The Research Of Stress Analysis And Stress Distribution Calculation Of Production Casing In Shale Gas Well

The shale gas is the ideal energy to replace the oil resources in the future. The exploration technology of shale gas in China, however, is still in its infancy, and far away from the developed countries. Horizontal well drilling technology and hydraulic fracturing technology is the key technology of shale gas exploration and development. The exploit of shale gas and the reconstruction to the shale gas reservoir require a lot of extensive hydraulic fracturing. This kind of high strength fracturing operation may cause the casing damage. The casing damage is serious, even may lead to the abandonment of a well and bring huge economic losses during the production and development of shale gas wells. As a result, the analysis of stress distribution on the casing wall for preventing casing damage has a very important practical significance.Based on a lot of surveys related technical papers and data at home and abroad, from the perspective of the geological and engineering factors, the detailed stress analysis has been made on the factors of casing damage. In addition, the factor of the casing damage caused by the hydraulic fracture has also been analyzed. In view of the problems of the casing damage above, at first, in this paper, the theories of thick-walled and thin-walled cylinder are adopted respectively to analyze the stress distribution of casing in the horizontal section focusing on the several shale gas wells in the Jiaoshiba area, and the differences of the casing stress analysis are compared with the same situation according to two different theories. Secondly, with the aid of finite element analysis software ANSYS Workbench, the analysis model related with formation, cement ring and casing stress have been set up. From the formation rock mechanics performance degradation, stress field changes caused by the fracturing, a finite element simulation has been taken to analyze the influence degree of casing damage. And in view of the problem that horizontal section of shale gas well is long, easy cause casing eccentricity, the influence of the casing damage has been studied. Finally, on the basis of the theoretical calculation and simulation of finite element, combined with the geological data and production casing design related data of well constructed by Sinopec Southwest Petroleum Engineering Company in Yong Chuan,Chongqing city, the analysis the geological and engineering factors that may cause the casing damage have been conducted, and the some reference opinions to the casing design about that well being drilled have also been suggested up.