Summary
Existing models to predict and analyze liquid loading in gas wells are based
on steady-state flow. Even when transient-multiphase-wellbore models are
employed, steady-state or pseudosteady-state inflow-performance relationships
are used to characterize the reservoir. A more-reliable approach consists of
modeling the dynamics in the near-wellbore region with its transient boundary
conditions for the wellbore. The development of new models to mimic the dynamic
interaction between reservoir and wellbore requires a purpose-built flow loop.
We have developed a design to construct such a facility.
This new facility will be the first to integrate pipe representing the
wellbore with a porous medium that will fully mimic the formation surrounding
the wellbore. This design will account not only for flow into the wellbore, but
also for any reverse flow from the pipe into the medium.
We used integrated wellbore/reservoir system analysis to screen the
parameters required to recreate liquid loading under laboratory conditions. Our
results suggested using a compressed-air system with a discharge pressure
between 470 and 650 psi with gas rates of 400 to 650 scf/min along with water
injected at a rate of 100 gal/min. Once the range in operating conditions was
defined, the equipment and mechanical components for the facility were selected
and designed.
Our results showed that three reciprocating compressors working in parallel
provide the smallest, most economic, and most flexible configuration for the
TowerLab facility at Texas A&M University (TAMU). The design of the
pressure vessel hosting the porous medium will require a cylindrical body with
top- and bottom-welded flathead covers with multiple openings to minimize
weight. The required superficial velocities for air and water indicate the
system will need independent injection into the porous medium through two
manifolds. Optimally, the system will use digital pressure gauges, coriolis or
vortex technology to measure air flow, and turbine meters for water flow.
A joint-industry project (JIP) on liquid loading in gas wells was initiated
in January 2009, which includes the implementation of the proposed design for
the TowerLab facility to generate experimental data that will significantly
improve our ability to mimic the physics of multiphase flow, and so develop and
validate flow models for the characterization of liquid loading in gas wells.
It is anticipated that a preliminary version of the new loop, including an
inlet multiphase-flow pump, has been assembled and will be operational early in
Fall 2010, with plans for the full design to be implemented in 2010-11.
© 2010. Society of Petroleum Engineers
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History
- Original manuscript received:
3 March 2009
- Meeting paper published:
1 June 2009
- Revised manuscript received:
23 July 2009
- Manuscript approved:
29 October 2009
- Published online:
10 June 2010
- Version of record:
10 June 2010
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