Supercharging drilling efficiency with HydroVolve’s percussive-enhanced drilling
The GeoVolve HYPERDRIVE, developed by HydroVolve, makes use of the precept percussive-enhanced drilling to scale back geothermal drilling prices.
Discount of drilling prices, whether or not via shortening of drilling operations or extension of drill bit lifetime, stays one of many high-impact frontiers for enhancing the economics of geothermal tasks. To this finish, improvements that may assist cut back drilling prices are of nice curiosity to geothermal builders and could be the key to unlocking deeper and warmer reservoirs.
HydroVolve is among the corporations introducing modern merchandise to deal with this space of enchancment. On this visitor article, Dr. Peter Moyes, Chairman and Founding father of HydroVolve, particulars the working precept of their drilling answer and presents the outcomes of the assessments accomplished on their know-how.
Geothermal has the potential to produce a good portion of the world’s power wants, but the best problem to scaling geothermal globally is the power to drill deeper and extra effectively via exhausting rock formations to scale back capital prices and supply higher return on funding.
Carving deep geothermal wells via 1000’s of metres of volcanic rock is fraught with technical challenges comparable to software survivability within the extraordinarily scorching and harsh effectively environments.
Drilling operations usually have to cope with sluggish charges of penetration (ROP) – one metre per hour or much less is typical – and are routinely halted for days and even weeks when drill bits turn out to be blunt and worn and should be changed. Such delays, referred to as flat time, can add thousands and thousands of {dollars} to prices.
Rotary drilling vs percussion drilling
At current, two forms of drilling technique are usually used – rotary drilling and percussion or hammer drilling.
Rotary drilling, by far the commonest technique to achieve the deepest reserves of oil, fuel and geothermal, makes use of two forms of drill-bit – the curler cone bit and the polycrystalline diamond cutter (PDC) bit.
The latter has gained ascendancy attributable to larger ROP and sturdiness but PDC bits nonetheless endure restricted efficiency in exhausting rock functions because the required cutter penetration or depth-of-cut (DOC) is harder to attain. Growing the DOC requires elevated weight-on-bit (WOB) to beat the upper rock power.
This in flip can enhance frictional warmth between the bit and the rock face, inflicting extra fast abrasive put on that shortens bit life. It additionally introduces different drill string dysfunctions comparable to stick-slip, helical buckling, lateral instability and high-frequency torsional oscillations, all of which may decelerate the drilling ROP and enhance the failure fee of the drilling parts, thereby making a rise in WOB an unviable possibility.
The usage of percussion drilling is extensively practiced in effectively development, mining, and development industries worldwide and utilises a hammer impact to repeatedly ship a blow via a crushing bit with sufficient drive to interrupt rock into smaller particles.
A fluid medium, often compressed air, is used to energy the hammer software and to clear away the crushed rock from the influence face and to reveal undamaged rock to the hammer. The method is regularly repeated at excessive frequency till the specified depth is achieved.
The efficiency positive factors that may be made as a direct results of introducing percussion drilling to a drilling marketing campaign will be important. As reported by Rodgers et al in 2013, the tactic delivered the quickest and deepest percussion air hammer run in Australia’s oil and fuel historical past at 24 m/hr.
In practise, nonetheless, these air powered percussion instruments can solely perform correctly in shallow wells as energy loss, wellbore instability, and temperature issues severely restrict their use in deep, scorching wells.
The design precept
Recognising that combining percussion drilling with rotary drilling may very well be the important thing to unlocking the potential of deep geothermal, Dr Peter Moyes, a UK-based skilled in effectively engineering, sought to develop a specialist software that may “supercharge” standard drilling assemblies – a plug-and-play machine to carry the entire recognized and confirmed advantages of percussive drilling to rotary drilling with none of the downsides.
Moyes’ percussion-enhanced rotary drilling course of depends principally upon the rotary drilling technique, utilizing PDC drill bits to fail the rock in rotary shear. To enhance the rotating WOB, a managed cyclic axial impulse is delivered to the bit to induce an impulse drive sufficiently giant to pre-fracture the rock forward of the cutter. In essence, it reduces the compressive power of rock forward of the bit making a softer, decrease power materials to drill. The bit is then in a position to last more and ship much-improved ROP.
The system was required to:
- be powered by the pressurised circulate of any recognized drilling fluid – from recent water to excessive density drilling mud laden with loss management materials (LCM).
- introduce minimal damaging impact to the hydraulic design of the drilling system by avoiding introduction of a big stress drop, extra circulate quantity or circulate velocity requirement.
- be operable to 300 levels C.
- keep away from affecting equal circulating density or wellbore stress administration.
- keep away from inducing undesirable damaging impulse or influence forces to the drilling backside gap meeting (BHA).
The HYPERDRIVE system
The result’s the GeoVolve HYPERDRIVE system, developed by Moyes and his crew at HydroVolve, an organization primarily based in Aberdeen, Scotland.
The machine will be deployed into a traditional rotary drilling backside gap meeting (BHA) behind the bit and is powered by the circulate of drilling mud to hydraulically cycle a percussive axial impulse drive system. This axial impulse drive is transmitted via the bit to the slicing construction and onward into the rock the place the impulse drive pre-fractures and breaks down the rock.
When rotary drilling, it’s important {that a} fixed pressurised circulate of drilling fluid is delivered via the drill string to the bit nozzles to chill and wash the bit, to clear cuttings and to move them to floor. This circulate generates a differential stress between the bore of the drill string and the annulus between the drill string and the well-bore.
The HYPERDRIVE system capitalises on this differential stress to energy the impulse generator by utilising HydroVolve’s INFINITY engine, a constructive displacement reciprocating piston engine that includes an inlet valve aligned to the drill string bore and an exhaust valve aligned to the annulus.
When the inlet valve is aligned to the drill string bore, the piston is uncovered to the total differential stress between the bore and the annulus. The piston is pushed below energy within the ahead route to create the impulse. When the exhaust valve is aligned to the annulus, the piston is stress balanced and is spring-returned to the beginning place.
The TERRABIT
To maximise efficiency and sturdiness, Moyes and his crew requested ZerdaLab, an Aberdeen-based agency with experience in drilling know-how, to analyse the HYPERDRIVE axial impulse load signature and draw on efficiency information to design and develop a bespoke PDC bit, the GeoVolve TERRABIT.
Its options embody a profile design to make sure the nostril space is effectively protected to take steady cyclic axial oscillations and to transmit the HYPERDRIVE power to the rock. The specialist software additionally has a big bit shoulder radius to make sure sturdiness from publicity to excessive linear velocities in abrasive rock and a radiused cone to permit extra space for the prolonged nostril space and supply lateral stability to the bit.
Testing setup and outcomes
Information on the efficiency of the HYPERDRIVE system in laboratory and discipline assessments have been offered finally month’s Geothermal Rising Convention in Reno, Nevada. In accordance with Moyes, the machine carried out past expectations.
“There’s nothing on the market in the meanwhile that may survive the depths, the pressures and temperatures in these effectively bores,” he stated. “Over the previous 18 months, we’ve launched and deployed a collection of 5 modular, interchangeable merchandise and methods with efficiency positive factors that have been hitherto thought inconceivable.”
All onshore trials have been carried out at HydroVolve’s bespoke onshore Drilling Take a look at Facility – a check rig that includes a 60-ft horizontal check mattress geared up with a 1,200 klbf push/pull functionality, a 120RPM, 15,000ft.lb rotary drive system and a 600GPM, 5000psi circulate loop. The rig is full instrumented to document WOB, axial impulse load, stress, ROP, RPM and torque at an information seize fee of 10,000hz.
A 6-inch HYPERDRIVE was fitted with a 6-inch TERRABIT and a sequence of check applications have been carried out, drilling in excessive UCS blue Rubislaw granite to find out the efficiency traits and to outline the optimum working parameters.
The system achieved a acquire in ROP by an element of two.6 over standard rotary drilling with an identical parameters.
In April and Might of this 12 months, discipline trials have been performed on land operations in continental Europe with three sizes of the HYPERDRIVE system: 12-1/4-inch, 8-1/2-inch and 6-inch.
The trials delivered the quickest ROP ever recorded in an extensively drilled basin; achieved the longest drilled interval ever recorded in an extensively drilled basin; and achieved ROP thrice the minimal pre-deployment success standards
Moreover, the sphere trials demonstrated the machine’s thermal stability with over 28 days on backside at temperatures exceeding 220 °C.
One of many trials, utilising a 6-inch TERRABIT, happened in a deep S-shaped profile effectively with inclination under 20 levels and complete depths in extra of 6000m. The effectively offered a excessive distinction in lithologies various between 5-8 kpsi shale and 22-25 kpsi sandstone reservoir and limestone stringers.
Traditionally, it was taking from 5 to fifteen drill bit runs to drill the 6-inch part with common ROP of 1m/hr.
The sector trial was performed in Might 2023 and drilled a complete depth of 229m at an averaged ROP of ~2m/hr, greater than double the anticipated drilled distance and triple the ROP anticipated. It’s estimated that had HYPERDRIVE been deployed for the total 6-inch gap part, price financial savings for this single gap part would have been in extra of $1,400,000.
Moyes is assured that the sphere trails show that the addition of managed axial impulse to PDC rotary drill bits delivers important positive factors in each ROP and bit sturdiness. He factors out that HYPERDRIVE works at any depth, introduces no stress loss and is all steel in development requiring no elastomeric seals: excellent for extremely HP/HT and geothermal environments.
“Principally, we’re taking present oil and fuel know-how and supercharging it for drilling deeper and sooner,” he stated. “This reduces the general capital burden on geothermal venture growth and equally reduces the levelized price of electrical energy considerably – significantly vital for globalising the chance for enhanced geothermal and superior geothermal methods and delivering geothermal in all places.”
