Environmental statement - Flyndre and Cawdor - Maersk Oil

Flyndre and Cawdor Environmental Statement
Section 2 Proposed Development
Section diameter
(inches)
36”
Casing
(inches)
30 x 20”
conductor
17 1 /2” 13 3 /8
Drilling fluid Depth (MDBRT)
Sea water and high
viscosity sweeps
Sea water and high
viscosity sweeps
12 1 /4” 9 5 /8 OBM
D/4114/2011 2‐7
≈520
≈4000
Total depth is
trajectory specific
8 1 /2” n/a OBM 19000
Table 2‐5 Cawdor well completion details.
The 36” top hole section will be drilled using seawater and high viscosity sweeps to an approximate
depth of 520 ft Mean Depth Bellow Rotary Table (MDBRT) with the 30” x 20” conductor being set and
cemented. The vertical 17 1 /2” section will be drilled to a total depth of approximately 4,000 ft MDBRT
with seawater and high viscosity sweeps. The 13 3 /8” casing will then be run and cemented in place.
A 12 1 /4” hole section will be drilled using approximately 14ppg Versclean Oil Based Mud (OBM) with
gamma ray, resistivity and possibly density and neutron measurements being logged (LWD tools).
The trajectory will kick off at approximately 8000 ft Measure Depth (MD) gradually increasing the
angle before entering the Tor chalk reservoir at +/‐ 89 o C incline at circa 11700 ft. The total depth of
the 12 1 /4” will be trajectory specific. A 9 5 /8” casing will be run to total depth and cemented in place.
It is planned to drill an 8 1 /2” hole to an anticipated total depth of 19000 ft MDBT, with a +/‐ 14.5 ppg
whilst using OBM, during this process logging information will be carried out this will consist of
gamma rays (with images) resistivity, neutron and density.
A CAJ (predrilled)/ solid 7” liner will be run to total depth and set near the 9 5 /8” shoe. This will enable
hydraulic fracking of the inner zones, before acid washing (with hydrochloric acid) the outer CAJ zone.
A 5 1 /2” top completion will be run and the well cleaned up, before de‐mobilising the rig. A schematic
of the proposed Cawdor production well design is illustrated in Figure 2‐5.