Analysis of the effect of experimental adsorption uncertainty on CH 4 production and CO 2 sequestration in Dadas shale gas reservoir by numerical simulations
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CitationMerey, Ş. (2019). Analysis of the effect of experimental adsorption uncertainty on CH 4 production and CO 2 sequestration in Dadas shale gas reservoir by numerical simulations. Journal of Petroleum Science and Engineering, 178, pp. 1051-1066. https://doi.org/10.1016/j.petrol.2019.04.022
The importance of unconventional gas reservoirs such as shale gas reservoirs has increased with the decline of conventional gas reservoirs and advancement in horizontal drilling and hydraulic fracturing in the world. Recently, there have been many exploration activities in Dadas shales, Turkey. Previously, the adsorption capacities of CH 4 and CO 2 on Dadas shale samples were measured by using volumetric adsorption experimental set-up. Although adsorption uncertainties of these experiments were calculated, their effects on CH 4 production or CO 2 sequestration in Dadas shales were not evaluated in field scale. In this study, the numerical simulations for CH 4 gas production via 500 m long horizontal well from Dadas shale gas reservoir with different adsorption cases due to experimental adsorption uncertainties were conducted by using TOUGH + RealGasBrine. It was observed that initial CH 4 adsorption capacity of Dadas shales varies from 2.1% to 20.9% because of experimental adsorption uncertainty and absorbed gas volume corrections. Numerical simulations showed initial adsorbed gas % and final adsorbed gas % vary significantly. Similarly, the injection of CO 2 into the depleted Dadas shale gas reservoir was analyzed by numerical simulations at different adsorption cases due to experimental adsorption uncertainty and adsorbed gas volume correction. Final adsorbed CO 2 % varies from 18.1% to 27.5%. Furthermore, there are important differences in the amount of CO 2 injected, final adsorbed CH 4 % and final adsorbed CO 2 % during CO 2 injection simulations. The main reasons of these differences are experimental adsorption uncertainty and adsorbed gas volume correction. This study showed that the volumetric adsorption experimental method is not reliable in low adsorption values as in Dadas shales. It only gives adsorption ranges. The implication of this study is that the effect of experimental adsorption uncertainty obtained with the volumetric adsorption method on CH 4 production or CO 2 sequestration in Dadas shale gas reservoir is significant in field scale.
SourceJournal of Petroleum Science and Engineering
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