Pore-Scale Analysis of Condensate Blockage Mitigation by Wettability Alteration

Abstract

Liquid banking in the near wellbore region can lessen significantly the production from gas reservoirs. As reservoir rocks commonly consist of liquid-wet porous media, they are prone to liquid trapping following well liquid invasion and/or condensate dropout in gas-condensate systems. For this reason, wettability alteration from liquid to gas-wet has been investigated in the past two decades as a permanent gas flow enhancement solution. Numerous experiments suggest flow improvement for immiscible gas-liquid flow in wettability altered cores. However, due to experimental limitations, few studies evaluate the method’s performance for condensing flows, typical of gas-condensate reservoirs. In this context, we present a compositional pore-network model for gas-condensate flow under variable wetting conditions. Different condensate modes and flow patterns based on experimental observations were implemented in the model so that the effects of wettability on condensing flow were represented. Flow analyses under several thermodynamic conditions and flow rates in a sandstone based network were conducted to determine the parameters affecting condensate blockage mitigation by wettability alteration. Relative permeability curves and impacts factors were calculated for gas flowing velocities between 7.5 and 150 m/day, contact angles between 45° and 135°, and condensate saturations up to 35%. Significantly different relative permeability curves were obtained for contrasting wettability media and impact factors below one were found at low flowing velocities in preferentially gas-wet cases. Results exhibited similar trends observed in coreflooding experiments and windows of optimal flow enhancement through wettability alteration were identified.

Development and Applications of a Compositional Pore-Network Model for Gas-Condensate Flow

“…The evaluation of wettability alteration in gas-condensate reservoirs is presented in Section 5.2.1. The results presented in this section have been published in the journal Energies, in an article entitled: "Pore-Scale Analysis of Condensate Blockage Mitigation by Wettability Alteration" [71]. Section 5.2.2.7 presents the evaluation of possible scenarios for condensate bank removal by gas injection.…”

Modelagem Composicional Em Escala De Reservatório Do Fluxo De Gás Condensado: Efeitos Da Permeabilidade Relativa

“…Os modelos de rede são usados por Fang et al (1996) [23] e Li & Firoozabadi (2000) [22] para estudar os efeitos da gravidade, das forças viscosas, da tensão interfacial e da molhabilidade na saturação crítica de condensado e nas permeabilidades relativas de gás e condensado. Ainda na escala de poros, Reis e Carvalho [17], [27] e [28] utilizam modelos de rede de poros para calcular a permeabilidade relativa para diferentes velocidades de escoamento do gás e para diferentes saturações de gás e condensado. Essas curvas são apresentadas com mais detalhes no Capítulo 3 deste trabalho.…”

“…A composição apresentada na Tabela 5.1 foi escolhida por representar uma mistura típica de reservatórios de gás condensado, compostos por dióxido de carbono e hidrocarbonetos leves, intermediários e pesados. Essa mistura exibe comportamento de gás condensado retrógrado entre as temperaturas de 15°C e 207°C, conforme pode ser visto no diagrama de fases apresentado na Figura 5.7, obtido através do software WINPROP [17]. Além da composição, as propriedades de pressão crítica (P c ), temperatura crítica (T c ), volume crítico (V c ), fator de compressibilidade crítico (Z c ), o parâmetro parachor (P), o fator acêntrico (ω) e o fator de correção do volume (ν) dos componentes utilizados no modelo são apresentados nas Tabelas 5.2 e 5.3.…”

“…c ), Fator de compressibilidade crítico (Z c ), Fator acêntrico (ω) e Fator de Correção de Volume (ν) para cada componente do fluido[17] …”