Classification and Management of Liquid Loading in Gas Wells

Abstract

Abstract Liquid loading in gas wells is the accumulation of liquids (water or condensate or both) in the wellbore due to pressure decline. It occurs in vertical or deviated wells during production from natural gas reservoirs as a consequence of condensation and coalescence of liquids from gas streams. This is common in both offshore and onshore production systems and results in the simultaneous flow of gas, liquid hydrocarbons and water. Both water vapour and intermediate hydrocarbons can condense, depending on the composition of the gas, the temperature and pressure within the wellbore. Liquid loading has remained a menace and a fundamental problem in gas wells as all gas wells will undergo this phase in their productive life cycle. It is more pronounced in aging fields but can also occur in new wells having poor completion designs. When improperly managed, liquid loading can cause not only a drastic reduction in production but also pose a potential challenge of killing the well. Several methods are available in aiding and managing production when severe liquid loading occurs, but there is no current solution available in preventing its occurrence in the industry This review considers a broad perspective of how liquid loading has been managed over the years and develops classifications for liquid loading problems based on the sources of the liquids, the severity of the problem, the preventive measures and the treatment strategies available in the industry. A comparative analysis of some of the predictive models was made along with a new model using Matlab. The result shows that at pressures below 2500psi and pressures above 5000psia; the modified model perform better than Turner et al's model whereas at pressures between 2500 and 5000psia, Turner et al's model performed better than other models. This work is intended to provide a "first aid" guide to professionals and early career engineers in one package – identifying different types of liquid loading problems and the available and best techniques in managing it; thus accelerating quick decision making and intervention in gas fields for the oil and gas industry.