重复压裂非均匀孔隙压力场对裂缝延伸的影响

Influence of non-uniform pore pressure field on fracture propagation during refracturing

黄婷 薛小佳 康博 董奇 周大伟 徐全胜

中国石油长庆油田分公司油气工艺研究院，陕西 西安 710018 中国石油大学（北京）石油工程学院，北京 102249

Oil and Gas Technology Institute, Changqing Oilfield Company, PetroChina, Xi′an 710018, China College of Petroleum Engineering, China University of Petroleum, Beijing 102249, China

针对低渗透油气田水平井产量递减快的问题，重复压裂技术逐渐成为提高水平井单井产量的主要措施之一。文中对边长30 cm立方体试件开展真三轴重复压裂实验，研究非均匀孔隙压力场对重复压裂裂缝扩展的影响规律。研究表明：老缝长度越长、缝间距越小，新老缝之间的应力干扰越明显，老缝长度增大50%，破裂压力提高14.8%；新老缝间距越小、老缝越长，新缝压裂导致的压力冲击影响越大，新缝越容易沟通老缝；通过数值模拟优化加密缝间距，减弱老缝对新缝扩展的抑制作用，实现水力裂缝有效控制储层体积最大化。该研究揭示了水平井压前补能对新裂缝扩展的影响规律，对水平井重复压裂及压前补能方案设计具有指导意义。

In view of the rapid production decline of horizontal wells in low-permeability reservoirs, refracturing technology has gradually become one of the main treatments to enhance horizontal well production. In this paper, true triaxial re-fracturing experiments are carried out on 30 cm cubic specimens to study the influence law of non-uniform pore pressure field on fracture propagation during refracturing. The results show long old fracture and less interval tend to create significant stress interface between new and old fractures. With the increase of old fracture length by 50%, the fracture pressure increases by 14.8%. The smaller the distance between new and old fractures and the longer the old fractures, the greater the pressure impact caused by fracturing of new fractures and the easier the connection between new and old fractures. Numerical simulation can optimize the spacing of refractures, weaken the inhibition effect of old fractures on new fractures, and maximize the effective control formation volume of hydraulic fractures. This study reveals the influence law of pre-fracturing injection on new fracture propagation of horizontal wells, which has guiding significance for refracturing and pre-fracturing injection design of horizontal wells.

10.6056/dkyqt202303015