FLOODING, CLEANING GAUGING & HYDROTESTING FOR 32” PIPELINE DURING PRE-COMMISSIONING

PROCESS

Mohamad Shukri Bin Rahmat

860103-10-5375

SX091166KKJ04

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Background Study

• PETRONAS Carigali Sdn. Bhd. has undertaken the development of the NC3 gas field located in SK316 Block, approximately 200km North of Bintulu, Sarawak.

• The water depth in NC3 field is around 104m-107m. • Subsea Pipeline connects NC3 Drilling Platform to

Existing Riser Platform E11R-C. The processed gas will be evacuated to shore via the existing trunkline through E11R-C or dedicated newly-to-be-installed trunkline to shore

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Background Study

Field of NC3 and E11-RC Platform

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Background Study

• The transportation of gas from fields (offshore) to the shore is normally by using the sub-sea pipeline.

• Pipeline pre-commissioning is the process of proving the ability of a pipeline and piping systems to contain product without leaking. In this cases, the said product is gases

• The gross volume of the processed gas is 660MMSCFD including 20% CO2.

• Installation of the pipelines will be completed before the offshore facilities are in place

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Background Study

• To discuss the requirements to perform the flooding, cleaning, gauging and hydrotesting of 32” dia. x 75.5 km pipeline from E11RC platform to NC3 platform, problem statement and how to overcome while doing the said services.

PROBLEM STATEMENT

Pipeline Details

Table below shown summarizes of the 32” Dehydrated Gas & Condensate Pipeline details covered by the procedure of Flooding, cleaning, gauging, dewatering and hydrotesting of offshore oil and gas pipelines during pre-commissioning

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PROBLEM STATEMENT

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PROBLEM STATEMENT

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PROBLEM STATEMENT

• Flooding, cleaning and gauging (FCG) operation can be defined as the flooding operation will introduce chemically treated filtered seawater into the offshore pipeline sections

• The cleaning operation will remove construction debris from the internal pipeline surface

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PROBLEM STATEMENTFailure to perform one of these Pre-Commissioning tasks as mentioned will lead to:1. Gas ingress into the water during flooding may make hydro

testing difficult.2. Inefficient dewatering of the pipeline may lead to hydrate

formation in gas lines or corrosion problems during production.

3. The tasks also take time to perform under difficult conditions.4. Piping Internal Gauging (PIG) operation that may get stuck

inside a pipeline section 5. Bad gauging performance, bad cleaning/testing/drying

performance 6. Work Schedule delay

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PROBLEM STATEMENT

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PROBLEM STATEMENT

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PROBLEM STATEMENT

Dewatering Pig

Flooding, Cleaning,

Gauging Pig

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PROBLEM STATEMENT

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Objectives of Study

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• To presents an analysis and requirements to perform of part of pipeline Pre-commissioning process which is flooding, cleaning, gauging and hydrotesting of 32” dia. x 75.5 km pipeline from E11RC platform to NC3 platform

• To discuss the problems that could be encountered during flooding, cleaning, gauging and hydrotesting during pre-commissioning process while install and commissioning of these 32” Pipeline

• To discuss the Risk Management in the Pre-Commissioning Phase during flooding, cleaning, gauging and hydrotesting

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Scope of Study

• Pipeline Pre-commissioning process of 32” Pipeline • Flooding operation which will introduce chemically treated

filtered seawater into the offshore pipeline sections. • Cleaning operation which will remove construction debris

from the internal pipeline surface. • Gauging operation which will confirm that there are no

pipeline deformations or intrusions/interruption. • Hydro testing operation to treat water used to drive the

cleaning and gauging pigs will be discharged to the environment at temporary subsea pig trap in the vicinity.

• Risk Management during Pre-Commissioning Phase of 32” Pipeline

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Flooding• Pipeline Filling or in other name Flooding can be explained

as method which can be carried out by propelling PIG’s through the pipeline with water or free flooding with water.

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Cleaning Gauging• Pipeline Cleaning is carry out by pushing PIG’s or Gel

PIG’s through the pipeline to remove any debris dirt • Pipeline Gauging is carried out to prove the dimensional

quality of the internal diameter of the pipeline

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Hydrotesting

• Hydrotesting is a process by which the pipeline in question is the pressure tested to a predefined pressure above the operating design pressure of the pipeline.

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Hydrotesting

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RESULT AND DISCUSSION

• To aid in the planning of such operations, a number of analyses can be undertaken to determine the duration to perform each of these tasks.

• The mathematical models can be used to optimise the equipment required (hoses, pumps, compressors).

• The subsea heads, hot stabs, and pig tracking system worked flawlessly during FCG (Flooding, Cleaning, Gauging) operations. 12/21/2015

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RESULT AND DISCUSSION

• All FCG pigs performed as expected and no damage was observed. The water filtration, additive system, and pumping spread operated consistently at or above their specified duty levels.

• Air content confirmed to be well within the Det Norske Veritas (DNV) requirement of less than 0.2% demonstrated the flooding operation's success

• A final cleaning run removed less than 2 kg of construction debris in each section. Iron oxide and small amounts of sand and some red-coloured dust were also removed.

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RESULT AND DISCUSSION

Section Length(km)

Volume (Cu M)

TestPressure

(barg)

Pressurization Duration

(hr)

Volume Added(Cu M)

Stabilization

period (hr)

Pressure drop

during test period, %

1 75.5 120,089 110 14.5 2,148 1 0.028

2 151.0 241,240 230 29.0 4,128 3 0.058

Table 4.1 Pressure Test Data of 32” Pipeline

Pressure Test Data of 32” Pipeline during Hydrotesting

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RESULT AND DISCUSSION

As a result:• Analysis of Pipeline Pre-commissioning system and method to provide

output that can be used for pre-commissioning operation is explained. • The problems that could be encountered without a clear knowledge of

how the operation will proceed can be avoided. • The operation can be monitored by comparing recorded and predicted

values by using mathematical module and from past experience. • The Risk Management in the Pre-Commissioning Phase of an oil and

gas pipeline project undertaken• Pre-commissioning may therefore be defined as all the checks that are

to be completed prior to commissioning being permitted to commence.

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CONCLUSION

• Successfully performing Pre-commissioning process which include the cleaning, gauging, filling, hydrotesting of 32” dia. x 75.5 km pipeline from E11RC platform to NC3 platform based on Pressure Test Data

• Pressure drop during test period is less than 0.2% which can be defined as the pipeline is clean from debris and other material tolerance

• These process is managing to meet client schedule and safety is in zero tolerance and now the said pipeline is successfully returned to Petronas to commence a gas flow.

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CONCLUSION

• The design of pipeline is important requirement. The designer has to foresee construction requirements and all project constrains have to be incorporated in his design.

• Any insufficient design can cause of problems for construction and pre-commissioning phase

• Risk cannot be eliminated as such pre-commissioning activities contains high risk that cause of schedule and cost impact

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RECOMMENDATION

• Flooding and Pigging subsea pipelines using a remote flooding module (RFM). This enables the use of available hydrostatic head to flood and pig subsea pipelines while meeting the project requirements in terms of pig speed, filtration, and chemical treatment.

• Recommended to use of ROV driven pumping units to complete flooding and pressurization

• The use of smart gauge tools (SGT) to gauge pipelines without using aluminium gauge plates.

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RECOMMENDATION• Using of subsea data loggers to record pressures

and temperatures during subsea testing, and use of systems to transmit this data to surface in real-time during the test.

• To have a good plan before performing pre-commissioning process

• Review the quality document and certificates completed with conformance inspect of materials and equipment are also conducted probably to prevent risk at work process

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Thank You