Establishment And Application Of Shale Standard Adsorption Isotherm

Shale is a sort of tight reservoir.It has complicated composition including clay minerals,detrital minerals,metallic oxide,metal sulfide,different types of kerogen and so on.The clay minerals include illite,chlorite,montmorillonite and chlorite.The detrital minerals include quartz,feldspar,calcite and dolomite.Because of that different components have different chemical property,so every component has its own unique characteristic of interaction force with the Nitrogen molecules,resulting in different ability of different components.Meanwhile shale has extremely complicated pore structure.In terms of pore shapes,shale has cylindrical pore,wedge-shape pore and slit pore.In terms of pore sizes,macropores occupy certain proportion.But because of its compactness,shale has vast micropore and mesoporous in its pore space.So the distribution of potential energy in the shale pore space has prominent particularity and variability.We can obtain a large amount of rock samples from every shale reservoir.Because different sample has different component and pore structure,so every sample has its own unique adsorption characteristic,that is resulting different shapes of their adsorption isotherms.How to find the general character of the rock samples from the same layer so as to obtain the standard adsorption isotherm of the whole layer is an important subject.The standard adsorption isotherm can be used in numerical reservoir simulation and calculating of the reservoir engineering.We do X-ray diffraction whole rock analysis to the 45 shale rock samples from Erdos long 7 shale reservoir,and we informed the nine major mineral type and their accurate contents.We use these crude ore of nine mineral to do liquid nitrogen isothermal adsorption experiment,and analysis their adsorption ability in combination with the crystal texture of the mineral.After classifing and standardizing the adsorption isotherms of 108 shale rock samples from Erdos and Sichuan Basin,we use Halsey adsorption thickness equation,de Bore thickness equation,Carbon Black thickness equation to do parameter fitting with these 108 shale rock samples.We use Matlab numerical analysis microsoft to do the parameter fitting.At last we get standard isothermal adsorption curve of each type of rock samples.The standard adsorption isotherm of every kind of mineral can be used as template to indicate the number of adsorption layers,the adsorption thickness and the adsorption quantity per unit area under different relative pressure.The standard adsorption isotherm of shale reservoir can be used in numerical reservoir simulation and calculating of the reservoir engineering.