FORMING MECHANISM OF CONVENTIONAL CRUDES IN NORTH TARIM BASIN
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摘要: 塔里木盆地北部地区有两种成因类型的常规油,与源岩类型及成熟度有关的常规油有:与中等成熟度的中生界源岩有关的陆相常规油,源区主要分布于库车拗陷,降解产物以轻质油一常规油为主;与中等成熟度的石炭系源岩有关的海相常规油,资源规模较小,集中程度也低,至今尚未发现以其为源岩的油气田(藏);与隆起及斜坡区奥陶系源岩有关的常规油,其中上统虽然有机质丰度偏低。但分布广、厚度大,降解产物为常规油一轻质油,其晚期的生油潜力值得重视。与成藏期及后生变化有关的常规油有:早期(海西期)成藏的油气经后生改造形成的残留油及重新组合形成的常规油;中期(印支一燕山期,最迟喜马拉雅中期)成藏的油气,由于成藏时封闭体系不严而形成的常规油。塔北地区不同源岩、不同演化阶段及相应的油气产物,经历了不同期次、不同程度的改造与变化,最终形成不同性质的油气藏,包括大量经后生改造而形成的常规油藏。Abstract: There are two genetic types of conventional oils in the northern area of the Tarim Basin. The conventional oils related to the types and maturity of source rocks include continental conventional oils related to Mesozoic moderate-mature source rocks whose source-regions are mainly distributed in Kuqa Depression and whose products are mainly light-conventional oils, marine conventional oils related to Carboniferous mOderate-mature source rocks which have less resource scale and low concentric extent and in which oil and gas fields (pools) have not been discovered so far, and conventional Oils related to Ordovician source rocks in upwelling and slope regions whose middle and upper series though with the low abundance of organic material have widespread distribution and large thickness and whose degraded products are conventional-light oils and the oil-bearing potential of the late stage is worth paying attention to.Conventional oils related to pool-forming stages and epigenetic changes include residual oils formed by epigenetic recreation and conventional oils formed by reassemblage from hydrocarbons pool-fOrmed at early (Hercynian) epoch and conventional oils formed by hydrocarbons pool-formed at middle (Indosinian-Yanshan, latest Middle Himalayan Movements) epoch because of untightly enclosed system in pool-forming periods.Different source rocks, different evolutionary stages and corresponding hydrocarbon products in North Tarim area have gone through the recreation and changes of different stages, times and extent , and formed at last the hydrocarbon pools with different properties, including a large number of conventional oil pools formed by epigenetic recreation.
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