I N NOVATIVE DR I LLI N G TECH N IQU E S
mud rollover. The new lower mud weight
cycles into the well, so back pressure must
increase again to reach the required BHP,
or a higher mud weight must be applied to
transition out of utilizing SBP.
CML eliminates these situations by
applying a balanced mud weight to the
well, starting the BHP closer to the frac-
ture gradient than SBP. Then, the pressure
is lowered to manage the BHP. One could
say that SBP approaches the MPD solu-
tion from the pore pressure side, risking
an influx, while CML approaches the MPD
solution from the fracture pressure side,
risking losses. For operators concerned
about the incredibly costly and environ-
mental expense of losses, CML provides
the tool to manage losses effectively while
lowering the risk of operating from the
pore pressure side of the pressure window.
Further, there is an additional ease of
use for cementing and completion opera-
tions, which require managing increas-
ing pressures as these operations proceed.
Excess pressure in cementing results in
costly losses and a possible poor cement
job, risking catastrophic failure. Excess
pressures in completion operations result
in a damaged reservoir that could impact
everything from initial production to total
recovered reserves. With CML, as the pres-
sure rises, lowering the riser level man-
ages the pressure profile and creates what
looks like a saw tooth: Pressure goes up
during the operation, then the pressure is
reduced by CML maintaining the window
throughout the cementing or completion.
As experienced in several cases with
the EC-Drill system, completion results
reached top-quartile
performance. Effectively finishing both – the alpha
and beta phases of completion operations
– without damaging the formation has
resulted in flow rates exceeding the drill-
ing rig’s ability to flare. As one customer
explained, “Wells estimated to have a 5- to
10-year lifespan are now turning out to be
10- to 15-year wells.” The exact flow rates
are proprietary to the operator.
For example, various drilling operations
require heavier/denser fluids using water-
based drilling fluids or heavy brines like
CaBr2 and ZnBr2. An overpressure of these
fluids can damage everything from the
casing shoe to the reservoir. The ability to
lower the overall BHP by reducing the riser
Figure 1: The EC-Drill CML system can help to eliminate intermediate casing strings
while navigating tight pressure windows in deepwater wells.
fluid level enables standardizing on other
proven technologies and fluids.
An issue offshore is that the casing
string length sometimes exceeds the
water depth, which heavily impacts the
value proposition of SBP-based MPD. Even
if the SBP drills the well, it cannot manage
the pressure while installing these longer
liners/casings. This issue does not affect
CML, which can apply MPD techniques
while installing all casing sizes. In addi-
tion, for operators who strive for a robust
separation between the primary and sec-
ondary barrier, CML provides a clear tran-
sition from the barrier envelope to stan-
dard well control procedures. Additional
steps are not required to roll over the
mud or close the BOP while tripping, as it
already uses a balanced mud. Operators
and drilling contractors can operate with
well-established and proven well control
procedures while also having MPD.
Improving sustainability
Apart from the operational advantag-
es, CML also contributes to environmen-
tal sustainability. By optimizing drilling
operations, these techniques minimize the
number of wells required to extract equiv-
alent hydrocarbons, reducing the overall
DRILLING CONTRACTOR • SEPTEMBER/OCTOBER 2023
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