2. • Well Completion Philosophy
• What is a Well Completion?
• Functions of a Well Completion
• Rig operations
1. Okpohuru 6 overview
2. Open hole logging/wellbore cleanup
3. Running 9-5/8 casing
4. Cementing casing
5. Nippling down/up of BOP/ wellbore cleanup
6. Wireline logging
Challenges encountered
Conclusions
Recommendations
3. • After careful interpretation and consideration of well test data
(coring, logging etc), a decision is made whether to set
production casing and complete the well or to plug and
abandon it.
• Decision to abandon is made when the well is not capable to
produce oil or gas in commercial quantities(economic
limit).i.e. the production is less than the operating cost
• “Completing a well” means getting the well ready for
production This principally involves preparing the bottom of
the hole to the required specifications, running in the
production tubing and it’s associated down hole tools.
4. • What is a well completion it is a series of connected
tubulars, with instrumented sections (accessories) and
valve system.
• Connecting the payzone to the surface facilities
• Allowing control of reservoir pressures
• Allow reservoir fluids to be produced in a controlled
manner.
• Allow the introduction of fluids/solids to the reservoir
system
5.
6. Okporhuru Field is situated in
OML-38, in delta state.
Directional drilling was carried
out with an inclination of
33°(deviated well)
The measured depth of the well
is 11350ft
The U3000 sand at (9305-
9445ft) and V4000 sand at
(10583-10948ft) are targeted
Cardinal drilling rig 201 with
2000 HP was used for the
operation.
7. Wiper trip
13-3/8
Running 9-5/8
casing
Cementing 9-
5/8 casing
Nipple down BOP,
install well head,
nipple up BOP
Wellbore cleanup
& displacement to
filtered brine
Wireline logging
Open hole
logging
Other processes
continued after rig
tour
8. Open hole logging
(GR,RESISTIVITY,RESERVOIR
CHACTERISATION INSTRUMENT)
was carried out by baker Hughes
Gamma ray log is used discriminate
potential reservoir rock from
impermeable rocks
Resistivity logs is used to identify the
hydrocarbon bearing zones
Reservoir characterization instrument
is used to determine initial reservoir
pressure
All the resistivity logs were in accurate
after running three tools
The 13-3/8 was wiper tripped with a
hole cleaner i.e a bit and a bull nose
9. 305 9-5/8 Casings were drifted and
tallied and the casing shoe and float
collar (non return one way valves)
were measured making a total of
11345ft in depth
A float shoe, float collar with joints
of casing (2 to 4) in between (shoe
track) was made up and run in hole
using elevators and spider slips to
shoe depth of 1345ft and rat hole of
5ft (11350ft)
the casings where run in hole above
the shoe track with 33 rigid and 3
bow centralizers placed at accurate
intervals to properly align the
casings in the middle of the well.
10. Cementing is done to hold casing in place and to
prevent fluid migration between subsurface
formations.
The slurry composes of water, cement and other
additives
Slurry composition was calculated. this is a very
critical part of cementing as the amount of slurry to be
used, sacks of cement, barrels of water, barrels of
displacement mud etc. is calculated
The cementing process was separated in two depths
LEAD(depth with the center of gravity) and TAIL
using different additives
Adding an excess of 25% incase of washout
11. CEMENT IN SHOE TRACK:
𝐼𝐷2
1029.4
× 𝐷𝑒𝑝𝑡ℎ=
8.6812
1029.4
× 89.09 = 6.5𝑏𝑏𝑙𝑠
CEMENT IN RAT HOLE:
𝐻𝐷2
1029.4
× 𝐷𝑒𝑝𝑡ℎ=
12.252
1029.4
× 5 = 0.72bbls
25% EXCESS: (0.25× 0.72)+0.72 = 0.91𝑏𝑏𝑙𝑠
CEMENT IN ANNULUS TAIL:
𝐻𝐷2−𝑂𝐷2
1029.4
× 𝐷𝑒𝑝𝑡ℎ= :
12.252−9.6252
1029.4
×
3909 = 218𝑏𝑏𝑙𝑠
25% EXCESS: (0.25× 218)+218 = 272.5𝑏𝑏𝑙𝑠
TOTAL FOR TAIL: 272.5+0.91+6.5= 280bbls of slurry
CEMENT IN ANNULUS LEAD:
𝐻𝐷2−𝑂𝐷2
1029.4
× 𝐷𝑒𝑝𝑡ℎ= :
12.252−9.6252
1029.4
×
717 = 40𝑏𝑏𝑙𝑠
25% EXCESS: (0.25× 40)+40 = 50𝑏𝑏𝑙𝑠
SACKS OF CEMENT:
𝑆𝐿𝑈𝑅𝑅𝑌×5.615
𝑌𝐼𝐸𝐿𝐷
SACKS OF TAIL:
50×5.615
3.27
= 85.86𝑏𝑏𝑙𝑠 of cement
SACKS OF HEAD:
280×5.615
1.17
= 1343.8𝑏𝑏𝑙𝑠 of cement
13. 100bbls x 9.2ppg of Oil based mud followed
by 50bbls x 6.5ppg of base oil was pumped at
10bbl/min to clean the well and remove mud
cake;
90bbls of 11ppg spacer was pumped in.
The bottom plug which was already attached
to the cement head was dropped,
the 50bbls x 11ppg Scavenger slurry for lead
was pumped followed by 280bbls x 15.8ppg
tail slurry.
The top plug was dropped; slurry was
displaced with 814bbs x 9.2 obm
displacement mud.
The top plug bumped the bottom plug and
there was a pressure spike of 1650psi
The cement was left to set.
14. The B.O.P was nippled down, the
9-5/8 slip and seal assembly was
installed into the well head
the slip and seal assembly is used
to firmly suspend the casing to
the casing head spool
the BOP was nippled up, and the
well was circulated with filtered
brine
The bit and scraper was run in
hole to remove mud cake and
pulled out of hole.
15. The log was carried out using a Reservoir Monitoring Tool
(RPM), because of the inaccuracy in resistivity for the open
hole log.
Carbon/Oxygen (C/O) and Pulsed Neutron Capture (PNC)
measurements acquired with the RPM tool provide water
saturation and the gas-oil-water contact.
PNC is mostly used to find gases, used to discriminate
hydrocarbon-bearing from salt water bearing reservoirs.
The PNC logs where logged up at a minimum of two passes
at 10ft/min between the different sand intervals from
11270ft to 8398ft.
C/O is used to measure the relative abundance of carbon to
oxygen.
16. 4 passes of C/O was performed at
1.67ft/min at the different sand
intervals between 11270ft to 8398ft,
It was noticed at the first interval
while logging up sand 11151-11270 that
drag was experienced therefore the
complete four passes was taken before
moving up to other sand intervals
taking 2 passes each.
This operation took a total of 5days
Cement Bond Logs (CBL) and Ultra
Sonic Imager Tool (USIT), was carried
out to check if the cement bonded
properly between the casing and the
bore.
17. Resistivity logs was inaccurate during the open hole logging causing a
downtime in well operations
The okporhuru 6 well has been the fastest completed well in SEPLAT
with very little downtime.
Well operations were strictly conducted according to well program
I learnt the basic well completion processes
The company loved me and they approved I work with them on my
research work and are willing to take me back to work with them, they
also paid me a lot for going to the rig.
The H.S.S.E personnel should be hands on deck throughout the rig
operation
All personnel on the rig should be very alert and safety conscious
