Case study: Colombia

DELTA-DRILL fluid delivered complex,
ERD well with narrow drilling window
A major international operator working
in Colombia’s Cosecha field required asynthetic drilling fluid on a challenging
extended-reach drilling (ERD)
application. The well plan called foralmost 11,000 ft (3353 m) of horizontal
displacement with a 76° inclination.
ERD wells are not very common in
Colombia due to a variety of drillingchallenges including high-instability
formations. However, an ERD well
was necessary due to environmental
issues. With large swamp sanctuariessurrounding the Cosecha field andlimiting the placement of potential rigsites, the only option for reaching many
reservoir targets is with an ERD well.

improved wellbore stability. The
intelligent fluids solution Baker Hughes
proposed included a DELTA-DRILL™
low-pressure-impact drilling fluid
enhanced with the NANOSHIELD™
wellbore sealing polymer andLC-LUBE™ sized, synthetic graphite
for increased wellbore strengthening.
The operator approved theBaker Hughes recommendation anddisplaced the competitor’s fluid tothe DELTA-DRILL system. After drilling
resumed, the next section of the well
was drilled to 13,969 ft (4258 m) with an
8½-in. bit and enlarged to 9½-in. withan underreamer.

The customer had attempted several
ERD wells in this area using competitive
mud systems and experienced
significant drilling issues including
wellbore instability and stuck pipe
events. These led to the loss of
directional drilling tools and significant
non-productive time (NPT) for thewells. Due to the ongoing operational
issues and the challenging wellbore
design, the operator decided tosuspend the project.

A managed pressure drilling (MPD)
system was planned in order to keep
a maximum equivalent circulating
density (ECD) of 14.0 lbm/gal (1.68 SG)
to control collapse pressure, prevent
wellbore instability, and minimize
the risk of cavings that were a major
problem during trips in the offset
wells. In addition to maintaining aminimum 14.0 lbm/gal (1.68 SG), it was
critical that the ECD not exceed
15.0 lbm/gal (1.8 SG) as that could
induce mud losses.

Following the suspension of drilling
activities, the operator reached out toBaker Hughes to help analyze the offset
wells and develop a solution thatwould allow the project to resume.
Working closely with the operator,
Baker Hughes recommended an
intelligent fluids solution leveraging
a low-toxicity oil-based mud (OBM)
to reduce the risk of stuck pipeand specialized fluids additives for

During a run-in-hole (RIH) trip, mudpressure accidentally reached15.2 lbm/gal (1.82 SG) in one section
which resulted in a loss of between
20 to 80 bbl/hr for a total loss of1338 barrels of mud. Based on that,
Baker Hughes and the operator
decided to remove the back pressure
from the MPD system and drill ahead
with the 12.7 lbm/gal (1.52 SG)
DELTA-DRILL system. This kept theChallenges• Drilling challenging
16,000-ft (3353-m) ERD wellwith 11,000-ft (3353-m)
horizontal displacement- 76° maximum inclination- 230°F (110°C) bottomholetemperature• Manage wellbore instability
in narrow (1 lbm/gal)
drilling window- 14 lbm/gal collapse pressure- 15 lbm/gal fracture pressure• Avoid multiple sidetracks
required on offset wells• Minimize downhole mud losses• Manage complicated logistics inremote location

Results• Drilled well with zero drilling
fluids-related NPT• Avoided barite sagging during120+ hours of static time
• Significantly reduced
tripping times• Minimized back-reaming andhole-conditioning requirements• Saved approximately$630,000 USD in estimatedoperating costs

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maximum ECD at 13.2 lbm/gal(1.58 SG) for the section to avoid any
further losses or fracture propagationin the section.

Removing the MPD system from these
operations with potential savings of$630,000 USD in 21 days of operation.

MPD services used in the well for the8 ½- x 9 ½-in. section cost the operator
approximately $500,000 USD in service
costs despite generating someassociated issues like induced losses.
The DELTA-DRILL fluid’s performanceserved to maintain wellbore stability
and allowed the operator to suspend
the MPD service in the 6-in. holesection. The lower section was drilled
to total depth (TD) at 16,888 ft(5147 m) with an adjusted
10.5 lbm/gal (1.26 SG) mud weight inorder to minimize formation damage.

This first-time deployment of theDELTA-DRILL system in Colombia
allowed the operator to drill theplanned hole sections while effectively
reducing operational risks and NPT inthe challenging ERD well. Once theMPD system was removed, theDELTA-DRILL system’s non-progressivegels permitted faster trip speeds
without compromising wellbore
stability. The system’s unique viscosity
profile ensured proper hole cleaning bykeeping the ECD lower and stable while
drilling and providing superior solids
suspension (with no barite sagging)

Stage

Permeability(mD)

ReturnPermeability
reduction

Ko original

142.9------Ko after drilling fluid

136.6

95.6%

4.4%

in the 76˚ inclination hole. The system
maintained a 12.5 lbm/gal (1.50 SG)
value into the hole after more than
120 hours of static time associated withinstalling the 7-in. liner.
Finally, the NANOSHIELD and LC-LUBE
additives improved wellbore stability
while drilling the overburden andreservoir sections.
Despite drilling much of the wellwithout the MPD system, the fluid
system remained within the desired
equivalent mud weight window andno fluid losses were recorded whiledrilling. A post-drilling evaluation of thereservoir section showed a minimal
reduction in formation permeability.

Post-drilling analysis of the reservoir section indicated minimal invasion from the DELTA-DRILL fluidwith a the tests showing a 95.6% return permeability.

40YP (lb/100 ft2)

356rpm reading
3rpm reading

Dial reading

30252015105210°F - 10,000 psi

240°F - 10,000 psi

185°F - 10,000 psi

160°F - 10,000 psi

240°F - 7,500 psi

210°F - 7,500 psi

185°F - 7,500 psi

160°F - 7,500 psi

240°F - 5,000 psi

210°F - 5,000 psi

170°F - 5,000 psi

185°F - 2,500 psi

150°F - 5,000 psi

160°F - 2,500 psi

120°F - 2,500 psi

85°F - 2,500 psi

170°F - 15 psi

150°F - 15 psi

120°F - 15 psi

85°F - 15 psi

0This graph shows that DELTA-DRILL fluid’s LSRV remained constant, ensuring proper hole cleaning athigh pressures and temperatures.

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