川东北气田伴生CO2注入川中油田EOR可行性分析——以普光气田伴生CO2注入桂花油田为例

四川盆地普光气田CO₂含量为8％～10%，每年高空燃烧排放的CO₂量约为6.9×10⁸ m³。为了实现低碳油气开发，挖掘资源潜力，建议将CO₂气从天然气中分离后注入川中侏罗系油藏，以提高这些低渗透致密油藏的采收率。在分析了川中桂花油田的开发历史后，绘制出桂花油田开采预测曲线，如采用大型压裂酸化、钻水平井、成像测井、三维地震储层预测技术，加上CO₂混相驱油提高采收率等，预计桂花油田的年产油量将在2015年恢复到4×10⁴ t，2020年达到7×10⁴ t，2025年达到10×10⁴ t。同时，经济分析的计算结果也支持这一建议，如把碳税和碳交易收入作为考虑因素，则该项目的可行性将更充分。随着川东北早三叠世-晚二叠世酸性大气田的陆续投产，比如同属于中国石油天然气股份公司的龙岗气田将有更多的CO₂需要加以埋藏，届时亦可将莲池油田、金华镇油田、公山庙油田和中台山油田等纳入CO₂混相驱油提高采收率试验区。

Potential analysis of oil recovery enhancing treatment by injecting the associated CO2 gas from the Puguang Gas Field into the Guihua Oil Field

The content of CO2 in the Pugugang Gas Field, Sichuan Basin, is 8% ~ 10% and the volume of CO2 emission from flare gas in this field is about 6.9×108 m3 each year. In order to tap resource potential and contribute to a low carbon economy, we suggest that the CO2 separated from the natural gas in the Puguang Field be injected into the Jurassic oil reservoirs in the Central Sichuan Basin, thus to enhance the oil recovery of these low permeability and dense oil reservoirs. Based on the analysis of the development history of the Guihua Oil Field in the Central Sichuan Basin, the curve of oil production forecast is drawn for this field. From this curve, if such EOR measures are taken including large scale fracturing and acidizing treatment, horizontal well drilling, image logging, 3 D seismic reservoir prediction, CO2 miscible displacement, etc., the annual oil production in the Guihua Field will be resumed to 40 thousand tons in 2015, even up to 70 thousand tons in 2020 and 100 thousand tons in 2025. This forecasting result agrees well with that from the economic analysis, if carbon tax and carbon trading income are taken into account, this project of EOR treatment using CO2 is more feasible in this field. Along with several large Early Triassic and Late Tertiary sour gas fields having been put into production in the Northeast Sichuan Basin, for example, the Longgang Gas Field operated by the PetroChina, more and more volumes of CO2 have to be sequestrated, under the situation of which, more pilot test zones will be built for the CO2 miscible displacement as one of EOR treatment measures in the Lianchi, Jinhuazhen, Gongshanmiao, and Zhongtaishan oil fields.