致密油藏压裂吞吐动态渗吸产油贡献量化研究

Quantitative study on contribution of dynamic imbibition to oil production during fracturing and huff-n-puff in tight reservoirs

刘红现 白雷 罗强 刘同敬 孙江飞 刘佳幸

LIU Hongxian BAI Lei LUO Qiang LIU Tongjing SUN Jiangfei LIU Jiaxing

1. 中国石油大学(北京)克拉玛依校区 石油学院, 新疆 克拉玛依 834000; 2. 中国石油 新疆油田公司 实验检测研究院, 新疆 克拉玛依 834000; 3. 中国石油大学(北京) 非常规油气科学技术研究院, 北京 102249

1. Petroleum Institute, China University of Petroleum (Beijing) at Karamay, Karamay, Xinjiang 834000, China; 2. Experimental Testing Research Institute, Xinjiang Oilfield Company, Karamay, Xinjiang 834000, China; 3. Unconventional Petroleum Research Institute, China University of Petroleum (Beijing), Beijing 102249, China

致密油藏压裂吞吐是一个动态渗吸过程，主要通过压差驱替作用和自发渗吸作用实现原油增产，但目前尚不清楚这两种增油机理对产油量量化的贡献程度。为研究致密砾岩油藏压裂吞吐采油过程中，动态渗吸增油机理对产油贡献的量化分析问题，借助高温高压多功能岩心驱替系统和高温高压在线驱替核磁共振成像系统，采用天然致密砾岩油藏岩心，开展室内物理模拟实验。首先通过不同类型压裂驱油剂的渗吸特征实验，筛选渗吸效果较好的压裂驱油剂类型；然后依据压裂吞吐采油效果评价实验，优选采油效果最好的压裂驱油剂；最后通过采油效果影响因素实验，对压裂吞吐采油的动态渗吸增油机理进行量化分析。实验结果显示：表面活性剂和流动控制剂的渗吸效果均较好，流动控制剂更有助于提高压裂吞吐的采油效果，渗吸作用和驱替作用在动态渗吸过程中对产油贡献的变化规律是相反的。当压裂驱油剂降低界面张力和改变湿润性的能力较强时，渗吸作用为主要增油机理，反之驱替作用为主要增油机理；表面活性剂和流动控制剂的渗吸效果都比较好，但前者对吞吐轮次的敏感程度较弱，后者的敏感程度较强；焖井时间是影响动态渗吸过程中渗吸/驱替贡献率的主要因素，但驱替贡献率始终大于渗吸贡献率。

Fracturing and huff-n-puff in tight reservoirs is a dynamic imbibition process, where crude oil recovery is enhanced mainly through two mechanisms: differential pressure displacement and spontaneous imbibition. However, the contribution rate of these two mechanisms to the quantification of overall oil recovery remains unclear. To address this, a quantitative analysis was conducted on the contribution of dynamic imbibition mechanisms during fracturing and huff-n-puff oil recovery in tight conglomerate reservoirs. Laboratory physical simulation experiments were carried out using natural tight conglomerate reservoir cores, utilizing a high-temperature and high-pressure multi-functional core displacement system and a high-temperature and high-pressure online displacement nuclear magnetic resonance imaging system. Firstly, experiments were conducted on the imbibition characteristics of different types of fracturing oil displacement agents, and the agents with superior imbibition effects were screened out. Secondly, based on evaluations of fracturing and huff-n-puff oil recovery, the most effective fracturing oil displacement agent was identified. Finally, through analyzing factors influencing oil recovery, a quantitative assessment of the production enhancement mechanisms of dynamic imbibition in fracturing and huff-n-puff oil recovery was carried out. The experimental results showed that both surfactants and flow control agents exhibited strong imbibition effects, with flow control agents more effective in enhancing fracturing and huff-n-puff oil recovery. Furthermore, the contribution of imbibition and displacement on oil recovery during the dynamic imbibition process showed opposite patterns. The main research conclusions are as follows. Imbibition dominates as the primary oil recovery mechanism when the fracturing oil displacement agent exhibits a strong ability to reduce interfacial tension and alter wettability. Otherwise, displacement becomes the dominant mechanism. Both surfactants and flow control agents demonstrate good imbibition performance. However, surfactants are less sensitive to huff-n-puff cycles, while flow control agents are more sensitive. Shut-in time is the key factor affecting the contribution rate of imbibition or displacement. However, the contribution rate of displacement remains consistently higher than that of imbibition.

省部级基金新疆天山创新团队项目“油气高效管输技术研究与应用创新”(2022TSYCTD0002)资助。

https://doi.org/10.11781/sysydz2025020417