高温高压高含硫气井固井水泥环封隔能力评价技术

随着中海油海上及海外复杂油气田大力开发，高温高压高含硫井开采数量不断增多，固井水泥环封隔性能失效引起的环空带压或酸性气体泄漏问题，已经成为制约高温高压高含硫气田安全作业和生产的瓶颈。从分析固井水泥环封隔能力影响因素、失效机理等方面出发，总结了高温高压高含硫固井水泥环封隔能力失效的主要原因，分析认为在高温高压高含硫条件下水泥石力学性能和结构变化是影响水泥环封隔能力的重要因素之一；结合高温高压高含硫井特点，设计了固井水泥环封隔能力评价思路，建立了固井水泥环层间封隔能力评价方法，提出了改善水泥环长期封隔能力的技术措施，为提高高温高压高含硫固井水泥环密封完整特性和延长油气井生产寿命，提供了新的工程技术发展方向与解决途径。

Evaluation technology for isolation capacity of cement sheath in HTHP high-sulfur gas wells

As CNOOC develops offshore and overseas complex oil and gas fields vigorously, there are more and more HTHP (high temperature and high pressure) high-sulfur wells. And the annulus pressure or acidic gas leakage caused by the isolation failure of cement sheath is the bottle neck which restricts the safe operation and production of HTHP high-sulfur gas fields. In this paper, the main reasons for the isolation failure of cement sheath in HTHP high-sulfur wells were analyzed from the aspects of influence factors and failure mechanisms. It is indicated that the mechanical and structural change of set cement is one of the main factors influencing the isolation capacity of cement sheath under high temperature, high pressure and high sulfur. Then, based on the characteristics of HTHP high-sulfur wells, the evaluation idea on the isolation capacity of cement sheath was proposed, the evaluation method on the interlayer isolation capacity of cement sheath was established, and the technical measures to improve long-term isolation capacity of cement sheath were developed. In this way, it provides the new technical development direction and solution for improving the isolation integrity of cement sheath in HTHP high-sulfur wells and prolonging the service life of oil and gas wells.