TSP - New Solution for Geotechnical Studies in Deep Water Environments

Abstract

ABSTRACT The oil and gas industry is constantly moving into greater Water depths. Determining the seafloor's ability to Support offshore structures, templates and pipelines is Among the numerous challenges. In deep water Geotechnical investigations have traditionally been Conducted using expensive drilling vessels or semi submersible rigs. Greater water depths require new Technology for the efficient, how cost acquisition of soil Design data. Lye Tethered Seafloor Platoons (TSP) Prototype was developed and tested for the purpose of Obtaining in situ soil property measurements in water Depths as great as 3,000 meters. INTRODUCTION Anticipating its future needs in deep water, Mobil Launched the TSP project in the fall of 1989. The Concept was to design and build a subset module that could continuously measure geotechnical properties fromThe seafloor down to approximately 70 meters. This Would be accomplished by using a remotely-operated package to push specially designed probes downwards through the seabed. The TSP system would be operated From vessels-of-opportunity equipped with dynamic Positioning facilities and would have a water depth Capability up to 3,000 meters. It would be simple in Operation, requires minimal maintenance, and provide Reduced operating cost. The ambitious project described above was the result of About thirteen years of dreaming, planning and Designing. The original idea was conceived by Researchers from Mobil and McClelland Engineers. In August 1981, the conceptual study was initiated by Mobil Research and Development Corporation in Dallas, Texas, and resulted in McClelland Engineers' report in March 1982, which recommended the TSP approach for? Deep water geotechnical data collection. A more detailed Feasibility study was authorized in January 1983 and a Report was issued the following December entitled "A New Approach" to Offshore Geotechnical Investigations - A Compact, Deep Penetration Tethered Seafloor Platform'. This study included yard and field testing of a standard Coiled tubing injector as a means for pushing Geotechnical test probes into the soil. Field testing was Conducted in Venice, Louisiana and nearly vertical penetrations to 53 meters were achieved in marine type Soil conditions. The results of the tests were encouraging and recommendations were made to proceed with building a prototype TSP. Progress on the implementation of the idea fell victim to The downturn in the offshore oil industry and a lack of funding for research projects during the mid 1980's. Work was suspended until the latter part of 1987, when The project was revived by Mobil Exploration Norway Inc.(MENI). This lead to the formation of the joint-venture Nonvoting company, Seabed Exploration A/S (SEAS), to Execute the development contract and begin work. Established in Bed, Norway during September 1989, Seabed Exploration is jointly owned and staffed by the Parent companies Rapp Marine in Bed, Norway and Forgo-McClelland Marine Geosciences, in Houston, Texas. The work was performed by an integrated team with personnel from mechanical system RappMarine providing expertise in Design, construction, and testing. And personnel from Forgo-McClelland, Houston, Providing geotechnical expertise and overall project Management. Forgo Engineers B.V., Holland, was Responsible for probe and data acquisition system Development.