致密油压裂套管变形应力特征数值模拟  

Casing Deformation Stress Characteristics Numerical Simulation under Tight Oil Fracturing

作　　者：张鹏[1,2,3] 蒲春生[1,2] 胡淑颖 马帅帮[3] 王红鹰 ZHANG Peng;PU Chun-sheng;HU Shu-ying;MA Shuai-bang;WANG Hong-ying(School of Petroleum Engineering,China University of Petroleum(East China),Qingdao 266580,China;Key Laboratory of Unconventional Oil&Gas Development,Ministry of Education,China University of Petroleum(East China),Qingdao 266580,China;TUHA Petroleum Research&Development Center,CNPC,Hami 839009,China;TUHA New Energy Center,Hami 839009,China)

机构地区：[1]中国石油大学(华东)石油工程学院,青岛266580 [2]中国石油大学(华东)非常规油气开发教育部重点实验室,青岛266580 [3]吐哈油田工程技术研究院,哈密839009 [4]吐哈油田新能源事业部,哈密839009

出　　处：《科学技术与工程》2022年第25期10968-10974,共7页Science Technology and Engineering

基　　金：中石油吐哈油田公司科技专项。

摘　　要：中国非常规油气资源丰富,是重要的接替资源之一,但由于其储层的致密性,主要通过大规模体积压裂获得工业生产油气流,压裂过程中套管发生复杂的应力变化特征,油气井套管变形也越来越严重,目前对于套管内外壁、射孔簇间、段间等特征的认识尚不清晰。为此,基于压裂特点,提出数值模拟方法,利用实际典型套变井的压裂参数进行模拟和验证。结果表明:在压裂和返排阶段,射孔孔眼处均产生应力集中,但应力梯度变化不大;返排时在射孔簇间套管段与射孔同轴线方向的外壁形成高度应力集中,存在发生椭圆形变形危险;射孔段到射孔簇间段过渡区间,等效应力存在突变拐点,压裂阶段先突减后骤增,返排阶段先突增后骤减,返排时该段剪切应力集中达到峰值,易发生剪切破坏,形成套管错断。压裂阶段水泥环除在射孔孔眼处形成应力集中外,在射孔簇间段的水泥环的环向截面在轴线方位也存在较高的应力分布,造成水泥环一定程度的破坏,返排时水泥环破坏程度被加强,套损率较高。在相同压裂排量条件下,适当提高射孔簇长度、缩短射孔簇间距离、缩短压裂段间距能够有效提高套管的安全性,三塘湖M56区建议Φ139.7 mm P110套管射孔簇长度为1.5~3.0 m,射孔簇间距小于10 m,段间距小于30 m。Unconventional oil and gas resources is very rich in China,it is one of the important replacement resources.Industrial production oil and gas flow is mainly obtained through large-scale volumetric fracturing because its compactness reservoir.During the fracturing process,the casing has complex stress change characteristics,and the casing deformation is becoming more and more serious.At present,the understanding of the characteristics of the inner and outer walls of the casing,perforation clusters and intervals is not clear.Therefore,based on the characteristics of fracturing,a numerical simulation method was proposed to simulate and verify the fracturing parameters of typical casing change wells.The results show that in the fracturing and flowback stages,stress concentration occurs at the perforations,but the stress gradient changes little.During flowback,the casing section between perforation clusters and the outer wall in the direction of perforation coaxial line form a high stress concentration,which is in danger of oval deformation.In the transition section from perforation section to perforation cluster section,there is a sudden inflection point of equivalent stress,which first decreases and then increases sharply in fracturing stage,and then increases and then decreases sharply in flowback stage.During flowback,the shear stress concentration in this section reaches the peak,which is prone to shear failure and casing dislocation.In the fracturing stage,the cement sheath not only forms stress concentration at the perforation hole,but also has high stress distribution in the axial direction of the circumferential section of the cement sheath in the perforation cluster section,resulting in a certain degree of damage to the cement sheath.During flowback,the damage degree of the cement sheath is strengthened and the casing damage rate is high.Under the condition of the same fracturing flow rate,properly increasing the length of perforation clusters,shortening perforation clusters spacing and fracturing sections s

关 键 词：致密油 水平井 体积压裂 套管变形 

分 类 号：TE331[石油与天然气工程—油气田开发工程]