Daniel Mcstay

Optoelectronic sensors for subsea oil and gas production

The potential for optoelectronic sensor technology to provide the monitoring and control systems required for advanced subsea hydrocarbon production management is described. The utilisation of optoelectronic sensor technology to produce a new class of subsea Christmas Tree with in-built enhanced production monitoring and control systems as well as effective environmental monitoring systems is reported.

Advanced feed-through systems for in-well optical fibre sensing

A new optical fibre feed-through for use in subsea in-well optical fibre sensing systems is reported. The new feed-through is compatible for use with standard subsea Christmas Tree penetrators and allows multiple re-mating of the feed-through over the lifetime of the device. The system has been extensively tested under in-well conditions and found to conform to the performance requirements. The new feed-through is planned to be used in one of the first subsea optical fibre in-well sensing systems.

Optoelectronic Leak Detection System For Monitoring Subsea Structures

Leak detection and monitoring on subsea structures is an area of increasing interest for the detection and monitoring of production and control fluids for the oil and gas industry. Current techniques such as capacitive (dielectric) based measurement or passive acoustic systems have limitations and we report here an optoelectronic solution based upon fluorescence spectroscopy to provide a permanent monitoring solution. We report here a new class of optoelectronic subsea sensor for permanent, real time monitoring of hydrocarbon production systems. The system is capable of detecting small leaks of production or hydraulic fluid (ppm levels) over distances of 4-5 meters in a subsea environment. Ideally systems designed for such applications should be capable of working at depths of up to 3000m unattended for periods of 20+ years. The system uses advanced single emitter LED technology to meet the challenges of lifetime, power consumption, spatial coverage and delivery of a cost effective solution. The system is designed for permanent deployment on Christmas tree (XT), subsea processing systems (SPS) and associated equipment to provide enhanced leak detection capability.

Wireless sensing on surface hydrocarbon production systems

The use of wireless sensor networks for monitoring and optimising the performance of surface hydrocarbon production systems is reported. Wireless sensor networks are shown to be able to produce comprehensively instrumented XTs and other equipment that generate the data required by Intelligent Oilfield systems. The information produced by such systems information can be used for real-time operational control, production optimization and troubleshooting.

The application of fibre optic temperature sensing for under insulation monitoring of subsea infrastructure

The use of insulation within the oil and gas industry to provide heat retention during production downtime is important to reduce the risk of hydrate formation within the flow-loops in the subsea infrastructure. Hydrate formation can significantly decrease the production efficiency and hence the profitability of the well. Hydrates can also introduce serious safety risks, if formed with in critical components such as safety valves. During production downtime the elevated temperature of equipment such as XTs will begin to equalize to the ambient subsea temperature. The accurate assessment of the effectiveness of such insulation is thus critical. Monitoring insulation performance during cool down trials is typically performed during test and assembly of production equipment using a limited number of electrical sensors. The use of multiplexed fibre optic sensors offers a reduction in the number of penetrations in the insulation, when compared to traditional electrical sensors and thus allows far more representative temperature measurements to be made. Additionally, conventional electrical sensors will rapidly degrade in the subsea environment, making them unsuited for long term subsea monitoring. In this paper we report the use of embedded optical fibre sensors, which should maintain their full performance over the lifetime of the subsea equipment. This would enable the long term insulation performance to be assessed after a tree is recovered for maintenance, or even allow continuous monitoring of the insulation performance during service. Results of tests carried out in an environmental chamber to show the performance of the sensors during cooling cycles are reported and initial results taken during production testing prior to deployment of the equipment subsea are reported.

Laser profiling for subsea hydrocarbon production systems

The correct alignment and setting of the components inside subsea wellheads is critical to ensure that all seals perform at the high pressures found in subsea hydrocarbon production systems. Of particular importance is the alignment of the tubing hanger and how it engages with the subsea trees or wellhead. The tubing hanger supports the production tubing string with carries the hydrocarbon from the reservoir and experiences pressures up to 15 kPsi. Full and correct engagement of the locking and sealing mechanisms of the tubing hanger is critical in containing the production fluids. Here we present the results of a trial of a laser profiler to assess the interior surfaces of a wellhead. The scanner has been shown to be capable of effectively inspecting the interior surface of the wellhead for damage and measuring the interior structures to allow the tubing hanger to be installed correctly.

Subsea downhole optical sensing

The potential for subsea downhole optical fibre sensing to optimize hydrocarbon production and hence contribute to enhanced oil recovery is described. The components of susbea downhole optical sensing systems are reviewed and the performance of a new subsea optical fibre feed-through for downhole optical fibre sensing reported.

Use of fibre sensors for temperature measurement in subsea infrastructure to monitor flow-loop cool-down

The interest in using optical sensors as replacements for typical electrical sensors in the oil and gas industry has increased as the potential benefits and reliability of such technologies become more established. Presented here are the results from initial tests using optical temperature sensors to monitor the effectiveness of subsea tree insulation to retain heat within the flow-loops of a Christmas Tree to prevent hydrate formation during system cool-down. Initial tests were carried out to compare the optical fibre sensor performance with traditional electrical thermocouples. Suggestions for further development and future tests are also presented and discussed.

Permanent underwater leak detector

A new optoelectronic sensor for the real time monitoring of key components such as valves and connectors within the subsea production equipment for leaks of hydraulic fluid is reported. The sensor is capable of detecting low concentrations of such fluids, allowing the early detection of small leaks, and the ability to monitor the evolution of the leak-rate with time, hence providing an important new tool in complying with environmental requirements, enabling early intervention and optimising subsea production