封闭性缝洞型碳酸盐岩油藏单元注氮气开发影响因素分析

ANALYSIS ON INFLUENCING FACTORS OF NITROGEN INJECTION DEVELOPMENT IN SEALING FRACTURE-CAVITY TYPE CARBONATES RESERVOIRS

塔河油田部分封闭性缝洞型碳酸盐岩单元天然能量、水驱开发后效果重新变差,为改善该类油藏单井生产,进行缝洞单元注氮气开发技术探索,为该区稳产提供技术支持。根据单元注气与其之前单元注水情况特征进行多组对比,研究了单元氮气驱影响因素及运移方式、方向。结合现场生产情况表明,以S67单元为例,结合区域构造,通过对比单元氮气驱、水驱开发特征,分析了单元氮气驱中的影响因素,给出了气/水共存介质中气相运移方式和方向,为后期注气井选择、受效井预判提供指导。分析表明,由于氮气与水的较大物理差异,缝洞型碳酸盐岩单元氮气驱油路径明显与水驱不同,提高单元注气采收率,是后期开发的关键。

In Tahe Oilfield,after the development of natural energy and water flooding,the production of some sealing fracture-cavity type carbonate units become poor. To improve the single well production,the technology of fracture-cavity unit nitrogen injection was researched to provide technical support for steady production. In this paper,the influencing factors,moving method and directions of nitrogen flooding were studied based on the comparison of unit gas flooding and unit water flooding. Take unit S76 as an example,combined with site production,regional structure,and the features of gas flooding and water flooding,the influencing factors of unit nitrogen flooding were analyzed and the moving method and directions of gas in gas / water coexistence medium were concluded,which provides guidance for gas injection well selection and responding well prediction. From the analysis,because of the great physical difference between nitrogen and water,oil displacement way of nitrogen flooding in fracture-cavity type carbonate units differs much from that of water flooding,which improves the unit gas injection recovery ratio and provide a good foundation for feasibility of economic benefit evaluation.