Design Model and Software Development of Casing String Strength for Horizontal Wells in ChangQing Region

In recent years, there have been frequent occurrences of casing damage in tight oil and gas wells in the ChangQing region, the pressure bearing of the casing string in production and construction wells cannot be fully guaranteed under large offset conditions. It is very necessary to construct a casing load profile for the three-dimensional horizontal well casing in the ChangQing area and analyze the ultimate stress conditions of the casing. Consider the calculation model of casing burst pressure profile and casing collapse pressure profile during the production operation stage. Design a calculation model for axial load of casing from four aspects: floating weight of casing, additional tensile force of cement injection, bending stress, and frictional resistance of running casing. Design the model by considering the triaxial strength intensity verification model of the casing string and the triaxial strength calculation method of the casing string. Using JavaScript and Python as the development languages for the software front-end and back-end, conduct strength testing of casing strings in horizontal wells based on actual operating conditions. The test results indicate that the calculation results of the software’s resistance to external compression, burst pressure, and tensile analysis are basically consistent with the actual situation, meet drilling construction conditions and API 5CT requirements.