利用高碳气运移驱替开发高烃气的机理研究及效果预测

Mechanism research and effect prediction of high hydrocarbon gas development through high CO_2 gas migration and displacement

南海西部莺歌海盆地部分气藏高含CO_2,常规开发方法下直接采出的经济价值较低,且不利于环保。提出通过建立高碳气藏与已开发高烃气藏之间的运移通道,依靠层间压力差将高碳气运移注入到高烃气藏,提高高烃气藏开发效果的同时间接开发高碳气藏的思路。从室内试验研究、数值模拟研究以及先导区开发效果模拟等多方面对新思路的开发机理及效果进行了深入研究分析,认为开发机理主要是高碳气驱替置换高烃气以提高高烃气采收率和地层束缚水溶解吸收部分高碳气中CO_2从而改善高碳气品质。在南海西部海域莺歌海盆地,通过本文方法开发利用高碳气藏,既可提高高烃气藏的采收率,又可改善部分高碳气品质,最终大部分高碳气仍封存在地下,可以实现经济效益和环境效益的双赢。

There are several high CO2 content gas reservoirs in the Yinggehai basin in the western South China Sea,and the CO2 produced with the conventional development method has only limited economic value and is harmful to the environment.A new idea was proposed to establish a migration pathway between high CO2 gas reservoirs and the developed high hydrocarbon gas reservoirs,and to divert high CO2 gas into high hydrocarbon gas reservoirs by means of pressure difference between layers,hence improving gas recovery of high hydrocarbon gas reservoirs and simultaneously achieve the indirect development and utilization of high CO2 gas reservoirs.In this paper,the mechanism and effect of this new development idea were deeply studied and analyzed through lab experimental research,numerical simulation research,and simulation of development effects in pilot area.Research suggests that the development mechanisms mainly include that high CO2 gas displaces high hydrocarbon gas to improve high hydrocarbon gas recovery,and the formation irreducible water dissolves and absorbs partial CO2 from high CO2 gas to improve the quality of high CO2 gas.This method can not only improve the recovery factor of high hydrocarbon gas reservoirs in the Yinggehai basin in the western South China Sea,but also improve the quality of high CO2 gas,and finally most of high CO2 gas is still underground after the development.This method can achieve a win-win situation between economic benefits and environmental benefits.