8 Production activities
8.8 Anomalies
The event of a possible loss of a well barrier, deviation from normal or predicted pressure behaviours, or change in fluid compositions that could negatively affect the well barriers, shall trigger an evaluation of the event.
Anomalies shall be evaluated to determine the cause and effects, considering the following:
a) method of normalization of the situation and restoring two well barriers;
b) gas and/or liquid leak rate across the well barrier;
c) ensure the acceptance criteria for qualifying the well barrier is maintained;
d) blowout potential, should the remaining well barrier envelope fail;
e) verification of well design to ensure the present design can manage new load scenarios; and f) ensure the operating limits are still valid.
Any further deterioration or additional failure shall not significantly reduce the possibility of containing the hydrocarbon/pressure and normalising the well.
If the well barrier status or monitoring ability is altered, production/injection shall only continue when supported by a risk assessment and MoC process.
When there is a risk of corrosion or erosion occurring, wall thickness loss calculations shall be performed.
The need for periodic systematic measurements, such as calliper runs, shall be evaluated. If wall thickness loss exceeds the design criteria, new load calculations shall be performed and/or operational limits re-evaluated.
See Norwegian Oil and Gas Association Guideline no. 117 - Recommended Guidelines for Well Integrity.
for guidance on handling of annulus leaks and sustained casing annuli pressures.
8.9 WBS examples
The following WBSs are examples and describe one possible solution for defining and illustrating well barrier envelopes.
Well barrier elements EAC
table Verification/monitoring Primary well barrier
In-situ formation 51 n/a after initial verification Casing cement
(shoe to production packer) 22 n/a after initial verification Casing
(below production packer) 2 n/a after initial verification Production packer 7 Continuous pressure
monitoring of A-annulus Completion string 25 Continuous pressure
monitoring of A-annulus Completion string
component 29 Periodic leak testing.
DHSV
(including control line) 8 Periodic leak testing.
AC DHSV: xx bar/xx min.
Secondary well barrier
In-situ formation 51 n/a after initial verification Casing cement (above
production packer) 22 Daily monitoring of B-annulus
Production casing
(above production packer) 2 Daily monitoring of B-annulus
Production casing hanger
with seal assembly 5 Daily monitoring of B-annulus/
Periodic leak testing Wellhead (annulus valve) 12 Periodic leak testing of valve
AC: xx bar/xx min.
Tubing hanger
(body seals) 10
Periodic leak testing and continuous pressure monitoring of A-annulus Wellhead
(WH/Tree Connector) 5 Periodic leak testing
Tubing hanger
(neck seal) 10 Periodic leak testing
Surface tree 33 Periodic leak testing of valves AC: xx bar/xx min.
Figure 8.9.1 – Platform production/injection/observation well capable of flowing
Well barrier elements EAC
table Verification/Monitoring Primary well barrier
In-situ formation 51 n/a after initial verification Casing cement 22 n/a after initial verification
Production casing 2 Continuous pressure monitoring of B-annulus Production packer 7 n/a after initial verification Completion string
component (CIVand CI line )
29 Periodic leak testing
ASV
(including control line)
9 Periodic leak testing.
AC ASV: xx bar/xx min.
Completion string (Between
ASV and DHSV) 25 Periodic leak testing
DHSV / control line
(including control line) 8 Periodic leak testing.
AC DHSV: xx bar/xx min.
Secondary well barrier
In-situ formation 51 n/a after initial verification Intermediate casing cement 22 Daily monitoring of C-annulus Intermediate casing 2 Daily monitoring of C-annulus Intermediate casing hanger
with seal assembly 5 Daily monitoring of C-annulus/
Periodic leak testing Wellhead (A-annulus valve) 12 Periodic leak testing of valve
AC: xx bar/xx min.
Wellhead (B-annulus valve) 12 Periodic leak testing of valve AC: xx bar/xx min.
Tubing hanger
(body seals) 10
Periodic leak testing and continuous pressure monitoring of A-annulus Wellhead
(WH/tree connector) 5 Periodic leak testing
Tubing hanger
(neck seal) 10 Periodic leak testing
Surface tree 33 Periodic leak testing of valves AC: xx bar/xx min.
Figure 8.9.2 – Platform production well on gas lift with ASV (GLV not qualified)
Well barrier elements EAC
table Verification/monitoring Primary well barrier
In-situ formation 51 n/a after initial verification Liner cement ( top reservoir to
production casing shoe) 22 n/a after initial verification Casing (production liner) 2 n/a after initial verification Liner hanger packer 7 n/a after initial verification Casing (between production
packer and liner hanger packer) 2 n/a after initial verification Production packer 7 Continuous pressure
monitoring of A-annulus Completion string 25 Continuous pressure
monitoring of A-annulus
DHSV / control line 8 Periodic leak testing.
AC DHSV: xx bar/xx min.
Secondary well barrier
In-situ formation 51 n/a after initial verification Production casing cement
(above production packer) 22 daily monitoring of the
B-Annulus Production casing
(above production packer) 2 Continuous pressure
monitoring of A-annulus Production casing hanger
with seal assembly 5 Continuous pressure monitoring of A-annulus Tubing hanger (seals) 10 Continuous pressure
monitoring of A-annulus Wellhead
(WH/tree connector) 5 Continuous pressure
monitoring of A-annulus Subsea tree 31 Periodic leak testing of valves
AC: xx bar/xx min.
Figure 8. 9.3 – Subsea production well with a vertical tree
Well barrier elements EAC
table Verification/monitoring Crossflow well barrier
In-situ formation
(cap rock between reservoirs)
51 n/a after initial verification
Casing cement (liner cement
behind plug) 22 n/a after initial verification
Casing (liner behind plug) 2 n/a after initial verification Deep set plug 6 n/a after initial verification
Primary well barrier
In Situ Formation (at casing shoe)
51 n/a after initial verification
Production casing cement (shoe to production packer)
22 n/a after initial verification
Production casing (below production packer)
2 n/a after initial verification
Production packer 7 Continuous pressure monitoring of A-annulus Completion string 25 Continuous pressure
monitoring of A-annulus DHSV / control line 8 Periodic leak testing.
AC DHSV: xx bar/xx min.
Secondary well barrier
In-situ formation 51 n/a after initial verification Production casing cement
(above production packer)
22 n/a after initial verification
Production casing (liner above production packer)
2 Continuous pressure monitoring of A-annulus
Liner hanger packer 7 Continuous pressure monitoring of A-annulus
Intermediate casing (between liner packer and tie-back packer)
2 Continuous pressure monitoring of A-annulus
Tie-back packer 7 Continuous pressure monitoring of A-annulus
Production casing (above tie back packer)
2 Continuous pressure monitoring of A-annulus
Production casing hanger with seal assembly
5 Continuous pressure monitoring of A-annulus
Tubing hanger with seals 10 Continuous pressure monitoring of A-annulus
Wellhead (WH/tree connector)
5 Continuous pressure monitoring of A-annulus
Subsea tree 31 Periodic leak testing of valves AC: xx bar/xx min.
Figure 8.9.4 – Subsea production well with a horizontal tree and zonal isolation
A B C
NOTE For wells that are injecting with a higher downhole pressure than the cap rock barrier integrity, the maximum reservoir pressure shall be stated on the WBS.
Design requirements: Production packer to be set below cap rock.
Well barrier elements EAC
table Verification/monitoring Primary well barrier
In-situ formation 51 n/a after initial verification
Production packer 7 Continuous pressure monitoring of A-annulus
Liner cement (production packer
to production casing shoe) 22 n/a after initial verification Casing (production liner) 2 Continuous pressure monitoring
of A-Annulus
Liner hanger packer 7 Continuous pressure monitoring of A-Annulus
Completion string 25 Continuous pressure monitoring of A-annulus
DHSV / control line 8 Periodic leak testing.
AC DHSV: xx bar/xx min.
Secondary well barrier
In-situ formation 51 n/a after initial verification Intermediate casing cement 22 Daily monitoring of C-annulus Intermediate casing
(between liner top packer and tie-back packer)
2 Continuous pressure monitoring of A-annulus
Tie-back packer 7 Daily monitoring of B-annulus Tie-back production casing 2 Daily monitoring of B-annulus Production liner hanger with
seal assembly
5 Daily monitoring of B-annulus.
Periodic leak testing
Wellhead (A-annulus valve) 12 Periodic leak testing of valve AC: xx bar/xx min.
Tubing hanger (body seals)
10 Periodic leak testing and continuous pressure monitoring of A-annulus
Wellhead (WH/XT Connector)
5 Periodic leak testing
Tubing hanger (neck seal)
10 Periodic leak testing
Surface tree 33 Periodic leak testing of valves AC: xx bar/xx min.
Figure 8.9.5 – Injection well with production packer in cemented liner
9 Abandonment activities