The Study Of Shale Gas Adsorption Influenced By Water

In the development and exploration of shale gas,the evaluation of gas and the technical recoverable reserves are of vital importance.In general,we use adsorption experiments to evaluate shale gas reservoir capacity in the laboratory.Currently,not only the lack of experimental results that under the condition of high pressure,but also lack the adsorption experiments of wet shale sample at home and abroad.The real reservoir usually contain a certain amount of moisture,it will bring errors for the study of shale reservoir adsorption mechanism without considering the influence of water.This article put forward a new experimental process for the high pressure adsorption experiment by using improved volumetric method;Spraying with distilled water and balanced water saturation method to balance the moisture for shale samples;Analyze clay minerals and the characteristics of shale samples' pore structure,then draw on the influence law of adsorption;After complex processing and experimental process,earned the adsorption curve,by which we analyze the influence of water adsorption of the sample.Through adsorption capacity control factors analysis: the clay minerals with large specific surface area have strong adsorption ability.In the case of water treatment,pore structure was damaged and adsorption capacity sharply lower.Water mainly influence the pore size between 5 ~ 100 nm,while seldom impact on the pore size that less than 1nm of shale.The higher moisture content,the worse adsorption capacity.When the moisture content reaches a certain degree and pressure is greater than 15 MPa,the stable adsorption quantity would be damaged with a slight decline,this may because the dissolution of a small amount of adsorbed gas.With the increase of pressure,the influence of moisture will be increased.The higher clay content,the greater the adsorption capacity affected by water,this may due to the high pressure during adsorption stability,moisture break into the shale and damage the pore structure of the clay interlayer,meanwhile absorbed onto the surface of hydrophilic clay.