Abstract:
Tight oil and gas is an important unconventional resource, equivalent to ultra-low permeability and ultra low permeability oil and gas in traditional low-permeability oil and gas. At present, tight gas is the most productive in China, and has achieved an annual gas production of over 600×10
8m
3 in 2023; tight gas are mainly enriched in Ordos Basin and Sichuan Basin. The tight oil production reached 1 193×10
4t in 2023; the main production areas include Member 6 of Yanchang Formation (Chang 6 Member) and Member 8 of Yanchang Formation 8 (Chang 8 Member) in Ordos Basin, the Permian-Triassic tight glutenite reservoir in Mahu sag of Junggar Basin, and Fuyu tight oil reservoir in Songliao Basin. This paper discusses the temporal and spatial distribution characteristics of tight oil and gas resources from the distribution and geological evolution of sedimentary basins in China, tight oil and gas resources are mainly distributed in the Carboniferous-Permian, Triassic-Jurassic-Cretaceous, and Paleogene-Neogene periods. China’s tight oil and gas are mainly accumulated near the source rocks; horizontally, they are primarily distributed within and near source rocks in slope and trough areas; vertically, they are mainly distributed in tight reservoirs above, below, and between source rocks. According to the geological characteristics, reservoir formation mechanisms and conditions, distribution patterns, and main controlling factors of tight oil and gas in China, three accumulation modes of tight sandstone gas are determined as below:continuous tight deep basin gas, quasi continuous tight gas, and tight conventional trap gas; there are three accumulation modes for tight oil:source-reservoir separated and far-source accumulation, source-reservoir connected and near-source accumulation, accumulation in reservoirs alternated with adjacent source rocks. During the 15th Five Year Plan period(2026-2030), in the fields of southern Ordos Basin, central-western Sichuan Basin, deep Songliao Basin, and Ahe Formation in Tarim Basin, the newly proved geological reserves of tight gas are expected to exceed 2×10
12m
3; and in the Chang 6 and Chang 8 members of Yanchang Formation in Ordos Basin, Fuyu oil layer of Quantou Formation in Songliao Basin, Mahu Fengcheng Formation in the western depression of the Junggar Basin and other fields and zones, the proven geological reserves of tight oil is expected to increase by (18-20)×10
8t.