TY - THES

T1 - Condensate Bank Modelling of Gas Condensate Reservoirs

AU - Abdul-Jaliel, Hussam-Eddien Mohamed

N1 - embargoed until null

PY - 2010

Y1 - 2010

N2 - Well productivity impairment due to two-phase flow in the near well region is a major concern in gas condensate reservoirs. These reservoirs differ from dry-gas reservoirs by complex flow behaviors. Understanding phase and fluid flow behavior relationships, therefore, is essential if we want to make accurate engineering decisions for gas-condensate systems such as in well testing, reserve estimation and production forecasting. Condensate banking occurs around the well when the bottom-hole pressure drops below the dew point. This decreases production significantly and the condensate bank may also be unrecoverable. The most important parameter for determining condensate well productivity is the effective gas permeability in the near wellbore region where very high flow velocities occur. An understanding of the characteristics of the high-velocity gas-condensate flow and relative permeability data is necessary for accurate forecasting of well productivity. My research aims at investigating the factors that lead to saturation buildup in gas condensate reservoirs, and to establish the sensitivity of the flow to near-well rate-dependent relative permeability. Both, rapid flow and capillary number effects on gas condensate reservoirs are dealt with using the [Henderson et. al.] Heriot-Watt Approach. In order to tackle this goal, a finely-gridded, one-dimensional radial flow, compositional, single well model is used to simulate well responses in a gas condensate system with taking to account a velocity dependent relative permeability and non-Darcy flow. The reservoir is assumed to be homogeneous. The model contains no water. The compositional simulator (Eclipse 300) with the Peng-Robinson equation of state (EOS) was used to investigate and account for the changes in fluid properties with pressure, phase change, process couplings (increase in relative permeability as IFT decreases or velocity increases) and inertia (decrease in relative permeability when velocity increases) when it is required to do so. My results show that non-Darcy effects cause additional pressure drops proportional to the flow rate while the increase capillary number causes a reduction of condensate saturation in the near wellbore area.

AB - Well productivity impairment due to two-phase flow in the near well region is a major concern in gas condensate reservoirs. These reservoirs differ from dry-gas reservoirs by complex flow behaviors. Understanding phase and fluid flow behavior relationships, therefore, is essential if we want to make accurate engineering decisions for gas-condensate systems such as in well testing, reserve estimation and production forecasting. Condensate banking occurs around the well when the bottom-hole pressure drops below the dew point. This decreases production significantly and the condensate bank may also be unrecoverable. The most important parameter for determining condensate well productivity is the effective gas permeability in the near wellbore region where very high flow velocities occur. An understanding of the characteristics of the high-velocity gas-condensate flow and relative permeability data is necessary for accurate forecasting of well productivity. My research aims at investigating the factors that lead to saturation buildup in gas condensate reservoirs, and to establish the sensitivity of the flow to near-well rate-dependent relative permeability. Both, rapid flow and capillary number effects on gas condensate reservoirs are dealt with using the [Henderson et. al.] Heriot-Watt Approach. In order to tackle this goal, a finely-gridded, one-dimensional radial flow, compositional, single well model is used to simulate well responses in a gas condensate system with taking to account a velocity dependent relative permeability and non-Darcy flow. The reservoir is assumed to be homogeneous. The model contains no water. The compositional simulator (Eclipse 300) with the Peng-Robinson equation of state (EOS) was used to investigate and account for the changes in fluid properties with pressure, phase change, process couplings (increase in relative permeability as IFT decreases or velocity increases) and inertia (decrease in relative permeability when velocity increases) when it is required to do so. My results show that non-Darcy effects cause additional pressure drops proportional to the flow rate while the increase capillary number causes a reduction of condensate saturation in the near wellbore area.

KW - Gas Condensate Reservoirs Condensate Banking Non-Darcy flow Relative Permeability Capillary Number

KW - Gaskondensat Lagerstaette Kondensat-Banking Non-Darcy flow Grenzflächenspannung Relative Permeabilität Kapillar-Phänomen

M3 - Master's Thesis

ER -