The Marinisation of a Subsea flow clap Electrical Capacitance Tomography ECT system. (Design Study)

As the exploration of offshore oil and gas resource are frequently located in inimical environments, due to its nature, it is a dangerous activity having higher cost to marine lives and the environment. While its social and economic benefits are high, regulatory authorities are to ensure there's a balance between the risks and benefits it presents. It is vital to measure the fluids produced from oil reservoirs accurately for efficient oil exploitation and production. Usually, multiphase flow meters (MPF) are used because of their capability to measure complex mixture of gas, oil and water. However, the MPF has limitations such as it's flow regime dependent and most of the equipment can only deal with homogeneous flows in order to achieve an acceptable accuracy. The efficiency and safety of the system is usually determined by the rate of multiphase flow in a flow line, which makes flow measurement major (Mgbeafulu, C.E. et al. 2015).

Toskey & Hunt (2015) developed a subsea prototype clap on the electrical capacitance tomography (ECT) flow measurement system; their design involves a capacitance measurement achieved by conventional rack type unit and processed images are displayed on a PC screen. It is based on measuring the changes in capacitance that are caused by the change in dielectric material distribution (I.Isamil et al. 2005). ECT flow measurement sensor has the capability to measure concentration and flow velocity in non-intrusive ways. This is due to its quality of flow imaging, as results can be visualised on either concentration contour, or flow structures in three dimensional images. The basic ECT sensor structure calls for the use of a non-metallic tube where the electrodes are placed. However, a tube made of a non-metallic material would not be strong enough to contain a high pressure flow (J.C Gamio et al. 2005). The ECT sensor is coaxially connected to the measurement unit, as their design arrangement require both the capacitance and the PC to interact through high speed Ethernet enhanced control system.

The ECT system undergoes a design improvement on its sensor casing arrangement as it needs to suit an average work class ROV handling. The improved design also had fixed sensor sleeve incorporated into the system, as well as the anchoring and clamping mechanism. Overall, a viable design was achieved but based on the project criterion there are areas of further work (Mgbeafulu, C.E. et al. 2015). As oil and gas companies have billions of dollars tied up in their reservoirs, use of the ECT system providing real-time information on reservoir production could provide a significant competitive advantage. Thus, the importance of this device to be able to survive long-term exposure to harsh marine conditions.

Therefore; this project will be focused on design improvement and marinisation of the existing subsea flow meter clamp on the Electrical Capacitance Tomography (ECT) system. It shall Ideally focus on the design of related mechanical and electrical hardwares suitable for use in extreme harsh weather conditions as well as offshore corrosive conditions.

The chapters give a detailed literature review on marinization of subsea components in the oil and gas industry. Based on recommendation from the previous work on the ECT system, an investigation on advance material which can be used in place of aluminum material for the equipment will be carried out. As buoyant forces and level of water pressure at the sea bed will be selection factors of this material. Also to attain the compatibility level of the ECT flow measurement sensor, series of non-metallic pipe samples will be acquired from manufactures to measure their electromagnetic spectrum.

The design aim to evaluate the current subsea flow meter clamp on the ECT system with a view to improve its effectiveness in term of durability, sustainability and reliability, specifically for use and long-term survival in harsh environments.

Objectives

1. Make empirical research on existing literatures on the marinization of components in the oil and gas industry.
2. Investigate the compatibility level of the ECT flow measurement sensor by acquiring series of non-metallic pipe samples from manufacturers to measure their electromagnetic spectrum.
3. Design a marinization system on existing ECT prototype using CATIA V8, subjecting it to the loading modes in marine conditions.
4. To perform Finite Element Analysis (FEA) and flow simulation on the design, and further redesigning it based on the results obtained.
5. Evaluation of the material selection on advanced materials for the ECT system which shall be based on results and stress calculations
6. recommendation drawn from the conclusive outcome and results from the marinization of the ECT system designed and understudied.

Project Outcomes

1. Provide a literature review on existing marinised subsea components before the end of the first month and a summary report on a subsea design and marinisation procedure for components.

2. An assessment report on the investigation carried out to attain the compatibility level of the ECT system on series of non-metallic pipe samples on measured electromagnetic spectrum within the fifth and sixth week of the project.

3. A design specification report on existing ECT system, detailing the finite element analysis procedure carried out when simulating the design to the loading modes in marine conditions within the second and sixth week of the project.

4. A material selection report on advanced materials that could be used in place of aluminum steel in the fabrication of the marinised ECT system. Also calculation of stress/strain that the component will be subjected to within the fourth and fifth week of the project.

5. A recommendation report on the conclusive outcome, detailing the laboratory and test procedure undertaken by the author within sixth and ninth week of the project.