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Collaborating Authors
Results
The First Application of a Coiled Tubing Catenary System in the Gulf of Thailand. A Technology Break Through for Offshore Facilities with Space and Weight Limitations
Uasetwattana, Jantima (Chevron) | Kanchiak, Surachai (Chevron) | Kornkitsuwan, Chaichana (Chevron) | Wattanasuwankorn, Reawat (Halliburton) | Jiemsawat, Nophadol (Halliburton) | Toh, YeaLee (Halliburton)
Abstract Coiled Tubing (CT) catenary technology supports the possibility of executing offshore interventions on platforms with space and weight limitations. Having the majority of the CT equipment remain on a separate support vessel vastly increases the platform working area and minimizes offshore heavy lifting. The system allows the operation of well control and pumping equipment from the vessel for a single control source and an overall faster, safer, lower-cost operation. Limited offshore platform space and crane capacity are a significant concern for intervention operations in the Gulf of Thailand. A conventional CT unit is simply unable to fit on a small offshore facility. The catenary system was introduced to eliminate these limitations by keeping the main CT equipment on the vessel while providing the connection and interface between the vessel and platform equipment, allowing a safe and efficient operation. It also has the flexibility to enable the vessel to adjust its location during bad weather if required, without affecting the overall safety of the operation. The same system can also be used on regular platforms without space and weight limitations during the same campaign. The catenary system saved two days per well, resulting in savings due to less equipment utilization, reduced personnel, and accommodation requirements, and reduced consumables used. Less heavy lifts also saved time, associated costs, and increased safety during the preparation phase. The CT operator can also load the maximum length of CT pipe onto the vessel without concerns about having to join multiple strings or using split reel spooler equipment. All well control equipment was function tested and operated as standard with real-time monitoring and capturing of well conditions, operation parameters, and CT fatigue the same as expected from a conventional CT setup. The paper will elaborate on the catenary principles, concepts, and engineering background for these types of operations. The CT catenary was proven to bring significant efficiency improvements, safety enhancements, and faster operations, leading to cost-saving when carrying out CT interventions in the Gulf of Thailand. The techniques and details will be elaborated on in the paper.
An Integrated System for Improving Geotechnical Performances of Jackup Rig Installation
Quah, M.. (Keppel Offshore & Marine Singapore) | Cahyadi, J.. (Keppel Offshore & Marine Singapore) | Purwana, O. A. (Keppel Offshore & Marine Singapore) | Krisdani, H.. (Keppel Offshore & Marine Singapore) | Randolph, M. F. (Centre for Offshore Foundation Systems, The University of Western Australia)
Abstract Predictability and consequential safety of jackup rigs during installation and removal remain non-trivial issues for the industry despite larger deployment of jackup rigs and operations in emerging frontier regions with more complex soil conditions. Jackup foundation hazards such as unpredicted leg penetration, rapid leg penetration, punch-through, spudcan-footprint interaction and leg extraction difficulties continue to occur in spite of the industry stepping up efforts to better control of the risks. Apart from improvements of the installation guideline and practice within the industry as well as implementation of proper site specific assessments, safer performance of jackup rigs may be achieved through advancement in jackup instrumentation technology. In the present paper, a new instrumentation technology integrated with jackup rigs is proposed to assist the jackup operators in making decision and taking measures to prevent or mitigate potential geotechnical hazards, particularly punch-through.
Abstract This paper presents the development of a completion and workover riser that incorporates a modified second-generation rotary-shouldered connection (RSC). This double-shouldered connection features a high-pressure, gas tight, metal-to-metal radial seal, a secondary back-up resilient sealing barrier and additional modifications to cope with subsea conditions. The comprehensive effort to design, test and qualify the completion and workover riser for offshore conditions in Australia and Africa is detailed. Results from extensive finite element analysis, laboratory tests, manufacturing processes and field results are presented. The results of a 15-month project are the design, testing, manufacture and deployment of a performance validated, RSC completion and workover riser system. The riser was successfully placed into service and utilized on the Enfield and Chinguetti oil, gas and water injection wells located offshore Western Australia and West Africa. The purpose of developing the RSC completion and workover riser was to create a cost effective and efficient riser system to meet the requirements of the innovative well completion system used on the Enfield and Chinguetti wells. The gas-tight, metal-to-metal seal RSC riser is robust, easy to handle, light weight and has a smaller deck footprint than conventional dual-bore risers. Introduction Conventional dual-bore completion and workover risers can be costly to purchase, take up considerable amount of deck space and result in increased riser string weights reducing net lifting capacity when deploying tubing or a subsea tree. The weight of dual bore riser systems can preclude the use of smaller, lower cost drilling rigs on development well work, particularly in deeper water. There are various designs of completion and workover riser connection systems, some of which require special, sometimes slow to operate, make-up spiders. Deployment of a tubing string or subsea tree requires both make up and break out of a large number of riser stands. Slow make-up and break out of joints can result in significant increased rig time particularly on a field development program comprising many subsea wells in deep water. In times of high rig rates, the cost associated with slow or non-optimized riser operations can be significant. Overview of Enfield The Enfield oil field is located 40 km (25 miles) northwest of Exmouth, Western Australia (Figure 1), within 16 km (10 miles) of the Ningaloo Reef Marine Park. The field started production in July 2006 and comprises five subsea production wells, six water injection wells and two gas injection wells tied back via manifolds and flow lines to a floating production, storage and offtake vessel (FPSO). The water depth at Enfield ranges from 400 to 600 m (1,300 to 2,000 ft). The wells were drilled and completed from an anchored semi-submersible drill rig. Overview of Chinguetti The Chinguetti oil field is located 80 km (50 miles) offshore Mauritania, west coast of Africa (Figure 2). The field started production in February 2006 and comprises six oil production wells, four water injection wells and one gas injection well tied back to an FPSO. The water depth at Chinguetti ranges from 700 to 850 m (2,300 to 2,800 ft). The wells were drilled and completed from a dynamic positioning (DP) drill ship. At this time Woodside no longer owns any assets in the Chinguetti field.
- Africa > Mauritania > North Atlantic Ocean (0.55)
- Oceania > Australia > Western Australia > North West Shelf (0.24)
- Africa > Mauritania > North Atlantic Ocean > Mauritania-Senegal-Guinea-Bissau Basin > PSC B > Block 4 > Chinguetti Field (0.93)
- Oceania > Australia > Western Australia > North West Shelf > Carnarvon Basin > Exmouth Basin > PL WA-28-L > EnField Field (0.92)
Abstract There will be a big marketing for drilling in deepwater in the world. But there are few drilling vessels or platforms to suit to drilling in deepwater or super deepwater in international. COSL (China oilfield Services Ltd.) has some semi-submersible platforms and they are only suit to operate lessen to 500 meters of water depth. It become a difficulty for the company how to enter deepwater drilling market in time according to its condition of equipment? COSL noticed a new concept of deepwater drilling from a Norway's company, and it means that some device might be fabricated, which may be matched with semi-submersible platform to drill in deepwater, operating depth about 500 m to 1500m. The concept name is Artificial Buoyancy Seabed (ABS). Its main principle is to set a tank of buoyancy under 300 m under sea level, which is located the center of bottom of the platform. The device utilizes the buoyancy force of the tank of column to support weight of BOP, so BOP will set in short distance from the face of sea. The result of using the device is that operation in deepwater will be the same as sallow water. It will improve the capability of the semi-submersible if ABS device would be used when drilling, which could increase the depth of water of operation, from 457 m to almost 1500 m in the offshore. It is very difference between shallow and deep sea that devices testing before operating in formal. In shallow sea, the device could be used directly after designed in primary. In contrary, the device of the deepwater will be used through a lot of testing and simulations because it is very expense that cost of operation in a day. The researchers and engineers would guarantee the device should be good properties and performances before it was used in the practice of the offshore. Since June 2004, COSL has carried out a series of item of the researches, experiments, and tests for the device, including to 9 experiments in some institutes in China and Norway, to proven its properties. The work correlative the device had been finished by cooperation both Chinese and Norwegian experts. This paper describes the procedure of work proven. The test in preliminary had been proven that the design of the device is reasonable, and COSL will do the first trial well in South China Sea at the end of 2006 or the beginning of 2007.
- Asia > China (1.00)
- North America > United States > Louisiana (0.25)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > Asia Government > China Government (0.55)
- North America > United States > Louisiana > China Field (0.99)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Green Canyon > Block 744 > Atlantis Field (0.98)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Green Canyon > Block 743 > Atlantis Field (0.98)
- (3 more...)
Proposal This paper presents the planning and execution to effectively mitigate the risk associated with uncontrolled leg penetration. Planning reviews the soil analysis work used to understand the hazards and the development of solutions for obtaining a suitable jack-up foundation. Execution describes the procedures used to implement the mitigation plan at the hazardous sites. Introduction A jack-up rig requires a suitable foundation that is ultimately governed by the soil properties at a respective location. During a mobilization, the jack-up is loaded with temporary weight or preload to simulate the storm reaction loads and the offset loads associated with drilling, thereby causing the spud cans and legs to penetrate the seafloor to an acceptable foundation. The soil bearing capacity at final penetration must offset the maximum rig weight that may result during operating and storm loads. Some locations have a hazardous soil condition challenging the ability to safely mobilize a jack-up rig and achieve leg penetration to an acceptable foundation. This hazard exists when a strong soil layer having insufficient bearing capacity to support the rig overlies a weaker soil layer. Failure to recognize and mitigate this hazard can lead to severe consequences associated with uncontrolled leg penetration or punch-through. Punch-through occurs when a stiff layer overlying a weaker layer gives way to the can load and uncontrollable penetration occurs into the weaker layer. Uncontrolled penetration is exacerbated as the load on the punching leg increases due to the weight offset (P-delta effect) and leaning instability. As the rig becomes unlevel, additional weight is applied to the penetrating leg with the change in center of gravity. A punch-through typically results in loads beyond the structural design of the leg and can cause significant structural damage. An industry practice known as "swiss cheese" drilling can be used to effectively weaken or degrade the thin, hard clay layer and allow controlled penetration in these environments. Although not common, "swiss cheese" has typically consisted of drilling 30 to 40 holes having a 26 to 36-inch diameter through the hard clay layer in each planned spud can footprint. The holes reduce the effective bearing capacity of the hard layer and allow controlled penetration into the weaker underlying layer during the preloading exercise. "Swiss cheese" operations are typically completed using the jack-up rig being mobilized on location. In general, the operation is completed in the afloat mode with the cantilever extended to position the rotary just beyond the transom. A four point mooring system is used to maintain position and achieve the target pattern of holes in each planned spud can location. Upon completion, the rig is repositioned over the planned footprint and preloaded to final penetration. The Raya B and Tapis F platform locations offshore Peninsular Malaysia were identified to have unacceptable risks associated with uncontrolled penetration or punch-through. The decision to "swiss cheese" the respective footprints at these two locations presented unique challenges compared to other known "swiss cheese" operations in the region. A support vessel equipped with a coring unit and four point mooring system was selected to conduct the operations prior to each rig's scheduled mobilization as a result of jack-up rig specification issues. Limited equipment specifications and operational constraints of the coring unit challenged engineering to develop an optimized "swiss cheese" pattern for maximum bearing strength reduction.