Underwater Positioning

Centimetric Accuracy Underwater-GPS
By Camille Béchaz, ACSA and Fran­­çois Boucquaert, Fugro-Topnav, France Fugro evaluated the accuracy of the GPS Intelligent Buoy (GIB-Lite) system for its possible use in shallow-water offshore underwater positioning applications. The trials proved that system accuracy could be brought up to centimetre level, the distance between two simultaneously tracked acoustic pingers having a standard deviation of 8cm. Additional works next to an offshore production platform are often required to increase oil recovery from an existing reservoir or to maintain its production rate over a longer period of time. The seabed near such a production platform typically shows pipelines, electric cables,... (read more)
2008-01-01 01:00:00

Satellite Positioning

Within the last twenty years Global Positioning System (GPS) receivers have revolutionised navigation. Integrated devices are capable of providing time, position, height, direction, heave and attitude to accuracies of a few nanoseconds time, 1cm position or 0.01 degree heading. All potentially displayed on a digital chart background with radar and auto-identification system overlays. In this first of two articles we look at current Satellite Positioning systems, how they work and how we can make them better. In a second article, to appear next month, we explore the future development of Satellite Positioning and the implications for navigation. How does Satellite... (read more)
2008-01-01 01:00:00

Subsea Positioning Transponders Order

Unique Systems (USA) has taken delivery of a major consignment of Compatt 5 subsea positioning transponders from Sonardyne. The order complements Unique's existing worldwide inventory of Sonardyne acoustic equipment which includes RovNav 5 Long BaseLine transceivers and Ranger Ultra-Short BaseLine systems.     Unique Systems is part of the Unique Group based in Sharjah (UAE), which is a major distributor and rental company for advanced marine and diving equipment. The Compatt 5 equipment will be made available to rent from their additional US office in Houston which opened a year ago to support clients and offshore projects throughout the Gulf... (read more)
2009-07-03 11:21:09

Pipe-lay Positioning Support

Offshore survey company UTEC has consolidated its presence in the Middle East completing a significant contract for a major international pipelay contractor. The UAE (Dubai) project involved UTEC supporting the DP pipelay vessel in extremely shallow water providing enhanced USBL methodologies. The company also provided survey support services on two additional DP vessels which provided diver support and remedial services to the pipelay vessel. This is the second year in succession that UTEC has provided support to the contractor in the region. UTEC's Global Sales and Marketing director Trevor Hughes commented: “Based on our prior year’s performance the contractor as... (read more)
2013-01-31 10:19:36

Veripos Americas Positioning Contracts

Veripos' Houston-based Americas Region has been awarded major offshore positioning contracts by DOF Subsea, LSP, Tidewater and WesternGeco for vessels operating in Brazilian, Mexican and US waters. The contracts also cover supply of proprietary integrated demodulator and GNSS receivers and associated software modules to ensure seamless high-precision sub-metre positioning for survey, construction support, seismic and general offshore operations.   Facilities being provided to LSP for its well-testing vessel, Aires Swan, operating in Mexican waters on long-term contract to PEMEX include Veripos' dual-beam Standard and Standard HF augmentation data services together with LD2 and LHD2 integrated demodulator and GNSS receivers. Meanwhile,... (read more)
2008-08-05 01:40:52

Brazilian Offshore Positioning Contracts

Veripos has been awarded a series of contracts in Brazil under which it is to provide high-precision GNSS positioning products and services to leading offshore operators, DOF Subsea, NorSkan Offshore and Companhia Brasileira de Offshore (CBO).     The DOF Subsea contract includes the provision of Veripos Ultra dual-beam precise-point positioning (PPP) service supported by two LD2-G2 integrated mobile demodulators and proprietary Verify QC processing software aboard the ROV support vessel, Skandi Chieftan.  Similar facilities have already been operational for some time aboard the company's other ROV vessels, Skandi Fluminense and Skandi Salvador.   Meanwhile, DOF Subsea's associate Brazilian concern, NorSkan Offshore, is to... (read more)
2009-08-19 03:45:48

Which Satellite Positioning Systems

The International Marine Contractors Association (IMCA, UK) has published new guidance on the selection of satellite positioning systems, warning that in recent years lower priority has been given to system selection than is wise. This is particularly the case when choosing a dynamic positioning (DP). The guide explains that the use of inappropriate systems has led to delays in project execution, vessel downtime and, in some circumstances, damage to assets. In the introduction to ‘Guidance on the Selection of Satellite Positioning Systems for Offshore Applications' (IMCA S 018) the association explains that the costs incurred during any of these incidents... (read more)
2011-07-08 12:00:00

Indonesian Positioning Contract

Veripos, headquartered in the UK, has been awarded a further contract for supply of precision services to PT Pageo Utama of Jakarta, one of Indonesia's leading independent offshore survey organisations.   The facilities involve supply of continuous positioning services aboard two Saipem construction support vessels, the derrick lay barge, Castoro Otto, and the diving support vessel, Eclipse, engaged on key offshore projects for Carigali-Triton Operating Company in Malaysia-Thailand and Premier Oil for the Indonesian Gajah Baru gas field project. Each vessel is being provided with Veripos's Ultra Precise Point Positioning (PPP) service for decimetre-level accuracies together with Verify QC software... (read more)
2011-07-18 11:28:41

Deepsea Positioning Accuracy

First NEMO Tower for Astrophysical Research
The Italian Istituto Nazionale di Fisica Nucleare (INFN) is developing a large underwater apparatus to investigate new frontiers in astrophysical research. The NEutrino Mediterranean Observatory, NEMO, consists of a 3D-array of optical sensors capable of detecting the primary source of extremely high-energy neutrinos. This article covers underwater positioning techniques: system architecture, technical, advanced and data processing aspects, and preliminary data analysis. The first prototype, NEMO Phase 1, was deployed in December 2006 off the coast of Catania. A set of synchronous acoustic beacons was installed in the sea at a depth of 2,000m to position a large number of optical... (read more)
2007-05-31 12:00:00

Guidelines for GNSS ­Positioning

A joint OGP & IMCA Revision of the 1994 UKOOA Guidelines
The original UKOOA Guidelines for the use of differential GPS in offshore surveying, published in 1994, were widely used within the offshore survey industry. In 2005, the International Oil & Gas Producers Association (OGP) took over the custodianship of the guidelines from Oil & Gas UK (formerly UKOOA). At that time it was recognised that the original guidelines needed updating in order to reflect the rapid technical advances in satellite navigation technology of recent years and to maintain the purpose and relevance of the original guidelines. OGP and the International Marine Contractors Association (IMCA) agreed to work together on the... (read more)
2013-01-18 02:14:13
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