure of drill fluid will substitute the supporting power of the layer, break the balance of stress, and will finally cause redistribution of rock stress around the sidewall. If the new rock stress exceed the maximum load of rock can withstand(no matter compressive resistance、strength of extension or shearing strength) sidewall instability will occur.In-situ stress、pore pressure、mechanical property、thickness of drill fluid are several key factors which determine the sidewall stability. the strike of formation collapse fracture pressure was basis for determining the reasonable safe drilling fluid density,Because of the good continuity logging data, informative, low cost, high accuracy of logging data, widely used in prediction of the formation pressure, stress, rock mechanics parameters. But because of its large amount of calculation and complex characteristics of strike, need to be programmed to achieve a reasonable prediction drilling fluid density, However, due to the limitations of construction site condition limitations, transmission between the field and the base has brought great inconvenience, but with the development of smart phones and3G networks, which provide a solution for the above problem.Firstly, according to the theory of elasticity is deduced stress distribution of vertical wells and deviated well studying how to use the logging data to calculate the rock mechanics parameters, pore pressure, stress, collapse pressure and burst pressure then a based on the above mechanics formula, using the programming language created system of formation collapse and fracture pressure. Verifying the reasonableness of results with developmenting stand-alone version of the deep strata pressure monitoring system. Finally with the application of mobile database and GPRS network module developed a network communication function mobile phone software in order to provide some guidance construction site.