水对不同生烃模拟实验系统产物的影响

The Effect of Water Medium on the Products of Different Pyrolysis System

通过总结分析水对不同生烃模拟实验体系实验产物演化机理的影响,进一步明确了水在有机质演化过程中的作用。生烃模拟实验系统的发展历程为：开放体系→封闭体系→半开放体系,实验介质也由无水模拟发展到加水模拟。研究表明半开放体系下的加水生排烃模拟实验更贴近常规油气实际地质演化过程。液态水在不同温度具有不同的性质,常温液态水（一般T〈100℃）、高温液态水（200-374.5℃）及超过临界点（临界温度T=374.5℃和临界压力P=22.1MPa）的超临界状态水的物理和化学性质均存在较大差异。实验中模拟温度一般都高于200℃,水在不同实验系统条件下具有不同的存在状态,对模拟产物也有不同作用。总体来讲,封闭体系下,水对生烃演化有一定的促进作用,并且气态烃产率与加水量呈正相关关系,而液态烃产率在加水量相当于岩样的20%-50%时最大;相对而言,半开放体系下,高压水蒸汽介质更有利于气态烃的生成,而高温高压条件下的临界态水则更有利于液态烃的生成和保存。所以,综合前人实验结果,总结水介质参与下的不同生烃模拟实验系统产物特征,将为明确水对有机质演化机理的作用提供重要的理论依据。

In order to further clarify the role of water in the evolution of organic matter, we summarize the effect of water in different pyrolysis system. The development of hydrocarbon evolution and expulsion sire-- ulation experiment is open system→closed system→semi-open system. And at the same time,the medium of experiment has also changed from anhydrous to hydrous pyrolysis. In the above three pyrolysis systems, semi-open simulation system has been regarded as the process which is closer to the actual conventional geological evolution. As liquid water has different properties at different temperature and pressure, different state of liquid water will have different effects on the products of simulation experiment. For example, the temperature between room temperature and 100℃is called normal temperature water. High temperature liquid water ranges from 200℃ to 374.5℃. But after the critical temperature （T=374.5℃） and pressure （P=22.1MPa） point, the physical and chemical properties of water will have a big change. In general,in the closed system,the generation of gas hydrocarbon has a positive correlation with the added water, but when the amount of water has a percent between 20 and 50 on the rock sample, the yield of liquid hydrocarbon is the highest. But in the semi-open system,different states of water also have different properties. For example,the medium of high pressure water vapour improves the efficiency of gaseous hydrocarbon. And the critical water medium is conductive to the generation and preservation of liquid hydrocarbon. So clearly understanding how the liquid water affects pyrolysis products will have a significant implication.