Upwing Subsurface Compressor Systems™ (SCS) increase gas production by decreasing bottom hole flowing pressure and causing higher reservoir drawdown. Effective drawdown can only be achieved by downhole compression near the perforations, where the gas is denser due to the higher downhole pressure. The effective drawdown increases the production rate significantly, which increases cash flow and net present value.
Gas well simulations with SCS installations have shown gas production increases ranging from 20% to 150%. In addition to better gas production, analysis shows that the SCS increases condensate production rates and improves condensate yield, particularly in horizontal liquid rich formations, which positively impacts well performance and value.
The subsurface compressor aids in the delivery of proven developed reserves and increases the size of undeveloped reserves. The increased reserves by the SCS are accomplished by arresting the production decline rate, postponing liquid loading, and providing lower abandonment pressure.
- Stop production decline - The controlled drawdown by the SCS will stabilize the pressure oscillations, which facilitate the slowdown of production declines due to phenomenon like annular heading.
- Postpone liquid loading - The increased gas velocity produced by the SCS can decrease the minimum critical rate required to lift liquids to the surface in the vertical portion of a gas well so the well produces longer.
- Lower abandonment pressure - The increased gas velocity in the horizontal portion of the well can improve the effectiveness of liquid sweeping to prevent premature well abandonment caused by excess viscous losses.
In parametric studies conducted, the SCS increased recoverable reserves from 10 to 70%.
The SCS can delay the abandonment of gas wells by lowering the abandonment pressure. The delayed abandonment has a direct impact on recoverable reserves. The SCS will provide suction effects at the intake and boosting effects at the discharge.
- Suction effects - The suction effects with the lower intake pressure will lower the downhole flowing pressure to facilitate the flow of more gas from the formation into the wellbore.
- Boosting effects - The boosting effects with the higher discharge pressure from the SCS will increase the wellhead pressure to facilitate the flow of gas into the surface gathering system.
With both the suction effects and the boosting effects of the SCS at work, the gas well can still produce gas from the formation under the lowest possible downhole pressure or even vacuum, while forcing the produced gas uphole.
With the SCS, downhole pressure does not need to be higher than the wellhead pressure as long as the SCS discharge pressure is high enough to push gas upward. In this case, the effective abandonment pressure is dropped significantly by the SCS, thus delaying abandonment.
The SCS also can avoid the premature abandonment of gas wells by eliminating or postponing liquid loading, which interrupts gas production or makes it uneconomical to produce. The SCS can reverse a vicious cycle of liquid loading into a virtuous cycle of increased gas production.
- Vicious Cycle - When the gas well is liquid loaded, the back pressure generated by the liquid blockage will reduce gas production. The reduced gas flow will reduce gas velocity, which in turn reduces liquid sweeping capability, and allows more liquid accumulation in the gas well or formation.
- Virtuous Cycle - With the installation of the SCS, the gas velocity at both the intake and discharge of the SCS will increase. The increased gas velocity can sweep more liquid to reduce the back pressure caused by the liquid blockage. Once the liquids are removed, and the liquid loading is abated, the gas production will increase. The increased gas production will further increase the gas velocity to sweep more liquids, thus enacting the virtuous cycle of increased gas production.
The cycle reversal will extend the wells economic life and result in delayed well abandonment.