Even with active reservoir pressure maintenance, through water injection, the productivity of wells deteriorates with time. Sometimes this occurs gradually over a period of years but often relatively quickly over a period of months, requiring regular well intervention. Commercial viability of many wells is therefore often dependent on being able to intervene and rectify any downhole issues that may further limit production rates, in order to maximise their commercial life. This intervention can be achieved by a wide range of intervention techniques but, at the lighter end of the intervention spectrum, this covers the pumping of stimulation fluids to improve reservoir permeability or simply to remove reservoir restrictions such as sand or wax deposits.
If production rates continue to fall, despite the application of pressure management and light well intervention, then the well may become non-commercial. This means that at this stage it will be necessary to recomplete in another level, side track or ultimately plug and abandon the well. These decisions all have a significant capital cost that must be weighed against future reserves, oil price and liabilities. However, if the cost of light well intervention could be reduced, then such interventions can keep being applied to maintain the well at commercial levels for longer periods. Obviously this will avoid the need to shut in and abandon the well or to close off the opportunity to take advantage of any oil price increase.
Historically, intervention campaigns have been costly and continue to remain relatively high, even though some intervention rig rates have softened with a lower oil price. This is because of the complexity of manning, mobilising and maintaining such high specification rigs, combined with the time taken for them to transit and conduct the necessary work. This means that there is the risk of many wells being shut-in, even though they have the potential for many years of profitable future production.
The industry therefore needs a new type of technology that facilitates rapid, low cost, hydraulic light well intervention in a manner that allows wells to be continuously ‘touched and tickled’ to achieve optimal commercial production levels, in the same way as would be possible with a land wellhead. In view of the current reduced oil price, this low cost intervention capability is well overdue, with its availability having being delayed historically by a combination of higher oil price and a lack of suitable technology.
The high cost of conducting more frequent intervention is dominated by the cost and low availability of suitable intervention vessels. Whilst the focus of the problem of high costs is typically the intervention vessel day rate, this is not the full story, as the real problem is the riser system – the pipe deployed to make the connection between the vessel and subsea completion through which fluids are pumped at high pressure. These riser pipes are typically heavy and difficult to handle, and need large stable vessels to deploy them safely. Historically, alternatives like steel coiled tube can be prone to general handling damage, fatigue and chemical attack, making it necessary to replace this expensive element of the intervention system regularly, further reducing overall well costs and efficiency.
Additionally, such intervention spreads have typically been tailored for specific fields with respect to depth, pressure rating and chemical compatibility. This means that the potential to use such equipment more broadly to maximise utilisation levels is rarely achieved and further limited by high remobilisation costs, so when they are evaluated technically and commercially they are not always viable.
Magma has recognised the growing need for efficient light well intervention and the m-pipe® product it produces solves the root of this problem – the high pressure subsea riser pipe. m-pipe® is spoolable and light weight, one tenth that of equivalent steel coiled tube (CT) or Non Bonded Flexible (NBF) pipe, is fatigue and chemical resistant and is also capable of withstanding the increasingly high fluid pressures required for effective hydraulic light well intervention.
Working with Maritime Developments Ltd Magma has developed its IDP Integrated Deployment Package as a complete intervention riser pipe system which can be rapidly mobilised onto a vessel of convenience due to its light weight and size. This package includes the pipe handling system and the global riser configuration, facilitating rapid deployment and retrieval in a wide range of deep water depths up to 3,000m, and for operating pressures of up to 15ksi.
The key enabler is the composite m-pipe® itself, manufactured from two high specification materials, carbon fibre and Victrex PEEK polymer, providing a superior performance specification that allows safe and rapid deployment from a small intervention vessel. This new approach to the intervention riser pipe facilitates the ability to continuously intervene subsea completions efficiently to maximise their productivity.
A further benefit of the developed light well intervention spread is the breadth of application of the equipment in terms of depth, pressure and geography. This allows broad deployment, maximising utilisation and the ability to spread capital equipment costs and further enhanced by the relatively unique option to rent the m-IDP system direct from Magma.
It is apparent that during the fairly long recent period of high oil price that the attitude towards ‘new technology’ has become relatively dismissive. Almost universally the strategy has been for use of only ‘field proven technology’ in order to minimise any perceived risk of lost production.
However, we are now in a current period of low oil price which may be sustained for years rather than months. For this reason alone there has never been a more important time to rebalance the approach to reviewing and embracing new technology, with the opportunity being to allow use of more easily available lower cost vessels, to keep subsea wells and the oil and gas industry on-stream more commercially.