石油钻采工艺2017，Vol.39Issue(4)：417-423,7.DOI:10.13639/j.odpt.2017.04.005
瞬态力-热耦合作用下水泥环完整性分析
Analysis on cement sheath integrity under transient thermo-mechanical coupling effect
摘要
Abstract
The practical shale gas well engineering shows that casing fracturing can easily destroy the integrity of cement sheath, leading to sustained annular pressure (SAP). In this paper, the wellbore temperature field calculation model and the finite element model of casing-cement sheath-formation assembly were established based on the actual casing fracturing engineering. The effect laws of tran-sient thermo-mechanical coupling on the magnitude and distribution of cement sheath stress were calculated by using analytical method and numerical method comprehensively. It is shown that the temperature difference between inside and outside the wall of cement sheath increases firstly and then decreases in the process of fracturing. Steep temperature gradient occurs near the inside wall at the initial frac-turing and it tends to result in obvious increase of stress on the inside wall. Due to the effect of transient thermo-mechanical coupling, the stress on the inside wall of cement sheath is increased significantly, and the risk of cement sheath integrity failure is aggravated. The initial fracturing stage is the "risk period" when cement sheath failure tends to happen easily. As time goes, the maximum stress on the inside wall of cement sheath results in multiple cracks easily and makes the SAP more serious. The research results can provide the reference for the design and control of cement sheath integrity during the fracturing of shale gas well.关键词
页岩气/压裂/环空带压/水泥环/瞬态力-热耦合/完整性Key words
shale gas/fracturing/sustained annular pressure/cement sheath/transient thermo-mechanical coupling effect/integrity分类
能源科技引用本文复制引用
席岩,李军,柳贡慧,查春青,严攀..瞬态力-热耦合作用下水泥环完整性分析[J].石油钻采工艺,2017,39(4):417-423,7.基金项目
国家自然科学基金"长水平段非均质页岩储层非均匀分簇射孔优化研究"(编号:51674272) （编号:51674272）
中石油西南油气田分公司项目"威远长宁页岩气水平井固井质量对井筒完整性的影响"(编号:XNS21JS2014-04). （编号:XNS21JS2014-04）
