Marco Polo JIP - MARIN Project Marco Polo JIP Extension Full-Scale Monitoring Marco Polo TLP

Transcription

1 Marco Polo JIP - MARIN Project Marco Polo JIP Extension Full-Scale Monitoring Marco Polo TLP Rev. 2, MARIN reference 19811, dd. Feb. 7, 2008

2 Marco Polo JIP - MARIN Project BACKGROUND Tension Leg Platforms have proven their abilities for moderate water depths and are now being used for deep water and ultra deepwater. A number of issues in design, operation and inspection issues however still need to be resolved. Such issues are: Actual wind (hurricane), wave and (loop) current conditions, Platform motions (LF, WF and HF), Tensions in tendons and risers, VIV behavior of tendons and risers (including effect of fairings and strakes), Extreme loads and fatigue life of the platform. In 2004 the Marco Polo TLP has been installed in 4300ft of water in the GoM. In order to collect data to resolve the above issues, the partners in the Marco Polo TLP project decided to install a monitoring system on the platform. More specifically the envisaged monitoring campaign was aiming at: Damping in the stiff modes of motion, Platform behavior in loop current, Effect of strakes on risers and fairings on tendons to restrict VIV, Platform in hurricane conditions, Fatigue life consumption. To this end MARIN instrumented Marco Polo during the outfitting phase. In May 2004 the monitoring system was commissioned and from June 2004 onwards data has been collected continuously. By November 2007 the Marco Polo monitoring system will have recorded 42 months of data, including three major hurricanes: Ivan, Katrina and Rita and the Marco Polo Joint Industry Project will have successfully completed its scope of work, on time and within budget. 1.1 Marco Polo JIP As the monitoring campaign is of interest to all parties involved in deep water TLPs and the results can be used for design, interested companies were invited to join the data analysis and evaluation of the results in a 3 year Joint Industry Project. This Joint Industry Project consisted of 5 Tasks: Task Period Status 1. Instrumentation Completed 2. Installation & Commissioning 2004 Completed 3. Monitoring Jun Nov 2007 Ending Nov Data Analysis Nov Nov 2007 Ending Nov Design Method Verification Nov Nov 2007 Ending Nov 2007 In November 2005 the Marco Polo JIP had its formal kick-off and the JIP now has 10 participants (in alphabetical order): ABS, Hess Anadarko (Operator), MARIN, BHPB, MMS, BP, Modec, Enterprise, WorleyParsons Sea. The Marco Polo JIP under the current agreement is scheduled to end November 2007.

3 Marco Polo JIP - MARIN Project Project Objective The Marco Polo JIP is aiming at the dynamic behavior of TLPs in operational and survival condition and the verification of design methods and numerical analysis to enable development of new TLPs for even deeper water (see also ref [1]). 1.3 Project Deliverables Since the start of the monitoring campaign 39 months of data are available (as of Sept. 2007). Furthermore, during that time Marco Polo has encountered three major hurricanes: Ivan (2004), Katrina (2005) and Rita (2005). Throughout these hurricanes data has been recorded and detailed analysis of these and other events has been discussed in the following bi-annual progress meetings. November 29, 2005 (kick-off Sea Engineering office, Houston) May 16, 2006 (progress Enterprise office, Houston) October 19, 2006 (progress Anadarko office, Woodlands) May 3, 2007 (progress BP office, Houston) The following progress meeting is still planned as part of the present JIP: Dec 2007 (scheduled progress mtg, Houston) The Marco Polo JIP has the following deliverables for Task 3, 4 and 5: Monthly long term statistics reports (June 2004 Nov 2007) Report with description of short term analysis method (in progress) Report on 'lessons learnt' of Marco Polo instrumentation (in progress) Presentations of short term analysis during bi-annual progress meetings Report on design verification study (WP Sea, in progress) Summary report of all short term analysis in period (to be issued March 2008) All reports, presentations and minutes of meeting can be found on the Marco Polo JIP website: This website is accessible to JIP participants only. Username and password can be obtained by sending an to: r.r.t.van.dijk@marin.nl. Figure 1: Measured waves & wind and calculated wave spreading on Marco Polo

4 Marco Polo JIP - MARIN Project EXTENSION OF MARCO POLO JIP General The Marco Polo JIP under the present contract is scheduled to end in November Analysis of the available data has provided insight in both the environmental conditions in the GoM as well as the response of the TLP in these conditions. Furthermore, the biannual meetings have proven to be a very valuable platform for discussions on the measurements and analysis results. In the past 3.5 years Marco Polo encountered three major hurricanes. Although these have been recorded and analyzed in detail, it is still a limited data set. Furthermore, part of the measurement period no ADCP current data was available. More can be learned on the effect of hurricanes and loop current events on the TLP by extending the measurement campaign. It is therefore proposed to extent the measurement campaign and associated analysis for at least two more years, i.e. running from Dec to Nov Objective The objective of the extension of the Marco Polo JIP with two more years is: 1) To extent the database of wave statistics from 3.5 years to 5.5 years, 2) To capture more occurrences of hurricanes and loop current events and analyze the TLP response to these events, 3) To better assess occurrence of riser and tendon VIV events. 2.3 Scope of Work For the two year extension period the following scope of work is proposed: Monitoring The measurements on board the Marco Polo TLP will be extended for a period of 2 years, starting in December 2007 and ending November The data collected by the monitoring system during this period will be analyzed and reported to the JIP Participants. For each one-month data set a so-called long-term statistical analysis will be conducted. The 30-minute statistics (min, max & stdev) will be presented as a time trace over the whole month. In this way the changes in weather, TLP response, loop current events and operational effects can be identified at a glance in the data set. Results of the long-term analysis will be reported every month on the JIP website. To ensure a constant quality of the measured data, a maintenance visit to the platform by a MARIN engineer is planned twice a year. During the visit the engineer will check for wear and tear, perform general system maintenance and perform preventive maintenance Data Analysis From this long term statistical overview events will be selected for a more detailed shortterm analysis. This short term analysis will include statistics, spectral analysis, calculation of transfer functions and distributions as required. This data analysis will be directed specifically to the design issues. The choice of these events, as well as the analysis methods and procedures, will be decided in close co-operation with the JIP participants and may be refined or augmented when required by the results. Results of

5 Marco Polo JIP - MARIN Project the short term analysis will be reported during the bi-annual progress meetings and in a summary report at the end of the JIP extension period. 2.4 Design Verification Further design verification is proposed in order to compare design values against actual measured values in the period from June 2004 to December The comparison will focus on expected platform response versus actual measured response during extreme events (hurricane & loop current), and will consider the following topics: - Environmental conditions (design - Tendon loads - Tendon fatigue: - Low frequency and wave frequency motion response of the TLP - Gusset loads (provided gusset load RAOs can be provided by WP Sea / Modec) Given the available budget, the extent of this design verification study will be limited. 2.5 Deliverables The following deliverables will be presented as part of the extension of the Marco Polo JIP: 1) Monthly long term statistics reports (Dec 2007 Nov 2009). 2) Detailed analysis of possible hurricanes and other special events in the period Dec 2007 to Nov ) Presentations of short term analysis during bi-annual progress meetings 4) Summary report of all short term analysis in period ) Calculation, monitoring and reporting of cumulative fatigue damage on the TLP tendons, based on the measured tendon tensions and the derived correlation between platform motions and tendon tensions. The calculated cumulative fatigue damage will take into account the whole set of measured data, starting June ) A user-friendly tool to assess the measured hurricane wave data more easily by JIP participants, taking into account corrections based the measured LF and WF platform motions. This tool will have the option to assess the effect of diffracted and radiated waves on the measured waves (based on linear diffraction theory and assuming long crested waves). The tool will also have the option to calculate wave direction and spreading based on the Maximum Likelihood Method, as presented in the progress meetings. The tool will be delivered to all participants as executable Graphical User Interface (GUI) on DVD, combined with the measured hurricane data. The wave database will contain existing hurricane data of Ivan, Katrina and Rita. Further significant hurricanes that occur in the period will be added to this database. 7) A detailed evaluation of the Marco Polo wave data measured during hurricanes Ivan, Katrina and Rita by Forristal Ocean Engineering. The purpose of this independent review is to assess the quality of the measured wave data during the hurricanes, with special emphasis on the measured maximum crest heights, in order to make distinctions between accurately measured wave crests, inaccurately measured or false high wave crests and suspicious wave crest measurements of uncertain origin. 8) A design verification report, focussing on comparison between measured motion and tendon load response and expected response based on design reports in extreme events.

6 Marco Polo JIP - MARIN Project Instrumentation The instrumentation of the Marco Polo JIP will be almost the same as during the previous phase and consists of: Marco Polo Measurement System (MPMS) Data Acquisition The monitoring system comprises a dedicated control cabinet with the monitoring computer, signal conditioners, control and test switches and power supply including an UPS system. This main cabinet is installed in the control room on the SE corner of the production deck. Motions: 1) A dedicated motion sensor unit with accelerometers and solid state rate gyros to measure the wave frequency and high frequency motions (1-30 sec range) 2) A DGPS to measure low frequency motions (surge, sway and yaw) with very high accuracy (range > 20 sec). Risers tensions: Riser tensions are recorded at the top-tensioning device. The riser top tension as recorded by the Danfoss device is logged by the MPMS. Also, vertical accelerometers are located on the upper section of the risers to measure the riser vibrations due to VIV. Tendon tensions: The tendon tensions are measured by the Tendon Tension Measurement System (TTMS) by means of strain gauges in the tendon supports. These tendon tension measurements of the TTMS are logged in MPMS. Gusset Plate Stress: Gusset plate stress measurements will not be included in the measurements, as they are not required for the objectives of the JIP extension. Waves: The wave conditions are monitored by means of 3 down looking wave radars which are fitted on the East, South and West sides of the lower deck. The wave radars record the wave elevation at these locations. From the 3 wave records also the wave direction and the spreading of the waves can be derived. Wind: Wind speed and direction are measured by means of two solid state ultrasonic Wind Observer II wind meters measuring the wind speed and direction. Wind meter # 1 is fitted on a light pole on SW corner of the main deck. Wind meter 2 is located on the flare structure at approx. 1/3 rd of the height. Current: In July 2005 the current speed and direction monitoring was upgraded following the new MMS legislation. Now the current profile is measured over the full water depth column of 4300 ft. Installed at the bottom of the TLP, the 38 khz Ocean Observer measures the current over the top 1000 m of the water column, while the 75 khz Workhorse Long Ranger is placed in a sub sea buoy system, moored to the sea floor, measuring the current profile in the bottom 600 m of the water column. This sub sea system is retrieved every 6 months.

7 Marco Polo JIP - MARIN Project DGPS Riser tension & vibrations Wind 6-DOF motion sensor waves Strain gauges ADCP Figure 2: Marco Polo Instrumentation

8 Marco Polo JIP - MARIN Project PROJECT ORGANIZATION 3.1 Participants The project is aiming to have the same participants as in the first part of the JIP, see section 1.1. New participants are also welcome, but are subject to a late participation fee. 3.2 Management and Bi-annual Progress Meetings MARIN is the JIP manager. All progress meetings will be held in Houston. Results, reports and other relevant JIP information will be available from a dedicated website to participants only. Two progress meetings per year will be organized for both MMS and industry, one meeting around the OTC time and one in the fall (Nov-Dec). All meetings will be held in Houston. The first meeting will be held May 2008, to insure continuity in the project, and the last meeting Nov/Dec During the progress meeting issues related to MMS Rules and Regulations, U.S. Coast Guard Regulations, etc. can be discussed, as well as discussions on events that occurred during the past six months or any other measured event regarding the Marco Polo JIP that is of interest to the JIP participants. All travel expenses related to these progress meetings are on the account of the participants themselves. 3.3 JIP Agreement The work will be performed under the existing JIP agreement, see ref [2]. Participation is confirmed by signing the "Addendum to Participation Agreement JIP Full-Scale Monitoring MARCO POLO, describing the scope of work of the extension. 3.4 Project Schedule The two-year Marco Polo JIP extension is scheduled to start in December 2007 and ends November 30, Finance The cost of the Marco Polo JIP extension consists of maintenance to the system, analysis and reporting (general long term and detailed short term) and hardware replacements (if needed). The hardware used for the JIP monitoring can be split into two parts: 1) Hardware directly related to operation of the Marco Polo TLP: tendon tensions (TTMS), riser tensions (Danfoss) and current (ADCP), 2) Hardware specifically used for monitoring related to the JIP: data aquisition (MPMS), motions (DGPS & MRU), waves (wave radars), wind (anemometer) and riser vibrations (accelerometers). All hardware replacements related to the operational part (part 1 above) will be paid for by the operator of the Marco Polo TLP, i.e. Anadarko Petroleum Corporation. All hardware related specifically to the JIP (part 2 above) will be paid for by the JIP.

9 Marco Polo JIP - MARIN Project All cost for maintenance, monitoring, detailed analysis and reporting will be paid for by the JIP. The cost to the participants to the JIP will consist of equal shares in the overall costs. The cost for maintenance, monitoring, detailed analysis and reporting for the two year period is 360,000 USD for maintenance, analysis & reporting and 40,000 USD contingency for hardware replacements (JIP specific hardware only). Total cost for the two year JIP extension period is therefore: 400,000 USD Based on the present 10 participating companies to the JIP the participation fee for the two year extension period is therefore: 40,000 USD per participant. Payment of the participation fee will be done in two equal yearly payments (2008 & 2009). 4 CONTACT Further information on the Marco Polo JIP and the proposed extension of the Marco Polo JIP can be obtained by contacting: Radboud van Dijk Senior project manager Trials and Monitoring Maritime Research Institute Netherlands r.r.t.van.dijk@marin.nl Tel Fax Cell Or: Arjan Voogt Manager MARIN USA Inc. a.j.voogt@marin.nl 2500 City West Blvd #300 Houston, TX USA Tel Fax REFERENCES [1] "Full-Scale Monitoring Marco Polo JIP Proposal, Phase 3, 4, 5", rev. 6, July 2005, MARIN reference 19811, including supplement MMS (per ). [2] Participation Agreement JIP 'Monitoring Marco Polo".