四川盆地中部高石梯-磨溪地区震旦系灯影组储层沥青拉曼光谱分析

Raman spectroscopy of bitumen from the Sinian Dengying Formation reservoirs， Gaoshiti-Moxi area， central Sichuan Basin

李纯泉 陈红汉 肖雪薇 汪泽成 姜华

Chunquan Li Honghan Chen Xuewei Xiao Zecheng Wang Hua Jiang

拉曼光谱分析是刻画有机质成熟度的一种有效技术方法。通过对四川盆地中部高石梯-磨溪地区21块震旦系灯影组储层样品中的沥青开展系统的拉曼光谱分析，并用经验公式获取沥青的等效镜质体反射率，表征了沥青所处的成熟阶段，进而探讨了储层经历的热演化及改造作用。结果表明，高石梯-磨溪地区震旦系灯影组储层溶蚀孔洞及裂缝充填沥青绝大多数都处于高-过成熟阶段，占比达81.1 %；沥青拉曼光谱参数在等效镜质体反射率3.0 %处存在明显的转折点，构成两段式变化趋势特征。沥青等效镜质体反射率偏离正常演化趋势的异常高值，记录了储层经历的热异常，是明显的高温热流体活动响应，其空间上的分布特征反映了热流体活动的多期性，表明储层经历了多期热液蚀变改造，佐证了原油裂解成气而构成现今全是气藏分布的格局。

As an effective technique to characterize the maturity of organic matter， Raman spectroscopy was employed to analyze bitumen in 21 samples from the Sinian Dengying Formation reservoirs in the Gaoshiti-Moxi area， central Sichuan Basin. The equivalent vitrinite reflectance values of the bitumen were calculated with empirical equations to determine the maturity stage of the bitumen and the thermal alternation of reservoirs sampled. The results indicate that most bitumen （81.1 %） filled dissolved pores and fractures are highly to over mature. The Raman spectrums change drastically near the equivalent vitrinite reflectance of 3.0 %， suggesting a two-section evolving trend. Anomalous high equivalent vitrinite reflectance values are typical responses of hot fluid activities， indicating thermal anomalies experienced by the reservoirs. The spatial distribution of the equivalent vitrinite reflectance values also points to the possibility of multiple thermal alteration， which may serve to confirm the assumption that gas is generated from oil cracking and to explain the distribution of current gas reservoirs in the area.

10.11743/ogg20220217