AUTOMATED LIQUID UNLOADING IN LOW PRESSURE GAS WELLS USING INTERMITTENT AND DISTRIBUTED HEATING OF WELLBORE FLUID

This paper presents a comprehensive simulation study demonstrating technical and economic merits of automatic intermittent and distributed heating for reducing back pressure and maintaining flow in low pressure gas wells.

Reduction or elimination of the additional wellbore backpressure plays a key role in boosting gas wells productivity and extending the lifetime of the field. The backpressure is mostly due to the development of excess liquid water along the tubing stopping the low pressure gas flow. We present two phase thermal flow simulations to study the impact of intermittent volumetric heating along the wellbore to reduce or eliminate the excess backpressure caused by either water condensation in the upper part of the wellbore, or the overall increase of density of the two phase fluid. The proposed method helps in continuous prevention of the excess water development enabling the well to produce without interruption up to its natural limit.

Modeling the thermal transients of the wellbore, two phase flow pressure simulation demonstrates that flowing and thermodynamic conditions of the water/gas mixture along the wellbore have a substantial impact on the overall backpressure. Our results show that by modifying the thermal profile of the wellbore fluid at specific locations and times, we can maintain significantly lower backpressures and increase well productivity. Our case studies highlight that for very low pressure gas wells, the external power requirements can be more acquiescent to automation and cost control than the existing methods. The results yield valuable insight in the development of a novel liquid unloading techniques based on volumetric heating of the wellbore fluid. Our results can also be applied to the elimination of hydrates in gas wells.