摘要
川西地区新场气田主产层位是上侏罗统蓬莱镇组。以往观点认为“侏罗系红层”不具生烃能力，新场气田的气源来自上三叠统须家河组陆相含煤碎屑岩系。通过对新场气田蓬莱镇组沥青地球化学特征及成因的初步研究，探讨了川西地区侏罗系是否具备生烃能力，是否有过液态石油烃生成和运移过程等问题。沥青饱和烃生源构成表明，沥青变异前的原油由两部分构成，即下伏上三叠统须家河组和侏罗系暗色泥岩供给的原油。色谱特征和族组成碳同位素资料表明，前者经过较强氧化和菌解作用，后又经脱沥青作用改造，继而混合侏罗系原油，再经弱的生化降解形成目前的储层沥青，较低的Ｒ０ｍ值表明，沥青是早期运移的液态石油变质的结果。ＧＣ—ＭＳ资料研究结果认为侏罗系烃源岩品质优于上三叠统烃源岩品质，川西坳陷中段侏罗系暗色泥岩可能是不可忽视的重要生烃源岩。因此，川西已有的天然气资源量还可望增大。
The major
producing formation in Xinchang gas field in West Sichuan belongs to Penglaizhen Formation of
Upper Jurassic.In the past,it was thought that the Red Beds of Jurassic was not possessed of
hydrocarbon generation capacity and the natural gas in the Xinchang field came from the
continental coalbearing clastic rocks of Xujiahe Formation of Upper Triassic.Some problems of
whether the Jurassic was possessed of hydrocarbon generation capacity and whether the
processes of the liquid hydrocarbon generation and migration had happened are discussed
through a primary research on the geochemical properties and origin of the bitumens in
Penglaizhen Formation in Xinchang gas field.According to the composition of saturated
hydrocarbon in the bitumen,the crude oil before converting to bitumen is composed of two parts
which came from the underlying dark mudstones belonging to the Xujiahe Formation of Upper
Triassic and the Jurassic respectively.It is shown by the chromatographic properties and the
data on carbon isotope of group composition that the former suffered relatively strong
oxidization and bacteria degradation,then reformed by deasphalting,and then mixed with the
latter to form the bitumen found in the reservoir at present through a weak biochemical
degradation.Its low R0m value indicates that the bitumen was converted from the liquid oil
which migrated into the reservoir from the underlying strata in the early time.According to the
data on GCMS,it is considered that the quality of hydrocarbon source rocks in Jurassic is better
than that in Upper Triassic and that the dark mudstones in Middle Jurassic in West Sichuan
Depression may be the important hydrocarbon source rocks not to be ignored,so that the gas
resources proved in West Sichuan may be still increased.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
1999年第3期18-32,共15页
Natural Gas Industry
基金
"九五"国家攻关项目
关键词
晚侏罗世
沥青
地球化学特征
天然气资源
气田
Sichuan Basin,West,Late
Jurassic Epoch,Asphalt,Geochemistry,Feature,Origin
