Abstract:

The Carboniferous-Permian coal measure strata in Dongpu sag is a fair source rock unit of Wenliu gas pool due to its stable distribution and high organic content. There are two hydrocarbon-generating periods in the burial history of coal measures. The first one occurs when the T_1-2 formation is deposited. Vitrinite reflectance, apatite fission track and fluid inclusion analyses indicate that the burial depth of coal measures is about 3500 m, with the palaeotem-perature of 118℃ and R_o of 0.80%-0.85%.Hydrocarbon generation of coal measures was interrupted in the Meso-zoic uplift and erosion period (about 1.8 million years).During the Paleogene rifting period,the coal measures was entered into its secondary hydrocarbon-generating period as the burial depth increases, reaching its hydrocarbon-generating peak after the deposition of Dongying formation. The gas-prone source rock is mainly distributed in the region of Wendong-Qianliyuan, with the buried depth of 5290-6360m. The discovery maturity (percentage of ultimately proven reserve with respect to total resources) of gas resources in Wenliu area is more than 90%. In the effective gas supply area of Wenliu gas pool, the hydrocarbon-generating volume and hydrocarbon-expelling volume of Carboniferous-Permian coal measures are estimated to be 3253.3 million m³ and 2657.0 million m³ respectively, with a gas accumulation coefficient of 5.92%.

Key words: Wenliu gas pool, Carboniferous-Penman coal measures, hydrocarbon-generating potential, first hydrocarbon-generating period, secondary hydrocarbon-generating period, accumulation coefficient