Thermochemical Fluids Dual Benefit: Enhancing Hydrocarbon Productivity in Organic-Rich Shale and Liquid Loading Removal from Gas Wells
Authors: Moh-Ali Abdelaziz Elyasa Elsadig 
Published: September 2024

The energy sector has shifted its focus to unconventional hydrocarbons such as tight oil, coalbed methane, and shale gas and oil due to the rise in global energy demand and improvements in extraction technology. Along with changing the industry, this change has also presented new opportunities and challenges. This study aims to improve the gas recovery from shale formations by injecting thermochemical fluids to induce pressure and temperature changes, enhancing hydrocarbon productivity, and addressing the challenges of liquid loading in gas wells.

This study focused on using unconventional shale samples with diverse mineralogy and total organic content (TOC). Moreover, the research involved conducting laboratory experiments utilizing a flow loop system to evaluate the performance of thermochemical fluids in removing liquid loading issues from gas wells. Then results acquired were used in the pipe simulation modeling program (PIPESIM) to simulate the liquid loading issues and the removal performance on a well scale. The research involved conducting different measurements, including chemical core-flooding injections, X-ray diffraction (XRD), and Rock-Eval pyrolysis. The rock samples underwent artificial maturation using different thermochemical fluids under varying high-pressure (2000-3500 psi), high-temperature (70-90 °C) (HPHT) conditions and treatment durations. Additionally, heat-induced maturation and supercritical CO2 assisted maturations were also conducted to compare them and thermochemical fluids treatment. The next step was to analyze the effects of induced shale maturation on petrophysical and geochemical properties through evaluation before and after maturation processes. Furthermore, the impact of thermochemical treatment on improving productivity and mitigating liquid loading issues was examined.

Thermochemical-assisted maturation resulted in a decrease in TOC by 10-40% in the rocks. Moreover, artificial maturation altered petrophysical and geochemical properties positively. The free hydrocarbon volume (S1) increased by 2.5 folds, indicating a rise in hydrocarbon reserves. Gas chromatography was used to analyze the effluents of core-flooding after the treatment. Furthermore, the injection of thermochemical fluids in gas wells that are suffering from liquid loading showed a promising result by removing more than 90% of the holdup, which led to resume the gas production.

This study aimed to propose a method for enhancing gas production through the acceleration of kerogen maturation. Thermochemical injections were found to be highly effective in expediting this process in organic-rich shale, leading to more efficient hydrocarbon recovery compared to traditional maturation methods. The approach enhances shale gas production and extends well life by promoting kerogen thermal cracking and unloading of gas wells respectively. Ultimately, adopting this method could contribute to sustainable gas production and environmental stewardship.