American Oil and Gas Reporter - October 2015 - 96

SpecialReport: Drilling Fluids Technology
bottom of the inhibition scale is the Clear
Seal System TM , our basic wellborestrengthening WBM, which is based on
our Clear Seal-5® product. If we need
more inhibition, we can add Clear Seal-5
PlusTM, or if that is not enough, our Black
Sack® or Black Blend® Gilsonite® products. For even more inhibition, we add a
potassium source and our Z-Clear FluidTM
in varying concentrations. For maximum
inhibition, we can increase the xanthan
concentration."
At the bottom of the scale, Farish estimates the fluid will cost only $20-$30
a barrel. At the upper end, he puts the
cost between $120 and $150 a barrel,
with the exact price depending on the
amount of Z-Clear Fluid required and
whether the well needs low shear rate
viscosity.
Farish says Horizon has been working
with operators to keep fluid systems as
close to the bottom of the cost scale as
possible. "When we started in the
Delaware Basin, we thought we would
need a 20-30 percent concentration of
Clear Fluid, but we are running many
wells at 10-20 percent, which is taking
$30-$60 off the cost per barrel," he illustrates.
In the Midland Basin, the company
has discovered that it can drill wells using

only Clear Seal-5 and Clear Seal-5 Plus
systems. "The Clear Seal systems work
through stress caging," Wilson notes.
"They contain inerts that fill small fractures
in the formation, strengthening the wellbore and helping it maintain its integrity
before and after drilling."
In one Permian Basin well, Horizon
ran the Clear Fluid system in an area
where the operator had been told he
would need drilling beads or a lubricant,
Wilson recalls. "We were monitoring
torque throughout the well to see if a lubricant would be needed," he relates.
"We did not run a single drum. The operator was used to buying a lubricant to
help with torque, so that provided $20,000$30,000 in savings."
Because of its high inhibition, the
Clear Fluid system allows an operator to
switch from an OBM to a WBM, Farish
says. "The system can be built on site
rather than in a plant, so transportation
costs are lower. It also is much easier to
dispose of," he reports. "As a result, the
all-in cost often is half that of an OBM."
Proven WBM
Before many operators will try a water-based mud in an area traditionally
drilled with an oil-based fluid, they want
proof the system works, notes Carl Tolbert,

Oil-based mud

LSRV Properties
(Low Shear Rate Viscosity)
Noninvasive, mechanical inhibition

+ Increase Xanthan Concentration

Scale of Inhibition

+ Add Z-Clear Fluid™

+ Add Potassium Source

+ Add Master Black Sack®/Master Black Blend®

By adding products to its waterbased fluid system, Horizon
Mud Company can vary the sys+ Add Master Clear Seal-5®/Master Clear Seal-5 Plus™ tem's inhibition to match the
needs of the well. The company
says it is helping operators reduce costs by finding ways to
use fewer additives.

96 THE AMERICAN OIL & GAS REPORTER

a global client manager for fluids at National Oilwell Varco. Toward that end,
NOV has kept meticulous records of its
success with the POLYTRAXXTM WBM,
which he describes as an easy-to-maintain,
flexible fluid system that offers OBMlike performance.
"In the Eagle Ford Shale, we have
completed 248 wells with POLYTRAXX
WBM for one operator," Tolbert reports.
"We have matched or exceeded the operator's OBM drilling curves while eliminating the costs associated with OBMs,
such as diesel for dilution and hauling
off cuttings for disposal. The operator's
assessment was that he saved $300,000 a
well as compared with similar wells
drilled using OBM."
NOV also has applied the POLYTRAXX WBM in Illinois, Wyoming,
Oklahoma, Florida and Louisiana, as well
as in wells in Europe and Central and
South America. Tolbert says this shows
the system's flexibility.
The heart of the POLYTRAXX WBM
is TRAXXTM TC, an inhibitor that creates
an extremely thin coating on solids and
filter cake that prevents hydration of clay
particles, minimizing torque and drag,
Tolbert says. The charge carried by the
thin coating prevents balling of clay particles and stabilizes the drilling fluid's
flow properties.
On a 16-well program in Turkey, the
system's lubricity and ability to enhance
wellbore conditions helped reduce or
eliminate nonproductive time, allowing
the operator to take an average of eight
days off drilling times on each well, Tolbert relates. He adds that the environmentally friendly system allowed the
company to use the cuttings to build
roads and future well sites, rather than
hauling them for disposal, providing a
total savings of $2.5 million.
"A strength of the POLYTRAXX
WBM when compared with other premium WBMs is its cost," says Filemon
Flores, an NOV technical support representative. "The system is easy to engineer,
easy to maintain, and easy to reuse. We
have used the same mud on five wells-
enough to cover every well on many
pads in the Eagle Ford."
Tolbert describes the system as an alternative to OBMs rather than a replacement. "Each well or project should be
reviewed to determine if it is a proper
application for this high-performance
WBM. If a well has a particularly lengthy
lateral or challenging directional plan,

American Oil and Gas Reporter - October 2015

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