Patterns of Braided Architecture and its controlling of remaining oil in L4+5 sand group reservoir in Laojunmiao oil field, Jiuxi Basin, Northwest China

The study about subsurface reservoir architecture characterization gives a better analysis of the remaining oil. In order to explore more oil and on the base of less research about L4+5 sand group in the Laojunmiao oil field,... [ view full abstract ]

The study about subsurface reservoir architecture characterization gives a better analysis of the remaining oil. In order to explore more oil and on the base of less research about L4+5 sand group in the Laojunmiao oil field, the paper mean to study the architecture characterization and its controlling of remaining oil in L4+5 sand group . Based on comprehensive analysis of core data, well logs, seismic and dynamic data, the architecture unit in the braided river were classified and analyzed. On this basis, taking the modern braided river deposit and the tectonic belt sedimentary environment as a guide, using the analytic hierarchy, the multidimensional interaction and size constraints as the methods, the different level of the internal reservoir architecture were studied and the signs of single braided belt boundary were clarified. The study showed that distribution patterns of the sand body in the west is flake-like distributary while interweave stripped distributary in the east. 4-5 single braided belt which is about 500 meters width were identified in the west .The single braided belt contained with wide braided bars which is about 500-800 meters length and 200m～400m width and narrow channel which is about 150 meters width. The sand body scale is decreased significantly in the east where the river width is about 100 meters
On this basis, the remaining oil distribution patterns controlled by sandy braided river reservoir architecture were analyzed by comprehensive using exploitation geology and dynamic information of production. The results show that the configuration boundary such as overbank sand body, channel side edge cutting, semi - mud and mud filling channel have certain shielding effect on the water drive in the lateral and plane. Then combining the control factors of the remaining oil ，with the fruit of numerical simulation, the characteristics of remaining oil are summarized. The enrichment area of the remaining oil is usually at the edge of the Chanel, in the overbank sand body, the superimposed channel sand bodies ,in which the reservoir heterogeneity is usually strong. Besides, the place between the two adjacent injection well or production well and the area where the size of the sand body is too small to be controlled is also the main zone of enrichment.