Performance analysis of thermochemical fluids in removing the gas condensate from different gas formations

This paper presents the performance of thermochemical treatment in removing the condensate banking from different formations. Results of coreflooding experiments and nuclear magnetic resonance (NMR) measurements are thoroughly discussed. In this work, rock samples from sandstone, shale, and carbonate formations were used. Chemical solutions that can generate pressure and temperature at certain conditions were used. Coreflooding experiments were carried out using Huff and Puff injection mode, four cycles of injection and production phases were implemented. Sufficient soaking time was provided for all samples to ensure that the reaction between the injected fluids and the rock matrix is completed. The impact of formation type and injection cycles on the treatment performance is analyzed. The cumulative condensate recoveries are 72.97%, 68.09% and 43.37% for sandstone, carbonate, and shale samples, respectively. For all samples, more liquid removal was achieved during the first cycles of the chemical treatment. Moreover, coreflooding and NMR experiments indicate that the thermochemical fluids are compatible with the treated rocks and no formation damage was induced. The products of thermochemical reaction can stabilize the clay minerals and prevent clay swelling, fines migration and pore throat plugging. For shale rocks, thermochemical treatment showed better performance than gas injection in mitigating the condensate banking. At the same treatment conditions, thermochemical fluids increased the condensate removal by a factor of 1.7 compared to the cyclic methane injection. Overall, thermochemicals are very effective in removing condensate banking from shale, tight sandstone, and tight carbonate rocks.