关键词: 松辽盆地南部, 致密油, 致密气, 煤层气, 新领域, 资源潜力

Abstract: With the deepening exploration from conventional to unconventional hydrocarbon, and shallow to deep reservoirs, a batch of new fields of tight oil and gas reservoirs are gradually emerging in southern Songliao Basin. Based on geological theory innovation and key technological breakthroughs, significant breakthroughs and progress have been made in exploration of tight oil and gas in southern Songliao Basin in recent years. By summarizing progress in three major fields of tight oil in Fuyu oil reservoir, deep tight gas in basin, and coalbed methane in fault depression, the paper analyzes the geological conditions, exploration progress, accumulation mechanism and resource potential in southern Songliao Basin, and also proposes the next research and development direction. (1) The study clarifies the coupling accumulation mechanism of "three in one" for Fuyu tight oil reservoir, involving overpressure drive of high-quality source rocks in Qingshankou Formation, transport of intensive interlayer faults, and hydrocarbon accumulation in the thick sand bodies of main channel of Member 4 of Quantou Formation. The tight oil resources in Fuyu oil reservoir amount to 9.72×10⁸t, and the undiscovered resources are estimated to be 4.91×10⁸t. Three favorable areas are selected, namely Xinbei, Gudian, and Yuzijing-Tahucheng. Moreover, it is pointed out that Fuyu tight oil reservoir plays a key role in increasing reserves and production in Jilin oilfield (PetraChina Jilin Oilfield Company), and efforts should be made to sustainably promote the integration of reserve increase and productivity construction. (2) The study reveals the source-reservoir integrated accumulation mechanism of deep tight gas based on the coupling of high-maturity coal-bearing source rock and volcanic material-rich reservoir. The deep tight gas resources amount to 7.67×10¹²m³, and five favorable zones that can be effectively utilized have been identified, including Wukeshu, Huajia-Guojia, Xiaochengzi, Shenzijing, and Hashituo areas. It is clarified that deep tight gas is an important replacement resource in Jilin oilfield. (3) Based on the parameters of coal rock, coal quality, coal reservoir characteristics, and gas content, the coal bed methane resources are estimated to be 1.11×10¹²m³. Three favorable areas for coalbed methane exploration have been identified, i.e., Wangfu fault depression, Dehui fault depression, and Fulongquan fault depression, with a favorable exploration area of 19 370 km². In conclusion, the three favorable areas for tight oil and gas exploration provide important resource foundations for stable production in Jilin oilfield, and will provide replacement resources for high-quality development of Jilin oilfield. Relevant exploration experience and understandings are expected to provide reference and inspiration for neighboring areas and similar basins.

Key words: southern Songliao Basin, tight oil, tight gas, coalbed methane, new field, resource potential