1. Dual Casing Running for deep water spud in

2. OPTIONS Presentation Focusing the issue
Deep water operation: Riserless top hole section
Deep Water Dual Casing: MAIN PHASES
OPTIONS
REQUIRMENTS
Applications
Conclusions 2

3. Deep water activities: extreme environment
heavy load conditions with unconsolidated sea bed
high daily spread rate
The improvement of operations with the aim to increase the efficiency can produce a time reduction and as consequence a
cost saving

4. Conventional technique Jetting & Drill-Ahead
Drill 36” hole
Run and cement
30” CP
Drill 26” hole
20” csg
Jet 30” CP and
drill 26” hole
Run and cement
20”csg

5. Deep Water Dual Casing Traditional techniques – CONSTRAINS:
uncertainty about the formation to cross
perfect verticality of WH and correct stick up
not granted
Deep Water Dual Casing

6. Conventional technique Jetting & Drill-Ahead Deep Water Dual Casing
Drill 36” hole
Run and cement
30” CP
Drill 26” hole
20” csg
Jet 30” CP and
drill 26”or 23”
Run and cement
20”csg
Drill 23” x 36” hole with HO in tandem
Run and cement 30” CP and 20” csg
1 jetting phase
1 drilling phase
1 cementing job
2 round trips
2 drilling phases
2 cementing jobs
4 round trips
1 drilling phase
1 cementing job
2 round trips

7. by using straight hole drilling device and motor
No Rotation
by using straight hole drilling device and motor

8. Drill
23” or 17 1/2” hole
Start Rotation
for
42” or 36” Hole

9. approximately 0° (zero degree)
Drill
23”or 17 1/2” hole
+ 42” or 36” hole
With Rotation
for
36”/42” Hole
The hole inclination
approximately 0° (zero degree)

10. End of
23” or 17-1/2” hole
+ 42” or 36” hole
POOH

11. 36” or 42” hole +
23” or 17 1/2” hole

12. Ready to Run:
Combination
36” or 30” C.P. +
20” csg or
20”+13 3/8” Tapered csg

13. MS 700 Wellhead Systems Guidelineless Type Drilling System without Guide structure
Cement Port
Low-pressure Housing Lowered into Mud Mat
Hydrate Gas Seals
Shown with mud mat & ball valve

14. DA COMPLETARE Standard cement DeepCRETE Foam cement CART 18” 3/4
Housing
18” 3/4
Housing 30”
Standard cement
DeepCRETE
Foam cement
Mud Mat
Casing 20”
36” Hole
Conductor pipe
30”
Casing 13 3/8”
Inner string DP 5”
17 1/2” Hole

15. Case History ENI Angola 1 Job: 30”x20”x13 3/8” Casing
3/31/2017
Case History
ENI Angola
1 Job: 30”x20”x13 3/8” Casing
2 Jobs: 30”x20” Casing
Title 15

16. ANGOLA OFFSHORE – CASE HISTORY
# 1: Standard cement
WD: 1300 m; Sea-bed temperature: 4 °C
Shallow water risk: no
Cement job: 30” C.P.x 20” x 13 3/8” tapered combined string
Lead slurry: 1.44sg (12ppg) LiteFIL
Tail slurry: 1.90sg (15.9ppg)
Displacement: no cement returns at seabed
WOC: 13 hrs
Slack-off: casing string unstable
WOC: additional 6 hrs
Slack-off: OK
Top job: cement job performed to ensure cement to sea bed
In two slides or less describe what lead up to the loss

17. ANGOLA OFFSHORE – CASE HISTORY
# 2: DeepCRETE Cement
WD: 500 m; Sea-bed temperature: 6 °C
Shallow water risk: yes
Cement job: 30” C.P. x 20” casing
Lead slurry: 1.20sg (10ppg) DeepCRETE with D500 GASBLOK
Tail slurry: 1.90sg (15.9ppg) with D500 GASBLOK
Displacement: returns at seabed
WOC: 15 hrs
Slack-off: casing string 1 cm “sink”
WOC: additional 3 hrs
Slack-off: OK
Top job: no top job performed
In two slides or less describe what lead up to the loss

18. ANGOLA OFFSHORE – CASE HISTORY
# 3: Foam Cement
WD: 1070 m; Sea-bed temperature: 5 °C
Shallow water risk: no
Cement job: 30” C.P. x 20” casing
Lead slurry: 1.25sg (10.4ppg) Foam cement
Tail slurry: 1.90sg (15.9ppg)
Displacement: partial returns at seabed
WOC: 15 hrs
Slack-off: OK
Top job: no top job performed
In two slides or less describe what lead up to the loss

20. Wellhead cut and retrieved Annulus 20” - 30”
CART 18” 3/4
Housing 18” 3/4
Housing 30”
Mud Mat
Casing 20”
36” Hole
Conductor pipe
30”
Casing 13 3/8”
Inner string DP 5”
17 1/2” Hole
Wellhead cut and retrieved Annulus 20” - 30”

21. 3 different options:
M/U C.P. and surf. csg during flat time and hang up them on Moon Pool trolley
M/U C.P. during flat time but surface casing on line after drilling tapered hole
M/U C.P. and surf. csg on line after drilling tapered hole

22. Requirements for full application:
VDL to load spud in materials
Motion compensator capability
Moon pool trolley capacity > (C.P.+surface csg+inner string) weight w/S.F.
Distance moon pool – sea bed > lenght of surface casing

23. If all requirements are NOT fully satisfied:
Partial time saving but all other advantages are exploited:
no C.P. sinking can occur
housing pre-fixed stick up and verticality near to 0° is granted
applicability in all lithology types
latch between LP and HPWH Housing performed at surface, ensuring mechanical structural integrity

24. Dual Activity rig:

25. Drill 8 ½” P.H.
M/U 36” C.P.
Run BOP
Drill 23”x42” hole
Run BOP
Run Dual csg string
Run BOP
Cementing op.

26. Operating time during riserless phase
(drilling pilot hole and running BOP not included)

27. Advantages: Constrain:
Deep water Dual Casing, a patented technology, is the most efficiency alternative to conventional techniques.
Advantages:
Hole inclination approximately 0 deg
Reduction of risk assessment in C.P. setting for unknown lithology
No subsidence events
Top Cement Job feasibility
LP HSG and HP HSG latch performed at surface
Time reduction
Constrain:
Water depth longer than surface casing setting depth (Reduction of system efficiency)
Rig technical characteristics
If shallow hazard phenomena imposes the use of 26” intermediate casing (36” LP HSG & CP)