论文部分内容阅读
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 main producing layer of the Xinchang gas field in western Sichuan is the Upper Jurassic Penglaizhen Formation. In the past, it was considered that “Jurassic red beds” did not have hydrocarbon generation ability, and the gas source of Xinchang gas field came from continental coal-bearing clastic rocks in the Upper Triassic Xujiahe Formation. Based on the preliminary study on the geochemical characteristics and genesis of asphalt in Penglaizhen Formation in Xinchang Gas Field, the authors discussed whether the Jurassic in the western Sichuan area possesses the ability to generate hydrocarbons and whether there is any process of the formation and migration of liquid petroleum hydrocarbons. The composition of bitumen saturated hydrocarbon shows that the crude oil before bitumen mutation consists of two parts, that is, crude oil supplied from underlying Xujiahe Formation and Jurassic dark mudstone of Upper Triassic. Chromatographic characteristics and composition of carbon isotope data show that the former after a strong oxidative and bacterial hydrolysis, and then modified by deasphalting, followed by mixing Jurassic crude oil, followed by weak biochemical degradation of the formation of the current reservoir asphalt, lower The R0m values indicate that bitumen is the result of the deterioration of the liquid petroleum that migrated early. GC-MS data suggest that the quality of the Jurassic source rocks is superior to that of the Upper Triassic source rocks, and the Jurassic dark mudstone in the middle part of the western Sichuan depression may be an important source rock source. Therefore, the existing natural gas resources in western Sichuan is also expected to increase.