气顶油气田开发程序的探讨

DISCUSSION ON DEVELOPMENT PROGRAMS OF GAS-CAP RESERVOIRS

气顶油气田因气顶及油气界面的存在,同时因气顶和油环的大小、储层物性、几何形态不同和边底水活跃程度不同,致使气顶油气藏在开采过程中具有多种驱油机理,采收率变化较大,这关键是气顶油气藏在开发过程中存在油气界面的移动问题,而调整和控制油气界面是相当困难。文章以唐家河油田东三段油气藏为例,应用动态分析法和数值模拟法,讨论了不同类型气顶油藏中油气水的分布特征以及气顶气投产时机等对油气采收率的影响,提出了高效开发气顶油气藏的具体措施。在精细地质描述的基础上正确选择开发方式,加强动态监测,适时完善注采系统,保持油环和气顶开发相协调。当气顶气储量相对较大时,采取气顶、油区同时开发;而对于气顶体积相对较小并且边、底水能量充足时,采取先依靠天然能量开采油区,然后人工注水,最后开采气顶。

Depending on the geometry of gas-cap and oil column, the physical property and geometric shape of reservoir, and the mobility of edge and bottom water, the multiple oil-driving mechanisms exist in gas-cap reservoirs where there are gas cap and oil/gas interface, and the recovery factor changes a lot because the oil/gas interface moves during exploitation of gas-cap reservoirs and it is very difficult to adjust and control the oil/gas interface. Taking the Dong 3 reservoir of Tangjiahe oil field as example, with dynamic analysis and numerical simulation, the influence of the oil/gas/water distribution and the gas-recovering time of gas cap on the oil and gas recovery factors are discussed for different kinds of gas-cap reservoirs. The concrete measures are proposed for efficient development of gas-cap reservoirs. Based on the fine reservoir description, the measures include to properly choose the production mode, strengthen the performance monitoring, timely improve the injection/production system, and keep coordinating the exploitation of the oil column with the gas cap. When the gas reserves of the gas cap are relatively bigger, the gas cap and the oil column should be exploited simultaneously. When the volume of the gas cap is relatively smaller and the energy of the edge and bottom water is sufficient, the oil column should be exploited first depending on the natural energy, then water injection should be done artificially, and the gas cap should be exploited at last.