Significant productivity loss occurs in gas condensate reservoirs due to condensate and water accumulation near the production well. Our experimental study shows that gas relative permeability decreases by more than 95% due to liquid blockage (high water saturation along with condensate accumulation) and the reduction is even more pronounced in presence of mobile water.

Significant advances have been made during this study to develop and extend a chemical treatment to reduce the damage caused by liquid blocking in gas condensate reservoirs. The treatment is composed of a non-ionic polymeric fluorochemical in a glycol/alcohol or glycol ether/alcohol solvent mixture. The chemical treatment alters the wettability of water-wet sandstone to neutral wet and increases the gas relative permeability. It also reduces the liquid trapping in pores, which increases the relative permeability to oil or condensate and makes the removal of water blockage from treated zone easier. Selection of solvents to deliver the fluorochemical to the rock surface is critical to the success of the treatment, especially in the presence of high water saturation and high salinity brine.

The treatment improved the gas and condensate relative permeabilities by a factor of about 2-4 on liquid blocked outcrop and reservoir sandstone rocks. The improvement in relative permeability after chemical treatment was quantified by performing coreflood experiments at reservoir conditions. The treatment also shows good durability against flowing gas, condensate, brine and solvent.

We have developed a chemical treatment that shows great potential to increase production from liquid blocked gas wells with relatively small treatment volumes since only the near-well region needs to be treated.