37 Advances In Completion And Production Operations

Friday, 28 May 2010
1:30 PM - 5:00 PM
Platinum 10

CHEMICAL TREATMENT TO MITIGATE CONDENSATE AND WATER BLOCKING IN CARBONATE GAS WELLS

Paper number: 37-2
Program: Theme Sessions
Time: 2:00 PM – 2:30 PM

Authors

Abstract

Many gas wells are suffering from near wellbore liquid accumulation. Stimulation in near wellbore region is used as a remedy, attempting to alter the wettability to non‑liquid wetting using chemicals. Successful treatments increase the fluids mobility and the wells deliverability. This paper presents, to our knowledge, the first effective treatment for carbonates. We have developed an appropriate solvent to deliver the chemical to the rock surface. The treatment solution is compatible with both brine and condensate; therefore, it will not precipitate and will not reduce permeability of the rock. We demonstrate measured relative permeability values from high‑pressure, high‑temperature coreflood experiments before and after treatment. Measurements were taken under pseudo‑steady‑state method using gas‑condensate mixtures. The chemical treatment developed in this research can be applied to increase the well deliverability and final recovery of both gas and condensate in the field, providing that, it is designed properly for different conditions of reservoir's temperature, brine salinity, and initial water saturation. We found X‑ray photoelectron spectroscopy an effective and a quick tool to screen out potentially effective chemicals from a large pool of compounds. During drop imbibition tests (water and n‑decane) we observed a quick and complete imbibition before treatment compared to no imbibition after treatment. The gas relative permeability increased considerably ‑ 80% ‑ after treatment compared to that before treatment. This increase remained substantial‑ higher than 60% ‑ upon injection of more pore volumes of fluids‑ 1000PV. We found even more increase in gas relative permeability during unsteady displacement of water. Chemical stimulation of carbonate gas wells is now possible with our new treatment and a special primer. The primer will enhance the adsorption of chemical. This will increase the durability of the treatment and will reduce the frequency of retreating a well.