Dependency of wettability alteration on hydrocarbon composition and interfacial tension in gas/condensate systems

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In gas-condensate reservoirs, soon after the pressure falls below the dew-point pressure, condensate liquid drops out of the gaseous phase. In such conditions, high surface energy minerals render spreading of the condensate film on the rock surface, wetting out the pores' surfaces. Condensate consequently starts to accumulate, restricting the open paths for the flowing gas, which could result in significant reduction in well productivity.

Modifying the surface energy of the reservoir minerals by chemicals, aiming at altering the rock wettability from strongly liquid-wetting to intermediate gas-wetting conditions, has been proposed as a solution to improve the oil mobility around the wellbore and mitigate the corresponding blockage issues.

Over the last decade, large numbers of experimental investigations have been dedicated to study the performance of different chemical groups on wettability alteration of reservoir rocks. However, in all these studies, conventional fluids, e.g. decane/air, have been used to measure the contact angles at oil/gas/rock boundary. In this paper, for the first time, gas/condensate fluids, with various compositions and at different interfacial tensions (IFTs) have been used to evaluate the performance of wettability modifiers under more realistic conditions. The observations revealed that at similar IFT values, as the number of carbon atoms increases, i.e. there are heavier hydrocarbons (e.g. C1/nC10), the condensate/gas/treated rock contact angle (?condensate/gas ) increases, whilst for the lighter hydrocarbons (C1/nC4), the condensate wets the rock surface quickly. IFT also showed a significant impact on the treatment performance. That is, at lower IFTs, smaller contact angles through the liquid phase were observed, e.g. for C1/nC10 mixture, when IFT decreased from 10 to 1.5 mN/m, ?condensate/gas reduced from 65° to 40° towards liquid-wet.

The results highlight the significance of the dependency of the wettability modifiers performance to the original fluid composition and thermodynamic conditions in a gas-condensate reservoir. This also underlines the careful considerations that are required in design and application of these treatments in such reservoirs.
Original languageEnglish
Title of host publication75th EAGE Annual Conference & Exhibition
PublisherSociety of Petroleum Engineers
Number of pages9
ISBN (Print)9781613992548
Publication statusPublished - Jun 2013
Event75th EAGE Conference and Exhibition 2013 - London, United Kingdom
Duration: 10 Jun 201313 Jun 2013


Conference75th EAGE Conference and Exhibition 2013
Abbreviated titleSPE EUROPEC 2013
Country/TerritoryUnited Kingdom


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