Measured Wave Force Data on Offshore Platforms

Abstract

ABSTRACT Wave forces on vertical cylinders and wave profiles were measured with instruments on two oil production platforms in 30 ft (1954–58) and 100 ft (1960–53) of water, respectively, in the Gulf of Mexico. Waved data were recorded during a number of storms and for waves up to 40 ft in height. The Standard Oil Company of California designed, installed, and operated the measurement systems. Shell Development Company and Esso Production Research were financial participants in the projects; the U.S. Navy obtained these data as a data purchaser. These data have been proprietary but will soon be deposited in public archives. The purpose of this paper is to present the following background information that defines the wave force data being made available.Instrumentation.Raw data collected.Data processing steps.Location of archives. INTRODUCTION A Gulf of Mexico platform designer needed especially strong nerves during the period around 1950. He was designing drilling platforms for a multimillion dollar investment in the hurricane belt, but didn't know what would happen when those hurricane waves smashed into his platform. How big are such waves and what force do they exert? He had asked oceanographers and ocean construction men who offered calculation schemes but had little actual data on wave heights, wave forces, and tide levels that he could use for design. Recommended wave force values had a 4t to 1 spread. The only way the designer could decrease that spread was to place instruments in the ocean and take the measure of the waves. Designers in several oil companies took that step. Table 1 lists some of the wave measurement projects that were started. Probably the construction and operation phases alone of those projects have cost the industry in excess of $2,000,000 and the data obtained are the most complete and accurate information available today for platform design. This paper describes the information obtained in two of the listed projects, Wave Projects I and II, operated by Standard Oil Company of California, and announces the availability of the measured data. THE INSTALLATIONS The wave measurement installations were located in the Gulf of Mexico because the immediate design problem was there, and hurricanes occurred frequently to generate the large waves important to platform design. Figure 1 shows the locations of the two installations. The first installation, Wave Project I, was completed in late summer 1954 on Chevron D platform, Bay Marchand in a water depth of about 30 feet. Data were obtained during five hurricanes and many smaller storms. After more than four years of operation, the instruments were dismantled at the end of the 1958 hurricane season. A study of the data obtained during Wave Project I indicated that further measurements were warranted. To obtain data from larger wave in deeper water, a second installation, Wave Project II, was placed in operation in late summer of 1960 on a Chevron platform at South Timbalier Block 63. The water depth is about 100 feet.