A self-contained downhole recording instrument was developed and used to measure and record drilling string forces and motions. The eight signals recorded by pulse-width modulation on magnetic tape were: axial, torsional, and bending loads; axial, angular, and lateral accelerations; and internal (pipe) and external (annular) pressure. The device was used over a two-year period to collect data in fifteen wells under a wide range of drilling conditions. After about nine minutes of cumulative recording time, the tool was retrieved and brought to the surface. Data were converted from the magnetic tape to analog type oscillograph display and, in some cases, were digitized for analysis purposes. Normal variations in measured downhole bit load usually ranged between 25 and 50 percent of the mean value. Maximum bit loads reached over 3.5 times mean loads in some instances. Frequencies of weight, torque and bending traces showed evidences of rock bit tooth action, of cone action, of rotation, and also of pump pulsations. Large annular pressure variations accompanied large load variations.
The need to produce oil and gas in water depths beyond the physical and economical limits of fixed platforms and pipelines has led to the development of a feasible concept for an articulated multiline flexible marine production riser system. This paper covers the history of the concept development from inception to readiness for engineering design and fabrication of a prototype test model.
This paper was prepared for present~tion at the Seventh A~nual Offsho~e Technology Conference to be held in Houston, Tex., May 5-8, 1975. PermisSlon to co~y 15 restricted f to ,an abstract of not more than 300 words. Illustrations may not be copled. Such US~0 an abstract should contain conspicuous acknowledgment of where and by whow. the paper 1S presented.
AbstractEngineering and development work to provide means for simUltaneously flexing multiple rigid lines has produced a multi-line universal joint capable of high degree flexure in any direction. The work included conceptual and engineering design, manufacture and field testing of a prototype, and redesign of the joint based on field test results.The end product of this development can be applied worldwide to any offshore system of multiple flowlines, such as a deepwater production riser system, where simultaneous free flexure in any direction is required.
Properly designed and developed swivels represent a reliable and practical means for providing required flowline flexibility in multiline marine production risers. The lack of suitable commercially available swivels caused Exxon Production Research Company, in the early 1970’s, to initiate a research and development program to produce swivels that would meet the requirements for marine riser service. This paper provides some basic information about swivels and describes some promising swivel design concepts. It also discusses potential applications for swivels and the need for continued development effort.
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