大庆榆树林油田天然气驱油研究

随着勘探开发的不断深入和发展，我国低渗油藏所占的比例正不断加重，如何高效开发这类油气藏是石油工作者面临的一项重要任务。注天然气开发油藏已成为提高原油采收率的重要技术手段，对于高含水中后期油藏、注水困难的强水敏油藏和低渗透油藏，注天然气开采具有显著的效果。注天然气可更好地保持地层压力，解决注不进水造成的困扰。大庆榆树林油田属于低渗透的大型油田，注水开发效果差，为了大幅度提高此类油田的采收率，进行了一系列天然气驱油实验，包括细管实验和长岩心注入工艺实验，分析了影响采收率的因素和机理，并且采用数值模拟技术手段进行了模拟研究，结果表明大庆榆树林油田天然气驱只能非混相驱，天然气驱非混相驱可以大幅度提高油田采收率，天然气驱关键的因素是注入段塞的大小和注入的压力等方式的选择。

STUDY ON GAS DISPLACING OIL OF YUSHULIN OIL FIELD IN DAQING AREA

As exploration and production are conducted deeper and deeper, the proportion taken by low-permeability reservoirs becomes more and more. It is an important task for oil technicians how to develop the reservoirs effectively. Enhancing oil recovery by gas injection has become one of significant tools to improve the recovery factor in oil reservoirs. As for the medium or late stage reservoirs with high water cut, the reservoirs with strong water sensitivity that is difficult for water injection, and the reservoirs with low permeability, the method of gas injection that has proved to be powerfully effective. With the help of gas injection, the reservoir pressure can not only be maintained better but the serious problem of water injection can be solved. Yushulin oil field of Daqing oilfield is a large oil field with low permeability. The effect of water flooding is not good. To improve the recovery factor of the oilfield greatly, a series of experiments with gas displacing oil are conducted, including the tests with thin tubes and long cores. The mechanism and factors to influence the recovery factor are analyzed. With numerical simulation tools, the simulation study is conducted. The results show the immiscible gas displacement can be only used in Yushulin oil field. The immiscible gas displacement can improve the recovery factor greatly. The key points of successful gas displacement are to choose the size of the injection slug and the injection pressure etc.