Advancement in Geotechnical Site Investigation Practice Using ROV Technology
Authors: Barwise Andy , Cowie Michael 
Published: May 2013

This paper discusses the use of ROV technology to enable conventional geotechnical site investigations to change focus. The move to deeper water, close proximity work and decommission works has meant that the integration of ROV technology and conventional geotechnical equipment has led to a greater variety of solutions that can be tailored to fit a client's needs.

The paper will cover the application of this technology in some recent projects. These will cover a decommissioning project where investigations were required on drill cuttings that existed underneath an existing structure and also locations close to seabed infrastructure. By integration of a CPT (Cone Penetrometer Test) and sampling equipment on to an ROV it was possible to fly around the structure to investigate both environmental and geotechnical properties of the ground. It will also cover the utilization of a fully developed ROV drilling system for a variety of projects from shallow water wind farm sites to deepwater developments, proving the versatility and cost effectiveness of these solutions.

In summary, results will be presented to demonstrate the next generation of site investigation tools and explain how, after years of traditional one size fits all solutions, new technology is enabling project teams to fine tune investigations. Utilizing a variety of working platforms makes geographically remote areas more accessible and economical to work.

The use of new developments, utilizing industry standard testing and sampling solutions, with deployment systems, incorporating ROV technology, is changing the way site investigations can be performed. This enables a client-focused approach to offshore geotechnical site investigations in technically and geographically challenging environments.

Introduction

The fundamentals of offshore geotechnical site investigations have not changed for decades. There is a requirement to measure soil properties insitu via the Cone Penetration Test (CPTU) and to recover soil samples to enable the assessment of soil properties by means of testing within a soils laboratory. The procedures and requirements for performing these testing or sampling activities are prescriptively described in various International Standards that are well documented.

What is driving change is the nature of the site investigations. As developments continue to move towards deeper water, more geographically remote areas and locations that already have significant existing subsea infrastructure, the traditional forms of investigation are not always the most practical, technically suitable or economic solutions. This has led to the adaptation of the traditional methods of sampling and testing of soils being integrated with ROV technologies to enable a flexible and often more cost effective solution. It should also be considered that in many of the applications that are now using ROV technology there is less manual intervention with operations happening at seabed and thus a much reduced HSE risk than conventional deck mounted drilling and testing operations.