塔里木盆地三叠系沉积特征及生烃潜力

塔里木盆地三叠系以河、湖相含煤碎屑岩为主,夹有海泛相碳酸盐岩及砂、泥岩,厚500～1900m,分布面积约34×10⁴km².烃源岩主要发育于深、浅湖亚相、三角洲相及海泛相,岩性以暗色泥、页岩、炭质泥岩为主,夹灰色碳酸盐岩、煤层及油页岩,累计厚200～800m.满加尔拗陷带及唐古孜巴斯拗陷带是盆内两大烃源岩分布区,面积约13×10⁴km².有机质类型以ⅡB～Ⅲ型为主,次为ⅡA～Ⅰ型.R°为0.6～1.2％.具有良好的生烃潜力.近年来塔东北地区已在三叠系连续获得重大油气突破,塔里木盆地三叠系具有广阔的油气前景.

SEDIMENTARY FEATURES AND HYDROCARBON POTENTIAL IN THE TRIASSIC SYSTEM OF THE TARIM BASIN

The Triassic system of the Tarim Basin mainly consists of the coal-bearing clastic rocks of fluvial-lacustrine facies,intercalated with pan-marine carbonates,sands and mudstones;the thickness of the system ranges 500-1900m,and the distributing area reaches to about 30×104km2.In the system the source rocks mainly developed in deep-shallow lake subfacies,delta facies and pan-marine facies,lithologically it is characterized by dark mud,shales,carbonaceous mudstones intercalated with grey carbonate rocks,coals and oil shales.The accumulated thickness is up to 200-800m.The Majiar and Tangguzibasi depressions in the basin are the two major source rock areas totalling to about 13 ×104km2.The organics are predominately attributed to types Ⅱ_B~Ⅱ,then to types Ⅱ~Ⅰ,with the R°values ranging 0.6~1.2%,therefore,they have a good hydrocarbon potential.In recent years,the several significant break-throughs of oil/gas exloration have been made in the Triassic system of the Northeast Tarim Basin,suggesting there is an extensive prospect for the petroleum exploration in the Triassic system of the basin.