An Overview of Methods to Mitigate Condensate Banking in Retrograde Gas Reservoirs

Abstract

Condensate blockage is one of the major problems that have been addressed in the industry for many decades. When the reservoir fluid pressure drops below the dew point pressure during the production process, the liquid drops out of the gas phase and forms condensate in the formation. There are two scenarios that can result in a pressure drop. The first one is the pressure drop due to the flow of the reservoir fluid. The reservoir fluid flows from a high pressure of the reservoir to a lower pressure of the separators at the surface. The second scenario is the drop in reservoir pressure due to pressure depletion. During the production of gas and condensate, the reservoir pressure will decrease with time and when it drops below the dew point pressure, condensate forms everywhere inside the reservoir.

The condensate dramatically reduces the gas permeability. Hence, it decreases the gas productivity. Several methods have been suggested to solve this problem such as gas injection, CO₂ Huff-n-Puff, wettability alteration, interfacial tension reduction, hydraulic fracturing, and nonconventional wells. Some of these methods have been implemented in the field and showed positive results, but each method has its own advantages and disadvantages that need to be studied further in order to improve its efficiency. This paper will give a general review of all these methods and their effectiveness in mitigating condensate banking. The decision of using a proper treatment of condensate banking can then be made based on different scenarios that are described in this paper.

Key words: Mitigate condensate banking; Retrograde gas reservoirs; CO₂ Huff-n-Puff