A major challenge in oil production is to maximise the oil recovery of the reservoir. Today, only a limited quantity of the oil in a given reservoir is actually recovered before the field is shut down. There are strong incentives for developing new technology in order to increase oil production and recovery. Two factors of particular importance in order to increase production and recovery are obtaining maximum reservoir contact and preventing negative effects of gas and/or water breakthrough.
Preventing negative effects of gas and/or water breakthrough
There have been various inflow valves developed to prevent negative effects of gas and/or water breakthrough such as ICDs and ICVs, and more recently AICDs, developed by Statoil and Halliburton. AICDs reduce the negative effect of breakthroughs and perform better than ICDs, but do not stop the water/gas breakthrough fully. On the other hand, ICVs are controlled from the surface and although they stop gas/water completely, they are very expensive and can be applied only to limited zones (around five per well).
Now the same group of people who designed AICDs at Statoil have established a company in Norway, InflowControl AS, and are developing a new Autonomous Inflow Control Valve (AICV) which does not require any surface control and almost fully stops water/gas breakthroughs autonomously. InflowControl has successfully bid for an EU grant called Revival, which involves a consortium of universities and companies from Norway, Sweden, Germany, and the UK.
AICVs are completely self-regulating and do not require any type of control, electronics or connection to the surface. They enable the opportunity to drill longer wells and achieve maximum reservoir contact at each well. They also remove the risk, cost and requirement for separation, transportation and handling of unwanted fluid. Very simply, AICVs eliminate gas and water breakthrough problems without limiting the length of the well.
EU-funded REVersible Inflow control VALve (REVIVAL) programme
In laboratory tests, using AICVs has led to a 20% increase in oil recovery rates, with the target to increase this to 25%. The fact that only a 1% improvement in the Norwegian part of North Sea is worth 40 billion euros to the oil industry, demonstrates the huge potential benefits of the Revival project to the EU economy. From a global perspective, a 5% increase in the recovery rate would yield as much oil as is expected from all future exploration efforts.
Scientists from the Engineering Analysis, Simulation and Tribology group at Anglia Ruskin University in the UK are one of the major contributors to the Revival project, leading a team responsible for three out of the project’s six work packages. Anglia Ruskin is working with companies in the UK, Germany, Sweden and Norway, mainly supporting the project on Computational Fluid Dynamics (CFD), which can provide a better understanding of the complex multiphase flow phenomena, design optimisation and calibration.
AICV in operation (areas of water and gas infiltration highlighted).
Laboratory work collaboration
CFD is about using numerical methods to solve complex and non-linear fluid flows including multiphase (mixed gas, oil and water), turbulent and transient phenomena, and has huge applications in aerospace, automotive, renewable energy and power industries. Fluid flow due to non-linearity cannot be solved by analytical mathematics and experiments have been used to analyse various phenomena such as the use of wind tunnels in the aerospace industry.
The two advantages of computational methods are extreme reduction in development cost compared to creating laboratory test rigs, as well as detailed analysis of flow, which is sometimes impossible to measure in the laboratory environment.
Although CFD has huge advantages in cost, time and quality of data achieved, for complex phenomena such as turbulence, huge computational resources are required to model the smallest variations of flow, which influence the whole flow. The world’s largest computers are used for CFD purposes and some validation with experimental results is still required to make sure that the data is correct. This is why Anglia Ruskin will also be collaborating on the laboratory work, which is mainly taking place at Statoil laboratories in Norway, and is being led by InflowControl AS. The laboratory results will be used to validate parts of CFD work at Anglia Ruskin University.
Anglia Ruskin University
Hassan Shirvani, Professor of Engineering Design and Simulation at Anglia Ruskin, said: “It is inevitable that at some point during the oil extraction process, water and gas will enter the well recovery pipe. This means that rather than oil, a toxic cocktail will come to the surface and will need to be treated and disposed of. The carbon footprint of such processes is huge.
“This technology will close the valve as soon as water or gas is detected and will remain closed until oil returns to that area of the pipe. Therefore the well will produce more oil and far fewer harmful chemicals than is currently the case.”
A growing market
There are about 4,000 horizontal wells opened every year and each has an average horizontal length of between 2-3km. Considering that inflow valves are installed approximately every 12m along the pipe, the potential market for inflow control valves globally is 800,000 units per year.
Sent in by Anglia Ruskin University.
Edited by Cecilia Rehn.
Read the article online at: https://www.oilfieldtechnology.com/drilling-and-production/19022014/eu_project_testing_autonomous_inflow_control_valves_aims_revolutionise_oil_extraction/