A Deepwater Vessel and Riser Measurement Program collected 93 days of data describing 83 channels of environmental conditions, vessel response, and riser response in 1700 feet of water in the Gulf of Mexico. On the order of 10 million data measurements were recorded using a minicomputer-controlled data acquisition system. This program has produced the most comprehensive and extensive field database for such systems to date.
Recently our client was preparing to drill several exploratory wells in deepwater in the Gulf of Mexico. In planning these operations it was desirable to conduct analyses of the expectable behavior of the moored semi-submersible drilling vessel and the marine riser.
The computer programs used for these analyses require as their input a description of the expected environmental conditions. Our client did not possess a comprehensive database which described these environmental conditions In the area of interest. Moreover, the output of these computer programs had not, in large part, been verified to any degree with field data. A database which also contained measured vessel and riser responses could be used for this purpose.
Our c1ient also wanted to obtain better information concerning the ordinary range of operating conditions from a drilling program management point of view, particularly for the riser. As an example, it is commonly presumed that a moored semi-submersible drilling vessel typically operates within 1% of the hole nearly all the time, but Whether or not this was in fact the case could not be confirmed, nor was a distribution available as to "what percent of the time could the vessel be expected to be more than 1% of water depth away from the hole, more than 2%, etc.?".
Systems Management and Engineering Corporation was contracted to obtain this information by assembling and operating a comprehensive data acquisition system, and to reduce the acquired data. This paper' describes the design, installation, and operation of the system instrumentation hardware and software. An outline of the data reduction performed to date is also presented.
In planning the Deepwater Riser and Vessel Measurement Program (hereafter referred to as DWMP), we first separated the data to be measured into the three general categories of Environmental Conditions, Vessel Responses, and Riser Responses. The parameter's which we desired to measure in these categories are given in Table 1.
For the Environmental Conditions it was decided that wind, wave, and current information was sufficient as these are the only parameters which significantly affect vessel and riser response and are used as input to an.1ysis programs.
The Vessel Responses and Riser Responses to be measured were also based on the input requirements and output provided by vessel and riser programs, together with what was felt useful for operations planning. These included vessel mean position and dynamic motions, and riser axial and bending loads, motions, and inclinations.
