Application of temperature-dependent adsorption models in material balance calculations for unconventional gas reservoirs

Abstract

Langmuir isotherm is the most common adsorption model used in the prediction of gas adsorption in most shale and coal bed methane reservoirs. However, due to the underlying assumption of single temperature, it fails to model gas adsorption where temperature differential exists in the reservoir. To address this shortcoming, temperature-dependent gas adsorption models have been incorporated into material balance calculations for accurate prediction of original gas in place as well as determining both average reservoir pressure and future performance in coal/shale gas reservoirs. The material balance equation has been expressed as a straight line with both Bi-Langmuir and Exponential models used in prediction of gas adsorption rather than the Langmuir isotherm. With this methodology, several adsorption capacities can be obtained at multiple temperatures which will allow for better estimation of original gas in place and future gas production. The results from this works show that temperature-dependent gas adsorption models can be used in place of Langmuir isotherm to account for the effect of temperature variations and more accurate representation of the adsorption of gas in coal/shale gas reservoirs.

Advances and Prospects of Supercritical CO2 for Shale Gas Extraction and Geological Sequestration in Gas Shale Reservoirs

“…Some scholars have found the model to be applicable to shale systems where kerogen and clays are the main storage sites for CH 4 . 58 However, a typical shale sample has more than two locations, and sorption in a nonhomogeneous system is a function of the location within the system. The adsorption model is as follows…”

“…This model considers that the most favorable site will be filled with the adsorbent, and the gas will fill the other sites, assuming that there are only two significant adsorption sites and energy sites in the system. Some scholars have found the model to be applicable to shale systems where kerogen and clays are the main storage sites for CH 4 . However, a typical shale sample has more than two locations, and sorption in a nonhomogeneous system is a function of the location within the system.…”

A review on polymer, gas, surfactant and nanoparticle adsorption modeling in porous media

“…These equations can be used for modeling adsorption studies at different temperatures (Fianu et al, 2019b). The D-R and D-A models were developed for a homogenous pore structure (Hutson and Yang, 1997).…”

In‐situ temperature‐depth profile evaluation of South African unmineable coal seams to determine CO2 sequestration potential

“…In CO 2 sequestration reservoirs, temperature variations due to geothermal gradients are common, making the prediction of temperature‐dependent gas adsorption essential for accurate gas recovery estimates. [ 19 ] Reliable adsorption equilibrium models are therefore vital for optimizing these processes. Various frameworks, such as the Langmuir, Freundlich, and Temkin isotherms, are used to describe and correlate pure and mixture adsorption isotherms.…”