A Taranaki sheddie invents a unique drilling aid for the oil and gas industry
A TARANAKI ENGINEER HAS COME UP WITH A PATENTED DEVICE THAT ENABLES DRILLERS TO WORK ON PROBLEMS THOUSANDS OF METRES UNDERGROUND
ATaranaki farm boy has come up with an invention that could save the geothermal and oil and gas industry millions of dollars — in his shed.
Well, Mark Horwell is no longer a boy, though he was raised on a farm. In fact he has a degree in engineering, his shed has some high-tech equipment, and the concept and development of his invention have involved more than a dash of Kiwi ingenuity. Mark has come up with a device called a ‘Switchfloat’, which enables drillers to work on problems thousands of metres underground.
The Switchfloat is basically a nonreturn valve that can be opened downhole to allow wireline tools to be conveyed down the well.
The Switchfloat system provides drilling operations with float-valve functionality while also allowing the valves to be locked open when required. All Switchfloat valves are able to be locked open by either pumping a ball or using a simple wireline tool. A clear path is created through the valve so that tools can be conveyed safely within the drill string. Following this, the valves may then be closed to reinstate float-valve functionality.
The major benefit of Switchfloat is when the drill pipe becomes stuck, it enables tools to be conveyed down the drill pipe to find out where it is stuck, and cut the drill pipe off. Switchfloat also allows surveys in the drill pipe without the removal of drill-string float valves.
“This reduced tripping saves rig time, and wear and tear, and the device allows
immediate wireline access in stuck pipe scenarios,” said Mark.
“It reduces make and break cycles on drill-string-threaded connections and there’s safety benefits associated with reduced drill-string movements.
“It also provides the ability to reverse circulate through a drill string containing float valves. The Switchfloat system is a patented technology and it has been successfully utilized in geothermal air-drilling operations with well temperatures exceeding 300°C.”
Geothermal wells in New Zealand are often drilled to around 3000m underground. High-pressure air and water are pumped down the drill pipe and return up the annulus (outside of the drill pipe) to lift the drilled rock out of the bore hole.
One-way non-return valves are often spaced about 150m apart down the string. This contains the pressure within the drill pipe and reduces the time taken
The concept and development of his invention has involved more than a dash of Kiwi ingenuity
when adding additional lengths of pipe to the drill string. However, prior to the invention of the Switchfloat, if the drill pipe got stuck or anything went wrong, specialist tools could not be lowered through the valves to diagnose or rectify the problem.
Mark’s invention changes all that. “To run a geothermal drilling operation can cost $100K a day,” Mark said.
“Previously, rectifying a stuck drill string could be a hit-and-miss operation, simply turning the drill pipe backwards and hoping it unscrews somewhere good.
“This could mean long delays in the drilling programme, or possibly losing the entire well.”
Mark worked on geothermal rigs near Taupo putting diagnostic and functional tools in the well and even setting off explosive charges down the well to shoot holes into and cut the pipe if necessary.
“I thought there must be a better way to access the problems and six years ago I came up with the Switchfloat idea. I did the basic designs and started the patent process to protect the idea. I went to Contact Energy with the concept and they were prepared to run the prototype.
“You can’t afford for these things to break down in a $20M well, so the valve bodies are manufactured from 4145H high-tensile steel.”
The first Switchfloat was assembled in Mark’s father’s tractor shed on the farm and the 250kg device was shifted round with the farm tractor, a trusty Ford 3000. A bigger shed was needed and Mark purchased a 6m shipping container and set it up on the farm, and a second container followed as Mark got more orders. The containers were carted to the well sites then back to the farm.
“The Switchfloats are pretty heavy and I moved up from using the farm tractor and chain blocks to buying a forklift. That was a great investment.”
Fully equipped workshop
Two years ago Mark, his wife Lucy, and two boys aged three and one, bought a rural property near Lepperton in Taranaki and Mark converted the farm shed into a fully equipped workshop.
“Having a good-size shed changed my life. It’s a bit isolating sometimes working for myself, but the boys like to watch the action and check things out,” he told us.
Mark outsources most manufacturing of parts to suppliers in New Zealand and the US, and he assembles the final product himself.
He makes some of specialized parts of the tools himself and for this he purchased an electrical discharge machine (EDM), which is a wire cutter designed to accurately cut very hard material with high-current pulses of electricity. They are mainly used for tool and die making, etc.
“It’s quite a tool. It’s like a real fancy bandsaw. It cuts with a .25mm brass wire and the cooling water is de-ionised so it won’t conduct electricity,” said Mark. The machine was pre-digital and an interface board was added to allow the machine to be computer controlled.
Mark has just purchased a milling machine and is getting a metal lathe and told us that he is at present working on another new tool design for the oil and gas industry.
“I really need a bigger shed already,” he said.
Check out his website switchfloat.com.
The first Switchfloat was assembled in Mark’s father’s tractor shed on the farm
Right: The patented valveopening device in the Switchfloat Below: The non-return valve on the Switchfloat
Above: Mark Horwell and his Taranaki workshop Far left: The control panel for the EDMLeft: The EDM cuts hightensile steel with electrical pulsesBelow: Mark’s rural shed, where it all happens