基于井孔散射波能量的水力压裂效果评价方法

Evaluation methods of the hydraulic fracturing effect based on the energy of borehole scattered wave

水压致裂是非常规油气开采的重要增产手段,水力压裂效果的评估对油气开采十分重要。现有的基于测井数据的水力压裂效果评价方法(如正交偶极各向异性、同位素测井等)仅能评价井壁附近的水力压裂效果。利用声波在水力压裂裂缝中传播产生背向散射波原理,提出了一种基于井孔散射波能量的水力压裂效果评价方法,建立了水力压裂随机介质模型,利用有限差分数值模拟了横波在水力压裂地层中的传播特征。数值模拟结果表明,在水力压裂区域偶极阵列波形产生了明显的散射波,声场的空间分布特征表明SH波(水平偏振横波)的散射以S-S散射为主,利用散射波的能量可以有效识别水力压裂的区域。该方法极大地提高了水力压裂效果的评价范围(井孔周围数十米范围),实际数据处理结果验证了该方法的可行性。

Hydraulic fracturing is an important means of increasing production in unconventional oil and gas exploration,and the evaluation of the effect of hydraulic fracturing is very important for oil and gas exploration.Existing methods for evaluating the effect of fracturing based on logging data(e.g.orthogonal dipole anisotropy,isotope logging,etc.)can only evaluate the effect of fracturing near the well wall.In this paper,a hydraulic fracturing effect evaluation method based on the energy of borehole scattered wave was proposed by using the principle of backscattering waves generated by acoustic wave propagation in hydraulic fracturing cracks.A random medium model of hydraulic fracturing was established,and the propagation characteristics of shear wave in the fracturing formation were simulated by using finite differential values.The numerical simulation results show that the dipole array waveform in the fracturing area produces obvious scattered waves,and the spatial distribution characteristics of the sound field indicate that the scattering of SH wave(horizontally polarized shear wave)is mainly S-S scattering,and the energy of the scattered wave can effectively be used to identify the area of hydraulic fracturing.This method greatly improves the evaluation range of the effect of hydraulic fracturing(tens of meters around the borehole),and the processing results of the actual data verify the feasibility of this method.