CPT innovations - deeper, safer, faster, better

Back in the 1930s, when CPT was in its infancy, hand power was used to push the cone ever deeper into the ground. Hydraulically powered systems were introduced in the late 1950s and Fugro developed the first electric cone in 1965.

Digitised test data became the norm in the early 2000s, but for land and nearshore CPT, very little has changed with the hardware since then. And that’s pretty surprising, given the scale and the pace of technological advancement during that timescale.

Applying learnings from marine CPT

For many years we’ve been busy developing and refining our marine CPT technologies to meet the evolving needs of our offshore clients and we are now applying learnings from this mature technology to our land and nearshore CPT operations, to address many client challenges, including:

• Safety - traditional CPT techniques expose operators to serious risk of repetitive strain injury to their wrist or elbows, caused by years of screwing and unscrewing heavy one metre rods

• Data quality – with conventional rods, the data profile is interrupted every metre

• Depth capability achievable depths are limited using current techniques

• Efficiency – traditional techniques create high levels of friction

• Access – everyday CPT methods can’t be applied in challenging and often dangerous environments, such as nearshore and dams where people are exposed to risk or even prohibited.

Our next-generation CPT products address all these issues and more. They are causing quite a stir among operators and operatives in the land and nearshore environments.

Deep Drive^® benefits

Deep Drive^® is our latest land-based CPT system. It includes many important innovations that deliver a wide range of improvements to our clients, including:

• Safety – the system is operated remotely from our specially built control cabin, up to 1000 m away. We can therefore test in restricted areas and eliminate the risk of crush injuries and RSI to our operators

• Efficiency – rather than rods, Deep Drive^® uses a continuous coil of steel, which passes through straightening wheels before being pushed steadily into the ground. This remote, continuous coil approach is far more efficient than the stop-start rods-based alternative. It produces uninterrupted data profiles that require less processing and result in a better data plot

• Depth capability – in the Netherlands we found that using the coil enabled us to push around 30 % deeper in some soil types

• Seismic geophysical testing – Using our seismic CPT cone and Deep Drive’s^® remotely operated seismic hammer we can carry out seismic tests at multiple depths, to provide an accurate view of ground layers

• Data volume – in Brazil, for example, where dams can be 85 metres high and hold 6 million cubic metres of tailings, we remotely deployed 10 piezometers. The devices will remain in situ, providing high-quality data about changes to the dam’s water levels for many years (possibly even decades)

• Access – the CPT crawler uses tracks rather than wheels, so it can move across rough ground and wet terrain to obtain datasets that provide important new safety insights.

Deep Line^® benefits

Deep Line^® is our downhole CPT method for use on land and nearshore. Its advantages include:

• Energy efficiency – with Deep Line^® the CPT tool is lowered on a pressurised umbilical cable in energy-efficient ‘pushes’ of 1.5 metres. With no energy wasted on pressurising the whole drill string, we’re able to apply all the force to the tool at the bottom of the hole.

• Safety – once the Deep Line^® is in the ground, it’s a safe (hands-free), remotely operated process. Not only is the data quality far superior to standard penetration test (SPT) but the all too familiar risk of injury from SPT hammers is removed.

• Speed – doing 10 metres of CPT at a depth of 80 metres is 30 % quicker than the conventional ‘top-push’ method.

• Reduced friction – on land we use our Deep Line^® crawler in conjunction with the drill rig to provide a full reaction force of 100 kN to the cone. We clamp both items of equipment firmly onto the casing, to prevent it from rising up from the ground. There’s no need to waste time moving the drill rig and position the traditional CPT rig.

• Deeper sampling – with Deep Line^® we can also do extensive seismic testing and use our work in progress tool to collect ‘push in’ samples of up to 1.5 metres long in challenging geological layers.

• Better data quality – test results are based on live data that produces an accurate data plot. It’s far more scientific than the SPT method, which relies on the driller counting the number of hammer blows.

More innovations to come…

We’re continuing to develop and improve our Deep Drive^® product.

We are continuing to develop technological solutions to meet our client challenges, including accessibility to unreachable locations and carbon emission reduction.

Did you know?

• Deeper and accurate: Deep Drive® pushes to a depth of 105 metres and uses the Starfix® positioning system, which enables us to achieve pinpoint accuracy when programming test coordinates

• Faster:  Deep Line^® can execute a 1.5 metre downhole push in under 30 minutes