GLOBAL MARINE GEOCONSULTANCY

 

The AUV as a survey sensor platform

 

The search for hydrocarbons has led Explorationists into ever deeper water.  Their success has caused oil and gas field developers to follow them.

Until relatively recently, deep-water geophysical site surveys have not delivered particularly satisfactory results, mainly due to:

Hull-mounted survey sensors are so far away from the seabed sediments that they are imaging that the energy transmitted by the sensor has largely dissipated and spread out.  The data is therefore weak and has poor resolution.

Deep-tow survey sensors can get close to the seabed sediments they are imaging but they are hard to position, making it both difficult to get a complete data set and to relate what is seen to real-world coordinates.

Tow cable lengths are approximately three times the water depth of the survey area so that the survey vessel spends more time manoeuvring to get on line than it spends on-line acquiring data.

 

The above factors result in relatively poor quality data, imprecisely positioned, that takes a long time to record and therefore is expensive to acquire.  The remoteness of deep-water acreage adds to the difficulty and cost.

 

AUVs have come to the rescue.  They:

Place the survey sensors optimally with respect to the seabed, enhancing resolution.

 Proceed calmly along the survey line at a steady speed, providing the best data density.

Go quickly from line to line, spending much more time productively acquiring data.

Are precisely positioned, placing features seen on the seabed accurately in the real world

The result is data of "stunning" quality.  The topography of the seabed is revealed in unparalleled detail.  So are the seabed features and the structure of the sediments immediately underlying the seabed.  The quality of the data is such that the information about the survey that is abstracted from it is frequently superior to the information from data conventionally acquired on shallow water sites.

 

The "engineering quality" data from AUV surveys is being used to not only determine where and what these geo-hazards are but also as an input to a quantified assessment of the risk that a geo-hazard, either by itself or in combination, poses to the development.

 

 Global Marine GeoConsultancy

 

Fugro is a company that specialises in the interpretation of geophysical, geological and geotechnical data.  They have global experts on all types of geo-hazards such as gas hydrates, mud volcanoes and large sediment slides.   There are groups of specialists concentrating on disciplines ranging from the interaction of oilfield furniture foundations (suction piles, wellheads, manifolds etc.) with specific soil conditions, to pipe span analysis and seismology. Calling upon its well established, world-class resources and experience, Fugro is launching a Global Marine GeoConsultancy which is designed to combine the capability of individual experts and groups located in offices across the world into one coherent unit. This will be enabled by the electronic sharing of computer models, using the web, videoconferences, desktop sharing, email and high rate data transfer methods as well as actual visits and working groups. Fugro can therefore provide this expert information to clients irrespective of where they are and irrespective of where their development is or what their geo-hazards are like, using advances in survey technology, but also advances in communications technology to deliver this global expertise.  

Four main centres, in the Netherlands, United Kingdom, USA and Singapore, will form the hub of this initiative, essentially providing a 24-hour service.

 

Regional offices can call upon this service as necessary and conversely, the network can call upon regional expertise as required.

 

What is being provided is a worldwide interpretation facility to support the worldwide survey acquisition capabilities  that are already offered.