超低渗透油藏CO吞吐利用率实验研究

CO Utilization Ratio Simulation during a CO Huff-and-Puff Process in Ultra-Low Permeability Oil Reservoirs

钱坤 杨胜来 马轩 窦洪恩 黄宇

QIAN Kun YANG Shenglai MA Xuan DOU Hongen HUANG Yu

1. 油气资源与工程国家重点实验室(中国石油大学(北京)), 北京 102249; 2. 中油(新疆)石油工程有限公司, 新疆克拉玛依 834000; 3. 中国石油勘探开发研究院, 北京 100083

1. State Key Laboratory of Petroleum Resource and Engineering(China University of Petroleum(Beijing)), Beijing, 102249, China; 2. Zhongyou(Xinjiang) Petroleum Engineering Co., Ltd., Karamay, Xinjiang, 834000, China; 3. PetroChina Research Institute of Petroleum Exploration and Development, Beijing, 100083, China

CO2吞吐技术是开发特低渗透、超低渗透油藏的有效方式，但吞吐过程中CO2的利用率如何亟待研究。利用长庆油田某超低渗透油藏天然岩心进行了室内CO2吞吐物理模拟实验，分析了不同注入压力下CO2吞吐的采收率规律和CO2利用率。研究发现，CO2吞吐的累计采收率随着注入压力的升高而增大，并逐渐减缓；CO2利用率随着吞吐轮次的增加明显降低，前4轮CO2吞吐中CO2的利用率较高；提高CO2注入压力使CO2-原油体系达到近混相或者混相状态，不仅能够获得更高的采收率，而且不会显著增加CO2气源方面的成本。研究结果表明，油田应用CO2吞吐技术时采用近混相或者混相方式进行4个轮次的吞吐，能够取得较好的开发效果和经济效益。

CO2 huff-and-puff is an effective method in the development of extra-low permeability and ultra-low permeability reservoirs.In order to use this technique to cut the cost and increase oil recovery in oilfields,the gas utilization ratio during CO2 huff-and-puff process was investigated.CO2 huff-and-puff tests using ultra-low permeability cores from Changqing Oilfield were carried out to investigate oil recovery factors and CO2 utilization under different injection pressures.The test results show that ultimate oil recovery increases with the increase of injection pressure and the increasing amplitude would decrease gradually.In addition,CO2 utilization ratio is relatively high in the first four cycles,but is significantly reduced with the increase of huff-and-puff cycles.The increasing of injection pressure can make the CO2-crude oil system enter into a miscible phase condition, which is beneficial for obtaining higher oil recovery without significant increase of the cost of CO2 supply.The results show that CO2 huff-and-puff with four cycles will be close to miscible condition and could achieve better development effect and economic benefits.

国家科技重大专项"国内油气开发发展战略研究"（编号：2016ZX05016-006）资助。

https://doi.org/10.11911/syztjs.2018147