【摘要】 水平井水力压裂是非常规致密气藏增产改造的关键技术，对致密气藏的生产具有重要意义。掌握水平井近井地应力场分布情况，有利于指导和优化地质和完井类似的压裂设计以及老井重复压裂的设计。水力压裂微震事件的震源机制和水力裂缝网络的断裂属性得到的方位角和倾角信息，都可以用于新井地应力场的反演。本文提出一种利用微震震源机制与裂缝网络提供走向、倾角和滑移角信息从而开展地应力反演的新方法。该方法针对具有足够可靠微震事件震源机制解的压裂段，从震源机制解中得到走向、倾角和滑移角信息反演地应力；而对于没有可靠震源机制解的压裂段，采用连续裂缝网络提供的方位和倾角信息并结合其他压裂段微震事件震源机制解提供的滑移角信息来反演地应力，最终获得水平井全部压裂段的地应力分布。因此，无论是否存在高质量的水力压裂诱发微震事件，均可反演各压裂段的近井地应力场。将该方法应用于水力压裂改造过程中星型阵列采集的地表微地震数据集，反演得到的近井地应力场与室内水力压裂试验得到的应力场基本一致，表明基于微地震震源机制和裂缝网络的走向、倾角和倾角数据反演方法能够正确地获得最大、最小水平应力方位。更多还原

【Abstract】 The hydraulic fracturing of horizontal wells is a key stimulation technology for unconventional tight oil/gas reservoirs.Good knowledge of the near-well stress field of a horizontal well can be helpful for the hydraulic fracture design optimization of new wells and refrac design optimization of fractured wells.Azimuth and dip data derived from either focal mechanisms of hydraulic fracturing-induced microseismic events or fracture attributes of hydraulic fracture networks can be used for new-well stress field inversion.In this work,we present a novel stress inversion method integrating azimuth,dip,and rake data from the focal mechanisms of hydraulically induced microseismic events and fracture attributes of hydraulic fracture networks.For those stages having sufficient reliable microseismic focal mechanisms,strike,dip,and rake data derived from microseismic focal mechanisms are taken as input data for stress inversion.Meanwhile,for those stages that have no microseismic events or insufficient reliable microseismic focal mechanisms,azimuth and dip data derived from fracture attributes of prebuilt hydraulic fracture network are used for stress inversion,along with azimuth dip,and rake data derived from other stages with sufficient reliable microseismic focal mechanisms.Thus,the near-well stress field of each stage can be inverted,regardless of whether or not it has hydraulically induced microseismic events.The new method has been applied in the field surface microseismic dataset during hydraulic fracture stimulation.The results reveal that the inverted near-well stress fields are consistent with the stress orientation derived from shear-wave splitting analysis for sonic logs.This finding demonstrates that the stress inversion method based on strike,dip,and rake data derived from microseismic focal mechanisms and fracture networks can correctly obtain the azimuths of maximum and minimum horizontal stress.更多还原