羌塘盆地三叠系、侏罗系石油地质特征和含油远景评价

羌塘盆地是发育在前泥盆结晶基底和上古生界浅变质褶皱基底之上以中生界海相沉积为主体的复合型残留盆地。它由北羌塘坳陷带、中央隆起带和南羌塘坳陷带3个二级构造单元组成,主要发育三叠系和侏罗系两套生储盖组合。北羌塘坳陷带内,三叠系及侏罗系组合发育良好;中央隆起带内基本没有侏罗系组合,三叠系组合也仅分布于倾伏部位;南羌塘坳陷带内,三叠系组合发育良好,局部范围内也有较好的侏罗系组合。青藏高原的油气勘探实践表明,该区含油远景取决于构造运动的强弱及保存条件的好坏。结合生储盖组合情况,羌塘盆地可分为3类含油气远景区:北羌塘坳陷带有利区、南羌塘坳陷带有利区和中央隆起带次有利区。

PETROLEUM GEOLOGICAL CHARACTERISTICS AND OIL-PROSPECT EVALUATION OF THE TRIASSIC AND THE JURASSIC IN THE QIANGTANG BASIN, TIBET

The Qiangtang Basin, which is developed on the Pre Devonian crystalline basement and the Upper Paleozoic epimetamorphic folded basement, is a composite residual basin dominated by the Mesozoic marine deposit. It consists of the North Qiangtang Geotectogene, the Central Mole Track and the South Qiangtang Geotectogene three secondary tectonic units, and mainly developed the Triassic and the Jurassic two sets of source rock reservoir cap rock assemblages. The Triassic and the Jurassic assemblages developed well in the North Qiangtang Geotectogene. There is scarcely the Jurassic assemblage and the Triassic assemblage is only distributed in the pitching parts within the Central Mole Track. In the South Qiangtang Geotectogene, the Ttiassic assemblage developed well, and the Jurassic assemblage exists well in some regions. The hydrocarbon exploration practice in the Qingzang Plateau shows that the oil prospect of this area depends on the strong and weak of tectonic movement and the good and bad of preservation conditions. Considered the information of source rock reservoir cap rock assemblages, the Qiangtang Basin can be divided into three types of prospective oil lands: the North Qiangtang Geotectogene favorable region, the South Qiangtang Geotectogene favorable region and the Central Mole Track subfavorable region.