- BOP & Wellhead Jetting
- Core Bypass
- Differential Sticking
- Dry Tripping
- Hole Cleaning
- Liners & Screens (In-hole Drifting)
- Lost Circulation
- Motors, Mills, Reamers & Turbines
- Pipe Filling & Surge Relief
- Stuck Pipe
- Pressure Testing
- Reverse Circulating
- Running Lower Completion (Packer Setting)
- Wellbore Clean Up
- Mud Shearing, Milling, Perf & Wash
- Mechanical Bypass (Section Mill)
BOP & Wellhead Jetting
The DAV MX™ CircSub has been used many times for BOP and wellhead jetting applications. It's ideal for removing drilling debris when pulling out of hole and especially useful in deep water. Efficiency is optimized by doing this in the normal course of exit eliminating the need for a special trip.
Double benefit is provided as the installed DAV MX™ can also be deployed during the drilling phase, secure in the knowledge that it will open again on demand when jetting. It’s this ultra-high reliability that allows it to be cycled by the user with confidence for multiple applications.
2019 - A major North Sea operator, having completed drilling operations had to remove cuttings debris from its wellhead base prior to wellhead installation. The local sea currents were not enough to wash away the cuttings naturally, and the operator wanted to avoid the cost of a dedicated jetting assembly run.
Working in partnership with the Churchill team, the decision was taken to run the DAV MX™ CircSub in the drill string. Remaining dormant through the drilling phase, the tool was activated using a Churchill smart dart to achieve the desired jetting bypass of 1,200 gallons per minute. This high velocity stream of fluid jetting through the CircSub’s four custom angled ports was powerful enough to remove the cuttings from the wellhead base. Just two 30-minute sweeps of the wellhead base cleared away all debris enabling successful installation of the wellhead shortly afterwards.
The operator was very pleased with the result. It avoided the complexity of a time-consuming dedicated cleaning trip that would have taken several hours. The drilling team now use the DAV MX™ CircSub for all wellhead jetting operations.
2018 - 5-ported DAV MX™ CircSub, run as a part of 17”x20” drill-out assembly, was activated upon pulling out of hole to jet the liner landing profile across the 20” casing. The valve locked-open with Standard Diverter Dart, was also used to jet and clean the Wellhead before aiding in dry-tripping the assembly to surface. With the quick and easy tool activation sequence as well as sufficient TFA across the subs ports’, the operator was able to speed up cleaning and tripping operations and save valuable rig time.
2017 – 3,198ft – North Sea Norway - DAV MX CircSub utilised for jetting the BOP at the end of the window mill-out run - 1 x ADD - System’s Multifunction Capability.
2015 - GOM, 23,620ft, activated for hole cleaning, then dry tripped and finally jetting the wellhead. 2 x Standard Diverter Darts were pumped (1 for Hole Cleaning, 1 for Jetting / Tripping). This demonstrates the diversity of the DAV MX, saving time during tripping and removing the need to run in with specialist wellhead jetting assemblies.
2010 - In one 58° well three separate bypass cycles were required to cure losses at around 14,755ft before the section drilling was completed. After each pill was spotted the valve was cycled shut, with a fourth cycle deployed on reaching the BOPs on the way out.
Using the DAV MX™ CircSub, cement can be pumped safely into the annulus without the risk of contaminating the lower BHA. The tool is designed to be robust and simple, with minimal cavities that could be contaminated, Churchill use single use Smart Darts as opposed to J-slots. The latch and seal protection which is unique to the Smart Darts guarantees operators won’t see LCM in their BHAs. A cementing sequence can be performed using the tool, with the closing cycle naturally flushing any potential contamination to the BHA out of the ports, prior to the resumption of thru-bit circulation.
The resilience and reliability of the Smart Dart, combined with its unique latch and seal protection, provides a stable barrier against cement ingress into the BHA, which in turn delivers surety of closing after the cementing cycle. The tool also offers class-leading resilience when thru-bit cementing is unavoidable.
2016 - 28,423ft, - GOM - 250bbls of 16.6ppg cement slurry successfully displaced through DAV MX CircSub to treat substantial losses - 1 x Standard Diverter Dart - DAV Robustness in Extreme Loss Curing Operations
In 2011, whilst drilling on a deepwater exploration well an operator used the DAV MX to pump a significant amount of cement into the annulus to cure massive losses. The DAV MX was activated whilst RIH at 5,293ft with the Alternative Diverter Dart, activating the valve when pumping, and preventing any through flow of cement to the BHA. The tool was then deactivated as pumping was stopped, allowing the operator to RIH and drill ahead having safely stabilized the well.
Once taken, a valuable core sample can be protected from excessive circulation by opening a DAV MX CircSub™. This allows users to circulate above the core, and get a clean exit from hole, without compromising the sample taken.
In 2012 the DAV MX was used for a successful core barrel isolation. By using the 100% bypass Standard Diverter Dart with its lock-open capability, pulling out of hole could be done in the "open" position to deliver a safer and faster dry trip.
Due to the flexibility of the MX™ system, the DAV MX can be easily customized for users requiring a low shear closing. The number of shear pins used in the make-up of the Smart Darts can be reduced, allowing for a shear out at pressures as low as 600psi, or the Ultra Series Darts could be used with a built in soft shear mechanism.
Churchill offers two solutions to differential sticking: firstly a slightly unconventional one to release the pipe from the stuck formation and secondly recovery options when free-up attempts fail.
Reducing the mud-weight in the well can reduce or even remove the differential forcing the pipe onto the formation. If it is safe to do so, a quick way to reduce the mud-weight is to pump down a lighter mud into the string and then allow the heavier annulus mud to U-tube it back out of the string. This effectively lowers the head in the annulus and reduces down-hole pressure. Using one of our unique lock-open darts to hold the valve open will allow this U-tubing to occur. It can also be used to relieve pressure by pumping in the lighter fluid. This method has traditionally been achieved by perforating the drill-pipe to facilitate the displacement.
If free-up attempts fail, stuck pipe can be released from hole above the sticking point using a HyPR™ dart to sever the string. (See product page).
Circulating a mud displacement through the bit can be inefficient. It is often much faster to use a circsub to improve hydraulics achieve a much quicker result.
The DAV MX™ CircSub has completed scores of displacement operations. By using the DAV MX to displace directly into the annulus (bypassing the bit) a much greater annular velocity can be achieved.
2018 -DAV MX CircSub was used on an MPD lower completions run, providing a North Sea operator with a robust contingency against losses while withstanding substantial amounts of differential pressure and resisting exposure to acid breaker fluid. Upon the screens’ instalment and before pulling out of hole, the sub was activated to boost displacements rates, significantly cutting down on operations time.
2017 – 10,100ft - North Sea Norway - Churchill Drilling Tools successfully deploys its 5.00” (NC38) DAV MX CircSub on a tapered assembly WBCU run – 1 x Split Flow Dart – WBCU Compatibility.
In an MPD off-shore displacement in 2014, the DAV was cycled four times at depths of around 13,500ft to make various displacements ranging between 11.7 to 15.9ppg. When complete a fifth cycle was used for boosted hole-cleaning prior to pulling out of hole.
The DAV MX is unique in its class because Smart Darts are highly resilient to heavy muds. Field proven up to 19.5ppg there is no practical limit to the weight of mud that can be securely bypassed.
Dry Tripping has many safety and performance benefits and again the lock-open feature of the DAV MX system provides a unique cost-saving solution. In fact this application is probably the most commonly exploited benefit that operators get from the system, with the valve having being “tripped-out” on hundreds of occasions.
The valve is commonly deployed at the end of the run for boosted hole cleaning, activated with either the Split-Flow or Standard Diverter Dart. Simply skipping the closing cycle will deliver a faster and safer dry trip. This confirms the DAV MX as the best value in class with two application savings for the cost of a single tool in the string.
GoM, 2015, 29,896ft. a Standard Diverter Dart was left holding the tool in the open position after hole cleaning to POOH and allowing fluid to drain from the drill-string.
Hole cleaning is a common challenge in angled or extended reach sections, where annular velocity (AV) is insufficient to flush the cuttings from the hole efficiently. With AV hampered either by BHA restrictions or by ECD or pressure window considerations a bypassing CircSub is often the go-to solution.
Hole cleaning is the number one application for the DAV MX™ and accounts for around a third of all dart activations. By using the unique lock-open darts (Standard or Split Flow), users also have the opportunity of tripping out dry by leaving the valve open after the bypass cleaning interval.
Additionally, by using the Split Flow Dart to lubricate and cool the BHA, further efficiency can be gained by spinning the pipe to increase agitation of the cuttings. Measured flow rates from these applications indicate that the Split Flow Dart delivers around 15% of flow to the bit, providing sufficient flow to maintain temperature control whilst sustaining continuous rotation. The multiple dart configuration options give the operator maximum flexibility in selecting an optimized hole-exit strategy.
2017 - 10,754ft – Netherlands - Operator achieves optimal Hole Cleaning on two separate runs, by activating two DAV MX CircSubs spaced out in a single drillstring on a challenging geothermal well – 2 x Standard Diverter Darts & 2 x Split Flow Darts – Optimal Hole Cleaning.
2017 – 5,736ft - Germany - DAV MX CircSubs utilised for hole cleaning across multiple sections in a challenging development well – 5 x Standard Diverter Dart, 1 x US Standard Diverter Dart & 1 x Split Flow Dart – System’s reliability and ease of use across multiple runs.
2016 - 12,696ft, - North Sea Norway - DAV MX CircSubs utilised for hole cleaning and mud screening in a challenging North Sea development well - 1 x Split Flow Dart - Sufficient Split-Flow while Hole Cleaning.
2015 - 29,896ft., Gulf of Mexico, hole-cleaning for 4 hours, Standard Diverter Dart
2015 – 12,538ft., Norway, hole-cleaning 22% flow to bit, Split Flow Dart
2015 – 27,770ft., Gulf of Mexico, hole-cleaning followed by BOP jetting whilst POOH, 2 x Standard Diverter Dart
2014 – 11,715ft North Sea, Hole Cleaning whilst reducing ECD, Split Flow Dart
2014 – 13,415ft, North Sea Hole Cleaning and displacements (5 Activations, HPHT), Standard Diverter Dart
2013 – 26,012ft., Gulf of Mexico, hole-cleaning and reamer bypass (bypass interval 64 hours), Standard Diverter Dart
2011 – 14,500ft, North Sea, Hole Cleaning, Split Flow Dart
2010 – 13,878ft., Ghana, hole-cleaning and anti-swab POOH, Split Flow Dart
Liners & Screens (In-hole Drifting)
As a well nears completion, sunk costs rise and the cost of failure escalates. Before installing the liner or screen, the drill pipe requires to be drifted to ensure that it's clear for setting balls and/or cement plugs. This is because it may have become compromised during the drilling operations.
Since drilling began, operators have been drifting their pipe, however depending on the method normally deployed the Drift Catcher™ method can save a lot of time, increase process visibility and significantly reduce operational risk.
Note pipe obstructions are not common, but their cost is so high that they need to be checked for. Further note that it has been known for ad-hoc drifting methods to cost a well by actually introducing obstructions to pipe that would have otherwise been clear.
Used since 2003 with more than 2,000 runs by around 120 different operators, the system has become the preferred method for many rigs. A GoM operator based study concluded that a saving of over a minute per stand can be achieved by not having to drift manually while tripping the pipe in or out of hole. This means that with the Drift Catcher downhole drifting method, over one and a half hours can be saved per 10,000ft of drillpipe tripped out of hole.
2016: Our client, a major operator, opted to run two Drift Catcher™ Subs as a part of the WBCU assembly. The bottom sub was placed just above the scrapers and debris clean-up tools run to scrape & wash across the 7-5/8” x 9-5/8” casing, while the top sub was placed just above the 11-3/4” casing clean-up tools. Just before the assembly was POOH, a 3.00” OD Hollow Drift was dropped from surface and pumped to top landing sub, drifting over 4,800ft of 5.5” drillpipe. Once the top Drift Catcher™ Sub was pulled out to surface, the Hollow Drift was retrieved and put aside. Then, after pulling out and B/O the 11-3/4” casing clean-up tools, the same Hollow Drift was dropped and pumped to bottom sub, drifting additional 6,200ft of pipe. Upon both landings, the Drift Catcher™ system provided the rig crew with a visible pressure increase indicating a positive drift.
After hole-cleaning and tripping from hole, curing losses is the next most common dart application for the DAV MX™ CircSub. That being said the impact of severe losses on well control are such that the tool is very often run as a contingency for loss situations. Including these “non-activated” contingency applications make it the number one application for the tool. This application applies equally to both use of LCM or cement.
Low Cost: As contingency insurance, the tool is the most economical solution because it is simple, doesn’t require a service hand, has the largest straight thru-bore in class and the highest level of dormancy integrity available. So when not activated it has the least impact on the program of any tool on the market.
Speed: Not only can they be pumped down quickly but our smart darts will have dropped several thousand feet towards the tool by the time the top-drive is made back up. When losses occur, there is no tool that can deliver bypass faster, saving the operator both time and mud. Firstly with a single shot high speed activation the time to activate is extremely rapid. Secondly there is a very precise and clear opening stroke so spotting can start immediately; and thirdly anti-blow-thru means there is very little danger of secondary cycling attempts being required and causing NPT.
Isolation Integrity: Keeping contamination out is the main purpose of application. Unique latch and seal geometry means that the jewelry is fully protected from any LCM ingress by the darts (all darts except the Split Flow Dart). The darts are resilient to U-tubing, which is quite common with heavy LCM, and can’t be unseated as a barrier. Furthermore the high shearing safety factor in the darts means that even the heaviest muds will not be able to prematurely shear them out of the way.
Multiple Loss Intervals: On some sections, multiple curing cycles are often required, which is where simplicity and reliability comes to the fore. With these single use high integrity darts in a simple and rugged tool design, the sub is maintained in optimum condition for secondary operations.
Soft Shear: Where there are concerns that shear-out may re-fracture the formation after curing, the Smart Darts can be easily customized to shear out at lower pressures. The number of shear pins in the MX™ mechanism can be reduced to allow a shear out at a much lower pressure (~600 psi), yet is still protected from premature blow-thru. This soft-shear option is available on request and is also well suited to coring applications.
2018 - DAV MX CircSub proved to be a vital contingency tool, when used to combat total losses encountered by a Persian Gulf operator while drilling the 12 ¼” section. The tool was activated four times with full bypass Standard Diverter and Alternative Diverter Darts. This allowed a total of four concentrated (100-120ppb) LCM pills to be pumped through, while by-passing the BHA below. On each activation, the Smart Darts were pumped down between 200gpm to 300gpm reaching the valve in less than 10 minutes, meaning losses could be tackled rapidly.
2018: The DAV MX CircSub & HyPR HoleSaver™ provided the ultimate contingency combination when a Middle East based Operator had a stuck pipe issue on the way out of hole. The DAV MX was activated using a Standard Diverter Dart to allow full circulation and acid spotting directly into the formation causing issues. This allowed the operator to get free without the need to sever the string.
2017 – 12,011ft – Middle East - DAV MX™ CircSub allows a major UAE operator cure 150bbls/hr Losses by spotting a total of 376bbls of LCM – 1 x Standard Diverter Dart – System’s Reliability when spotting vast amount of LCM
2015 – 5064ft, North Sea, Dynamic losses of 121bbls/hr cured, LCM, 43bbls,10.9ppb, 1 x Standard Diverter Dart
2015 – 11,509ft, Ivory Coast, Spotting LCM, 121bbls,
100ppb, 1 x Standard Diverter Dart
2014 - 4,765ft, Saudi Arabia, Dynamic Losses of 253bbl/hr cured, LCM, 700bbls, 200ppb, 3 x Standard Diverter Dart
2014 – 15,644ft, GOM, Spotting LCM, 170bbls, 200ppb, 3 x Standard Diverter Dart
2014 – 9,507ft, English Channel, Static/ Dynamic losses of 40/200bbl/h cured, LCM, 90bbls, at 98°, 2 x Standard Diverter Dart
2013 – Southern Italy, Static/ Dynamic losses of 500/1000bbl/h cured, LCM, 10 course pills spotted, 2 x Standard Diverter Dart
2010 – 14,735ft, North Sea, Static/ Dynamic losses of 30/180bbl/h cured, LCM, 217bbls, 224ppb, 3 x Alternative Diverter Dart
Mud Shearing, Milling, Perf & Wash
There are a couple of useful applications for our tools that make P&A operations more efficient:
Firstly, tripping in hole with the DAV MX™ CircSub locked open allows self-filling and faster tripping in times whilst protecting the knives of the mill. The second useful application is displacing from the old mud in the well to the milling fluid. The milling fluid also has to be conditioned because of its viscosity properties which carry the swarf out of hole.
The Mud Shear-Sub at surface combined with the DAV MX™ placed above the mill allows for fast displacement to the milling fluid and faster shearing of the milling fluid whilst the mill is bypassed - protecting the knives of the mill. The DAV MX can also be used to hole clean post section milling.
Tripping bypass is easily obtained by using one of the lock-open darts, usually the Split Flow Dart, and if required a tool can be supplied with a lock-open dart pre-installed. At TD, a closing dart can be deployed quickly to activate the mill before a second cycle is used to bypass and accelerate hole-cleaning. As is often desirable the valve can be left locked open for a fully relieved dry trip from hole with the bit bypassed.
Swarf is obviously a highly destructive form of debris, one which is able to contaminate and damage both top-side and down-hole equipment very quickly. Using this application and some unique features on the darts and tools will minimizes operators' risk of being affected by swarf contamination.
2018 -A single DAV MX CircSub was activated five times across five separate runs on two North Sea Plug and Abandon wells. It was used multiple times to self-fill and drain the string while tripping in and out of the well. The sub was also used to displace and condition fluids prior to, and hole clean after section milling. The applications helped the operator carry out crucial P&A operations smoothly and efficiently, contributing to substantial time savings across the two wells.
Instead of section milling a relatively new method in P&A is the perforate and wash method instead of section milling. During a recent job in the North Sea the DAV MX™ was used to self-fill, condition mud and bypass the perforation cutters.
2018 - Eight NC38 DAV MX CircSubs were run nine times and activated on 20 occasions in total, during a challenging P&A campaign for one supermajor operator in the UKCS. The circulating subs, run as a part of 7” casing perforation and wash assemblies, enabled the operator to trip in and out of the well faster through its unique lock open feature. Running the tools, the operator was also able to better hole clean and condition mud after each perforating run, by bypassing the flow above the constricted perf and wash tools. The operator was impressed with the circulating subs’ overall performance praising its user-friendly design and its reliability in harsh HPHT conditions, where fluid density reached 19.5ppg (2.3SG).
The Mud-Shear Sub has been run many times by a number of different operators and cuts shearing times by around 50%. This sub is extremely compact, convenient and quick to install just below the rotary table. When combined with the locked open DAV MX CircSub it delivers extremely rapid and efficient shearing with massive time savings. Mud is brought into condition far more quickly than with conventional methods and so milling can commence much earlier.
2018: The Mud Shear Sub saved an operator hours of rig time when utilised over three separate wells during a North Sea Plug and Abandon campaign. On each occasion the sub was utilised to shear viscus milling fluid during displacements from sea water. Introducing an additional shearing point to the circulating system, cuts down on the fluid’s conditioning time meaning subsequent P&A operations could commence ahead of time.
In a 2013 case study across seven wells during a P&A operation, the sub delivered approximately 28 hours of time saved on the platform. Region - North Sea.
Motors, Mills, Reamers & Turbines
Cutting assemblies which consume a lot of flow power or which are activated by flow, can impede some of the phases of a section’s operation. Typically this can be either running into or out of the hole or during a hole-cleaning session. It can therefore be extremely useful to have bypass valve in the string to take control over the flow path and the hydraulics. This will produce both a quicker operation and/or reduce some of the risks associated with running the cutting tool.
Dart lock-open is a very useful option for running some of these devices into or out of the hole in the de-activated state. The Split Flow Dart, most commonly, will fully de-risk and accelerate the trip with pressure fully relieved as the string moves through the hole.
2018 - A single DAV MX CircSub was activated a total of five times across five separate runs on two North Sea wells. The DAV MX™ was used multiple times to self-fill and drain the string while tripping in and out of the well. The sub was also used to displace and condition fluids prior to, and hole clean after section milling. The applications helped the operator carry out crucial operations smoothly and efficiently, contributing to substantial time savings across the two wells.
Reamer Bypass - 2013 - 26,012ft, Gulf of Mexico, angles up to 44°, SDD
Motor Bypass – 2014 – Central North Sea, Split Flow Dart
Mill Bypass (used in conjunction with Mud Shear Sub) – 2013 – 15,675ft, Central North Sea, Split Flow Dart
Recovering circulation will regain primary well control and with a DAV MX™ CircSub above the pack-off point (and below 60° degrees in angle) it is possible to do so quickly. We have a 100% success rate when attempts were made to regain circulation in these rare scenarios. We also have a strong track record in helping users regain circulation after the string becomes plugged, this is however highly dependent upon pressure and mud volume.
Pack-off: In most cases the pack-off point is on the stabilizers, so positioning the valve above them will mean when the valve opens circulation has been regained. Once regained further attempts can be made to free the pipe until such time as a severing decision is required.
Plugged string: As with pack-off, sufficient compression in the fluid between the valve and the plugged point must be available to allow the piston to travel so the ports can open. Whilst this is possible in a plugged string this is more restricted as fluid volumes are smaller and there is no access to any elasticity in the formation. However once opened, recovery prospects are good if the wellbore has remained in condition.
Drop the ball: Each tool is supplied with an Emergency Opening Ball (EOB), a steel ball is proven to have the best chance of reaching and seating in the tool under gravity alone. For lower angles (below 50°) there is an optional Retrievable Diverter Dart for special applications.
The DAV MX CircSub has been used many times where the string has been packed off or plugged. Pack off occurs when insufficient hole cleaning leads to cuttings building up and plugging the wellbore around the BHA. It can also be caused by troublesome formation collapsing or swelling whilst drilling. Plugging has been seen due to tool failures in the BHA, heavy materials plugging the string, cementing or pumping LCM into loss zones through the BHA and not the DAV MX, which can be activated to regain circulation as per the case histories below.
2018 - The DAV MX™ CircSub & HyPR HoleSaver provided the ultimate contingency combination when a Middle East based operator had a stuck pipe issue on the way out of hole. The DAV MX was activated using a Standard Diverter Dart to allow full circulation and acid spotting directly into the formation causing issues. This allowed the operator to get free without the need to sever the string.
Pack-off - 2016 - 6,515ft, - Italy - Operator succeeds in freeing packed-off 12-1/4” section drilling assembly twice, across two runs after activating Churchill’s DAV MX™ Circulating Sub - 1 x Split Flow Dart & 1 x Standard Diverter Dart - DAV MX able to clear Pack-off and free the string.
Pack-off – 2015, North Sea, 1 x EOB operated at 42°, the tool worked well and circulation was regained.
Plugged String – 2015, GOM at 28,414ft , 1 x EOB operated at 25°, successfully regained circulation.
Plugged String – 2013, North Sea at 10,742ft, 1 x EOB operated at 18°, successfully regained circulation.
Once circulation has been regained around the pack-off a HyPR™ Dart can be deployed into its sub to sever the string quickly for sidetrack or fishing.
In March 2019, a major Middle Eastern operator’s string became stuck and circulation was lost due to a pack-off. Given the risk of stuck pipe and well aware of our unique technology, the operator included two Churchill tools in the string as contingency.
Firstly, the DAV MX CircSub was activated to regain and establish reliable circulation and well control. Subsequently, the HyPR dart was deployed activating the HyPR HoleSaver which harnessed the existing drilling fluid and severed the string. The ‘HyPR cut’ took just 2.5 hours. The operator avoided the need for any explosives, chemicals, other additional topside equipment or any extra personnel. The operator recovered 8,335 feet of string and after cementing began sidetrack operations soon after. The client was impressed with the result and the significant time savings achieved.
Pipe Filling & Surge Relief
In certain applications the inconvenience of running into hole (RIH) with floats can be costly, either in terms of top-fill time or slow RIH for surge mitigation. Three products in our range can be used to greatly relieve the situation with slightly different approaches.
One conventional mitigation method is to run ported floats, however for many applications this may not be compliant, for example in HPHT situations. Ported floats tend to fill much slower effecting RIH speeds, meaning that top-filling is still required. A second method is a type of float, in which the float is held open by a temporary fixing latch until pumping unlatches and closes the float. This technique doesn’t support shallow hole testing of the MWD on RIH, which will prematurely activate the float.
The DAV MX has been deployed many times for self-filling the string when running into hole. Using the unique lock open dart mode, a useful filling path around the bit allows the string to be filled from the annulus as it runs into the mud.
2018: The DAV MX was picked up in the cleanout BHA. The BHA was run in hole to displace the well and drill a cement plug at 4,437ft. The assembly was then run in hole to 6000ft to circulate and condition the mud prior to dropping the Dart. The DAV MX was then activated and locked open. An inflow test (negative pressure test) was performed by pumping 127 bbl of 6.0ppg base oil down the drill string to achieve a maximum pressure of 1,624 psi. The operator closed the annular and bled off stand pipe pressure incrementally. Monitored well for flow; well static. The client then increased pressure back to 1,624 psi, opened the annular and allowed base oil to u-tube. The remaining base oil was reverse circulated out at 125 gpm. The tool was then closed.
2016 - 25,196ft, - North Sea Norway - Operator saves hours of rig time utilising locked-open DAV MX™ CircSub for self-filling of the Perforating Assemblies across two runs on two separate wells - 2 x Split Flow Darts - Reliable String Self-Filling.
In a North Sea operation in 2013 the DAV MX was estimated to have saved 5 hours of rig time running into hole locked open down to 15,675ft.
The Self-Filling Float can be used either partially on tripping in (cased hole only) or fully (open hole too) depending on the application. In super critical (MPD) and deepwater applications where tripping to replace failed floats is very expensive, the system can also be run as a back-up to conventional floats to save trips. The SFF can also be applied in Completions and P&A operations where using standard drilling floats can be operationally inconvenient. In those specialist runs the ‘dart activation’ aspect of the SFF proves very useful.
2015 - during a North Sea Completions setting operations, the SFF successfully safeguarded the string and the rig from uncontrolled influx of CO2
2012 - during a case study across two different runs during a 8-1/2” section drill-out, the tool helped save over 7 hours of rig time by allowing the pipe to self-fill while running into hole locked open. Region - North Sea. De-activation depth - 11,900ft.
An evolution of the Self Filling Float, the Self-Filling Float Trigger is the simplest and fastest float system available for tripping into hole, delivering savings all the way to the shoe and beyond.
It provides all the benefits of the original Self-Filling Float including time savings of up to 18 minutes per 1,000 feet and double float protection. However, with automatic depth-arming and pump-triggering, the Self-Filling Float Trigger increases capability and simplicity even further.
2019: A single NC50 Self-Filling Float Trigger was run in a 8.5” x 10.25” drilling assembly. It enabled Shallow Hole Testing to take place and delivered Self-Filling of the string all the way to the shoe, significantly reducing tripping in time. With the permanent through bore the Self-Filling Float Trigger was run in conjunction with the operator's reamer system which required multi ball drops to be able to drift through the float.
When top-filling simply can't be avoided there is no faster or easier way to couple and fill than with the TopJet™. Used on over 600 occasions by more than 40 operators, the tool has proven to be a very useful piece of rig floor equipment. Saving up to 10 minutes per 1,000 feet run in hole, it can be used either stand-alone or in conjunction with down-hole tool options.
2018: The coupling was utilised over three runs, across two subsequent wells, and saved an average of 10 minutes per 1,000 feet run in hole, reducing the open hole exposure times and thus minimising risk. The operator also reported a reduction in rig floor spillages.
Pressure testing an upper part of the drill string is easily done using the Pressure Test Sub MX™. The system is a simple yet accurate way to pressure test to a specific pre-set pressure and be able to regain circulation after the test.
The Pressure Test Sub is operated by placing it below the section that is to be tested. Pumping the pre-configured PTS™ Dart to the landing seat will deliver the testing pressure. Users have found the shearing pressure to be extremely configurable and accurate when regaining circulation, thanks to the consistency of the MX™ design. A catcher sub below stores the used darts for multiple test cycles.
On the special occasions when fluids are to be circulated in the reverse direction, the DAV MX™ CircSub can help manage hydraulics more efficiently.
Opening up a generous TFA between the annulus and the string, using the unique DAV MX™ lock-open mode is an extremely robust solution. The Split Flow lock-open mode gives a fully vented option allowing reverse circulating with ease. The preferred method, however, is to use it in conjunction with a float below the CircSub.
2018: The DAV MX was picked up in the cleanout BHA. The BHA was run in hole to displace the well and drill a cement plug at 4,437ft. The assembly was then run in hole to 6000ft to circulate and condition the mud prior to dropping the Dart. The DAV was then activated and locked open. An inflow test (negative pressure test) was performed by pumping 127 bbl of 6.0 ppg base oil down drill string to achieve a maximum pressure of 1,624 psi. Closed annular and bled off stand pipe pressure incrementally. Monitored well for flow; well static. Increased pressure back to 1,624 psi, opened annular and allowed base oil to u-tube. The remaining base oil was reverse circulated out at 125 gpm. The tool was then closed.
2016 - 6,000ft, - GOM - DAV MX™ used to perform an inflow test, Dry-Trip and Jet the Wellhead in P&A operation - Standard Diverter Dart - System’s Versatility
Running Lower Completion (Packer Setting)
Setting the packer on the lower completion is often made easier with greater control of the hydraulic flow paths. We have a number of tool options that have assisted operators to control flow rates, pressures and barriers during these operations.
The DAV MX has been used many times as a means of bypassing a lower completion packer. Typically the valve will be run in hole locked open above the setting assembly to permit full circulation and pressure relief. Once at depth the valve is closed to activate the liner/packer.
In one HPHT well, it was locked-open at surface using a Split Flow Dart before being RIH to 13,630ft. After allowing the lower completions packer to be hydraulically bypassed (so as to not activate prematurely), the DAV MX was closed before setting the packer using 9000psi.
DAV MX™ CircSub allowed operator to reduce tripping time by eliminating the top-filling requirement and provided an alternative circulation path for fluids, hydraulically bypassing the Perforating Assembly beneath. Once deactivated, the DAV MX™ withstood ~3,200psi of differential pressure needed to activate the perforating guns.
The DAV MX CircSub has a class leading 10,000psi differential pressure envelope (both inside-to-out and outside-to-in) to provide operators with the widest possible operating and safety margins.
The flapper version of the Self-Filling Float has a through-bore prior to activation, allowing setting balls to pass through as well as bi-directional flow. After the setting of the lower completion, the float is activated by a dart to release its flappers and prevent any returns up the string.
In 2015, the Self-Filling Float protected a drill string from CO2 influx after allowing the setting of a lower completion at 10,194ft.
In May 2019 a major operator recovered from stuck pipe by severing its drill string in just one hour using the HyPR HoleSaver.
To recover from a previous stuck pipe incident in the same well our client contracted high energy source cutting services. However, the additional equipment, personnel and logistics cost two days of valuable rig time. So, when the operator became ‘differentially stuck’ in the same well at 12,785ft on May 28th due to heavy losses, the team were ready with the HyPR HoleSaver to sever, plug and abandon the section much more quickly.
To provide the optimum circulation parameters, the operator first activated our DAV MX™ CircSub which had been placed beneath the HyPR™ sub in the drill-string. The HyPR HoleSaver™ dart was subsequently dropped and pumped to redirect the flow of mud creating a high velocity stream of fluid, using the existing mud system, to erode and sever the string.
The operator witnessed the expected drop in circulating pressure over a period of 45 minutes of pumping at 520 gallons per minute. Satisfied that enough progress had been made, applying torque and overpull parted the string with ease. On previous HyPR™ severs operators have cut through around 90% of the HyPR™ sub’s full strength inner connection before applying torque to twist-off, generally taking two to three hours. However, on this occasion the operator applied torque (25 klbf.ft) much earlier to save the extra time. In total, the process took just an hour, a record for Churchill, and widely thought to be the industry’s quickest planned severance from stuck pipe. The operator subsequently plugged and abandoned the section and moved operations to another well.
Working in partnership with the operator the Churchill team optimized the tools’ configuration and supported the client to get out of hole quickly and safely. The Drilling Manager was delighted with the performance of both the DAV MX™ CircSub™ and the ‘excellent’ HyPR HoleSaver™.
HyPR HoleSaver gets operator 'out of a hole'...
Meanwhile, in March 2019, a major Middle Eastern operator’s string became stuck and circulation was lost due to a pack-off. Given the risk of stuck pipe and well aware of our unique technology, the operator included two Churchill tools in the string as contingency.
Firstly, the DAV MX™ CircSub was activated to regain and establish reliable circulation and well control. Subsequently, the HyPR dart was deployed activating the HyPR HoleSaver which harnessed the existing drilling fluid and severed the string. The ‘HyPR cut’ took just 2.5 hours. The operator avoided the need for any explosives, chemicals, other additional topside equipment or any extra personnel. The operator recovered 8,335 feet of string and after cementing began sidetrack operations soon after. The client was impressed with the result and the significant time savings achieved.
Mechanical Bypass (Section Mill)
2018 - A single DAV MX™ CircSub was activated a total of five times across five separate runs on two North Sea Plug and Abandon wells. The DAV MX™ was used multiple times to self-fill and drain the string while tripping in and out of the well. The sub was also used to displace and condition fluids prior to, and hole clean after section milling. The applications helped the operator carry out crucial P&A operations smoothly and efficiently, contributing to substantial time savings across the two wells.
2018 - Eight 5.00” (NC38) DAV MX CircSubs were run nine times and activated on 20 occasions in total, during a challenging P&A campaign for one supermajor operator in the UKCS. The circulating subs, run as a part of 7” casing perforation and wash assemblies, enabled the operator to trip in and out of the well faster through its unique lock open feature. Running the tools, the operator was also able to better hole clean and condition mud after each perforating run, by bypassing the flow above the constricted perf and wash tools. The operator was impressed with the DAV MX's overall performance praising its user-friendly design and its reliability in harsh HPHT conditions, where fluid density reached 19.5ppg (2.3SG).
Wellbore Clean Up
The DAV MX CircSub is a popular choice for assisting WBCU. Thanks to the generous bypass TFA the operator can bypass the restrictive TFA of the WBCU equipment, boost Annular Velocity and ensure the process of cleaning the well is significantly faster.
2019: The DAV MX CircSub allowed a Norwegian operator to significantly reduce hole cleaning and fluid conditioning times during two separate WBCU runs. Upon flushing of the 7” liner clear from debris, the 7.00” (NC50) sub was activated to boost the annular velocity inside the 9-5/8” casing. Each time, the generous TFA of the CircSub’s ports allowed for greater hole cleaning and fluid conditioning flow rates.
2019: The DAV MX™ CircSub was chosen by a Norwegian Service Company to assist the Operator across three separate runs. Each time, a specifically optimised version of the DAV MX was run to carry out the required application. The DAV MX enabled the operator to:
- Boost Hole Cleaning during clean-out run
- Allowed the Perf Assembly to Self-Fill upon tripping
- Optimised fluid conditioning during ECD restricted displacement run
- Allowed the operator to carry out ops faster and saving valuable rig time in the process
Operators can save up to 10 minutes per 1,000 feet RIH and at the same time improve safety by running our TopJet tool. Incredibly simple to use, placed between the drill pipe and the top drive, the TopJet™ enables faster pump-in flow rates and reduces overspill.
It has been used on more than 650 occasions by 42 operators across the globe.
2018 - The TopJet™ was used to top-fill the drill pipe during liner and completions running operations, significantly cutting down on fill-up times, while at the same time eliminating rig floor spillage and improving safety. The coupling was utilised over three runs, across two subsequent wells, and saved an average of 2 hours and 20 minutes per run, reducing the open hole exposure times and thus minimising risk.
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