注N₂开发有水气藏的敏感性因素研究

 Research on sensitivity factors of gas reservoir with water by injecting N₂ development

 李登伟¹ 张烈辉² 易建国³ 焦健¹ 姜自然⁴

中国石化国际石油勘探开发有限公司开发生产部，北京 100083 西南石油大学油气藏地质及开发工程国家重点实验室，四川 成都 610500 中国石油西南油气田分公司川中对外合作项目部，四川 成都 610016 中国石油东方地球物理勘探有限责任公司研究院，河北 涿州 072751

注N₂开发有水气藏具有保持压力、非混相驱替、解堵助排以及建立附加地层压差等4种优势，是一种新的探索。同时，分形理论已成为勘探者和油藏工程师们的有利工具。在分形理论的基础上，建立了孔隙型气藏中注N₂开发有水气藏的气水两相三组分分形渗流模型，利用有限差分方法将其离散，采用全隐式方法进行求解。根据实际气藏参数，对N₂、天然气、水三相驱替进行了敏感性分析，结果表明：稳产期末注入N₂可以有效地减缓边水的锥进；注N₂可以补充地层能量，保持较高压力开采，延长气藏无水采收期；一直注气和气藏稳产期末注气的采收率相差较大，建议开展早期注气。

 N₂ injection development of gas reservoir with water has four advantages such as pressure maintaining, non-miscible flooding, cleaning up and additional reservoir pressure difference building. This is a new exploratory research. Meanwhile, fractal theory has become a powerful tool for prospectors and reservoir engineers. Therefore, based on the fractal theory, the fractal percolation model of two phases and three components was established for the pore gas reservoir by injecting N₂ development, which was dispersed using finite differential method and solved using fully implicit method. The sensitivity factors of three phases flooding (N₂, natural gas and water) were analyzed based on the actual parameters of gas reservoir. The results show that N₂ injection can slow down effectively the edge of the water coning at the end of stable production period, maintain formation energy and high reservoir pressure, and prolong the recovery period without water. The recovery has big difference between injecting N₂ in early time and in the late time. So, the early injecting N₂development is proposed.

10.6056/dkyqt201203017