石臼坨凸起Q31区块馆陶组气测异常原因分析

Analysis of abnormal gas measurement in Guantao Formation in Block Q31 of Shijiutuo Uplift

针对石臼坨凸起西南缘Q31区块馆陶组油藏录井气测仅见高含量的C;烃组分,不含其他烃组分的特殊地质现象,利用常规原油物性、族组分及生物标志化合物等地球化学资料,探讨研究区馆陶组油藏的基本地化特征、原油菌解过程及甲烷气的生成机理。结果表明,研究区馆陶组重质油为成熟油,在成藏后遭受生物降解作用导致稠化,并且在稠化过程中,原油降解气以油藏伴生甲烷气(溶解气)的形式产出,当钻头钻开储集层时,地层能量快速释放而造成录井气测仅见高含量的C_(1)烃组分的现象。研究认识对于油藏开发方案制订具有一定指导意义。

In light of the special geological phenomenon of high C;hydrocarbon content but no other hydrocarbon components in the gas logging of the Guantao Formation reservoir in the Q31 Block on the southwestern margin of the Shijiutuo Uplift,the basic characteristics,the process of crude oil biolysis,and the mechanism of methane gas generation were discussed using geochemical data such as conventional crude oil physical properties,family components,and biomarker compounds. The results show that the heavy oil of the Guantao Formation in the study area is mature oil that thickened after accumulation due to biodegradation and crude oil degradation gas was produced in the form of methane gas(dissolved gas)associated with the reservoir during the thickening process. When the drill bit drilled into the reservoir,the formation energy was immediately released,resulting in the logging gas measurement containing only high levels of C_(1)hydrocarbon components. This knowledge of the study has a certain guiding significance for the formulation of a reservoir development plan.