Paraffin Inhibition in the Tubing of a Gas-Lifted Production Well Using Pre-Conditioned High Temperature Gas

Abstract

Gas lift technology involves the introduction of gas in the tubing to improve vertical lift performance and over all well productivity. However, when wax is deposited in the tubing, the pressure drop across tubing is increased and vertical lift performance is adversely impacted. This paper reviews the performance of two wells known to have wax deposition issues leading to sub-optimal production, thus necessitating intermittent paraffin inhibition /hot oiling which have associated costs. A Fluid Thermodynamics model which demonstrated that production from the two wells can be optimized by gas lifting wells at points deeper in the tubing than the nucleating points at a threshold gas lift temperature was developed. The minimum gas lift temperature at any given pressure required to attain this flow assurance solution was simulated from the model developed. The model illustrates that a thermodynamic state can be attained without the use of an inline heater. This was due to the high discharge of thermal energy from the lift gas supplied from the gas lift manifold. Results from model application to the two case study wells showed improvement of flow rates from sub-optimal values to steady rates of total increments of about 1,000 Barrels of Oil Per Day. In addition, wax deposition ceased as confirmed from the laboratory re-estimation of the Wax Appearance Temperature (WAT) of the wellbore fluids. This model application eliminated yearly remediation operations such as hot oiling operations that was in place to manage and ensure that the wells produced continually, resulting in an annual cost saving of about $30,000 per well. This Thermal inhibition method can be applied in all wax producers to eliminate or reduce wax in tubing and hence the flow line.