柴达木中新生代盆地演化及其控油气作用

Evolution of Meso-Cenozoic Qaidam basin and its control on oil and gas

柴达木中、新生代盆地演化经历了 4个不同的阶段 ,即早、中侏罗世裂陷阶段 ;晚侏罗世—白垩纪挤压阶段 ;早第三纪 (路乐河期 )—上新世晚期 (上油砂山期 )区域挤压坳陷与局部走滑、逃逸阶段 ;上新世晚期 (狮子沟期 )—第四纪挤压、推覆阶段。裂陷阶段 ,在柴北缘形成中、下侏罗统烃源岩 ;挤压坳陷阶段 ,伴随盆地西部整体坳陷 ,在盆地西部形成第三系烃源岩层 ;挤压、推覆阶段 ,随着盆地西部的隆升 ,东部地区的强烈沉降 ,在盆地东部第四纪坳陷中沉积了第四系烃源岩。柴达木盆地断裂、褶皱构造十分发育 ,油气藏类型以构造油气藏为主 ,其中背斜、断鼻油气藏主要分布于盆地西部茫崖凹陷 ,而与断层有关的断鼻、断块油气藏主要分布于柴北缘断陷区。柴达木盆地第三系油气储层中沸腾包裹体的发现 。

The Meso Cenozoic Qaidam basin has experienced four evolution stages including the Early to Middle Jurassic chasmic stage, the Late Jurassic to Cretaceous compression stage, the Early Tertiary (Lulehe age) to Late Pliocene (Shangyoushashan age) regional compressive downwarping and local strike slipping and squeezing out stage, as well as the Late Pliocene (Shizigou age) to Quaternary compressive napping stage. The Middle and Lower Jurassic source rocks were deposited in the northern edge of Qaidam basin during the chasmic stage. The Tertiary source rocks were deposited while the massive deppression developed in western basin during the compressive downwarping stage. The Quaternary source rocks were deposited in the Quaternary depression in eastern basin along with the uplifting of western basin and the strong subsidence of eastern basin during the compressive napping stage. Fault and fold structures are well developed in Qaidam basin. Structural reservoirs are the main reservoir types, of which anticlinal and fault nose reservoirs are mainly distributed in Mangya sag in western basin, while the fault related fault nose and fault block reservoirs are mainly distributed in the downfaulted area in the northern edge of Qaidam basin. The discovery of bubble inclusions in the Tertiary indicates that pulse migration of hydrocarbons under faulting is an important mode of reservoiring in Qaidam basin.