缝洞型油藏氮气辅助重力驱可行性分析

Feasibility study on nitrogen-assisted gravity drainage in fractured-vuggy reservoirs

张慧 鞠斌山 刘中春 宋传真 朱桂良

中国地质大学（北京）能源学院，北京 100083 中国石化石油勘探开发研究院，北京 100083 中国地质大学（北京）非常规天然气能源地质评价与开发工程北京市重点实验室，北京 100083

School of Energy Resources, China University of Geosciences, Beijing 100083, China Research Institute of Petroleum Exploration and Development, SINOPEC, Beijing 100083, China Beijing Key Laboratory of Unconventional Natural Gas Geology Evaluation and Development Engineering, China University of Geosciences, Beijing 100083, China

为了动用塔河油田奥陶系中下部剩余油，文中探索了氮气辅助重力驱技术在缝洞型碳酸盐岩油藏中提高采收率的可行性，建立了缝洞型油藏中启动最小裂缝尺度的计算公式。当裂缝宽度达到1.0 mm以上时，其沟通的盲端剩余油可被动用；当裂缝宽度达到0.2 mm以上时，其沟通的溶洞剩余油可被动用。制作了缝洞体二维可视化剖面模型，研究氮气辅助重力驱技术在缝洞型油藏中的力学机制，提出驱动准数的概念，定量表征气驱垂向重力分异力与水平驱替力的比值，明确了缝洞型油藏氮气辅助重力驱发挥作用的生产界限为驱动准数大于0.05。实施氮气辅助重力驱现场试验并取得了成功，井组含水率从71.7%下降到39.7%，累计增油3 100 t。文中论证了氮气辅助重力驱技术在塔河油田缝洞型油藏应用的可行性，为改善塔河油田缝洞型油藏注气效果提出了技术方向。

In order to utilize the remaining oil in the middle and lower Ordovician of Tahe Oilfield, the feasibility of nitrogen-assisted gravity drainage in fractured-vuggy carbonate reservoir is explored, and the calculation formula of start-up minimum fracture size in the fractured-vuggy reservoir is established. When the fracture width is more than 1.0 mm, the communicated remaining oil in blind end hole can be utilized. When the fracture width is more than 0.2 mm, the communicated remaining oil in karst cave can be utilized. A 2D visual profile model of fractured?鄄vuggy reservoir is made to study the mechanical mechanism of nitrogen?鄄assisted gravity drainage in fractured?鄄vuggy reservoir. The concept of driving criterion is proposed to quantitatively characterize the ratio of gravity differentiation force and horizontal displacement force of gas drive oil and gas, and the production limit of nitrogen-assisted gravity drainage in fractured-vuggy reservoir is defined as driving criterion greater than 0.05. The field test of nitrogen-assisted gravity drainage has been carried out successfully. The water cut of well group has been reduced from 71.7% to 39.7%, and the cumulative oil production has increased by 3, 100 tons. The feasibility of application of nitrogen-assisted gravity drainage technology in Tahe Oilfield fractured-vuggy reservoir is demonstrated, which provides a technical direction for improving gas injection effect in fractured-vuggy reservoir of Tahe Oilfield.

10.6056/dkyqt202203019