INNOVATION - The key to cost-effective well intervention

By Tom Murdoch, Engineering Director, Brimmond Group

In 2019, the Oil & Gas Authority (OGA) issued its updated asset stewardship expectations, a key element of the regulator’s Maximising Economic Recovery strategy, designed to provide clarity on expected behaviours and good practices.

One of the 10 expectations encourages the deployment of technologies designed to deliver optimum levels of performance – including production and cost efficiency; as important in oil and gas hubs worldwide as it is in the North Sea.

When you consider the challenging times that the sector is navigating currently, we firmly agree on the crucial role technology innovation has to play in satisfying energy demand in the safest, most cost-efficient way.

AN EFFICIENT WAY TO LOWER OPERATIONAL COSTS

Well intervention is one area that offers a practical solution for optimising performance, through deploying technology to manage declining production and maximise value.

According to the OGA’s 2018 Wells Insight Report, 21 million barrels of oil equivalent (boe) production was safeguarded through interventions in 2017, with 22.5 million boe production delivered by improving underperforming wells and/or reactivating shut in wells. The size of the prize is clearly significant.

However, well intervention does not come without its challenges. While a coiled tubing set-up can provide high-rate circulation, it can also be heavy, bulky and time-consuming. Wireline, meanwhile, provides a smaller unit, but without the same circulation capability.

That’s why Expro, our customer, has introduced a new approach, an alternative solution for light well interventions. Its CoilHose Light Well Circulation System (LWCS) has been designed to minimise the loss of hydrocarbon production and lower the overall cost of intervention, building on its heritage in this space, differentiating its offering and adding value through improved work practices.

Unlike conventional coiled tubing and downhole tractors, the CoilHose LWCS substitutes steel pipe with a small diameter hose that can be rigged up using standard wireline, integrating the benefits of time efficiency associated with conventional wireline, while still allowing pumping to take place; with a reduced footprint and decrease in mobilisation time.

A NON-STANDARD SOLUTION

After more than a decade of providing Zone 1 centrifugal pumps to Expro, and recognising our in-house design and manufacturing capabilities, and focus on high-quality engineered solutions, Expro asked Brimmond Group to help develop a non-standard pump for the CoilHose LWCS solution.

The result is an ATEX Zone 2, Modular High Pressure Pump Unit, equipped with a 200kW diesel engine, designed to power a triplex plunger pump that is capable of pumping cement, water, glycol and hydrochloric acid.

Ensuring the technology’s ability to support a wide range of projects, we worked closely with the pump manufacturer to develop a pump with a super duplex head, ensuring its compatibility with acids, while a unique sealing arrangement was used to ensure the pump remains leak-free. The pump has also been specified to have additional lubrication, allowing it to operate continuously from 5lpm to 54lpm at the full system pressure of 860 Bar.

Weight too was a significant driver for this project, with the technology likely to be used to improve production from ageing oil and gas assets. With many of these assets equipped with derated cranes that are approaching the end of their usable life, there can be strict limitations in place in terms of what they can and cannot lift.

By using marine-grade aluminium for the pump’s doors and panels, engine base frame and tank support frame, we have been able to build units with a maximum lift of just 5.5 tonnes. Further, a plug-and-play, modular design – consisting two parts that can be bolted together – guarantees alignment with maximum craneage capacity. With conventional units typically weighing in at around 12-15 tonnes, this is an important feature of the solution.

By integrating low- and high-pressure filters into the design, components that would typically be standalone, we have reduced mobilisation time as well as the equipment’s overall footprint, while making for a simpler system overall.

OVERCOMING THE COVID-19 CHALLENGE

With Expro placing the order for the new pumps shortly before the first outbreak of COVID-19, this presented us with a significant challenge to overcome – with the need to ensure the availability of personnel required to design and manufacture the equipment safely, while navigating the impact on our own supply chain, with some companies’ operations obstructed as a result of the pandemic.

This was particularly evident when it came to the drive trains for the pump units, for which the gearbox and clutch were both sourced from a supplier in Italy. With the country going into total lockdown, including its manufacturing sector, for a number of weeks, this naturally impacted our schedule.

However, through the adaptability and flexibility of our team, complemented by measures implemented in our workshop – such as social distancing and a split shift rota – as well as supporting our office-based employees in working from home – Brimmond Group has been able to keep going.

Two of a total four units have now been delivered to the customer, with the final two due for shipment in the coming weeks. These will be deployed for use on jobs across Australia, South America, the Middle East and Norway.

THE TECHNOLOGY IN BRIEF

• Each pump unit has a maximum lift of only 5500kg, making them among the lightest weight, 200kW, fully enclosed pump units of this type on the market.
• Designed for light well intervention projects, the pump units have been designed to be extremely versatile and can be used for acidising, cementing and water jetting.
• Configured with different heads, and with a flow and pressure range from 3500 Bar at 15lpm to 150 Bar at 450lpm, the pumps can be used for a variety of applications; from ultra-high pressure jetting to high flow flushing.
• The technology has a number of safety features designed to negate the possibility of operator error, with a multitude of automatic shutdowns – including in response to various low oil pressures, discharge overpressure, engine overspeed and engine exhaust high temperature.
• With the unit being fully enclosed and acoustically lined, the operating noise level is extremely low in comparison to an open-framed equivalent.
• A pneumatically operated wet clutch means the diesel engine can be run and taken up to temperature under no load, allowing for easier starts.
• The unit has been designed with safety and ease of maintenance at the forefront, with no electrics and a number of other features – from removable panels for access and a removable tank frame, to separate outlets for cement and acid jobs.

Read the latest issue of the OGV Energy magazine HERE.