扇中沉积微相特征及对剩余油分布的控制作用

MICROFACIES FEATURES OF MIDDLE FAN MICROFACIES AND ITS CONTROL ON REMAINED OIL DISTRIBUTION

在取心井的岩性、电性、沉积韵律、沉积构造、粒度和化石生物等资料的基础上，对阿11断块进行了沉积微相研究。共划分出辫状水道、水道间、水道前缘和水道侧翼4种微相，其中辫状水道微相在该地区各砂体中最为发育。结合测井水淹层判断方法和油藏开发动态数据，总结不同微相的水淹层特征和开发特征，揭示不同沉积微相的剩余油分布规律，并指出有利的剩余油分布潜力区。分析结果表明，辫状水道砂体最先水淹，水道前缘砂体次之水淹，扇中水道间及水道边部砂体不易水淹；沿辫状水道主流线方向注水受效好，单井日产量和累计产量高，剩余储量较少，而水道边部注水受效较差，累计产量低，含水相对低，水道前缘离注水井距离远、注水受效差。因此，辫状水道边部、水道前缘、水道间砂体为剩余油的有利富集区。

Based on the data of lithology, electric property, sedimentary rhythm, sedimentary structure, granuarity and fossils from cored wells, study on sedimentary microfacies of fault-block A-11 has been conducted, and 4 types of sedimentary microfacies have been identified, including braided channel, middle braided channel, channel front and channel flank, among these, the microfacies of braided channel develops best in the sand bodies of the area. Combing the method of identifying watered-out reservoirs by well logging and reservoir production performance data, as well as summarizing watered-out reservoir features and development features of different microfacies, the rule of remained oil distribution in different microfacies and the potential area where remained oil may exist have been revealed and pointed out. The results of analysis indicate that it is the braided channel sand bodies that are watered-out prior to other sand bodies, which are successively followed by channel front sand body, while the sand bodies of middle channel in middle fan and channel margins are not easily watered-out. Water injection functions better if implemented along the dominant flow direction of the braided channel, obtaining higher daily production and cumulative production in single well but less remained oil. The effects of water injection in channel margins are poor, with low cumulative production but also low water cut. The sedimentary sequence of channel front differs from that of the braided channel, which, meanwhile, is far away from the injection wells, so the water injection effects are also poor. As a conclusion, sand bodies of braided channel margin, channel front and middle channel are favorable places for the accumulation of remained oil.