Santoso, Bestramy D (2015-12). Modeling of Near-Wellbore Wettability Alteration for Gas Well Liquid Blocking Remediation. Master's Thesis. Thesis uri icon

abstract

  • Gas condensate reservoirs are prone to developing condensate blocking. This occurs because of the nature of condensate gas reservoirs, wherein reservoir gases experience retrograde condensation; a phenomenon where gases temporarily turn into liquid due to reduction in pressure. This is most pronounced near the wellbore region due to pressure decrease associated with gas production. Because of the reservoir rock's liquid wetting state, the liquid condensate mobility is severely reduced, blocking both gas and condensates from being produced, and severely reducing the productivity of the well. Several studies, both experimental and simulation work suggests that wettability alteration is a serious option available to mitigate condensate blocking, especially as a long-term solution. This thesis presents both experimental wettability alteration with a commercial surfactant and modeling work done on a well that has near wellbore wettability altered. The experimental studies will explore the effect of surfactants on rock cores to alter its wettability to intermediate wet. The model will investigate effectiveness of wettability alteration when applied to a well. It will examine the effects of chemical reach on ultimate gas recovery, the impact of multiple treatments, and most importantly, costs associated with such treatments. The results of the study show that increasing treatment reach is beneficial to overall gas recovery, and that multiple treatments still yield better recovery than untreated case. However, the cost of the treatment is prohibitive, and is largely dependent on both treatment chemical cost and the cost of lost production during treatment. This study illustrates the importance of treatment longevity and the need of low-cost chemicals for well deployment.
  • Gas condensate reservoirs are prone to developing condensate blocking. This occurs because of the nature of condensate gas reservoirs, wherein reservoir gases experience retrograde condensation; a phenomenon where gases temporarily turn into liquid due to reduction in pressure. This is most pronounced near the wellbore region due to pressure decrease associated with gas production. Because of the reservoir rock's liquid wetting state, the liquid condensate mobility is severely reduced, blocking both gas and condensates from being produced, and severely reducing the productivity of the well. Several studies, both experimental and simulation work suggests that wettability alteration is a serious option available to mitigate condensate blocking, especially as a long-term solution.

    This thesis presents both experimental wettability alteration with a commercial surfactant and modeling work done on a well that has near wellbore wettability altered. The experimental studies will explore the effect of surfactants on rock cores to alter its wettability to intermediate wet. The model will investigate effectiveness of wettability alteration when applied to a well. It will examine the effects of chemical reach on ultimate gas recovery, the impact of multiple treatments, and most importantly, costs associated with such treatments. The results of the study show that increasing treatment reach is beneficial to overall gas recovery, and that multiple treatments still yield better recovery than untreated case. However, the cost of the treatment is prohibitive, and is largely dependent on both treatment chemical cost and the cost of lost production during treatment. This study illustrates the importance of treatment longevity and the need of low-cost chemicals for well deployment.

publication date

  • December 2015