ABSTRACT
The objective of unloading valves in a gas lift string is to transfer gas to the lift point. Normally, the valve test rack opening (TRO) for nitrogen charged dome pressure valves is based upon the estimated flowing temperature profile. This is appropriate for most situations. However, the valve settings may not unload consistently when a significant difference exists between the shut in, unloading, and producing temperature gradients. Such temperature differences are very pronounced in either high rate wells or in wells with a large upper well bore heat sink, such as when penetrating the Arctic permafrost, and in deep sea completions.
A procedure has been developed to determine an appropriate TRO for each valve to accommodate the range of temperature conditions expected during kick-off operations. It reduces the likelihood of unloading valves operating out of sequence and improves efficient transfer of lift gas to the design lift valve under a variety of well bore temperature gradients.
