塔中地区油藏烃类组成的非均质性及其意义

Hydrocarbon Compositional Heterogeneities of Petroleum Reservoirs in Tazhong Area and Its Geological Significance

张　敏,张　俊,毛治超,赵红静,胡伯良

Zhang Min , Zhang Jun, Mao Zhichao, et al

江汉石油学院地球化学研究中心

Geochemistry Research Center of Jianghan Petroleum Institute , Hubei 434102 , P. R. China

利用岩石热解分析技术、薄层色谱- 氢火焰检测技术、气相色谱分析技术, 可以有效地表征油藏烃类组成的非均质性。塔中北斜坡石炭系油藏烃类组成东西端表现出共同性质, 即总烃含量高, 极性化合物丰度相对较低, 含油率T 值较高, 表现出油层的特征。相反, 中端各井尽管T 值含量高, 但烃类组成中, 总烃含量低, 沥青质含量高, 表明该油藏曾遭受破坏。塔中北斜坡志留系油藏地球化学描述表征西端古油藏遭到较严重的生物降解作用, 且后期轻质油的注入对此油藏影响较少; 而东端古油藏原油没有发生生物降解作用,且后期轻质油的注入比例高。根据储集岩烃类正构烷烃的分布特征, 塔中北斜坡石炭系油藏存在着两期充注过程, 第一期充注的石油形成现今的沥青砂或油砂, 而第二期充注的石油形成现今的主要产层。

Hydrocarbon compositional heterogeneities of petroleum reservoirs are effectively described using Rock-eval ,thin layer chromatography-flame ionization detection ( TLC-FID) and gas chromatography ( GC ) techniques. Hydrocarbon compositional characteristics of Carboniferous reservoir rocks between eastern part and western part in Tazhong area show total hydrocarbon ( saturated and aromatic hydrocarbon ) contents are abundance ,but polar compounds (asphaltene and resin) contents are lower. These geochemical characteristics imply CⅢ reservoirs layer in this area are oil legs. In constract , Hydrocarbon compositional characteristics of Carboniferous reservoir rocks of middle part in Tazhong area show contents of total hydrocarbons are lower and contents of polar compounds are higher. Based on the distributions of nalkane in petroleum reservoirs , there are two phase field filling process for Carboniferous reservoirs in Tazhong area. The petroleum reservoirs filling at the first phase formed asphaltic sands and oilsands , but petroleum reservoirs filling at the later phase become important produced layers.