Journal of Petroleum Science and Engineering ( IF 5.168 ) Pub Date : 2020-03-22 , DOI: 10.1016/j.petrol.2020.107215 Manojkumar Gudala , Suresh Kumar Govindarajan
Dynamic variation of porosity, permeability, and elastic modulus was considered in order to investigate the single-phase fluid flow in a fractured porous media using fully coupled hydro and geomechanical models. The development of streamlines, pressure distribution, effective stress and strain generations have been extensively studied. However, from the present model results, it can be critically noted that the development of streamlines and pressure are highly dependent on (a) fracture orientation; (b) the distance from injection/production well; and (c) the fracture density. The results have been analyzed both in the presence and absence of geomechanics. It was observed from the model results that there was no fluid flow within the fracture when the fracture aperture varied between 10−6 and 10−9 m; and the respective streamlines were very smooth at the fracture-matrix interface, whereas, a significant fluid flow was observed within the fracture when the aperture sizes exceeded 10−6 m; and in this case, streamlines and pressure variations were very sensitive at the fracture-matrix interface. The model results clearly projected that this sensitivity primarily resulted from the lateral stresses arising from the generation of effective-stress and its associated strains. It was further observed from the numerical results that the effective stress, strain, and pressure in the fractured porous media were extremely sensitive to the Biot-Willis coefficient; and thereby clearly projecting the significance of the considered lateral stresses (which are generally absent, while characterizing a typical conventional reservoir). In addition, it was also observed that the lowest effective stress occurred in the vicinity of the injection well, while the highest value was found nearer to the production well for Biot-Willis coefficients with values less than 0.6. Thus, it can be critically concluded that the compressive strains were dominating over the highest sweep volume of the fractured porous media that starts a little bit away from the injection well, and that gradually increases to the maximum at the production well, when the Biot-Willis coefficient falls below 0.6. Finally, the model has been upscaled by increasing the scale of the porous medium with complex embedded fracture along with the dynamic variation of permeability, porosity, and elastic modulus so that the developed numerical model will better replicate the complex reality associated with the field scale.
中文翻译:
裂隙多孔介质中单相流体与地质力学耦合的数值模拟
考虑孔隙率,渗透率和弹性模量的动态变化,以便使用完全耦合的水力和地质力学模型研究压裂多孔介质中的单相流体流动。流线的发展,压力分布,有效应力和应变产生已得到广泛研究。但是,从目前的模型结果可以看出,流线和压力的发展高度依赖于(a)裂缝方向;(b)距注入/生产井的距离;(c)断裂密度。在存在和不存在地质力学的情况下都对结果进行了分析。从模型结果可以看出,当裂缝孔径在10 -6和10 -9之间变化时,裂缝内没有流体流动。 m; 并且在裂缝-基质界面处的各个流线都非常光滑,而当孔尺寸超过10 -6时,在裂缝内观察到大量流体流动 m; 在这种情况下,裂缝-基质界面处的流线和压力变化非常敏感。模型结果清楚地表明,这种敏感性主要是由有效应力及其相关应变的产生所引起的侧向应力引起的。从数值结果进一步观察到,破裂的多孔介质中的有效应力,应变和压力对Biot-Willis系数极为敏感。从而清楚地反映出所考虑的侧向应力的重要性(在表征典型的常规油藏时通常不存在)。此外,还观察到最低有效应力发生在注入井附近,而对于Biot-Willis系数而言,发现最高值的位置更接近生产井,其值小于0.6。因此,可以批判性地得出结论:在应变多孔介质的最大吹扫体积上,压缩应变起着主导作用,该最大吹扫体积从注入井开始一点点,然后在Biot-威利斯系数降至0.6以下。最后,通过增加具有复杂埋藏裂缝的多孔介质的比例以及渗透率,孔隙率和弹性模量的动态变化,对模型进行了放大,以便开发的数值模型将更好地复制与油田规模相关的复杂现实。可以批判性地得出结论,压缩应变在压裂多孔介质的最高吹扫量上占主导地位,该最高吹扫量从注入井开始一点点,然后在Biot-Willis系数时逐渐增加到生产井的最大值。低于0.6。最后,通过增加具有复杂埋藏裂缝的多孔介质的比例以及渗透率,孔隙率和弹性模量的动态变化,对模型进行了放大,以便开发的数值模型将更好地复制与油田规模相关的复杂现实。可以批判性地得出结论,压缩应变在压裂多孔介质的最高吹扫量上占主导地位,该最高吹扫量从注入井开始一点点,然后在Biot-Willis系数时逐渐增加到生产井的最大值。低于0.6。最后,通过增加具有复杂埋藏裂缝的多孔介质的比例以及渗透率,孔隙率和弹性模量的动态变化,对模型进行了放大,以便开发的数值模型将更好地复制与油田规模相关的复杂现实。