College of Engineering, Peking University, Beijing, 100871, China.
Department of Petroleum Engineering, Texas A &M University, Collage Station, TX, 77843, USA.
Sci Rep. 2017 Jan 16;7:40507. doi: 10.1038/srep40507.
Since a large amount of nanopores exist in tight oil reservoirs, fluid transport in nanopores is complex due to large capillary pressure. Recent studies only focus on the effect of nanopore confinement on single-well performance with simple planar fractures in tight oil reservoirs. Its impacts on multi-well performance with complex fracture geometries have not been reported. In this study, a numerical model was developed to investigate the effect of confined phase behavior on cumulative oil and gas production of four horizontal wells with different fracture geometries. Its pore sizes were divided into five regions based on nanopore size distribution. Then, fluid properties were evaluated under different levels of capillary pressure using Peng-Robinson equation of state. Afterwards, an efficient approach of Embedded Discrete Fracture Model (EDFM) was applied to explicitly model hydraulic and natural fractures in the reservoirs. Finally, three fracture geometries, i.e. non-planar hydraulic fractures, non-planar hydraulic fractures with one set natural fractures, and non-planar hydraulic fractures with two sets natural fractures, are evaluated. The multi-well performance with confined phase behavior is analyzed with permeabilities of 0.01 md and 0.1 md. This work improves the analysis of capillarity effect on multi-well performance with complex fracture geometries in tight oil reservoirs.
由于致密油藏中存在大量的纳米孔，因此由于大的毛管压力，纳米孔中的流体传输非常复杂。最近的研究仅关注纳米孔约束对具有简单平面裂缝的致密油藏中单井性能的影响。尚未报道其对具有复杂裂缝几何形状的多井性能的影响。在这项研究中，开发了一个数值模型来研究受约束的相态行为对具有不同裂缝几何形状的四口水平井的累计油和气产量的影响。根据纳米孔尺寸分布，将其孔径分为五个区域。然后，使用 Peng-Robinson 状态方程在不同的毛管压力水平下评估流体性质。然后，应用有效的嵌入式离散裂缝模型（EDFM）来明确模拟储层中的水力裂缝和天然裂缝。最后，评估了三种裂缝几何形状，即非平面水力裂缝、具有一组天然裂缝的非平面水力裂缝和具有两组天然裂缝的非平面水力裂缝。分析了具有 0.01 md 和 0.1 md 渗透率的受约束相态行为对多井性能的影响。这项工作改进了对致密油藏中具有复杂裂缝几何形状的多井性能的毛细效应分析。
