Design Testing of a Blowout Preventor and Controls System For Drilling in 1,000 Feet of Water
- C.P. Peterman (Shell Oil Co.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- September 1966
- Document Type
- Journal Paper
- 1,023 - 1,028
- 1966. Society of Petroleum Engineers
- 4.3.4 Scale, 1.10 Drilling Equipment, 4.1.2 Separation and Treating, 1.7 Pressure Management, 1.6 Drilling Operations, 4.1.5 Processing Equipment
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This paper describes the design considerations for selecting a blowout preventer control system and associated handling techniques required for drilling in 1,000 ft or more of water from a semi-submersible drilling vessel. Design, manufacture, fabrication and assembly testing have been completed. This system is described and a summary of test information is included. The control system is entirely hydraulic using either hose or remote pilot operated circuits, depending on response time required for each control. A steel wire-reinforced hose bundle was designed and built in one continuous length to allow operation without extra support or guidelines. Handling techniques have been developed which should allow the control equipment to be run and retrieved without pulling the marine conductor. A unique unitized triple ram blowout preventer unit was designed and built so that the over-all height of the drilling control wellhead could be reduced to allow it to be used with existing vessels. Other components such as the control panel, hose reel, kill and choke line assembles and underwater hydraulic connectors are discussed.
The problem was to secure a blowout preventer system capable of drilling in all water depths up to 1,000 ft or more. Previously used control systems were reviewed to determine what blowout preventer experience was directly applicable and what modifications or new developments would be required. In addition, this study took into account the sea conditions existing along the West Coast where this system will be tested. Maximum storm conditions in this area include wave heights exceeding 40 ft, current in excess of 3 ft/sec and winds in the range of 100 mph. Continuous operation under these conditions is not a requirement, but the equipment selected must survive the wave forces and rig motion which may occur during these storms. As explained in the report, the primary control linkage between the blowout preventer stack and the vessel is to be attached to the marine conductor. Successful operation of the marine conductor is assumed during the discussion of this primary control linkage. This report reflects the effects of sea environment on the controls, reviews the developments required and describes the final system which is now awaiting drilling tests. This review places many of the significant design factors for a subsea blowout preventer system and associated operating techniques in one place. There may be disagreement with the equipment and techniques selected, but the effect of the severe environment (depth and sea conditions) on the design should be appreciated. Hopefully, additional design criteria concerning the vitally important blowout preventer operation will be presented by others as it is revealed both by experience and study. Analytical solutions for design problems were used several places. Some of these data are to display the order of magnitude to be expected rather than to be used for detailed design. In some cases data are restricted to a particular item, good only for that item but furnishing characteristics which may be expected from similar items. Many times, however, simple tests provided adequate design information with much less effort. For instance, full scale tests of the control circuits were used to evaluate the feasibility of remote, pilot operated hydraulic controls. Design data for the control hose bundle were obtained by subjecting a full-sized prototype bundle to maximum forces calculated to exist during actual operation. Finally, full scale land assembly tests of the equipment were accomplished to further check handling and operational characteristics.
The equipment to be used in this blowout preventer system will be identified in ascending order, from the sub sea wellhead to the control equipment located on the drilling vessel. A symmetrical four line system will be used to guide the blowout preventer stack and other drilling equipment to the wellhead. One of the basic design criteria was that the control system should be in place and fully tested on the spider beams of the vessel before the stack was lowered into position. The blowout preventer stack will normally be lowered and retrieved while attached to the marine conductor.
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