东营凹陷民丰洼陷深部天然气储层酸性溶蚀作用的流体包裹体证据  

Acid Dissolution of Deep Natural Gas Reservoirs in the Minfeng Sag in the Dongying Depression:Evidence from Fluid Inclusions

作　　者：任拥军[1] 陈勇[1] 

机构地区：[1]中国石油大学(华东)地球资源与信息学院,山东青岛266555

出　　处：《地质学报》2010年第2期257-262,共6页Acta Geologica Sinica

基　　金：国家"863"计划课题(编号2007AA06Z210);国家自然科学基金(编号40772082);山东省自然科学基金(编号Y2008E25);中国石油天然气集团公司石油科技中青年创新基金(编号07E1018)资助成果

摘　　要：通过对东营凹陷民丰洼陷深部天然气储层岩芯描述、薄片观察、流体包裹体显微观察和拉曼光谱分析,讨论了民丰洼陷深部天然气储层的酸性溶蚀类型,描述了流体包裹体的岩相学特征和成分。实验分析表明,酸性溶蚀作用是东营凹陷民丰洼陷深部天然气储层次生孔隙形成的重要机制之一,碳酸盐、长石和岩屑的溶蚀现象较明显,石英溶蚀主要发生在颗粒边缘。储层包裹体成分分析结果显示,包裹体中CO2的含量与储层物孔隙度和渗透率呈正相关性,与储层碳酸盐含量呈负相关性。包裹体中烃类流体与CO2流体共存,证实天然气成藏过程中存在酸性流体。CO2对碳酸盐等胶结物的溶蚀作用使得储层次生孔隙发育,促进了民丰洼陷的天然气成藏。同时,包裹体中的不饱和烃类物质为民丰洼陷热解成因天然气成因给出了直接证据。本次研究为东营凹陷民丰洼陷深部储层的酸性溶蚀作用给出了证据,研究结果暗示酸性溶蚀作用形成的次生孔隙发育带在未来东部深层勘探中应当受到重视。This study discussed the types of acid dissolution in reservoirs and described the characteristics and compositions of fluid inclusions based on the description of drilling cores, observation of thin sections, microscopic and Raman analysis of fluid inclusions at deep natural gas reservoirs in the Minfeng sag in the Dongying depression. The results show that acid dissolution is one of the important mechanisms responsible for formation of secondary porosity in deep natural gas reservoirs in the Minfeng sag. The dissolution of carbonates, feldspars and rock bits is obvious, with dissolution of quartz occurring mainly around margin of grains. Analysis of the compositions of fluid inclusions in reservoirs using Raman spectroscopy shows that content of carbon dioxide in inclusions shows positive relation with the porosity and filter rate of reservoir rocks but negative relation with the content of carbonates in reservoir rocks. Coexistence of hydrocarbon fluid with CO2 fluid proves existence of acid water during the accumulation of natural gas. Secondary porosity in reservoirs is well developed due to the cement dissolution by carbon dioxide, giving way to the formation of natural gas reservoirs in the Minfeng sag. Meanwhile, unsaturated hydrocarbon material in the fluid inclusion provides direct evidence for the thermal cracking origin natural gas. This study give reliable evidence for acid dissolution of deep reservoirs in the Minfeng sag, and the results imply that we should pay more attention to the secondary porosity zone caused by acid dissolution during future exploration.

关 键 词：储层 酸性溶蚀 流体包裹体 拉曼光谱 东营凹陷 

分 类 号：P618.13[天文地球—矿床学]