塔东地区下古生界固体沥青特征与油气成藏  

Relationship between hydrocarbon accumulation and solid bitumen characteristics of the Lower Paleozoic in the eastern Tarim Basin

作　　者：程宏岗[1,2] 魏国齐[2] 冉启贵[2] 伍大茂[3] 刘立炜[4] 肖中尧[4] 桑洪[4] 

机构地区：[1]山东省沉积成矿作用与沉积矿产重点实验室 [2]中国石油勘探开发研究院廊坊分院 [3]中国地质大学(北京)能源学院 [4]中国石油塔里木油田公司

出　　处：《天然气工业》2013年第10期40-46,共7页Natural Gas Industry

基　　金：国家科技重大专项(编号:2011ZX05007);山东省沉积成矿作用与沉积矿产重点实验室开放课题(编号:DMSM201001)

摘　　要：塔里木盆地东部地区下古生界固体沥青比较发育,由于固体沥青是原油裂解的产物,分析其特征和形成期次有助于了解该区油气的生成、运移历史。为此,研究了该区下古生界各地层中固体沥青的富集形式、产状、类型、含量及分布特征,将下古生界富含的固体沥青划分为源内沥青和储层沥青2种类型,并根据产状细分出7种类别。该区固体沥青含量整体上并不太高,源内沥青主要分布于碳质泥岩中,而储层沥青主要分布于碳酸盐岩中;层位上,下古生界主要以源内沥青为主,储层沥青仅见于该区东、西部上寒武统白云岩和中下奥陶统石灰岩中,沥青含量整体上以寒武系为最高。固体沥青形成期次研究结果表明,该区不同构造单元发育不同期次的固体沥青:①只受沉积埋藏作用而形成的单峰型沥青,主要分布在库尔勒鼻隆和罗布泊鼻隆西部地区;②受沉积埋藏及1期构造热事件影响而形成的双峰型沥青,主要分布在英吉苏凹陷及其东南部地区;③受沉积埋藏及2期构造热事件影响而形成的三峰型甚至多峰型沥青,主要分布在古城鼻隆和塔东低凸起。结论认为:塔东隆起区和斜坡区下古生界不但可能发育古油藏,而且原油发生多期裂解,晚期油气可能再次聚集成藏。Solid bitumen is well developed in the Lower Paleozoic in the eastern Tarim Basin. As solid bitumen is the product of crude oil cracking, its characteristics and periods of formation are indicative of the hydrocarbon generation and migration in the study area. Through analyzing its accumulation forms, occurrences, types, content and distribution, we divided the solid bitumen in the Lower Paleozoic there into two types： insitu bitumen and reservoir bitumen. Seven subtypes were further identified according to their occurrences. The content of solid bitumen is not high as a whole in the study area. The insitu bitumen is mainly distributed in the carbonaceous mudstones, while the reservoir bitumen mainly occurs in carbonates. The insitu bitumen mainly occurs in the Lower Paleozoic, while the reservoir bitumen only occurs in the Upper Cambrian dolomites and the MidLower Ordovician limestones. In general, the content of bitumen is the highest in the Cambrian. According to the characteristics of reflectivity, there are different phases of solid bitumen in different tectonic units of the region. One is the singlepeak bitumen, which is only influenced by the sedimentation and mainly distributed in Kurle noseuplift and west of Lop Nor noseuplift. The other is the dualpeak bitumen, which is influenced by the sedimentation and one tectothermal event, and is mainly distributed in the Yingjisu sag and the area to its southeast. The third is the tripeak even multiplepeak bitumen, which is influenced by the sedimentation and two tectothermal events, and is mainly distributed in Gucheng noseuplift and Tadong low uplift. It is concluded that not only palaeooil reservoirs possibly occurred in the Lower Paleozoic in the uplift zones and slope zones of the eastern Tarim Basin, but also secondary oil/gas reservoirs formed through late reaccumulation of hydrocarbons from multiplestage cracking of crude oil.

关 键 词：塔里木盆地东部 固体沥青 早古生代 源内沥青 储层沥青 多峰型 碳质泥岩 原油裂解 

分 类 号：P618.13[天文地球—矿床学]