注伴生富化气近混相多级接触驱替机理研究

THE RESEARCH ON NEAR-MISCIBLE MULTI CONTACT FLOODING MECHANISM OF INJECTING ASSOCIATED RICH GAS

根据近混相驱理论,适当选择注入气的组成,形成湿气或富化气,在低于最小混相压力下可能会形成蒸发-凝析双重传质作用的近混相驱,在适当降低注入压力的同时能使驱替达到与混相驱相同的效果。以我国海上油田某一实际油藏为例,采用该油藏伴生的富化气进行回注,通过注入气体与地层原油之间互溶性膨胀实验以及多级接触PVT相态特征实验和模拟研究,描述了近混相驱多级接触过程中注入气和地层油之间组成变化特征以及PVT高压物性变化规律,探索了我国海上油田注伴生富化气近混相驱油机理。

Based on near miscible flooding mechanism, the miscible phase can be achieved with the increase of miscible pressure, even though there is little middle molecular weight of crude oil. High miscible pressure of this kind of crude oil is required, which is hard to be achieved for reservoir gas injection engineering. However, based on near-miscible flooding mechanism, the near-miscible flooding of vapor-condensate double mass transportation action under lowest miscible pressure may be formed with wet gas or enriched gas produced by proper choose of composition of gas injected. Its character is the creation of low interface, which can reduce the injection pressure and arrive at the miscible flooding efficiency. Based on a practical reservoir in offshore oil field, the associated rich gas in the reservoir is rejected, through the simulation and experiment of multiple-contact PVT phase behavior and inter -miscibility swelling between gas injected and formation oil, the change laws of PVT high pressure physical property and the change characteristic between the formation oil and gas injected during near-miscible multiple-contact process are described and the near miscible flooding mechanism of associated rich gas injection of marine oil field are explored.