Gas Condensate Damage in Hydraulically Fractured Wells

Abstract

This project is a research into the effect of gas condensate damage in hydraulically fractured wells. It is the result of a problem encountered in producing a low permeability formation from a well in South Texas owned by the El Paso Production Company. The well was producing from a gas condensate reservoir. Questions were raised about whether flowing bottomhole pressure below dewpoint would be appropriate. Condensate damage in the hydraulic fracture was expected to be of significant effect.In the most recent work done by Adedeji Ayoola Adeyeye, this subject was studied when the effects of reservoir depletion were minimized by introduction of an injector well with fluid composition the same as the original reservoir fluid. He also used an infinite conductivity hydraulic fracture along with a linear model as an adequate analogy. He concluded that the skin due to liquid build-up is not enough to prevent lower flowing bottomhole pressures from producing more gas.This current study investigated the condensate damage at the face of the hydraulic fracture in transient and boundary dominated periods when the effects of reservoir depletion are taken into account. As a first step, simulation of liquid flow into the fracture was performed using a 2D 1-phase simulator in order to help us to better understand the results of gas condensate simulation. Then during the research, gas condensate models with various gas compositions were simulated using a commercial simulator (CMG). The results of this research are a step forward in helping to improve the management of gas condensate reservoirs by understanding the mechanics of liquid build-up. It also provides methodology for quantifying the condensate damage that impairs linear flow of gas into the hydraulic fracture.

Evaluating Factors Controlling Damage and Productivity in Tight Gas Reservoirs

“…Figure 3: Reduced effective permeability due to phase trapping damage (Bennion et al, 2006) Producing gas at low flowing bottom-hole pressure may reduce the phase trapping damage, since water content of the gas phase is higher at lower pressure, and water 20 phase may partially be vaporized into the gas phase in the reduced pressure zone around the wellbore (Lokken et al, 2008). However in the cases that are not truly dry gas situation, producing with the large pressure drawdown may cause condensate banking in the reservoir near the wellbore, if the flowing bottom-hole pressure drops below the dew point pressure of the gas phase (Ravari et al, 2005).…”

“…Therefore typical published oilgas relative permeability data had to be considered in the reservoir simulation studies related to oil-gas system (Ravari et al, 2005).…”

“…For the oil-gas system, there was no core flood test data available, and therefore, published typical oil-gas relative permeability data in a tight-gas reservoir simulation study (Ravari et al, 2005) was used. The relative permeability data for gas-water and gasoil systems are shown in Figures 4a and 4b, respectively.…”

Effect of Non-Darcy Flow on Well Productivity of a Hydraulically Fractured Gas-Condensate Well

“…Several studies (Ravari et al 2005;Kumar 2000;Mohan 2005) have been done to understand the impact of hydraulic fracturing of gas-condensate wells. Mohan (2005) found that non-Darcy flow plays a significant role in determining the productivity improvement.…”