针对压裂过程中射孔段水泥环完整性失效,导致压裂中出现环空窜流,从而无法有效改善储层渗流能力的问题,通过建立射孔段套管-水泥环有限元模型,对压裂过程中射孔段水泥环力学响应进行了分析,并研究了不同射孔参数对射孔段水泥环的力学影响规律.结果表明:压裂过程中射孔段水泥环孔眼周围存在明显的应力集中和孔间应力干扰现象;压裂过程中固井一界面较二界面更容易产生密封性问题;射孔段水泥环应力分布与射孔相位角有密切关系,应尽量选取90.相位角螺旋射孔方式射孔;射孔孔径的增加对射孔段水泥环应力分布影响不大,为增加单孔泄油面积,可在小范围内增加射孔孔径;射孔密度对水泥环应力的影响要大于射孔孔径,但射孔密度超过16孔/m以后应力增加幅度会减小,且影响都在一个数量级以内,在有效控制水泥环射孔损伤的前提下可有限度地增加射孔密度.该研究可为压裂射孔方案制定提供理论依据.%Perforation affects the mechanical integrity of cement sheath,leading to annulus channeling in fracturing,thus cannot effectively improve the flowing capability of reservoir.In this paper,through the establishment of perforated casing-cement finite element model,the mechanical response of perforated cement during fracturing was analyzed,and the effects of different parameters on the cement sheath were studied.The results show that the phenomenon of stress concentration and interference exists around the holes of cement sheath;the stress on the inner wall of cement sheath is higher,so the casing-cement interface is easier to have sealing problems than the cementing-formation interface in the fracturing;the stress distribution of perforated cement has close relationship with perforation phase angle,and 90° is a better choice;the hole size has little effect on the stress distribution of perforated cement,the hole diameter can be increased properly in order to increase the drainage area;the effect of the increase of perforation density on the stress of perforated cement is in an order of magnitude,and the increment magnitude of stress decreases while perforation density exceeds 16 holes/m,so a limited increase in perforation density is acceptable.This study provides a theoretical basis for the formulation of perforation.
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