长6致密油空气泡沫驱注入有效性地质因素研究

空气泡沫驱是目前最具前景的提高采收率技术之一,研究影响空气泡沫驱受效性的地质因素,为空气泡沫驱注入井位选择和方案调整提供依据。提出沉积相控制体系和物性控制体系两个地质因素,从理论上系统阐述两个体系对空气泡沫驱受效性的控制作用,然后选取A油田长6致密油8100井组,利用测井曲线划分该井组的河道控制体系,并进一步利用砂体孔隙度、渗透率和饱和度数据及计算的流动带指数划分不同井间的流动单元系统,以此为基础分别研究8100井组8100-3井注泡沫受效原因、8100井不受效原因,并用动态生产资料进行验证。结果表明:沉积相控制体系和物性控制体系对空气泡沫驱受效性具有重要影响;若注入井和生产井的河道控制体系和流动单元系统对应,则可以完全受效;若注入井和生产井完全属于不同的河道控制体系,则多不受效;若注入井和生产井属于同一河道控制体系,但流动单元系统部分连通或不连通,则可造成部分受效或完全不受效。生产时尽量选择在主河道主流动单元中心部位选择注入井;对于河道边缘井组,可以通过角井转注方式将不规则反9点注采井网转成反5点井网;在顺河道方向加大井距,垂直于河道方向,尤其在河道及流动单元边缘部位减少井距。
Air foam flooding is one of the most promising techniques to enhance oil recovery, which has dual roles of profile control and oil displacement with relatively low cost in comparison with other gas injections. In order to study the influence of geological factors on air foam flooding efficiency, reservoir sedimentary facies and physical property control systems were featured out in a case study of the well group 8100 in a tight oil reservoir of Chang-Six, in which well logging data were used to characterize the sedimentary and channel systems and classify the flow unit systems among the injection and production wells. The reasons for good and poor performance of different well groups were analyzed based on the dynamic production data. The results show that the sedimentary facies and the physical property control systems have a significant effect on the performance of air foam flooding. If the injection and production wells locate in a different channel control system, the production will be not effective. If the injection and production wells belong to the same channel control system and same flow unit system, good production performance can be observed. If the injection and production wells belong to the same channel control system but with poorly connected flow unit system, a mixed (good or poor) production response can be observed. Based on the analysis results, the following recommendations should be adopted in order to increase the air foam flooding efficiency. The injection well should locate in the center of the main channel. If the well group is near the channel margin, nine-spot injection pattern can be changed to five-spot pattern. The inter-well distance can be increased along the channel direction, but reduced in perpendicular directions