Halliburton provided reliable data from gas-cut cement when no one ...

A CASE STUDY: Accurate evaluation of gas-contaminated cement
Halliburton provided reliable data from gas-cut
cement when no one else could
Halliburton deployed a unique tool combination for effective cement
evaluation in challenging well conditions
OVERVIEW
A major oil and gas company in the Asia-Pacific region
wanted to increase production from an offshore well that
had been completed 12 years ago. The company drilled
a sidetrack to a pay zone that was originally bypassed.
However, during cementing, gas seeped into the cement,
which made cement evaluation of the sidetrack challenging.
The operator needed assurance that an accurate cement
evaluation could be provided in this gas-contaminated well.
Halliburton recommended its CAST-M/CBL-M tool
combination to collect the data and its Advanced Cement
Evaluation (ACE) software to process it. The combination
of technologies helped the operator accurately evaluate the
cement job and verify cement bond conditions. The speed
and accuracy of the job led to client trust and the use of
the CAST-M/CBL-M tool combination in future wells. It
also marked Halliburton’s successful re-entry into the area.
CHALLENGE
Small diameter casing and deviated sidetrack
The logging interval was located in 4.5-inch outer diameter
(OD) casing at a 60-degree deviation, which provided a very
small clearance. This small clearance created conveyance
issues for other tools, which could enter the hole but were
unable to navigate through the deviation.
Accurate cement evaluation in presence of gas
Gas presence in cement lowers density and can interfere
with accurate cement evaluation. This well had two such
gas-contaminated zones. The operator needed accurate
cement evaluation to help ensure cement integrity.
SOLUTION
CAST-M tool small enough to fit
Halliburton’s CAST-M tool is only 3.125 inches OD – the
smallest ultra-sonic cement evaluation tool in the industry.
The tool’s small size enabled Halliburton to navigate through
the turns of the wellbore.
ACE software enabled accurate evaluation
Halliburton used its unique ACE software to interpret the
data from the CAST-M/CBL-M tool combination. The
software algorithm is designed to distinguish the level of
comparable acoustic impedance, which aids in properly
identifying any type of cement over fluid behind pipe.
Mobilizing resources
Halliburton Wireline and Perforating only recently
re-entered this area. While this job presented the
opportunity to come back under the right conditions,
a solution needed to be developed quickly.
Halliburton made commitment to market
Halliburton made a commitment to the market and quickly
mobilized the personnel and equipment to complete the
project. This was also the first time the CAST-M/CBL-M tool
combination was used in the Asia-Pacific region.

A CASE STUDY: Accurate evaluation of gas-contaminated cement
FROM
TO FLOWING
A major oil and gas company drilled a sidetrack off an existing well that had declined in
production. The targeted sidetrack depth had never been explored. The unexpected gas intrusion
contaminated the drilling mud, reducing tool reliability and raising concerns about cement integrity.
CAST-M TOOL
ONLY 3.125 INCHES
1 2 3 4 5 6 2 33 347
3538 39 40 41 36 42 43 44 45 46 47 3748
CAST-M TOOL
EFFECTIVE,
ACCURATE CEMENT
EVALUATION
The logging interval deviated by 60 degrees and the casing OD was only
4.5 inches. This small clearance created conveyance issues for other tools.
The CAST-M tool is only 3.125 inches. Its small size provided room
to navigate through the turns of the wellbore.
Halliburton used its CAST-M/CBL-M tool combination to effectively evaluate
cement bonds in a well with gas-cut drilling mud. This marked the first run for
a mono-conductor cement evaluation tool string that included ultrasonic and
CBL measurements.
ACE software, Halliburton’s dedicated
cement evaluation processing software,
can re-process raw data from the
CAST-M/CBL-M cement evaluation service
and discern between lightweight cements
and fluids behind casing.

A CASE STUDY: Accurate evaluation of gas-contaminated cement
Halliburton deployed a unique tool combination for effective cement evaluation
in challenging well conditions
Accurate evaluation of gas-contaminated cement needed
Reliable cement evaluation is important for any well, but can be critical when
dealing with cement that has been contaminated with gas. In order to ramp up
production in an offshore well and produce additional hydrocarbons, a major oil
and gas company in the Asia-Pacific region drilled a sidetrack from the existing
offshore well. However, because the drilling mud had been contaminated with
gas, ensuring a reliable cement bond proved challenging. Gas can interfere
with the cement and its ability to properly set, causing integrity issues that
could impact the future of the well. Gas contamination also decreases the
accuracy of cement evaluation needed to determine proper cement bond.
Previous evaluations did not provide the information the operator needed to
ensure zonal isolation, and the company wanted to make sure it had accurate
information before it started production. The operator hired Halliburton to
provide a unique solution to this challenging situation.
CAST-M tool navigated small diameter of liner and deviated well
The 60-degree sidetrack and 4.5-inch OD casing made it difficult for conventional
cement evaluation tools to reach the targeted zone. Many tools were unable to
maneuver in such tight turns. Halliburton recommended using its CAST-M tool.
The tool is only 3.125 inches OD so it can enter the liner and navigate through
the turns of the wellbore.
As well as providing cement evaluation, the CAST-M tool can also help assess
the inner wall conditions of the casing. The rotating ultrasonic transducer acts
as both a transmitter and receiver of ultrasonic waves. The different acoustic
wave components are analyzed for both casing and cement evaluation. The
CAST-M tool’s acquisition rates are fully programmable to maximize resolution
based on casing sizes between 4.5-inch OD and 9.625-inch OD. The efficient
operation of the CAST-M tool also minimizes nonproductive time (NPT).
CBL service helped reveal effectiveness of cementing
Halliburton used its CBL logging tool in combination with the CAST-M tool. The
combination helped evaluate the cement bond to both the pipe and formation,
indicate where there was only a partial bond, and locate the top of the cement.
The CBL logging service helped determine where there was moderate and
strong cement bonding, as well as poor bonding. The logging service also
detailed the quality of the cement in the targeted perforation zone. Halliburton
used the logging data to determine that the top of the liner was at a depth of
3,123 meters (10,246 feet) and that the targeted perforation zone had moderate
cement bonding.

A CASE STUDY: Accurate evaluation of gas-contaminated cement
Halliburton deployed a unique tool combination for effective cement evaluation
in challenging well conditions
ACE software enabled accurate evaluation
Evaluation of lightweight cement can be challenging. Halliburton used its ACE
software to help accurately interpret the data from the CAST-M/CBL-M tool
combination. This dedicated cement evaluation processing software evaluates
raw data variance to help determine the presence, or lack, of cement behind
the pipe.
ACE software incorporates a statistical variance-mapping product for both
sonic and ultrasonic tools. The resulting variance image detects minor changes
in cement or fluid composition and helps distinguish cement from liquid. This
technique accurately evaluates cement bond and channels in cement.
Halliburton mobilized quickly and provided proven results
Without formal operations in this area for a number of years, Halliburton
Wireline and Perforating quickly assembled the personnel and equipment
needed to conduct the logging operation. Halliburton completed the job the
first time, with no need for multiple trips and no NPT, saving the operator time
and money. The accurate evaluation also helped the operator get the answers it
needed to perforate the sidetrack and restart production.
Successful evaluation led to more wells
Despite challenging conditions, Halliburton proved the effectiveness and
accuracy of its cement evaluation services in gas-contaminated wells. The
CAST-M/CBL-M tool combination along with ACE software provides a complete
cement evaluation service that can be a game changer in the Asia-Pacific
region. The operator believes Halliburton delivered accurate results with a high
level of confidence. Halliburton has become a trusted advisor that the operator
can turn to for cement evaluation in future wells.
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