鄂尔多斯盆地油沟区长4+5低渗透油藏二氧化碳驱先导试验

Pilot test on CO flooding of Chang 4+5 oil reservoir in Yougou region of the Ordos Basin

齐春民 李瑞冬 朱世东 刘立虎 李金灵

QI Chunmin LI Ruidong ZHU Shidong LIU Lihu LI Jinling

延长油田股份有限公司吴起采油厂 西安石油大学材料科学与工程学院 石油石化污染物控制与处理国家重点实验室 陕西省油气田环境污染与储层保护重点实验室

Wuqi Oil Production Plant, Yanchang Oilfield Company, Wuqi 717600, Shaanxi, China College of Materials Science and Engineering, Xi'an Shiyou University, Xi'an 710065, Shaanxi, China State Key Laboratory of Petroleum Pollution Control, Beijing 102206, China Shaanxi Key Laboratory of Oil/Gas Field Environment Pollution and Reservoir Protection, Xi'an 710065, Shaanxi, China

鄂尔多斯盆地低渗透油藏储量丰富，但注水驱油效果不佳且陕北地区水资源匮乏，亟需新的驱油技术降本增效。为此，基于吴起油沟油区长4+5¹油藏特征，利用20 m细管在60 ℃下进行了CO₂驱替模拟实验，在此基础上，结合油藏特征设计了施工参数，并选取了5个井组进行CO₂驱先导试验，通过注CO₂前后地层压力对比、CO₂驱油效果、实施区CO₂泄露监测对现场施工情况进行了分析。研究表明：长4+5¹低渗透油藏满足CO₂混相驱的要求，井口压力8 MPa、流速0.6 t/h的施工参数可保障其混相，CO₂可在储层中均匀推进，地层压力稳步回升，注气2年同比注水驱油增产原油2 935.6 t，其换油比为3.03∶1，且在试验区土壤中未监测到CO₂泄漏。该研究可为碳捕集、利用与封存(CCUS)技术在鄂尔多斯盆地的安全推广提供技术支持，为保障延长油田稳产及陕北地方经济可持续发展提供技术参考。

In the Ordos Basin, there are abundant reserves in low-permeability oil reservoirs, but their water flooding effects are not satisfactory. In addition, the water resources in northern Shaanxi are deficient. Therefore, it is in urgent need to develop a new flooding technology for cost reducing and efficiency increasing. In view of the characteristics of Chang 4+5 oil reservoir in Yougou oil region of Wuqi Oilfield, the simulation experiment of CO flooding was conducted by using the slim tube of 20 m at the temperature of 60 ℃. Then, the construction parameters were designed based on the characteristics of the oil reservoir, and 5 well groups were selected for the CO flooding pilot. Finally, the field construction situations were analyzed from the aspects of formation pressure comparison before and after CO injection, CO flooding effect and CO leakage monitoring in the construction area. It is indicated that Chang 4+5 oil reservoir satisfies the conditions of CO miscible flooding and the wellhead pressure of 8 MPa and the flow rate of 0.6 t/h can guarantee its miscible phase. CO advances uniformly in the reservoirs and the formation pressure recovers steadily. The oil increment of two years’ CO miscible flooding is 2 935.6 t higher than that of water flooding in the same period, its CO to oil exchange ratio is 3.03∶1, and no CO leakage is detected in the soil of the test region. The research results can provide the technical support for the safe popularization of carbon capture, utilization and sequestration (CCUS) technology in the Ordos Basin, and the technical reference for the stable production of Yanchang Oilfield and the sustainable development of local economy in northern Shaanxi.

10.13639/j.odpt.2019.02.020