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Results
Integrity Management of Deepwater Drilling Riser Based on Monitor and Inspecting
Xu, Liangbin (CNOOC Research Institute) | Zhou, Jianliang (CNOOC Research Institute) | Sheng, Leixiang (CNOOC Research Institute) | Chen, Guoming (China University of Petroleum) | Jiang, Shiquan (CNOOC Research Institute) | Li, Jiayi (China University of Petroleum)
Abstract Deepwater drilling riser is the key component of offshore drilling rig and directly affects safety and efficiency of offshore drilling operation. Therefore, Integrity management (IM) of deepwater drilling riser is significant for successful field operation. With the effect of serious environment loads in South China Sea, including frequent typhoon and high speed soliton, IM of deepwater drilling riser confronts with severe challenges. Based on Detection and monitor, IM assessment method is proposed, suitable instrument and software systems are developed in this paper. Monitor system, which is helpful for operator to know the real time status of drilling riser, monitors main parameters of drilling riser including VIV, flex joint angle, stress, current speed and floating rig position. With sonar transfer plan, monitor system is developed and applied in 3 deepwater wells drilled by HYSY981 semisubmersible drilling rig, complete real time data is obtained. Simultaneously, based on ACFM (alternating current field measurement) method, rapid inspection technology of riser is proposed, it can timely and effectively inspect defect of riser such as micro-crack, corrosion, etc. Combine with monitor data and integrity comprehensive assessment theory, design of integrity evaluation software are introduced, including mutual verification of monitor data, inspecting data and assessment method of fatigue life and fatigue reliability improvement method. Evaluation model are proposed, suite hardware and software systems are developed, which comprise IM series technique of deepwater drilling riser. Introduction Deepwater drilling riser that connects subsea wellhead with drilling platform, often affected by complex metocean environment loads and drilling operation loads. The IM of riser is an effective way to guarantee the safety performance of drilling riser. The IM of riser focus on identification and evaluation of the risk of riser failure in the whole life. In event of the failure evidence was detected, many relevant remedy measures are adopted, including monitor, inspection and maintenance to avoid the negative influence of riser failure. Many corporations, such as 2H Offshore, BP, MCS, Petrobras, WGIM and DNV, adopt the IM to manage riser, and the relevant recommendations or guidelines of IM of riser have been initially formed (DNV-RP-F206, 2008; 2H, 2000; HOWELLS, 2000; DNV, 2006; MMS, 2008; BOTTO etc, 2010).
- Well Drilling (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Risers (1.00)
Wind Tunnel Experiment on Suppression of Vortex induced Vibration for Circular Cylinder with Fairings at Large Mass-Damping Parameter
Wang, Jiasong (Shanghai Jiao Tong University) | Suijuan, _ (Shanghai Jiao Tong University) | Tian, Zhongxu (Shanghai Jiao Tong University) | Jiang, Shiquan (CNOOC Research Center) | Xu, Liangbin (CNOOC Research Center) | Sheng, Leixiang (CNOOC Research Center)
Abstract A wind tunnel experiments on the suppression of vortex-induced vibration for large mass-damping-parameter (m*ζ=1.415) cylinders attached with fairings is investigated. For the bare cylinder, the nondimensional response amplitude is far less than the low massdamping cases and the typical maximum amplitude response region falls into a large reduced velocity (Ur) range, which can be considered due to large mass-damping value based on the analysis of the previous studies called as "natural frequency" region. For the faired attaching cylinders at the shape angles of 60, 75 and 90 degrees at Ur from 2 to 40, the maximum and RMS response amplitudes of cylinder with fairings are far less than those of the bare cylinder both in the CF and IL directions. The suppression effort of 60° fairing is the most optimal case with the CF RSM amplitude reduction by 67%. The Strouhal number of fairings is also smaller than that of bare cylinder.
- Asia (1.00)
- North America > United States (0.94)
Numerical Simulation of VIV for a Marine Riser in Uniform and Linearly Sheared Currents
Wang, Jiasong (Shanghai Jiao Tong University) | Zhan, Lulu (Shanghai Jiao Tong University) | Jiang, Shiquan (CNOOC Research Center) | Xu, Liangbin (CNOOC Research Center) | Sheng, Leixiang (CNOOC Research Center) | Tian, Zhongxu (Shanghai Jiao Tong University) | Shi, Jianwei (Shanghai Jiao Tong University)
ABSTRACT A numerical simulation of VIV characteristics for an actual size marine riser (342.9 m in length and 0.5334 m in diameter) in uniform (V=0.8 m/s) and linearly sheared (V=0.1~1.5 m/s) currents is presented by using a FSI approach which was ever well validated (Wang, et al, 2011). The riser is pinned at its two ends with no pre-tension. The Reynolds number covers a wide range from subcritical to critical flow regimes appearing in practical engineering. The results showed that the IL (in-line) maximum deflection of risers in the two currents are up to 5D; it occurs at the middle section in uniform current, while at a slightly higher position in the linearly sheared current. CF (cross flow) VIV response of both risers shows 3rd mode with the maximum CF RMS value up to 0.7D; the CF RMS peak value at the middle section in sheared current is much smaller than that in uniform current. Overall, both risers in the two currents have large, unsymmetrical and bending deformations and the risers vibrate with multi-mode.
Abstract In the mid 2012, three deep water exploration wells have been accomplished in the South China Sea by CNOOC as the operator employing the deep water drilling unit HYSY981, which symbolizes the epoch of deep water drilling of CNOOC. By reviewing the history of deep water drilling implemented by CNOOC and its partners, this paper put forward the key challenges of deep water drilling in South China Sea, such as typhoon, soliton, gas hydrates and so on. Potential solutions to these challenges are discussed in the paper, aiming at drilling safety. Firstly, this paper focuses on the strategy of the typhoon resistance for the new building deep water drilling unit (DWDU) HYSY981. On which the preliminary research results are given in the paper. The typhoon resistance solution is drawn up in combination with the platform dynamic analysis and operational mode that have been performed to demonstrate its feasibility. Secondly, the paper shows solutions to the soliton for deep water drilling in the South China Sea. And finally, the recommendation to deal with the risk of hydrate formation in deep water drilling is summarized. 1 Introduction The construction of deep water semi-submersible drilling unit HYSY981, which was sponsored by CNOOC, begun from April 28th, 2008 and was finished on February 26th, 2010. The drilling unit HYSY981 is the first sixth generation semi-submersible drilling unit in China, which is designed and constructed independently by CNOOC. For HYSY981, the operating water depth beyond 3000m, the deck area is 114m length and 89m width. General 3rd dynamic position system is deployed on the drilling unit, while the unit itself can be positioned by anchoring when it is operated in waters less than 1500m deep. The drilling unit was designed to be able to maintain position in the occurrence of a-200years-return typhoon condition.[1] The drilling unit HYSY981 carried out the first well drilling operation on March 6th, 2012 at the LH29–2–1 location. And until August 8th, 2012, the drilling unit has finished drilling and completion operation of three wells, which are LH29–2–1(754m water depth), LW6–1–1(1495m WD), and BY13–2–1(688m WD). During the process of drilling operations at these well locations, HYSY981 experienced four typhoons and twelve solitons. While taking reasonable measures to deal with these threats, the operator CNOOC has summarized experience of dealing with various deep water drilling problems, which forms recommendation for consequential deep water drilling operation of HYSY981 drilling unit in South China Sea. From 2006 on, CNOOC and its partners such as Husky and Devon, has finished drilling and completion operations of 32 wells, including LW3–1–1, BY6–1–1, LW3–1–2, LH29–1–1, LH34–2–1 and LW3–1–10. During these operations period, there are 56 accidents, 20 of which cost NPT more than 100hrs. Figure.1 shows that weather influence and BOP accident are two main factors influencing South China Sea deep water drilling. Severe weather conditions seriously affect drilling operations. When Husky carried out drilling operation at LH34–2–1 location, typhoon " Koppu" attacked the drilling unit HYSY981, with the drilling riser & LMRP hanged on rotary table, the drilling unit was push to shallow water district, the LMRP collided with seafloor, which resulted in the damage of riser joint, telescopic joint and tensioner. More than 50 regular work days and 50 million dollars were lost. [2] By reviewing the history of deep water drilling implemented by CNOOC and its partners in the South China Sea, this paper presents the key challenges to deep water drilling, such as typhoon, soliton, gas hydrates and so on, which are unique in the South China Sea. Firstly, proposed strategy solutions of the typhoon resistance for HYSY981 to these challenges are discussed in the paper, and these solutions should be draw up in combination with the platform structural analysis and operational mode.
- Asia > China (1.00)
- North America > United States > Texas (0.28)
- Well Drilling > Drilling Operations (1.00)
- Well Drilling > Drilling Equipment (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Risers (1.00)
- Facilities Design, Construction and Operation > Flow Assurance > Hydrates (1.00)
Three Dimensional Numerical Simulation of Vortex Induced Vibration For a 500-m-long Marine Riser
Wang, Jiasong (School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University) | Zhan, Lulu (School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University) | Wang, Chenguan (Key Laboratory of Power Machinery and Engineering, Shanghai Jiao Tong University) | Jiang, Shiquan (CNOOC Research Center, China National Offshore Oil Corp (CNOOC)) | Xu, Liangbin (CNOOC Research Center, China National Offshore Oil Corp (CNOOC))
ABSTRACT: A three dimensional vortex-induced-vibration (VIV) fluid-structureinteraction (FSI) simulation for a 500-m-long marine riser is presented in this paper. The simulations were implemented by solving the unsteady Reynolds Navier-Stokes equations and the k-ω turbulence model coupling with the dynamic response equation. A good agreement was achieved by modeling an available experimental VIV problem. Several cases of VIV simulations for actual size of a marine riser, 0.5334 m in diameter and 502.92 m in length with different top preloads were carried out to address the control of VIV. The obtained results indicate that large, unsymmetrical and bending deformations appear to the riser, the riser vibrates with multi-mode, and the in-line dynamical response should not be ignored. When exerting a proper preload, the vibration amplitude is reduced remarkably and the excited mode number is reduced as well, which reflects that exerting preload is a good manner to suppress the VIV of long marine riser. INTRODUCTION Vortex shedding due to flow around a fixed or oscillating cylinder exists widely in a lot of real practical engineering, especially in the offshore engineering. Vortex induced vibration (VIV) analysis plays a leading role in determining the life span of marine risers, which may be considered to be an important source of failure of marine riser in the offshore industry. With the development of deepwater oil exploitation, the need to enhance our knowledge about VIV of risers with considerably large aspect ratio of length to diameter has greatly risen. A better comprehension of VIV for risers in real ocean conditions is necessary. From the multi-physics point of view, when fluid interacts with a solid structure, fluid-structure interaction (FSI) will occur, then exerting pressure varying periodically to the structure. As a result, it leads to time-varying deformation of the flexible structure, and then alters the flow field conformation.