石油钻采工艺2017，Vol.39Issue(4)：435-441,7.DOI:10.13639/j.odpt.2017.04.008
水泥环环状缺失套损机理及防控措施
Mechanical and control measures on casing damage due to annular absence of cement sheath
摘要
Abstract
If cementing is of poor quality, a small section of cement sheath will be absent in a certain part of oil and gas well in the subsequent operation. As a result, clearance occurs between the casing and the cement sheath, so casing stress changes and the casing is ultimately damaged. A symmetric finite element model of casing-absent cement sheath-strata was established based on the field data of Zaonandong Oilfield in Dagang Oilfield and the principle of plasto elasticity. By virtue of this model, the effects of the height of com-plete cement sheath absence, the size of clearance between the casing and the cement sheath after the absence of cement sheath and the internal pressure on the casing stress were investigated, and the control measures for complete absence of cement sheath were proposed correspondingly. It is shown that the stress on the casing at the interface between complete cement sheath and incomplete cement sheath is the maximum value. The stress in the section where cement sheath is absent is higher and stable. The higher the internal pressure is, the higher the maximum stress on the casing in the annular absence section is. The stress on the sections with absent cement sheath is equal no matter what the absence height of cement sheath is. Casing stress is less affected by the clearance at the first interface. It is demonstrated that the casing damage in the section with absent cement sheath cannot be controlled effectively only by increasing the wall thickness, and the effective method is to increase the steel grade. These researches and analysis can be used as the beneficial reference to study casing damage control while cement sheath is completely absent.关键词
水泥环缺失/套管损环/有限元分析/防控措施/固井质量Key words
absence of cement sheath/casing damage/finite element/control measure/cementing quality分类
能源科技引用本文复制引用
练章华,罗泽利,步宏光,李才雄,李长平..水泥环环状缺失套损机理及防控措施[J].石油钻采工艺,2017,39(4):435-441,7.基金项目
国家自然科学基金"极端条件下气井油套管端力学行为及其螺纹密封机理研究"(编号:51574198) （编号:51574198）
国家教育部博士点基金项目"基于 XFEM 和细观力学的超深井钻工具疲劳破坏机理研究"(编号:20135121110005). （编号:20135121110005）
