含水泥环的变形套管修复过程实验

油气田现场经常凭经验确定旋压整形器修复变形套管所需的修复力和扭矩,而不合理的整形力或扭矩容易造成变形套管和周围水泥环的二次损伤及卡钻事故。为此,在YAW-200压力试验机上分别制作了无水泥环(水泥环完全损伤)、水泥环部分损伤和水泥环未损伤等3种类型的P110SS变形套管,并采用?126 mm和?133 mm的2种旋压整形器对3种变形套管进行整形测试,得到了变形套管整形所需的整形力和修复扭矩、变形套管回弹量的测试数据。实验结果表明:(1)修复过程中整形力与扭矩整形时间的关系密切——弹性变形阶段,随修复时间增加环向应变呈线性增加,整形力和扭矩早期呈缓慢增加后期保持不变,塑性变形阶段套管开始屈服,随修复时间增加环向应变呈非线性增加,整形力和扭矩急剧降低,直到整形工具通过变形套管,直到整形力和扭矩降低到最低为止;(2)修复后的回弹量不可避免且较大(2.90~3.04 mm),表明水泥环的损伤程度对变形套管的修复具有较大影响;(3)水泥环未损伤的变形套管修复所需机械载荷大于水泥环部分损伤变形套管所需机械载荷,带水泥环变形套管修复所需机械载荷大于无水泥环变形套管所需的机械载荷。

Experimental investigation on the repairing process of deformed casing with cement sheath

When a spinning casing swage is used to repair deformed casings in oil and gas fields, its repairing force and torque are often determined on the basis of experience. Under unreasonable repairing force and torque, however, a deformed casing and its surrounding cement sheath tend to suffer secondary damage and sticking accidents. In this paper, three kinds of P110SS deformed casings were made on the YAW-200 pressure testing machine, including completely damaged cement sheath (without cement sheath), partially damaged cement sheath and undamaged cement sheath. Then, reshaping test was performed on these three deformed casings by using two spinning casing swages (Ø126 mm and Ø133 mm), and the reshaping force and torque for the reshaping of deformed casing and the springback of deformed casing were measured. It is shown that in the stage of elastic deformation of reshaping process, when the reshaping force is in close relation with the torque reshaping time, the circumferential strain rises linearly as the reshaping goes, and the reshaping force and torque rise slowly in the early stage and stay constant in the late stage; in the stage of plastic deformation, casing begins yielding; and as the reshaping goes, the circumferential strain rises linearly, and the reshaping force and torque drop sharply until the reshaping tool runs through the deformed casing and the reshaping force and torque decline to the minimum. Besides, the springback after the repairing is larger (2.90–3.04 mm) and shall be noticed, indicating that the repairing of deformed casing is more affected by the damage degree of cement sheath. Finally, the mechanical load demanded to repair the deformed casing with complete cement sheath is larger than that for the deformed casing with partially damaged cement sheath; and the mechanical load demanded to repair the deformed casing with cement sheath is larger than that for the deformed casing without cement sheath.