1. GENERAL
This specification defines the minimum technical and
operational requirements governing flow-line pre-commissioning of the Infield
System. This specification is to be used in
conjunction with the following documents:
•
Basis of Design 84506-60-00-2L-060
•
General Specification 84506-60-00-2L-000 - Definitions
and Specification Directory
•
General Specification 84506-60-00-2L-010 - Quality
Assurance / Quality Control
•
General Specification 84506-60-00-2L-020 – General
Offshore Specification
•
General Specification 84506-60-30-2L-390 – Cleaning,
Gauging and Hydrotesting
This specification defines the minimum technical and
operational requirements governing flowline pre-commissioning of the Infield
System. This specification is to be used in
conjunction with the following documents:
2.
PROCEDURES
2.1 CONTRACTOR
shall supply all equipment, materials and manpower to successfully complete all
pre-commissioning operations for the infield system, to the satisfaction of COMPANY.
2.2 CONTRACTOR
shall develop detailed pipeline pre-commissioning procedures for the infield
flowlines, pipelines and risers, and submit for COMPANY approval 30 days prior
to the commencement of pre-commissioning activities. These procedures shall include,
as a minimum, the proposed equipment and operations for the following:
•
Dewatering pig train designed
arrangement
•
Disposal plan for fill water and
chemical additive certificates
•
Introduction of first gas
•
Handover to commissioning/operations
2.3
Instrument stand(s) shall be manned at
all times during pre-commissioning operations.
CONTRACTOR shall furnish communication equipment for use by CONTRACTOR
and COMPANY during pipeline pre-commissioning, where CONTRACTOR employs
personnel at different locations.
2.4 Detailed
acceptance criteria for each flowline, pipeline, or pipeline section shall be
agreed between COMPANY and CONTRACTOR prior to start of pre-commissioning
operations.
3. PIG DESIGN
3.1 The design of pipeline pigs for bulk
dewatering and introduction of first gas shall be the responsibility of the
CONTRACTOR. CONTRACTOR shall demonstrate
to the satisfaction of COMPANY the suitability of any pig design.
3.2 The
design of pipeline pig trains for bulk de-watering and introduction of first
gas shall be the responsibility of the CONTRACTOR. CONTRACTOR shall demonstrate to the
satisfaction of COMPANY the suitability of any pig train design.
3.3 Pigs
used during pre-commissioning may be launched from and received in temporary
traps furnished and installed by CONTRACTOR for pipeline cleaning, gauging and
hydrotesting.
3.4 COMPANY
acceptance of any design or procedure will not absolve CONTRACTOR of his
responsibility to complete the work in as diligent and as timely a manner as is
practically possible.
3.5 Every
pig shall be permanently marked with a unique number that shall be clearly
visible in a photograph. The condition
of all pigs shall be recorded photographically prior to and following the
pigging operation.
3.6
If in COMPANY opinion de-watering pigs
have not adequately de-watered the pipeline, the dewatering operation shall be
repeated until results obtained are satisfactory to COMPANY.
3.7
Refer Cleaning Gauging and Hydrotesting
Specification 84506-60-30-2L-390 page 8 paragraphs 4.7 & 4.8
4. DEWATERING REQUIREMENTS
4.1 CONTRACTOR shall dewater the flowlines,
pipelines and risers by running an adequate number of pigs in tandem through
the lines ahead of production gas to clear the lines of any water.
4.2 A flow meter of sufficient size and
accuracy shall be used to measure the quantities of all additives
required to bulk dewater each flowline, pipeline or pipeline section. CONTRACTOR’s
detailed pre-commissioning procedures shall include methods and equipment used
to measure and monitor pumping rates, and hence pig speeds.
4.3 During
bulk de-watering, samples of water shall be taken from between each pig batch
for salt testing. Acceptance of the
first bulk de-watering operation shall be based on the test results of the last
fresh water batch. The salt content in
the last batch shall be less than 200 ppm.
Should the salt content exceed 200 ppm, CONTRACTOR shall re-swab the
pipeline with additional fresh water batches.
4.4 CONTRACTOR shall be responsible for
proper dilution and disposal of any chemical additives that were used to fill
the lines for hydrotesting and corrosion inhibition, subject to prior approval
by both COMPANY and AUTHORITIES.
4.5 When discharging water, CONTRACTOR shall
install temporary piping from the receiving level to discharge water below, at,
or near the surface of the water.
CONTRACTOR shall submit his temporary piping layout and water
discharging plans to COMPANY for approval.
Water not discharged in this way shall be swept through the
line into the MOgPU separator by the production gas from the subsea wells.
5. DEWATERING PIG VELOCITY AND DRIVING PRESSURE
5.1 Dewatering
pigs shall be driven at a speed of between 0.3 meters/second and 0.7 m/sec for
the initial bulk de-watering run, and a speed of between 0.5 meters/second and 0.7 m/sec
for additional runs if required.
5.2 Driving
pressure shall be recorded on a COMPANY approved recording pressure chart. Chart time shall correspond to actual
time. Charts and other data relating to
dewatering operations shall be submitted to COMPANY at the completion of each
run.
5.3 Pumps
shall be capable of driving pigs at the required speed and pressure range. Pressure, volume and temperature shall be
monitored and recorded at all times during the pigging operations.
5.4
Should any pig become stuck, operations
shall be shut down, the pig located and cut out of the pipeline and the
pipeline shall be repaired. Repaired
pipeline sections shall then be cleaned, regauged & re-hydrotested (as per
specification number 84506-60-30-2L-390), and dewatered.
5.5
Refer Cleaning Gauging and Hydrotesting
specification 84506-60-30-2L-390 page 5 section 3 pig design.
6. DEMOBILISATION
Once the dewatering operation has been accepted, Contractor shall remove temporary pig
launchers and receivers as appropriate.
The Contractor
shall ensure that all consumables, temporary equipment and personnel are
removed from site in a timely manner.
The Contractor shall leave
the site in a condition as good or better than it was before mobilization.
7. ACCEPTANCE CRITERIA
Acceptance criteria for dewatering shall be subject to
COMPANY approval. Minimum requirements shall include, but not be limited to:
•
All the dewatering pigs shall traverse
the pipeline and the last three pig’s sealing disc diameters shall remain
greater than the nominal pipe bore.
•
Relatively small volumes of water shall
precede the last two pigs.
•
Water preceding the final pig shall
have a salt content less than 200 ppm.
8. SUBMISSIONS BY THE CONTRACTOR
In addition to the requirements stated herein, CONTRACTOR
shall combine and submit to COMPANY all documents, records, charts and test
certificates in a detailed final report within seven (7) days of practical
completion of the job.
All data shall be submitted to COMPANY in both hard copy and
electronic format.