Application of Thermochemical in Removing Condensate Banking in Gas Condensate Reservoirs

DOI: 10.14800/IOGR.1325

Abstract

The accumulation of liquid near the wellbore, induced by condensate banking in gas condensate reservoirs, significantly impairs gas production rates, presenting a substantial challenge for hydrocarbon recovery. Conventional methods such as CO₂ injection and produced gas cycling offer only temporary mitigation, requiring frequent reapplication, which results in high operational costs and logistical complexities. This study explores the potential of thermochemical fluids (TCFs) as a more durable and cost-efficient alternative to address condensate banking. The exothermic reaction between sodium nitrite (NaNO₂) and ammonium chloride (NH₄Cl), catalyzed by acetic acid (CH₃COOH), produces heat, generating temperatures of up to 84^oC, and achieving a maximum recovery of 52% from four core samples. TCFs induce in-situ heating, the release of nitrogen gas, and the generation of pressure, which together create microcracks that facilitate the vaporization and mobilization of the trapped condensate. This approach also helps maintain reservoir pressure above the dew point and reduces capillary pressure in the pore spaces. The study investigates the influence of varying reactant and catalyst concentrations on the reaction kinetics, emphasizing the critical role of optimal stoichiometry to maximize heat generation. Core flooding experiments were conducted using the huff-and-puff injection technique to compare the performance of TCFs injection with CO₂ injection. The results consistently showed superior condensate recovery with TCFs injection across all experiments.