American Oil and Gas Reporter - November 2018 - 78

SpecialReport: MWD/LWD & Wellbore Optimization
Cesium Formate
Alan Carnegie, director of global business development and Asia, Middle-East
and Africa regions at Cabot Corporation,
says formates are giving operators new
alternatives to oil-based muds in shale
plays. "There have been some very well
publicized case studies where brine-based
fluid has outperformed oil-based mud in
terms of penetration rates and well bore
stability," he offers.
In the future, cesium/potassium formate
brine systems could be applied in deeper,
higher-pressure shale plays such as the
Utica and Haynesville. "Operators are
drilling more expensive horizontal wells
that tend to have longer lifetimes," says
Carnegie. "Formates also will do a good
job of cleaning out wells after fracturing,
so we could see an application there as
well."
Sharing van Oort's vision of a universal
drilling and completion fluid, Carnegie
predicts that Gulf of Mexico companies
will begin looking more at the full life
cycle costs of wells and take into account
formation damage, well intervention costs
and other issues that can drive the use of

formates over conventional bromides.
"That ultimately will lead to using
the same fluid to drill and complete, resulting in faster project completion and
with formates providing fewer problems
while drilling, less solid sag, and higher
borehole quality" he states, pointing out
that Cabot's cesium formate formulations
already are being used as drilling, completion and reservoir drill-in fluids.
"The beauty of cesium formate is that
it is designed to drill wells, not suspend
a weighting agent," Carnegie goes on.
"Because it does not use a weighting
agent like a conventional drilling fluid,
cesium formate provides a solids-free,
nondamaging system for superior well
control and long-term productivity. It has
low environmental risk, unique thermal
properties that reduce circulating temperatures, and it is thinner and more hydraulically efficient, helping to reduce
pumping pressure in deeper wells."
Direct-Emulsion Fluid
Lost circulation issues in shale plays
can be related to geologic features as
well as intervals depleted by old wells. A

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78 THE AMERICAN OIL & GAS REPORTER

direct-emulsion, brine-based fluid with
diesel as the internal phase can give operators a cost-effective option in wells
with known lost circulation concerns,
says Mike Redburn, engineering manager
at Newpark Drilling Fluids.
He points to a recent project in the
Oklahoma Arkoma Basin, where an operator was seeking an alternative to using
lost circulation materials with traditional
oil-based invert fluids in the Woodford
Shale play to reduce bit trips, stuck pipe
risk and fluid losses while drilling through
depleted zones. The solution was a density-reduced, direct-emulsion fluid customized for the downhole reactive formations.
"The benefits included significant reductions in both drilling times and fluid
cost, resulting in a dramatic improvement
in total drilling costs for the operator,"
Redburn reports.
For offshore applications, Newpark
has designed systems capable of maintaining flat rheological properties across
a temperature window from 40 to 325
degrees Fahrenheit, and prevent sag,
which is a major issue in high-temperature
environments, according to Redburn. "The
fluid package allows for equivalent circulating density (ECD) management and
permits narrow window drilling parameters
while maintaining stable rheology and
properties associated with sag," he says.
No matter the operational setting, laboratory testing and analysis are key to
designing an effective solution customized
to the requirements of a specific application, Redburn holds. "The goal is to experiment under simulated field conditions
in a controlled environment to learn as
much as possible about both the fluid
and its impact on the rock before anything
is pumped into a well," he says. "That
results in a more effective and a more efficient drilling operation."
Enabling Technology
Operators in resource plays are setting
new records practically every day for
lateral lengths, total well depths, penetration
rates, etc., pushing the limits of every
system involved. In these plays, the drilling
fluid is just as much of an enabling technology as the bit or rotary steerable system,
suggests Aaron Gobe, onshore product
manager for drilling and completions
fluids at Baker Hughes, a GE company.
"The drilling fluid is what maintains
wellbore stability and lubricity, as well
as optimal rates of penetration, to achieve
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