Predicting the water breakthrough time in bottom-water gas reservoirs considering the influence of waterbody gravity
Water breakthrough time in gas wells is of great significance for the development of bottom-water gas reservoirs which always feature complex water-producing conditions.Its previous prediction did not take the effect of waterbody gravity into consid-eration,leading to inaccurate time.So,a formula to predict this time in such reservoirs considering the gravity effect was created on the basis of the theory of seepage mechanics and the patterns of fluid flow in porous media.Moreover,some controls of the waterbody mobility and density,reservoir porosity,distance between bottomhole and bottom water,and drawdown on the breakthrough time were clarified through single-factor analysis.Results show that this time in the bottom-water reservoirs is positively correlated with not only reservoir porosity but the distance,and negatively with the mobility and density together with the drawdown.Since the proposed methodology considers the waterbody density to analyze the gravity influence on the breakthrough time,the time predicted is in better agreement with actual one than the other prediction which ignores the gravity.Thus,this methodology is of guidance for on-site pro-duction management.
Bottom-water gas reservoirWater breakthrough timeWaterbody gravitySeepage mechanicsSingle-factor analysisWaterbody mobilityWaterbody densityDistance between bottomhole and bottom water
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