摘要
火山岩储层压裂对天然裂缝的有效激活可改善储层渗流能力，提升压裂效果。因此，火山岩储层水平井分段压裂的天然裂缝剪切破裂体积和剪切位移的模拟与表征，对量化储层改造充分程度、优化压裂工艺设计具有重要意义。针对裂缝性火山岩储层水平井分段压裂水力裂缝的动态延伸行为，考虑扩展裂缝对应力￣压力场的干扰作用，以此触发天然裂缝的剪切破裂机制，建立了火山岩储层水平井分段压裂剪切破裂体积模拟方法。研究表明：剪切破裂体积随着水平应力差、天然裂缝逼近角、弹性模量、压裂液总量及注入排量的增大而增大，随着天然裂缝内聚力的增大而减小；泊松比对剪切破裂体积的影响不明显。该方法实现了对火山岩储层水平井分段压裂剪切破裂体积的定量模拟与表征，对提高火山岩储层压裂的优化设计及压后效果评估具有重要的理论指导意义和矿场应用价值。
Abstract
In the fracturing process of volcanic rocks, the effective activation of natural fractures of volcanic rocks is beneficial to improve the reservoir seepage capacity and the fracturing effect. Therefore, the simulation and characterization of the shear fracture volume and shear displacement of natural fracture in volcanic horizontal well segmental fracturing can quantify the adequacy of reservoir transformation, and the fullly-optimized fracturing process design is of great significance. In view of the artificial crack propagation behavior in the horizontal segmental fracturing process of fractured volcanic reservoirs, considering the disturbance of hydraulic fracture propagation on reservoir stress and pressure field, the shear fracture mechanism of natural fractures is triggered, and the shear fracture volume simulation method of horizontal well fracturing in volcanic reservoir is established. The results show that the shear rupture volume increases with the increase of horizontal stress difference, natural crack approach angle, Young′s modulus, displacement and total injection volume, and decreases with the increase of natural crack cohesion; Poisson′s ration has no obvious effect on the volume of cutting mesh. This study realized the quantitative simulation of fracturing shear fracture volume and shear displacement of horizontal wells in volcanic rocks, and has important theoretical guiding significance and application value for improving volcanic fracturing optimization design and post-pressurization effect evaluation.
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