The Integrity-based High-pressure Gas Well Casing Design

In recent years,there have been frequent occurrences of well integrity failures in high-pressure gas wells,so it is urgent to study the casing design of well integrity.There are many forms of well integrity failure,among which the casing accidents caused by the failure of the well barrier are increasing,which directly brings the scrap of the well and even causes environmental disasters.In order to ensure economic and safe production,the casing load and service environment need to be fully considered in the design of the casing,and the casing strength design,material anti-corrosion design,connection buckle seal effectiveness design,etc.Security is very important.This paper analyzes the barrier function of casing and determines that casing is an important component of well barrier,which plays a vital role in the safety of oil and gas wells.The cases of casing failure in complex deep wells in the Tarim block and Sichuan shale gas wells are analyzed.Cases of actual simulation casing failure tests are analyzed.The mechanism of casing thread failure,corrosion and wear is summarized.A comprehensive analysis of the casing service environment during the whole life cycle of the well,the impact of the tensile,internal pressure,external extrusion load,wear,corrosion,and thread tightness requirements on the casing under various working conditions,summarizes the previous In the design of the casing,the failure of the casing is caused by insufficient consideration of the load and influencing factors.On this basis,systematic design methods such as casing strength design,casing material design,and connection buckle design of the three high wells are proposed.Finally,taking a high-pressure gas well as an example,the method of this paper was used to complete the design of the casing string.The design was approved by domestic experts and proved to be safe and reliable in practice.