Install and cement production casing and liner as hydraulically sealing barriers
The operator wanted to install a 13⅜-in cemented casing to act as the secondary barrier
element against the reservoir section, where
the top of the cement was to be placed 100 m
above the sand formation. In the subsequent
section, the operator wanted to install a 9⅝-in
cemented liner as the primary barrier element
prior to drilling into the reservoir zone and placing
the top of cement up to the 13⅜-in casing
shoe. The job required a minimum of 30 m of
hydraulically isolating cement to be placed in
the cemented interval, where verification of
the barrier was performed using an ultrasonic
inspection tool (USIT) and cement bond log (CBL).
Determine optimal cement system for anticipated pressures and temperature cycles
Schlumberger performed a well life study using CemSTRESS cement sheath stress analysis software
to determine which cement system would be best suited for exposure to the anticipated pressures
and temperature cycles during the injection and production wells. Based on the simulation results and
subsequent recommendations, the operator decided to use CemFIT Flex system.
Deliver continuous cement slurry
The operator drilled the 17½-in open hole using RheGuard flat rheology drilling fluid system to
1,888-m MD without any issues. The cementing crew mixed and pumped 18.9 m3 of CemFIT Flex
system slurry. During displacement, no losses were observed as the spacer entered the annulus, and
a consistent lift pressure was observed as cement entered the annulus. The job signature pressure
match conducted using CEMENTICS zonal isolation software indicated that the openhole size
was very close to gauge hole.
The 12¼-in open hole was drilled using RheGuard system at 1.45 sg, and the 9⅝-in liner was run
to TD without any issues. For this operation, a 2 × 12-m3 batch mixer was mobilized to the rig as
a residence tank for the fly-mixed slurry prior to pumping the spacer downhole. This ensured that
the slurry volume was ready to be pumped downhole.
The 9⅝-in liner job was successfully executed. The continuous cement slurry mixing to the batch
mixer was very smooth with a total of 16.1 m3 of 1.60-sg CemFIT Flex system slurry pumped
downhole. Compared with a conventional foamed cement system, the CemFit Flex system reduced
cement content by 66% and simplified the job by eliminating foam usage. No losses were observed
during the job, and a consistent lift pressure was recorded during the entire displacement stage.
The liner was logged using Schlumberger USIT and CBL tools, with a top-of-cement bond identified
at the 13⅜-in casing shoe with a total of 330 m of hydraulically isolating circumferential cement.
When compared with a conventional foamed cement system, the CemFIT Flex system reduced
cement content by 66% and simplified the job by eliminating foam usage. CemFIT Flex system is
also rated 100% poses little or no risk (PLONOR) and has eliminated the use of micropolymers and
plastics used to impart flexibility.
Provide high bond quality
The operator achieved the required isolation objectives to install the cemented liner as the primary
barrier element prior to drilling into the reservoir zone. The solution achieved exceptional USIT and
CBL results. CemFIT Flex system provided a high bond quality from 1,882 to 2,130 m.