超低渗致密油藏二氧化碳吞吐合理注入参数确定

Determination of rational parameters for CO huff-n-puff in tight oil reservoirs with ultra-low permeability

王小龙 高庆贤 董双福 杨震 钟银 马尚娟 周洪涛

WANG Xiaolong GAO Qingxian DONG Shuangfu YANG Zhen ZHONG Yin MA Shangjuan ZHOU Hongtao

中国石油吐哈油田公司三塘湖采油管理区 中国石油吐哈油田公司鲁克沁采油管理区 中国石油大学(北京)克拉玛依校区

Santanghu Oil Production Management Area, CNPC Tuha Oilfield Company, Hami 839000, Xinjiang, China Oil Production Management Area, CNPC Tuha Oilfield Company, Hami 839000, Xinjiang, China Karamay Campus, China University of Petroleum (Beijing), Karamay 834000, Xinjiang, China

为解决三塘湖油田马56区块超低渗致密稠油油藏衰竭式开采采收率低的问题，开展二氧化碳吞吐先导性试验。通过对二氧化吞吐影响因素分析，从地层条件、储层条件、油井动态和井筒条件等方面明确了选井原则，并在分析二氧化碳吞吐从注入到稳产的7个阶段作用机理的基础上，采用数值模拟和现场试验的方法，以最优单井增油量和换油率为目标，在重点考虑二氧化碳混相和超临界态影响的条件下，进一步确定了合理的注气吞吐参数，即单井单轮次注入液态二氧化碳量2 000 t，注入速度100 t/d，闷井时间20 d，吞吐轮次在3个轮次以内。二氧化碳吞吐技术在马56区块超低渗致密稠油油藏实施6井次，有效率100%，平均单井增油1 073 t，累计增油为6 440 t，尤其马56-7H井在实施多轮次压裂及注水吞吐措施后，采用二氧化碳吞吐仍累计增油1 267 t。研究成果为超低渗致密稠油油藏衰竭式开采后进一步提高采收率探索了新路径。

In the tight heavy oil reservoirs with ultra-low permeability in Ma 56 block, Santanghu Oilfield, to address the issue of low recovery rate brought by depleted development, a pilot CO huff-n-puff test was conducted. By analyzing the factors influencing CO huff-n-puff, well screening principles were determined based on reservoir conditions, formation conditions, well dynamics, and wellbore conditions. On the basis of analyzing the mechanisms of CO huff-n-puff during the seven stages from injection to stabilized production, by combining numerical simulation and field tests, aiming at the optimal oil increment and oil change rate of a single well, and under the conditions of emphasizing the influence of CO miscibility and supercritical state, rational injection parameters for gas huff-n-puff were further determined, that is, an injection of 2 000 tones of liquid CO into a single well in a single round, with an injection rate of 100 t/d, soaking period of 20 days, and a maximum huff-n-puff rounds of three. The CO huff-n-puff technology was applied in six wells in the ultra-low permeability tight heavy oil reservoir in Ma 56 Block, achieving a 100% success rate with an average single-well oil increasement of 1 073 tones and a cumulative oil increasement of 6 440 tones. Notably, Well Ma 56-7H achieved an oil increasement of 1 267 tones even after multiple rounds of fracturing and water huff-n-puff. The research outcomes provide a new pathway for further enhancing recovery rate in ultra-low permeability tight heavy oil reservoirs developed by depleted pattern.

10.13639/j.odpt.202305007