论固井二界面封固系统及其重要性

The two contacts cementing system in cementing job and its importance.

固井二界面问题是一个亟待解决的工程难题。阐述了固井二界面封固系统的概念,分析了各系统组分对固井二界面封固系统的作用或影响,建立了系统的状态变化模型和动态破坏模型;并且从油田开采和防止气窜两个角度,剖析了固井二界面封固系统失效的危害性,阐释了解决固井二界面问题的重要性。固井二界面封固系统是指由水泥浆、死泥浆、滤饼和地层壁面四部分构成的一个固化胶结整体;通常地层流体只有破坏了滤饼才能产生水泥石(环)被破坏的情况,导致环空封固不良而引发诸多质量问题。其重要性主要表现在:一口井的产能主要取决于层间封隔程度,而层间封隔程度又主要取决于固井界面的密封程度和水泥环本体的密实程度;此外,固井二界面封固系统的胶结质量问题是环空气窜的根本原因,因为尽管环空静液压力大于地层孔隙压力,但因井筒热力变化或压力波动形成的界面微裂隙和滤饼或死泥浆形成的旁通渠道或微窜槽,仍会给被圈闭于地层的气体创造窜流路径。提出,固井二界面问题的研究和解决必须要从系统的角度出发,采用类似储层保护的技术和方法,才能实现固井二界面封固系统的整体固化胶结。否则,这一难题还将会长期伴随固井界。

The problem of two contacts cementing integrity is urgent to be solved in cementing field. This paper focuses on two aspects based on others' researches. One is that it describes the concept of two contacts cementing system, analyzes the influence of each element of the system on the cementing integrity and establishes the static model and dynamic damage model of the system. The other is presenting the danger of two contacts system cementing failure, from the points of field's production and gas channeling prevention, and the importance of the successful solution. It is proposed that to study the problem, technology and measurements similar to reservoir protection should be taken to realize the two contacts cementing system in integrity, or the problem will be a potential damage in the cementing field for a long time.