摘要:
基于测录井资料对比,结合区域构造演化特征,将草湖凹陷侏罗系划分为两个三级层序J-SQ1与J-SQ2。J-SQ1时期气候温暖潮湿,层序发育完整的上升半旋回和下降半旋回沉积,发育辫状河体系和湖泊体系;J-SQ2时期气候逐渐转为炎热半干旱,层序发育不完整,只发育上升半旋回沉积,主要由氧化型湖泊体系构成,发育滨浅湖砂滩、泥滩互层沉积。其中,J-SQ1早期辫状河河道砂体叠置厚度大,储层物性好,上覆中厚层湖相泥岩沉积,是本区有利的储集层段。
Abstract:
The Jurassic strata in the Caohu depression, Tarim Basin, Xinjiang are divided, on the basis of well logs and regional tectonic evolution, into two third-order sequences J-SQ1 and J-SQ2. During the deposition of J-SQ1 sequences, the climates were warm and humid. The sequence displays the complete rising-falling semicyclic deposits. Till the deposition of J-SQ2 sequences, the climates turned into hot and semiarid ones. The sequences display only the rising semicyclic deposits, and consists of oxidized lacustrine depositional systems in which the littoral-shallow lacustrine sand-mud beach deposits are developed. The braided channel sandstones in J-SQ1 sequences are believed to be the favourable reservoir rocks in the study area due to tremendous thickness, better physical properties and moderate to thick overlying lacustrine mudstone.
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