中国油气盆地研究及其评价

RESEARCH AND ASSESSMENT OF CHINA'S PETROLIFEROUS BASINS

中国可分为五大构造区,它们控制了沉积盆地的形成与演化。每一沉积盆地可有单一层次或多层次结构,分别构成一种或多种盆地原型;对两种以上原型盆地组成的叠合盆地,宜用双重分类命名。以印支旋回为界,可分上、下两大油气组合,上部组合约占我国油气资源总量的60—70%,今后仍应是重要勘探对象,同时要大力开展下部组合的勘探。为深入评价盆地的含油性,可建立计算机定量动态模拟系统。

China can be divided into five major tectonic areas:North(Siberian- Mongolian)continental margin area,North continent and continentalmargin area,South continent and continental margin area,South(Gond-wana)continent and continental margin area,and East(Peri-Pacific)conti-nental margin area(extensional tectonic system was superimposed after lateMesozoic).These sedimentary basins have two different basinal architectures,i.e.single-layered and multi-layered architectures,each of them forms adifferent basin prototype.Double classification nomenclature can be usedfor those superimposed basins that composed of various basin prototypes.Thebasins in China can be classified into 8 different types,they are:intraconti-nental rift/rift valley,continental marginal rift/rift valley,craton-rift,cra-tonic fold-rift,cratonic rise-fold,intra-orogenic depression,foredeep andcraton-foredeep.The Indosinian tectonic cycle,being a turning point,the evolutional andsedimentary histories of the pre- and post-Indosinian are quite different.Thepre-Indosinian is characterized by steable and widespread cratonic cover,mainly composed of marine carbonate platform deposit,and forms the lowergas-bearing series while the post-Indosinian is mainly comprised of conti-nental clastic sediments deposited in isolated,different sized intracontinentalbasins,which constitute the upper oil- and gas-bearing series.The lower gas-bearing series spread in an area of nearly 300×10~4km^2,in which prolific natural gas has been discovered in Sichuan,Tarim,Ordosand Bohai Gulf basins.The upper oil- and gas-bearing series distribute in anarea of 350×10~4km^2 More than 200 oil and gas fields has been discoveredin the series,constitute over 90% and 60% of our proved oil and gas reservesrespectively.The total petroleum resource in China is 700-1000×10~8t,of which theresource in the upper series accounts for 60-70%.However,only 10-13%have been proved.Vast vistas is,therefore,still awaiting to be opened up,or rather the upper series will be taken as the main exploration target in aperiod of considerable length.At the same time,of course,a large effort willbe devoted to the exploration of the lower series.The sedimentary basins in China are rather complex.But based on the tec-tonic settings,their oil- and gas-bearing characteristics can be approachedby integrating geological,geophysical and geochemical data,and traps andreservoir properties can also be delineated and defined.Thus,taking the ba-sins as a whole,the relational expression proposed by Professor Zhu Xia(1983)can be used to establish computer quantitative dynamic modellingsystem.A thorough study on the sedimentary basins,their petroleum bear-ing regularities and resource assessment can then be made.The resultswould provide scientific basis for exploration deployment.