页岩-液体作用对套管变形的影响研究

A Study on the Effect of Shale-liquid Reaction on Casing Deformation

李皋 李泽 蒋祖军 于浩 何龙

LIGao LIZe JIANGZujun YUHao HELong

油气藏地质及开发工程国家重点实验室·西南石油大学, 四川 成都 610500 中国石化西南油气分公司石油工程技术研究院, 四川 德阳 618000

State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China Engineering and Technology Research Institute, Southwest Oil and Gas Company, SINOPEC, Deyang, Sichuan 618000, China

页岩气井压裂后套管变形问题严重，已成为制约页岩气资源高效开发的瓶颈，但目前引发套变现象的原因仍认识不清，且无有效防治措施。根据页岩结构特征及力学性质，结合数值模拟技术对页岩-液体作用对套管变形的影响及其防治措施开展研究。结果表明，由于液相侵入导致的裂缝层间膨胀会造成页岩在液体作用下产生微弱形变，由于页岩力学强度高，且水化后仍具备较高的弹性模量，造成液-岩反应后的膨胀变形会产生较强的作用力，在无应力释放的情况下该作用力施加在套管上导致套管应力增加，对套管变形产生重要影响。水泥环弹性模量的降低以及密集射孔能够对防治套管变形起到积极作用。

The casing deformation after fracturing in shale is a serious problem, which has become a bottleneck restricting the development of shale resources. However, the cause of casing deformation is still unclear, and there is no effective prevention and control measures. In this paper, the effect of shale-liquid reaction on casing deformation and its prevention measures were studied by numerical simulation technology, according to the shale structure characteristics and mechanical properties. Results show that the weak deformation occurred because of the intergranular expansion in fractures in the reaction of shale and liquid. Due to the high mechanical strength and elastic modulus of shale, the weak deforamtion of shale will produce a strong force, and the force exerted on the casing will influence the casing safty. The reduction of elastic modulus of cement and the perforation can prevent casing deformation. The research results provide reference value for further understanding the causes of casing deformation and prevention measures.

10.11885/j.issn.1674-5086.2019.12.23.01