南黄海中部隆起CSDP-2井中—古生界烃源岩精细评价

CSDP-2井是在南黄海中部隆起上首钻的全取心深钻，在新近系之下钻遇下三叠统青龙组—上奥陶统多套碎屑岩和碳酸盐岩地层。钻井揭示的烃源岩有机质丰度、类型、热演化程度、可溶有机物分析及生烃强度计算证实，中部隆起发育倾油型的青龙组上段灰岩、上奥陶统—下志留统上部泥岩、油气型的石炭系中—上部灰岩3套有效烃源岩；生气为主的有效烃源岩主要为大隆组—龙潭组泥岩和炭质泥岩、栖霞组上部富含炭质的臭灰岩、石炭系中—下部灰岩和底部炭质泥岩。目前钻井揭示的中—古生界总生烃强度是(20.761 9~31.283 9)×108 m3气当量/km2，与国内外大中型气田分布区域的生气强度相当。其中，油源岩的总生油强度为(43.076~55.30)×104 t/km2，气源岩的总生气强度为(16.454 3~25.753 9)×108 m3/km2；同时，烃源岩的总生气强度是生油强度的4~5倍，碎屑岩的生烃强度是灰岩的2倍以上。巨大的生烃强度和多源层供烃为形成大—中型的油气聚集和成藏提供了充分的物质基础，显示了南黄海中部隆起中—古生界良好的油气勘探前景。

DETAILED ASSESSMENT OF MESO-PALEOZOIC HYDROCARBON SOURCE ROCKS: IMPLICATIONS FROM WELL CSDP-2 ON THE CENTRAL UPLIFT OF THE SOUTH YELLOW SEA BASIN

The well CSDP-2 is the first whole coring deep hole ever drilled on the Central Uplift of the South Yellow Sea Basin. It penetrated many sets of clastic and carbonate rocks from the Late Ordovician Formation up to the Early Triassic Qinglong Formation unconformably under the Neogene. The data of organic abundance, organic types, thermal evolution history, soluble organic matter and hydrocarbon-generating intensity of the sequence confirms that on the Central Uplift there occurs three sets of effective hydrocarbon source rocks: the lipophilic limestone of the Upper Member of the Qinglong Formation, the mudstone of the Upper Ordovician up to the upper member of the Lower Silurian and the oil-gas type limestone of the Middle and Upper Members of the Carboniferous. The effective hydrocarbon source rocks that generated gas are mainly the mudstone and carbonaceous mudstone of the Dalong Formation-Longtan Formation, the stink limestone of Upper Qixia Formation which is rich in organic, limestone of middle-lower Carboniferous and the carbonaceous mudstone in the bottom of Carboniferous. The Mesozoic and Paleozoic total hydrocarbon-generating intensity revealed by the drilling is (20.7619-31.2839)×108m3gas equivalent/km2 and its gas-generating intensity is roughly comparable to large and medium-sized gas fields of the world. According to our calculation, the total oil-generating intensity of the oil source rock is (43.076-55.30)×104t/km2, and the total gas-generating intensity of gas source rock is (16.4543-25.7539)×108m3/km2. The total gas-generating intensity of source rocks is 4-5 times higher than the oil-generating intensity, and the hydrocarbon-generating intensity of clastic rocks is twice higher than that of limestone. High hydrocarbon-generating intensity and abundance of hydrocarbon source layers have provide sufficient materials for a medium-large oil and gas accumulation, showing a good oil and gas exploration prospect of the Mesozoic-Paleozoic in the region of the Central Uplift of the South Yellow Sea Basin.