Hao Hongda, Yuan Dengyu, Hou Jirui, Guo Wenmin, Liu Huaizhu
School of Petroleum Engineering, Changzhou University Changzhou Jiangsu 213164 China
Exploration and Development Research Institute, PetroChina Daqing Oilfield Company Daqing Heilongjiang 163000 China.
RSC Adv. 2022 Jul 8;12(31):19990-20003. doi: 10.1039/d2ra01812h. eCollection 2022 Jul 6.
The CO huff-n-puff process is an effective method to enhance oil recovery (EOR) and reduce CO emissions. However, its utilization is limited in a channeling reservoir due to early water and gas breakthrough. A novel starch graft copolymer (SGC) gel is proposed for treating the channels and assisting with the CO huff-n-puff process. Firstly, the bulk and dynamic performances of the SGC gel including rheology, injectivity and plugging ability are compared with the polymer gel in the laboratory. Then, 3D physical models with water channels are established to reveal the EOR mechanisms of gel assisted CO huff-n-puff. Several pilot tests of gel assisted CO huff-n-puff are also discussed in this paper. The bulk and dynamic experimental results show that although these two gelants have similar viscosities, the SGC gelant has a better injectivity compared with the polymer gelant. The SGC gel is predominantly a viscous solution, which make it easier to flow through the pore throats. The RF of the SGC gelant is only 0.58 times that of the polymer gelant. After the gelation, a 3D network-like gel with a viscosity of 174 267 mPa s can be formed using the SGC gelant. The RRF of the SGC gel is about three times that of the polymer gel, which shows that the SGC gel has a stronger plugging ability within the porous media. The 3D experimental results show that four cycles of gel assisted CO huff-n-puff can achieve an EOR of 11.36%, which is 2.56 times that of the pure CO huff-n-puff. After the channels are plugged by the SGC gel, the remaining oil of the near-wellbore area can be first extracted by CO, and the oil of the deep formation can then be effectively displaced by the edge water. Pilot tests on five wells were conducted in the Jidong Oilfield, China, and a total oil production of 3790.86 m was obtained between 2016 and 2021. The proposed novel SGC gel is suitable for assisting with the CO huff-n-puff process, which is a beneficial method for further EOR in a water channeling reservoir.
CO吞吐过程是提高采收率（EOR）和减少CO排放的有效方法。然而，由于早期水和气突破，其在窜流油藏中的应用受到限制。提出了一种新型淀粉接枝共聚物（SGC）凝胶用于处理窜流通道并辅助CO吞吐过程。首先，在实验室中将SGC凝胶的体积和动态性能（包括流变学、注入性和封堵能力）与聚合物凝胶进行比较。然后，建立具有水道的三维物理模型以揭示凝胶辅助CO吞吐的提高采收率机理。本文还讨论了几个凝胶辅助CO吞吐的先导试验。体积和动态实验结果表明，尽管这两种凝胶剂具有相似的粘度，但SGC凝胶剂与聚合物凝胶剂相比具有更好的注入性。SGC凝胶主要是一种粘性溶液，这使其更容易流过孔喉。SGC凝胶剂的阻力系数仅为聚合物凝胶剂的0.58倍。凝胶化后，使用SGC凝胶剂可形成粘度为174267 mPa·s的三维网络状凝胶。SGC凝胶的残余阻力系数约为聚合物凝胶的三倍，这表明SGC凝胶在多孔介质中具有更强的封堵能力。三维实验结果表明，四个周期的凝胶辅助CO吞吐可实现11.36%的采收率提高，是纯CO吞吐的2.56倍。在用SGC凝胶封堵通道后，近井地带的剩余油可首先由CO采出，深部地层的油随后可被边水有效驱替。在中国冀东油田对五口井进行了先导试验，2016年至2021年期间共获得3790.86立方米的产油量。所提出的新型SGC凝胶适用于辅助CO吞吐过程，这是在窜流油藏中进一步提高采收率的有益方法。
