烃源岩-流体相互作用模拟实验研究

Simulated Experimental Study of Interaction between Fluid and Source Rock

为了探讨烃源岩与孔隙流体之间相互作用过程和机理以及有机酸的生成及其影响因素,我们开展了烃源岩-流体相互作用模拟实验研究。实验结果表明:Ⅱ型干酪根形成有机酸的能力大于Ⅰ型干酪根,水的矿化度对有机酸的形成影响甚微,随着温度升高,流体中有机酸的含量也随之增大。pH值对有机酸形成的影响非常明显,中性和碱性条件更有利于生成有机酸。其中乙酸的形成有利于碳酸盐矿物的溶解,而草酸的形成不利于碳酸盐的溶解。温度对烃源岩的影响与烃源岩的矿物组成有很大的关系,对于富碳酸盐烃源岩,Ca、Mg、Na三元素在水中的溶解量,与温度呈反相关的关系,对于贫碳酸盐烃源岩,与反应温度之间则呈现出正相关的关系。而无论碳酸盐含量高低,Si在溶液中的含量都会随着温度的升高而增大。酸性溶液对烃源岩的溶解能力最强,无论原始反应溶液的酸碱性,反应结果都最终趋于弱碱性。流体的含盐量对烃源岩中Mg的溶解影响差异较大,低盐度的流体有利于Mg溶解。

In order to study the interaction process of source rock and fissure fluid and their mechanism,the creation of organic acid,and its impact factors,the simulation experiment result of the interaction between the source rock-fluid was conducted.The experimental results show that the quantity of organic acid brought by type Ⅱ kerogen is more than that of type Ⅰ kerogen.Rising of temperature is advantageous to engender organic acid however,the mineral of water has little influence on creation of organic acid.The pH value has great influence over cause of organic acid： neutral and basic is more advantageous to the formation of organic acid than the acid condition.The formation of organic acid speeds dissolution of minerals in source rock,and the influence of the organic acid dissolving carbonate mineral influence is most obvious.The formation of the acetic acid also favors dissolution of carbonate mineral.Oxalic acid is disadvantageous to the dissolution of carbonate mineral.Temperature influences greatly on source rock and its mineral compositions,for source rock is rich in carbonate,the quantity of dissolution of Ca,Mg,Na in water appears inverse correlation with temperature.Regardless of what content of carbonate is,the Si content in the solution will be risen with increasing temperature.The acid solution has a strong ability to dissolve source rock.No matter original solution is acid or basic,the reaction finally tends to be weak basic.The salinity of fluid has big influence on the dissolution of Mg,with low salinity of fluid favorable to the dissolution of Mg.