AO 045 SG TEA 511363_03 Riser Monitoring Functional Specification

CLOV Project Document number: AO-045-SG-TEA-511363

Riser Monitoring Functional Specification Revision: 03 Status: AFD Document Type: PRC Discipline: PLR Rev. Date: 24/03/2010 Page 1 of 11

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Riser Monitoring Functional Specification

Rev. Status Date Revision memo Issued by Checked by Approved by

03 AFD 24-03-10 AFD (including changes reflection TB and clarification meetings)

APE PRA/JHM VDO

02 AFD 21-OCT-08 Issued for Tender ABL BBA VDO

01 AFD 24-SEP-08 Issued for Design BBA JPD VDO

00 IFR 16-JUL-08 Issued for Review BBA

This document has been generated by an Electronic Document Management System. When printed it is considered as a for information only copy. The controlled copy is the screen version and it is the holder's responsibility that he/she holds the latest valid version.




TABLE OF CONTENT

1 GENERAL..............................................................................................................................3

1.1 Introduction ..........................................................................................................................3

1.2 Purpose.................................................................................................................................3

2 CLOV RISER SYSTEM OPTIONS ........................................................................................4

3 MONITORING REQUIREMENTS..........................................................................................6

3.1 Monitoring for Full flexible riser solution Option 1........................................................6

3.1.1 Operating data........................................................................................................................6

3.1.2 Polymer Coupon monitoring ...................................................................................................6

3.1.3 Vent gas monitoring................................................................................................................8

3.1.4 FPSO motions ........................................................................................................................8

3.2 Monitoring for BHR Option 2 ...........................................................................................9

3.2.1 Flexible jumpers monitoring....................................................................................................9

3.2.2 Mechanical Integrity Monitoring..............................................................................................9

3.2.3 Pressure and Temperature Monitoring at riser base ..............................................................9

3.2.4 BHR Motion Record Unit (MRU).............................................................................................9

3.3 Monitoring for Gas Export SLHR........................................................................................10

3.3.1 Flexible jumper .......................................................................................................................10

3.3.2 Mechanical Integrity Monitoring..............................................................................................10

3.3.3 Pressure and Temperature Monitoring at riser base ..............................................................10

3.3.4 SLHR Motion Record Unit (MRU)...........................................................................................10

3.4 Monitoring system architecture..........................................................................................11




1 GENERAL

1.1 Introduction The CLOV fields are located in Block 17, approximately 200 km from the coast of the Republic of Angola. The CLOV Project develops fields within the Cravo, Lirio, Orquidea and Violeta Development Areas. The water depth over the CLOV area ranges from approximately 1050 m to 1400m.

1.2 Purpose The purpose of this document is to outline the requirements in terms of monitoring for the CLOV riser systems.




2 CLOV RISER SYSTEM OPTIONS The following options are considered for the CLOV riser system:

Option 1 : Full flexible riser solution Gas lift integrated production flexibles are used for production risers and standard flexible risers are used for the water injection. They are all installed in a free hanging catenary between the FPSO and the seabed.

Seabed end fitting

FPSO

Top side end fitting

Hang Off

I-tube

Bend stiffener

Flexible pipe




Option 2 : Bundles Hybrid Riser (BHR)

A vertical rigid bundle is maintained under tension between the seabed and a mid water buoyancy tank. The top of the rigid bundle is connected to the FPSO through several flexible jumpers (for production, Gas Lift and Water Injection) that accommodate the vessel motions.

Option 3 : Single Leg Hybrid Riser (SLHR) This riser system is similar to the Bundle Hybrid Riser except there is a single rigid line instead of a bundle and hence, the top of the rigid riser is connected to the FPSO through only one flexible jumper. This riser technical solution is the base case for the gas export riser only (not considered for other lines).

FPSO

Top side end fitting

Hang Off

I-tube

Bend stiffeners Buoyancy tank

Bundle tower

Subsea end fitting

Flexible pipe




3 MONITORING REQUIREMENTS This section details the monitoring requirement for each riser solution considered. Monitoring of flexible pipes is also addressed in GS EP PLR 109. In case of contradiction with the GS EP PLR 109, the requirement in this document shall apply.

3.1 Monitoring for Full flexible riser solution Option 1

3.1.1 Operating data The operating data shall be monitored to ensure the riser system is operating within the operating envelope considered during the design, and to allow an assessment of the actual ageing or a re-assessment of the residual service life after a few years of operation, based on the actual operating parameters seen by the riser system. CONTRACTOR shall provide the following Monitoring Systems related to the operating data:

- Continuous monitoring of operating pressure at riser bottom location, downstream gas lift injection point

- Continuous monitoring of operating temperature downstream gas lift injection point

Following additional operating parameters monitoring should be provided by others (FPSO Contractors):

- Continuous monitoring of Topside operating pressure - Continuous monitoring of flow conditions (flow rate, sand content) - Continuous monitoring of water cut when applicable - Liquid and gas composition when applicable. Frequency shall be adjusted depending on the

variability of the compositions - Continuous monitoring of chemical injection when applicable (composition, flow rate,

duration)

3.1.2 Polymer Coupon monitoring When material other than HDPE or PVDF is used for pressure sheath material, coupon monitoring shall be installed on the top side piping to allow an accurate monitoring of the actual ageing process of the polymer. The Coupon Monitoring system to be provided by CONTACTOR shall be fully qualified and field proven. It shall be able to hold a minimum of 10 polymer discs and shall allow retrieving the samples without depressurization of the line, with a double barrier isolation (typical coupon holder with the associate retrieval system is presented below). The supply of the Coupon Retrieval Tooling and associated intervention procedures shall be included in CONTRACTOR scope.




Coupon holder:

Retrieval & Isolation systems:




3.1.3 Vent gas monitoring Flexible risers may be very sensitive to seawater ingress in their armour annulus as corrosion fatigue could dramatically decrease their service life. For flexible risers that are critical from a corrosion fatigue point of view, Vent Gas Monitoring system (VGM) shall be fitted to the riser annulus venting system to detect seawater ingress in the riser armour annulus as soon as it occurs. This VGM system to be provided by CONTACTOR shall be fully qualified and field proven. It shall continuously monitor the gas flow rate venting from the riser annulus. In addition, such system shall be designed to enable to detect all minor leak on pressure containment layer,. VGM is required for the production and gas risers, and also for water injection risers if their calculated service life when the annulus is flooded with seawater is less than 5years. CONTRACTOR shall supply an integrated VGM system that permits to read, analyse and record, all the VGM parameters on a dedicated Working Station located in the FPSO Maintenance Room, as shown in section 3.4.

3.1.4 FPSO motions

For information, the following additional parameters shall be supplied by Others (FPSO Contractor)

FPSO excursions shall be continuously recorded using DGPS (Differential Global Positioning System)

FPSO high frequency motions (6 degrees of freedom) shall be continuously recorded with a MRU (Motions Recording Unit)

Wave height and frequency will be monitored with a wavebuoy installed in the vicinity of FPSO

Theses systems aims to ensure the FPSO motions (quasi static excursions + high frequency motions) remain in the envelope considered at design phase. Also, it enables to assess the actual residual service life of the riser system after a few years of operation, based on the actual motions experienced by the system.




3.2 Monitoring for BHR Option 2

3.2.1 Flexible jumpers monitoring The monitoring requirements presented in 3.1 also applies to the flexible jumpers of the BHR system.

3.2.2 Mechanical Integrity Monitoring Tension monitoring at the top end of the bundle core pipe shall be continuously recorded to detect any loss of buoyancy of the mid water buoyancy tank. CONTRACTOR shall design dedicated Electrical cables that link the acquisition system onboard FPSO to the local mechanical sensors in the Riser Tower. CONTRACTOR shall supply an Integrated Monitoring System that permits to read, analyse, record and assess all the parameters of both Riser Towers on a dedicated Working Station located in the FPSO Maintenance Room, as shown in section 3.4.

3.2.3 Pressure and Temperature Monitoring at riser base Pressure and Temperature parameters for the production risers shall be continuously recorded. These P&T sensors shall be located on production riser bottom section.or on the riser base spool. In the case that they are located on production riser bottom section, P&T sensors shall be non-intrusive. CONTRACTOR shall design dedicated Electrical cables that link the acquisition system onboard FPSO to the local P&T sensors in the Riser Tower Base. The P&T parameters for both Riser Towers shall be part of the Integrated Monitoring System Working Station located in the FPSO Maintenance Room, as shown in section 3.4.

3.2.4 BHR Motion Record Unit (MRU) Each BHR shall be equipped with a MRU that records the BHR motions and position and transmit these data to the Riser Monitoring PC onboard the FPSO.




3.3 Monitoring for Gas Export SLHR

3.3.1 Flexible jumper The monitoring requirements presented in 3.1 also applies to the flexible jumper of the Gas Export SLHR.

3.3.2 Mechanical Integrity Monitoring The monitoring requirements presented in 3.2.2 also applies to the rigid riser of the Gas Export SLHR. In this case, the tension is monitored directly in the rigid riser as there is no core structural pipe. Mechanical Integrity signals shall be incorporated within electrical cables in SIV control umbilical.

3.3.3 Pressure and Temperature Monitoring at riser base The monitoring requirements presented in 3.2.3 also applies to the Single Leg Hybrid Riser system. In this case, the P&T can be monitored directly in the SIV Module, and parameters are sent to FPSO though electrical cables in SIV Umbilical.

3.3.4 SLHR Motion Record Unit (MRU) The monitoring requirements presented in 3.2.4 also applies to the Single Leg Hybrid Riser system.




3.4 Monitoring system architecture A key point of the riser monitoring philosophy is to make the recorded data easily accessible for processing. To do so, there shall be one PC for each SURF Contractor scope dedicated to the acquisition of the monitored parameters. Those PCs shall be able to accommodate extra acquisition if the need for additional monitoring systems is identified further in the project. Each PC shall be interfaced with the ICSS in order for all the monitored data to be sent to an onshore IP server. Finally, a third part shall be commissioned to setup a web based system interfaced with the onshore IP server

Operating data: - P, T - Flow - Water cut - Chemical

injection

DGPS

Wave buoy

FPSO

FPSO ICSS Onshore IP server 3rd part system

BHR N1

SURF 1

GE Riser

SURF 2

SURF 1 PC monitoring

SURF 2PC monitoring

FPSOPC monitoring

MRU

SIV SIV umbilical

Onboard FPSO Subsea

VGM P, T & integrity signals, MRU

BHR N2

Flexible Jumpers

Electrical Cables for signals transmissions

Onboard FPSOSubsea

VGM

P, T & integrity signals

VGMP, T & integrity signals, MRU

Flexible Jumpers

Cables within SIV Umbilical

Documents

AO 045 SG TEA 511363_03 Riser Monitoring Functional Specification