EQUIPMENT & CABLING UPDATE 


ASV chose commercially available brushless servo motor technology for the steering and ride control actuators and fitted a sealed waterproof casing around each complete assembly, encasing the motor and angle sensor, and including connectors for motor power, commutation and sensor feedback. Te GL series angle sensors’ high resolution potentiometric output presents the steering and pitch angular positions as a proportional voltage output through a zero to 340º electrical range to the ASV designed control system. With independent linearity to ±0.25 per cent, the steering and ride stabilisation capability for the vehicle is more than sufficient. Te robust and durable shaft mounted GL sensor has a long pedigree of challenging angle position feedback applications such as autosports, construction equipment and agricultural machinery. Te range is supplied in four nominal sizes, suitable for shaft diameters from 6 mm to 30 mm. Te one-piece assembly is housed in an anodised aluminium casing with a slotted ball bearing for maximum support. 


Variohm EuroSensor Limited is based in Towcester, Northants, UK. www.variohm.com


Innovative approach to delivering integrated seismic PRM


S


tingray Geophysical Limited has adopted an innovative approach to providing integrated seismic permanent reservoir


monitoring (PRM) services to oil companies. In addition to maintaining a core team of experts with an extensive range of skills, Stingray is able to draw upon its network of trusted partners worldwide to assemble purpose-built teams with the key competences required to meet the specific challenges of each project and deliver complete customer solutions. Stingray’s flexible business model was applied


to the execution of two recent Seismic PRM Feasibility studies. In one case, on the Clair field, there is a complex


seabed environment, with unique geophysical and field infrastructure constraints to the installation of permanent seabed systems. Stingray and its partners were tasked with identifying how high data quality might be obtained in such challenging conditions within optimal timescales and using low risk installation methods. In addition, to reduce the need for power and space offshore, the study considered means of controlling and monitoring subsea equipment without installing the recording equipment on the platform.


In the other study, on the Schiehallion field,


surface seismic data acquisition is constrained by the presence of an FPSO, shuttle tankers, drilling rigs and construction vessels. This, coupled with the highly congested seabed around the various drill centres and the need to cater for future field expansion, creates a complex environment when considering the feasibility of installing a permanent array. By considering the risks involved in and around the current infrastructure, the study examined the practicability of utilising FosarDeep concepts to introduce a PRM system beneath the FPSO and in obstructed wellhead areas. To address the distinct challenges presented


by each of the fields and their unique study requirements, the Stingray project management group leveraged the expertise, resources and facilities of its project partners to provide optimised client solutions. The team comprised:


 Acergy: a seabed-to-surface engineering and construction contractor to the offshore oil and gas industry worldwide. Providing integrated services, Acergy plans, designs and delivers complex projects in harsh and challenging environments.


 Atlas Elektronik UK Limited: Stingray’s long-term manufacturing partner utilised its specialist applications expertise to define the subsurface hardware required for delivering an integrated system using the selected installation method.


A partner in the FosarDeep development programme, Atlas provides the capability to build scalable fibre-optic sensing systems that provide high resolution, low noise, highly repeatable seismic data for optimising reservoir management for enhanced oil recovery.


Other project team responsibilities included the optimisation of field layouts by VerdErg Connectors Limited, provision of a map-based interface for data integration by GeoSolveIT Limited, together with an evaluation of the feasibility of remote system monitoring through long tie-backs by the OptoElectronics Research Centre at Southampton University. Founded in March 2006 to commercialise a


unique fibre-optic sensing technology – now called Fosar – for seismic permanent peservoir monitoring (Seismic PRM), Stingray enables oil and gas companies to accelerate production and increase their reserves while reducing cost and risk through improved reservoir management strategies. The core technology was originally developed


for anti-submarine warfare and security purposes by the UK’s defence research laboratories and is now being exploited for advanced fibre-optic oil and gas seismic sensing applications by Stingray under exclusive licence. 


For more information, visit www.stingraygeo.com


www.engineerlive.com 27


Fig. 4. Complete ASV actuator assembly in sealed housing.


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