纯油条件下合成碳酸盐岩烃类包裹体及其捕获机制探讨

Synthesizing hydrocarbon inclusions in carbonate with pure oil and discussion of its trapping mechanism

设计了在接近实际储层温压条件下,流体介质为纯原油时在冰洲石中合成烃类包裹体的实验。合成样品的显微观察及荧光分析证实实验成功合成了烃类包裹体,实验证明油气对晶体生长和包裹体的形成有抑制作用,但不会终止其形成,纯油条件晶体仍能生长捕获包裹体,水并不是矿物生长捕获烃类包裹体的必须条件。结合矿物润湿性实验及前人研究将碳酸盐岩烃类包裹体捕获机制归纳为3种情况:油水共存(水润湿)、油水共存(油润湿)及纯油条件。水润湿条件下由水溶液提供矿物质来源,较易形成包裹体;油润湿条件下由水溶液和油中的极性组分共同提供矿物质来源;纯油条件下由原油中的极性组分和裂解产生的有机酸提供物源,形成烃类包裹体较少,晶体生长受到抑制。

The experiment which temperature and pressure were near the condition ofnatural reservoir was carried out to synthesize hydrocarbon inclusions in carbonate within pure oil.Through the microscopic and fluorescent characters of hydrocarbon inclusions in carbonate,it demonstrated that carbonate remained growing and trapping inclusions when fluid medium was pure oil.The water was not necessity for trapping hydrocarbon inclusions in growing carbonate.Combined with conclusions of predecessors and wettability determination of carbonate,the trapping mechanism of hydrocarbon inclusions in carbonate was concluded as follows：coexistence of oil and water（water wetted）,coexistence of oil and water（oil wetted）and pure oil.Under the conditions of water wetted,the mineral matter for carbonate growing was supplied by water solution.The speed of carbonate growing was relatively quick and quantity of synthetic hydrocarbon inclusions was big.Under the conditions of oil wetted,the mineral matter was supplied by both water solution and polar component of oil.Under condition of pure oil,the mineral matter was supplied by polar component of oil and organic acid generated when oil cracking.The mineral matter was limited,so carbonate growing was constrained and quantity of hydrocarbon inclusions was little.