.A comparative evaluation of adsoprtion isotherm in clay- dominated shale
International Journal of Latest Trends in Engineering and Technology
Unconventional reservoirs such as shale have become an important and available possibility to meet the increasing demand on energy worldwide. Gas reservoirs like shale have a large untapped reserve of gas in adsorbed form in both the organic and clay rich component of the source rock. The secret to unlocking these reserves lies in accurate experimental data which in turn depends on the experimental method used. Recently a number of procedures such as manometric, volumetric and gravimetric have
... een developed to quantify adsorption, which requires the determination of "void volume" using helium. In the context of this research on understanding the source of inaccuracies in adsorption data from void volume of Clay-rich shale, an experimental method was used which does not quantify void volume directly. The advantage of this method is that errors due to primary measurement of parameters are reduced. A series of low pressure void volume measurement were performed on dry and water saturated sand stone sample representative of an ideal shale inorganic component at 230C and Helium pressures of up to 95Psia under dry and water saturated conditions. Experimental results indicate that there was a small variation in average void volume with pressure for the Bandera Gray and Scioto samples. The pressure ranges investigated showed close results regarding the measured void volume value with measurement scattered about an average of 8.017cm^3 for Bandera Gray, and 4.5171cm^3 for the Scioto samples. Water content in clay rich shale impacts void volume because water blocks some of the pores accessible to helium and leads to a decrease in void volume, therefore when quantifying storage in clay rich shale which is water wet, correction must be made to account for water in its various form (free, adsorbed and gas solubility in water) or errors might arise. The investigation indicates that water content of 5.62 wt. % and 5.48wt. % for both samples respectively, can reduce the dry capacity by as much as 12.53% and 11.2%.