A Fuzzy Method to Quantitatively Evaluate the Effect of Foam Deliquification in Gas Wells

Abstract

Deliquification is the primary technique for stabilizing gas production and improving gas recovery in gas fields producing water, and foam deliquification is the key subject of research for the purpose of enhancing gas production and cutting down cost. However, there is no systematic method to evaluate and compare the effects of foam deliquification in gas wells in various conditions. Aiming at the above problem, a new fuzzy quantitative evaluation method for foam deliquification is proposed. The method focus on four indicators, namely, rate of change in daily gas production, rate of change in daily water production, rate of change in the difference between tubing and casing pressures, and rate of change in daily injection cost. The evaluation results are calculated by the linear analysis, hierarchy analysis and fuzzy relation synthesis operator. The method has been applied to 30 foam deliquification wells in Sulige gas field and Chongqing gas field, and the comprehensive index of foam deliquification effect is calculated. The advantage of this method is that the technical and economic factors affecting foam deliquifiction, the membership relationships of various indicators, as well as the weight coefficients of the indicators are integratedly considered. It can be used for comprehensive evaluation and quantitative comparison of foam deliquification effects in gas wells in various conditions, assisting in determining candidate wells for foam deliquification, and guiding the selection of foaming agents.