The present paper addresses comparison between predicted and measured bending stresses in one umbilical cross section during manufacturing. A factor with significant uncertainties has been which stresses that will occur during the manufacturing procedure when the umbilical is reeled on and off storage drums. The umbilical components may not only be exposed to pure elastic bending stresses due to the curvature radius but also second order axial stresses due to the combination of curvature gradients and finite length to the end fittings. In cooperation with Aker Kværner Subsea a.s., Marintek has developed a tool for stress analysis of Aker Kværner umbilical cross-section designs. The main motivation behind the development has been to reduce technical risk and costs associated with umbilical manufacturing, installation and operation. This is obtained by increasing the basic understanding of the umbilical cross-sections mechanical behaviour and the ability to quantify the stress response when exposed to various loads. In order to calibrate the mathematical model with regard to manufacturing stresses a 70 m long umbilical prototype was instrumented by strain gauges and reeled on an off a storage reel with radius 4.4 m. The paper presents the model applied to simulate this operation as well as the results from comparing predicted and measured stresses.
A. Figenschou, Articulated Column Norway A/S w IW130Summary. An articulated tower for drilling and production in the Norwegian Sea in water depths of L,150 ft [350 m] is presented. The main features are production trees it the deck level; a 19,000-ton [17 OOO-Mg]deck payload; limited motions; a steel structure, including main float and latiice; low-stressed mechanical articidation with antitorque device; and controlled bcndlng risers. This extensive study has considered in detail the behavior in extreme condkions, the fatigue of mtin WTIMLWII parts and risers, operating procedures, fabrication, and installation. Generaf results are given concerning behavior, structural design, articulation, bending riser, fabrication, and installation. A fabrication and installation schedule is also given.
A submudline protection silo system has been developed. The silo is a cylindrical shaped steel structure having a diameter of 9 metres and a total weight of 125 tonnes. The installation method described in the paper is presented in a step by step manner. The structure is transported from shore to the offshore site by a supply vessel. The silo structure is transferred from the supply vessel to a drilling rig. When the silo is placed on the seabed, an installation tool is run by the drilling riser and docked into the silo. The penetration of the silo into the seabed is achieved by using standard equipment onboard a drilling rig only. The excavation process is fulfilled by water jetting and the soil is removed by electrically driven mass pumps. The penetration force is achieved by creating a suction underneath the silo floor. The silo is equipped with systems to remove drill cuttings and excessive cement during drilling operation. The top of the silo has a roof system to protect the X-mas tree from falling objects. Maintenance and inspection of the silo x-mas tree is done by a guided ROV through a hatch system in silo roof. INTRODUCTION This paper presents a development work on submudline silo made by Kvrerner Eureka a.s on behalf of Saga Petroleum a.s. The main purpose of the work was to develop a simple and cost efficient method to install a silo system on one of Saga Petroleum's future wells in the North Sea. DESIGN DATA AND PHILOSOPHY Functional requirements The silo concept shall meet the following functional requirements: The silo concept shall be equipped with a standard drilling template. Drilling of a well and well completion shall be possible using standard drilling procedures and drilling equipment. The silo structure shall have sufficient internal space for a standard blow-out preventer. The silo concept must have a system to discharge the spoils during the 36 inch hole drilling operation. The silo shall have a protection roof. A discharge system to remove sediments or spoils during operation. The X-mas tree shall be retrievable without disconnecting the production pipeline. Design loads The silo structure, including the roof system, shall be designed for dropped objects, wire pulling (fishing gear) and impact from fishing gear. The following loads are used in this study:(available in full paper) Design philosophy The following presents the main philosophy for thisproject: To the maximum extent, make use of standard and well proven drilling related technology. Give priority to simplicity and existing technology. Try to avoid "point of no return" during installation. It should preferably be possible to carry out the silo installation and well completion as a continuous operation All methods, solutions and design details chosen shall be carefully weighed against the impact on the concept total cost.
This paper will present a new manufacturing method for Umbilicals. The new bundling principle presented here has eliminated the weight and volume limitations of the conventional systems. The conventional manufacturing method is to use a vertical or horizontal planetary machine which requires that the pay-off reels has a rotation about the centre of the umbilical during closing operation. Each of the planetary positions has a weight and volume limitation. The new manufacturing method, which is based on SZ stranding, is based on static pay-off reels and a static (non-rotating) closing point as opposed to the planetary system. This principle has been made possible by a periodically change in the lay direction during the bundling operation. Due to the long lay-length configuration, there are no requirements for a separate armour system as the internal elements carry the load without excessive rotation of the umbilical.
A new generation drilling mud pump has been designed and full scale prototype tested. The test program has confirmed the feasibility of the new concept and the special features.The pump, which is a piston pump, controls the pumped flow by changing piston stroke rather than speed and therefore eliminates the need for SCR systems.A membrane prevents the drilling fluid from coming into contact with piston. and cylinder, thus eliminating the liner wear problem.The pulsation in mud discharge is reduced and at constant frequency independent of flow creates an ideal condition for turbo drills and MWD.
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