永宁油田特低渗水驱油藏提高采收率技术对策研究

Research of EOR Technical Measures for Ultra-low Permeability Water-flooding Reservoir in Yongning Oilfield

基于永宁油田部分井区采出程度低、井区窜流严重等情况,优选永宁油田张柴窑子井区作为先导试验区,通过油藏模拟剩余油分布规律分析,明确其平面与纵向上的潜力方向。同时开展区域内标准井的空气泡沫驱试验,分析对比CO_(2)驱采油技术、空气泡沫驱采油技术通过挖潜剩余油来提高采收率的技术方法。结果表明:张柴窑子井区由于原始地层压力小以及CO_(2)驱成本相对较高等原因,不适宜采用CO_(2)混相驱采油技术;而张柴窑子井区采用空气泡沫液驱替,驱油效率平均为14.89%,与水驱相比驱油效率提高5.30~29.30个百分点,最终采收率平均可提高6.80个百分点,建议对永宁油田范围内与张柴窑子井区油藏特征相近的区块优先推广空气泡沫驱采油技术来提高采收率。

Based on the low recovery rate and severe crossflow in some well areas of Yongning Oilfield,the Zhangc-haiyaozi well area of Yongning Oilfield is selected as the pilot experimental area.By analyzing the distribution pattern of remaining oil through reservoir simulation,its potential direction in both horizontal and vertical directions is clar-ified.At the same time,the air foam flooding test of standard wells in the region was carried out to analyze and com-pare the technical methods of CO_(2) flooding and air foam flooding to improve oil recovery by tapping the remaining oil potential.The results indicate that due to the low original formation pressure and relatively high cost of CO_(2) flooding in the Zhangchaiyaozi well area,it is not suitable to use CO_(2) miscible flooding oil recovery technology;However,the Zhangchaiyaozi well block uses air foam fluid displacement,with an average oil displacement efficiency of 14.89%.Compared with water displacement,the oil displacement efficiency is increased by 5.30 to 29.30 percentage points,and the final oil recovery can be increased by 6.80 percentage points on average.It is suggested that the air foam flooding oil recovery technology should be preferentially promoted to the blocks within Yongning Oilfield that are close to the reservoir characteristics of Zhangchaiyaozi well block to improve oil recovery.