Si Shuanghu, Liu Yifei, Jiang Yinghui, Zou Chenwei, Yang Ning, Lv Dongfang, Miao Xizhuo, Dai Caili
State Key Laboratory of Deep Oil and Gas, China University of Petroleum (East China), Qingdao 266580, China.
School of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, China.
Gels. 2025 Apr 21;11(4):305. doi: 10.3390/gels11040305.
In fractured reservoirs, fractures serve as both water channeling and oil flow channels. Because of the impact of bottom water coning, the water channeling phenomenon becomes more problematic in the middle and late stages of reservoir development. Furthermore, residual oil is limited to small-scale fractures. In multi-scale fractures, the conventional pressure-bearing pattern of plugging agents is ambiguous. This results in low oil recovery, low sweep efficiency from water flooding, and low plugging agent application efficiency. Until now, the pressure-bearing patterns related to gel strength in multi-scale fractures have not been clear. In this paper, the gelation performances of temperature-resistant gel (TRG) samples with different elastic moduli were investigated. The elastic modulus of the TRG was normalized by the elastic modulus (G') and viscosity modulus (G″). Subsequently, we carried out research on the bottom water pressure patterns of TRGs. This study revealed the pressure-bearing patterns of the TRGs under multi-scale fractures. A corresponding influence pattern chart was established, and the optimal surface function was fitted using the MATLAB nonlinear surface data fitting method. Finally, an application experiment for the characteristic chart was carried out. The plugging rate was evaluated based on the permeability reduction and pressure differential across the core samples before and after gel injection. Subsequently, a TRG with certain elastic moduli before and after plugging the core fracture node was selected from the chart. The elastic modulus of the TRG at the injection node prior to plugging was 14.29 Pa. The elastic modulus of the TRG at the injection node after plugging was 19.42 Pa. The experimental results showed that the TRG with an elastic modulus of 19.42 Pa effectively plugged the fractures and remained stable for over 90 days under a pressure differential of 53 KPa, resulting in a 58.7% improvement in oil recovery compared with water flooding. However, it was difficult for the TRG with an elastic modulus of 14.29 Pa to plug fractures efficiently, and it only enhanced the oil recovery by 15.2%. The primary aim of this work was to establish a quantitative and normalized evaluation method for temperature-resistant gels (TRGs) used in fractured reservoirs. By introducing a classification system based on the elastic modulus (G') and correlating it with the fracture scale and plugging performance, this study bridges the gap between laboratory gel evaluations and field applications. The results provide practical design criteria and contribute to improving the efficiency and adaptability of gel plugging strategies under harsh reservoir conditions.
在裂缝性油藏中，裂缝既是水窜通道也是油流通道。由于底水锥进的影响，水窜现象在油藏开发的中后期变得更加严重。此外，剩余油局限于小规模裂缝中。在多尺度裂缝中，封堵剂的传统承压模式不明确。这导致采收率低、水驱波及效率低以及封堵剂应用效率低。到目前为止，多尺度裂缝中与凝胶强度相关的承压模式尚不清楚。本文研究了不同弹性模量的耐温凝胶（TRG）样品的胶凝性能。通过弹性模量（G'）和粘性模量（G″）对TRG的弹性模量进行归一化。随后，对TRG的底水压力模式进行了研究。该研究揭示了多尺度裂缝下TRG的承压模式。建立了相应的影响模式图，并使用MATLAB非线性曲面数据拟合方法拟合了最佳表面函数。最后，对特征图进行了应用实验。根据注入凝胶前后岩心样品的渗透率降低和压差来评估封堵率。随后，从图中选择了封堵岩心裂缝节点前后具有一定弹性模量的TRG。封堵前注入节点处TRG的弹性模量为14.29 Pa。封堵后注入节点处TRG的弹性模量为19.42 Pa。实验结果表明，弹性模量为19.42 Pa的TRG有效地封堵了裂缝，在53 KPa的压差下稳定超过90天，与水驱相比，采收率提高了58.7%。然而，弹性模量为14.29 Pa的TRG难以有效封堵裂缝，仅使采收率提高了15.2%。这项工作的主要目的是建立一种用于裂缝性油藏的耐温凝胶（TRG）的定量和归一化评价方法。通过引入基于弹性模量（G'）的分类系统并将其与裂缝尺度和封堵性能相关联，本研究弥合了实验室凝胶评价与现场应用之间的差距。研究结果提供了实用的设计标准，有助于提高恶劣油藏条件下凝胶封堵策略的效率和适应性。
