American Oil and Gas Reporter - June 2014 - 92

SpecialReport: Artificial Lift Technology
While the original Broad Oak drilled
a few horizontals, most of its wells
were drilled vertically and hydraulically
fractured in multiple zones. The wells
targeted three Wolfcamp zones and four
or five Spraberry zones, with production
from all completed intervals commingled.
The wells generally were completed
with seven or eight frac stages, with a
typical stage containing 75,000 gallons
of water and 120,000 pounds of sand.
Cross-linked gels were used to deliver

the proppant into the induced fractures,
but even the best gels would leave particles
in the formation that could clog pore
throats and limit oil production. Therefore,
the objective was to recover the frac fluid
as quickly as possible. That meant finding
an artificial lift method that could handle
high liquid volumes as well as sand.
The first 52 vertical wells used rod
pumps. While it is possible for rod pumps
to produce as much as 5,000 barrels a
day with the right engineering, they can
deliver such high volumes only under

TABLE 1
Rod Pump Characteristics
Characteristic

Typical Range

Maximum*

Operating Depth

100 to 11,000' TVD

16,000' TVD

Operating Volume

5 to 300 bbl/d

5,000 bbl/d

Operating Temperature

100 to 350° F

550° F

0 to 20° landed pump

0 to 90° landed pump
<15°/100' build angle

Wellbore Deviation
Corrosion Handling

Good to Excellent with Upgraded Materials

Gas Handling

Fair to Good

Solids Handling

Fair to Good

Fluid Gravity

>8° API

Servicing

Workover or Pulling Rig

Prime Mover Type

Results

Gas or Electric

Offshore Application

Limited

System Efficiency

45 to 60 percent

* Special analysis required

TABLE 2
Hydraulic Jet Lift Characteristics
Characteristic

Typical Range

Maximum*

Operating Depth

5,000 to 10,000' TVD

15,000' TVD

Operating Volume

300 to 1,000 bbl/d

>15,000 bbl/d

Operating Temperature
Wellbore Deviation

100 to 250° F

500° F

0 to 20° hole angle

0 to 90° pump placement
<24°/100' build angle

Corrosion Handling

Excellent

Gas Handling

Good

Solids Handling

Good

Fluid Gravity
Servicing
Prime Mover Type
Offshore Application
System Efficiency
* Special analysis required
92 THE AMERICAN OIL & GAS REPORTER

limited circumstances. More common
designs can reach 1,500 bbl/d in the right
situation, but in general, beam pumping
units are limited to about 300 bbl/d,
which was well below what was needed
to accommodate flow back and initial
high production rates from the Wolfberry
wells (Table 1).
To speed liquid recovery, we evaluated
several alternative artificial lift methods,
including gas lift and electric submersible
pumps. Eventually, we settled on a strategy
of using jet pumps during the initial production stage, then pulling the jet pumps
after a few weeks to switch to rod pumping
units.
Jet pumps have the capability to handle
liquid volumes as high as 15,000 bbl/d,
more than enough for our purposes; tolerate gas and solids, including the frac
sand we expected to recover; and can be
deployed or retrieved by circulation or
wireline (Table 2). With no moving parts,
and convenient and fast retrieval, the
pumps are durable and easy to repair.
They also handle extreme deviations, gas,
and corrosive fluids well, although that
was of minimal concern in the Wolfberry
application.

±8° API
Hydraulic or Wireline
Multicylinder or Electric
Excellent
10 to 30 percent

Broad Oak had no prior experience
with jet pumps, but even in the first application, it did not take long to get the
equipment working properly. The results
were impressive. On its second day, the
pump handled 2,500 barrels of liquid and
had its first show of oil. On the third day,
the well produced 355 barrels of oil. We
thought we had found the Holy Grail of
vertical Wolfberry producers.
The next wells delivered similar results,
so we began to start every vertical well
on a jet pump. In total, we put 358 wells
on jet pump. The pumps shortened the
average time to production from 12.3
days to 2.4 days, which allowed each
well to go from spud to first production
in less than one month.
The pumps also eliminated the 40-60
day break-in period common with rod
pumps. During the initial production period, any pump must contend with rapidly
changing fluid levels, and the sand and
solids from the frac treatment. Eventually,
gas would appear, potentially locking the
pump.
American Oil and Gas Reporter - June 2014

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