柴西地区中新世致密油藏源储特征及其组合特征

Source-reservoir characteristics and combination characteristics of Miocene tight reservoirs in western Qaidam Basin

致密油源储特征及其组合因素研究对发展非常规油气地质理论具有重要意义。选取柴达木盆地西部地区中新世致密油藏为主要研究对象,通过岩心描述、扫描电镜观察及高压压汞实验等手段,结合柴西地区的地质、地球物理等资料,重点探究了其烃源岩与储层特征,并分析了源储关系以及致密油藏中源储组合特征。结果表明:1)上干柴沟组烃源岩以泥岩和泥灰岩为主,有机质丰度较高,以较差-好烃源岩为主,有机质类型以Ⅱ_(1)型为主,且处于低熟-成熟阶段。2)上干柴沟组致密储层以细砂-粉砂岩为主,物性较差,低孔低渗特点显著,储集空间类型为残余粒间孔隙-微裂隙,属于细微孔喉型储层。3)柴西地区中新世致密油存在低熟原油和成熟原油2类油源,分别来源于上干柴沟组和下干柴沟组烃源岩。上干柴沟组致密油藏源储关系主要为源储互交组合和源储侧交组合,源储互交组合最为发育。

The study of tight oil source-reservoir characteristics and theircombination factors is of great significance to the development of unconventional oil and gas geological theory.The Miocene(N 1)tight reservoir in the western Qaidam Basin region was selected as the main object of study,and the source rock and reservoir characteristics were emphatically explored by means of core description,scanning electron microscope observation,high pressure mercury intrusion experiment,and the source-reservoir relationship and the characteristics of the source-reservoir combination in tight reservoir were analyzed based on the geological and geophysics data in the western Qaidam Basin.The results showed that:1)Shangganchaigou Formation source rocks are mainly mudstone and marl with a high abundance of organic matter,poor-good Formation rocks,andⅡ_(1) type of organic matter,and are in the low-mature-mature stage;2)Shangganchaigou group tight reservoir is mainly composed of fine sand-siltstone with poor physical properties,low porosity and permeability;3)There are two kinds of oil sources in the Miocene tight oil in Qaidam area,low mature oil and mature oil,which come from Shangganchaigou Formation and Xiaganchaigou Formation source rocks,respectively.The source-reservoir relationships of tight reservoirs of Shangganchaigou Formation are mainly source-reservoir interaction and source-reservoir lateral interaction,and source-reservoir interaction is the most developed.