梨树断陷八屋油田原油重排藿烷类化合物及其地质意义

DIAHOPANOID COMPOUNDS AND THEIR SIGNIFICANCES FOR THE CRUDE OILS IN BAWU OILFIELD OF LISHU FAULT DEPRESSION

梨树断陷八屋油田原油中重排藿烷类化合物异常丰富,对21个原油样品进行色谱-质谱分析,检测出17α(H)-重排藿烷和18α(H)-新藿烷两个重排藿烷系列化合物。研究表明:17α(H)-15α-甲基-重排藿烷(C_(30)*)和18α(H)-17α-甲基-30-降新藿烷(C_(29)Ts)相对丰度受沉积环境的氧化还原性和水体盐度双重控制,高成熟度的烃源岩有利于其富集,高丰度的C_(30)*和C_(29)Ts与低等水生藻类有关;八屋油田不同地区和层位的原油中重排藿烷的相对丰度差别较大,通过丰度差异可将原油划分为Ⅰ、Ⅱ两种类型;BK60和SN54区块的原油具有较高含量的C_(24)四环二萜、长链三环萜烷、C_(29)重排藿烷和C_(29)Ts。

The crude oils in Bawu Oilfield of Lishu Fault Depression are found to be extremely rich in diahopanes. Two series of diahopanesl 17α （H） -diahopanes and 18α （H） -neohopanes, were detected in twenty-one oil samples by means of GC/MS analyses. The achievements reveal that the relative abundances of C30 diahopane （ C30＊ ） and C29 30 nor-neohopane （C29Ts） are presumably controlled by the oxidation-reduction depositional environ- ments and the salinity, the high-maturity hydrocarbon source rocks are prone to be their accumulation, the laigh-a- bundance C30 diahopanes and C29Ts are likely related to the low-level aquatic algae; the relative abundances of the diahopanes differ in the crude oils from different regions and horizons of Bawu Oilfield, therefore, according to the differential of the relative abundances, the oils can be divided into two types ; the crude oils from Block BK60 and SN54 blocks are characterized by relatively high abundance of C24 tetracyclic diterpene, tong-chain tricyclic terpane, C29 diahopane and C29Ts nor-neohopane.