American Oil and Gas Reporter - February 2017 - 53

SpecialReport: Shale Resource Science
FIGURE 2
Progressing Cavity Multiphase Pump Testing at Texas A&M University

form of artificial lift." Reducing wellhead
pressure translates directly into improved
recovery. Also, for wells experiencing
liquid loading, lowering the wellhead
pressure using a multiphase pump often
can restore production by increasing wellbore gas velocities to allow liquids production from the well and extend its life.
In regard to reservoir management,
an MPF provides improved well/reservoir
management and surveillance through
frequent automated testing. The multiphase
meters utilized as a core element of the
MPF require far less time for each test.
Conventional well tests using a test separator require time for the separator to
stabilize once a well is placed on test.
This is eliminated, or at least reduced,
for multiphase meters.
As has been demonstrated in multiphase meter field applications, more frequent well tests with better accuracy improve reservoir analysis and forecasting.
Finally, the MPF approach gives operators the ability to take a "full life
cycle" view of operating expenditures.
While initial production from hydraulically
fractured shale wells is strong, more than
half of the reserves are recovered over an
extended period, which may be 20 years
or longer.
Field developments utilizing a MPF
provide value for the long-term operation
of the field through lower operating costs.
The automated nature of an MPF reduces
visits from field staff, and there is far
less equipment to maintain, inspect and
permit.

That said, it should be noted that the
higher-level pumping and metering technologies used in an MPF often require
field staff to be trained to a higher level.
Multiphase Pumping
Multiphase pumping has become the
standard production method in several
key oil and gas producing arenas. For
heavy oil, multiphase pumping is used
for pad-based development in Canada,
California and Venezuela. Off shore,
seafloor multiphase pumping is used
widely and has established a strong track

record of reliability.
There are several types of multiphase
pumps, but they fall into two main categories: rotodynamic and positive displacement pumps.
While rotodynamic systems such as
electric submersible pumps and seafloor
helico-axial pumps dominate subsea applications, positive displacement pumps
dominate on shore. The key for utilizing
them in MPFs is the gas-handling ability
of the pump.
The majority of wells drilled in U.S.
shale plays produce multiphase streams.
In fact, pad horizontal wells in tight oil
plays typically exhibit gas volume fractions
(GVFs) of 80 percent or higher at the
wellhead. Positive displacement pumps
such as twin-screw pumps (TSPs) and
progressing cavity pumps (PCPs) better
lend themselves to high-gas-fraction production.
The results of research projects examining the performance of both PCPs
and TSPs under high-GVF conditions indicate that both technologies are able to
boost pressures, even when GVFs are
greater than 90 percent.
Figure 2 shows a SEEPEX PCP on
the test stand during research conducted
at Texas A&M University. The PCP has
equal-wall-thickness stator technology,
which with a close fit between the metal
rotor and rubber stator, was able to reach
high volumetric efficiency. While the system achieved volumetric efficiencies above
95 percent for all test conditions at full

FIGURE 3
Twin-Screw Multiphase Pump Testing at Texas A&M University

FEBRUARY 2017 53

American Oil and Gas Reporter - February 2017

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