Influence of source-reservoir configuration patterns of hydrocarbon accumulation elements on tight oil convergence: A case study of Gaotaizi reservoir in Qijia area of Songliao Basin

Based on core observation, thin section identification, physical property and geochemical analysis, with detailed study on the source-reservoir characteristics of Gaotaizi oil reservoir in Qijia area of Songliao Basin, it is found that the source-reservoir configuration patterns of tight oil accumulation elements control the oil reservoir convergence. The source-reservoir configuration patterns of tight oil layers in the area are mainly lower-source-upper-reservoir type, thick source-reservoir interlayer type, and thin source-reservoir interbedded type. The lower-source-upper-reservoir type has the potential to form industrial oil-gas flow, but the reservoir thickness is underdeveloped and easy to form interbeds of dry layer and oil layer. The thick source-reservoir interlayer type has good source-reservoir conditions with great potential for industrial oil flow. The thin source-reservoir interbedded type is developed with reservoirs, but the geochemical conditions are ordinary, with weak oil-gas indication. Therefore, tight oil in the area is distributed mainly in the middle-upper part of G-Ⅳ reservoir, which is dominated by the lower-source-upper-reservoir and thick source-reservoir interlayer types, and the lower part of G-Ⅲ reservoir dominated by thick source-reservoir interlayer type. In the plane view, the south of the study area with developed prodelta subfacies deposits is the hydrocarbon generation center. To the north, the central part of the study area, where delta front subfacies deposits are developed, is favorable area for tight oil.