The economic viability of an unconventional resource play depends on well deliverability and the expense, both capital and operating, to develop and produce the hydrocarbon resource. Aside from those rock and fluid properties which dictate the amount of oil/gas in place and the flow characteristics of the reservoir itself, the reservoir pressure and resultant pressure drop within the formation, wellbore tubulars and surface facilities dominate the rate of hydrocarbon deliverability to the sales meter.
The high decline rates typical of the unconventional plays makes optimum tubing selection a challenge. Attempting to mitigate the effects of liquid loading issues often drives operators to select small tubing diameter that result in restrict flow due to high friction pressures.
This paper presents a method to reduce wellbore frictional pressure losses and increase production. The method makes use of the casing/tubing annulus to produce excess gas through the casing valve. The annular flow is managed to maintain mist flow in the tubing and eliminate loading risk. This paper provides design and operational details together with actual results. The proposed method was tested in 53 Marcellus gas wells. It proved to safely increase production by an average of 20% per well.
