井下烃类气体溶入系数求取的实验模拟及其在储层评价中的应用

Experimental simulation of calculation on coefficient of downhole hydrocarbon gas dissolved into drilling fluids and its application on formation evaluation

钻头破碎地层后,地层中的烃类气体组分由钻井液携带至地面,一部分随即散失在空气中,一部分溶解在钻井液内,检测溶解在钻井液内烃类气体组分的体积及体积分数是发现和评价油气显示的重要方式之一。不同的烃类气体组分溶入钻井液的能力是不同的,只检测溶解在钻井液内烃类气体组分,不能及时发现和准确评价井下油气藏。为此,首次提出"溶入系数"概念及求取方法,借助钻井液高温高压旋转模拟装置,进行了不同烃类气体组分在井下高温高压流动状态下溶入钻井液能力实验,得出不同体积烃类气体组分在井下状态下的"溶入系数"。根据不同烃类气体组分的"溶入系数",可计算出地下岩层某种烃类组分真实含量,更加客观地反映地层含油气信息,有利于油气显示的及时发现和准确评价。

When drilling bit has cut through strata, crushed rocks and gases are carried to ground by drilling fluid. Some of them are dissipated in the air immediately, and some are dissolved in drilling fluid. To detect the dissolved volume and volume fraction of hydrocarbon gas components is one of the most important methods to discover and evaluate oil-and-gas shows. Different hydrocarbon gas components have different dissolving capacities. And reservoir cannot be discovered and evaluated timely and accurately if the dissolving test of various hydrocarbon gases is just done. For this reason, a ＂dissolving coefficient＂ and its solving method are proposed for the first time. Through the dissolving test of various hydrocarbon gases with a rotary simulation device of drilling fluid in high temperature and high pressure, we recognize the dissolving coefficient in these circumstances. According to the dissolving coefficient, the true content of a certain hydrocarbon composition is calculated. This will be advan- tageous to discover and evaluate oil-and-gas shows timely and accurately.