snubbing unit vs workover rig brands

Snubbing units have evolved into one of the most capable and efficient well servicing tools in the oil & gas industry. In the 1920"s, the need for a rig to work with pressures at surface drove the invention of the snubbing unit. The first snubbing unit was primarily designed to work in well control situations to "snub" drill pipe and or casing into, or out of, a well bore when conventional well killing methods could not be used. The first snubbing unit relied on the draw works of the companion rig to supply its" power. A series of sheaves, cables and counter weights were rigged up so that as the rig"s traveling blocks hoisted up, the snubbing unit would snub in the hole. Conversely, when the traveling blocks on the rig were lowered, the snubbing unit would snub out of the hole. As you can imagine, this required close communication with several different contractors in order to perform the work safely and efficiently.

One of the main components of a snubbing unit is the slip. Stationary and travelling slips are operated in sequence to grip the pipe as it is snubbed into the well. Typically, a minimum of four slip bowls are used in snubbing operations. Two slip bowls are designated for "pipe light" operations. Pipe light is when the well bore forces are greater than the tubular weight in the well bore. The other two slip bowls are designated for "pipe heavy" operations. Pipe heavy occurs when either enough pipe has been snubbed into the well bore and fluid weight inside of the pipe is greater than the snub forces acting against the pipe in the well bore.

While snubbing into the hole, there is a transition point the tubular goes through from being pipe light, to pipe heavy. This transition is an equilibrium typically referred to as the "balance point". The balance point occurs when there is enough pipe weight in the wellbore to equal the snub forces generated against the pipe. In certain instances, thousands of feet of pipe can be moved with minimal effort since the pipe weight is at an equal state with the snub forces. Snubbing contractors calculate this snub force and add in a friction factor from the BOP and wall contact on either a casing or tubing string. If done correctly, the snubbing contractor can predict when this balance point will take place and can properly prepare for it.

Modern snubbing units are powered by sophisticated hydraulic systems. These hydraulic units typically supply all power required by the components of a snubbing operation. With a better understanding of hydraulics and modern advances, companies have been able to harness this hydraulic energy to develop precision controlled snubbing units. These units move tubulars into and out of a well bore by use of a "multi cylinder jack"; a snubbing jack comes in many sizes depending on the task at hand. They are usually denoted in size by the snubbing unit description (i.e. 460K, 340K, 200K, etc). The 460K snubbing unit has the ability to lift 460,000 LBS and a snubbing capacity of 230,000 LBS. Most snubbing units can typically snub half of their lift rating. Assume you had a well with 10,000 PSI at surface and wished to snub in a string of 2 3/8" tubing. The snubbing contractor can calculate the snub force, add in their respective friction calculations and project the snub force to overcome will be approximately 51,000 LBS. This would put a 120K snubbing unit to close to its maximum capacity of 60,000 LBS snub loading. The safest bet would be a 150K or 235K snubbing unit.

Well control is taken very seriously by snubbing contractors. The BOP is the only barrier between the well bore and personnel. Depending upon well conditions, pressures and work performed, the BOP stack configuration varies greatly; there can be a minimum of three BOP"s and in some cases, up to ten. All of this is determined in the pre-job phase of the operation.

Pipe handling is performed by the snubbing units "gin pole" and "pipe winches". The gin pole is typically telescoped out in excess of 40ft above the snubbing unit. With the use of dual tubing winches, multiple joints of pipe can be handled simultaneously, speeding up the operation.

The snubbing "basket" is the platform where the snubbing personnel work. The basket contains all of the necessary hydraulic controls to operate all the features of the snubbing unit, as well as a large bank of BOP"s and hydraulic valve controls.

Today"s snubbing units can be employed to provide a wide range of services. In essence, a snubbing unit is a hydraulic rig that can do everything a rig can do, plus it can perform under pressure in an under balanced live well state. This is especially critical to the operators in the Haynesville Shale, which is known for HPHT wells. With the use of the snubbing units" hydraulic rotary, the unit can be employed for fishing, milling, drilling, side tracking or any task needed to remove bridge plugs, cement or deepen wells.

The industry has become more aware of damages caused by heavy kill weight fluids and mud. This has helped make snubbing units more popular in a completion and workover role, versus its" traditional use as a well control response tool. With the advances in drilling technologies in the unconventional shale market, the benefits of snubbing units have become very apparent. These types of completions often have laterals extending out thousands of feet. With costly stimulations used to help extract the gas more efficiently, operators often times do not wish to turn around and load the well with heavy fluids to complete the well dead.

Coiled tubing has its limitations in reach, due to wall to wall mechanical friction in horizontal wells. Often times the coiled tubing units cannot reach TD or supply the needed weight on bit to mill up composite plugs typically used in completions.

Another clear advantage to using a snubbing unit is its" small footprint, which is critical on the tight locations in the unconventional shale"s. Moreover, the small size and ease of mobilizing is especially useful and cost effective with offshore wells.

In conclusion, with the snubbing unit"s size, ability to handle pressure, rotary capabilities, rigidity of jointed tubing and minimal wall contact, snubbing units have become the chosen resource for these types of completions.

Snubbing is a type of heavy well intervention performed on oil and gas wells. It involves running the BHA on a pipe string using a hydraulic workover rig. Unlike wireline or coiled tubing, the pipe is not spooled off a drum but made up and broken up while running in and pulling out, much like conventional drill pipe. Due to the large rigup, it is only used for the most demanding of operations when lighter intervention techniques do not offer the strength and durability.drilling and completions operations, snubbing can be performed with the well still under pressure (not killed). When done so, it is called hydraulic workover. It can also be performed without having to remove the Christmas tree from the wellhead.

A snubbing rigup is a very tall structure. It consists of a hydraulically powered snubbing unit, which provides the force on a pipe, above a string of multi-layered pressure control components.

At the top of the snubbing unit is the basket, which serves as the control post for the rigup. Below the basket are the hydraulic jacks, which power the pipe into and out of the hole. It consists of two mechanisms for applying force to the pipe in either direction. Each mechanism consists of travelling and stationary slips. The travelling slips are used to move the pipe, while the stationary slips are used to hold the pipe while the travelling slips are repositioned between strokes.

Unlike coiled tubing or wireline, where the wire or tubing is always the same diameter allowing for a single unmoving primary barrier (stuffing box or stripper), snubbing uses a pipe, which will have an enlarged collar at the connection between the joints. Therefore, the pressure control system must be able to accommodate this variable diameter. The stripping rams accomplish this. The first stage of lowering a collar through the stripping system is to close the lower rams so as to seal off the mechanism above from wellbore pressure. The space between the rams can then be bled off allowing the upper rams to be opened. The collar can then pass through the opened upper rams. Once the collar is in between the rams, the upper rams are closed and pressure is equalised either side of the lower rams. The lower rams are then safely opened and the collar is lowered through the rams.

Because snubbing is normally done under pressure, initially, the weight of pipe in wellbore is less than the force due to the wellbore pressure. This is described as light-pipe: downward force is required on the pipe to force it in against resistance. Once a sufficient amount of pipe has been run into the hole, the weight becomes sufficient to overpower the wellbore pressure and the pipe naturally wants to fall in the hole; this is heavy-pipe. At this point, the snubbing mechanism is changed over to the one which provides upward force to hold the pipe and lower it controllably into the well.

The more complex method of pressure control, as compared to coiled tubing and wireline, naturally invites more opportunity for things to go wrong. One such peril was seen in June 2007 on the Shearwater platform. Snubbing was being used to clean out large pebble, which had entered the well through a collapsed liner. While pulling out of hole, one stripping ram was not opened sufficiently and a collar on the pipe string caught on the ram. The excessive force applied to the pipe caused it to break apart, dropping the string below the failure into the well. In the time it took to prepare to fish out the pipe, the pebbles in the process of being circulated out, settled on the pipe, preventing successful fishing.

Not all Snubbing units are large and time consuming to rig up. In the Canadian oilfield many companies use small "Stand Alone" snubbing units which can be broken down and rigged up in less than 3hrs. These Units consist of 4 segments which can be placed onto 4 separate trucks. These 4 segments consist of the following:

Units varies in strength, there are 95K, 120K, 150K, 170K, 225K, 340K, 460K, 600K The number indicates their working strength in pulling force, and 150K means the unit is capable of pulling maximal 150000 pounds. This is based on the hydraulic force acting on the size of the unit"s piston size. Also are there more complex special built unit to find as the CSU 160 a special build rig assist unit, and stand alone units like

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Pumping services tend to get more expensive offshore, because of the degree to which the equipment must be assembled on location. Wire based services still require assembly, but because the parts are smaller can usually be mobilized in larger ‘chunks’ thus requiring less assembly on location. On land, fluid pumping equipment is much more readily portable on trucks or trailers. Workover rigs on land are incredibly cheap in most places as measured on a per diem basis. Part of their advantage is that they arrive to location with most of their key components already assembled in/on one truck. This advantage disappears offshore where the rig must be assembled on site first.

Paying for a drilling rig or intervention vessel is the price of gaining physical access to the well. Everything else must be added to it to get physical access to the general area and then gain access to the well. There is no need for various forms of standalone pumping services because the vessel or rig will already have a cementing unit and/or the mud pumps available for that sort of work.

Performing the same operation over and over again has significant cost savings attached to it. Once the correct housing and supply arrangements are in place, and all the necessary people and equipment have been assembled, continuing to use it altogether ‘as is’ can save an enormous amount of money compared to dispersing it all and starting over again later. For land operations, this is most pronounced in areas where reservoir, surface, and operational practices allow for grouping wells together in relatively small areas, and for clustering well pads. Depending on what work is being done to the wells and how close together they are it may be possible to ‘hop’ from one well to the other without ever moving the equipment on a road or doing a complete rig-down.

Deepwater operations can benefit from this too, but not as much as ‘traditional’ fixed or surface access facilities, because the overall day rate of the rig or intervention vessel is often much higher, and the process of switching between wells is often much lengthier.

On land, you hire the unit and crew, and a small diem fee is added to the cost of employing them so they can stay in a hotel and get food when they are not working. The crews will transport themselves to and from the well and move the equipment to and from the well also.

The costs of conducting business in each of these 3 areas tend to scale very roughly in factors of 10. 100 wells making 50 bbls of oil each on land is a cash cow. Offshore that is a disaster, because the cost of servicing those wells is prohibitive. A more reasonable scenario is 10 wells making 500 bbls of oil each. In deepwater, a well making 500 bbls of oil a day is an abandonment candidate, if indeed it got that far along before abandonment. One well making 5,000 bbls a day is more. The direct cost of hiring (for example) a snubbing unit do not scale by factors of 10, but the overall cost of employing a snubbing unit do. As a result, different types of well servicing make sense in one area which may not make sense in another. On land in areas with ordinary access to infrastructure (not the Sahara or Alaska) operations like slickline are often so cheap that they are a routine procedure, with preventative or predictive maintenance schedules to scrape away paraffin or remove small amounts of scale. By contrast, it is completely cost prohibitive to try and attempt to perform similar work in deepwater – you either design and operate the well in such a way that paraffin and scale do not build up in the wellbore at appreciable rates, or you P&A the well. The cost of routine mitigation is simply too high. The relative cheapness of most workover rigs on land is another major factor. Many types of operations which could in theory be carried out in some other way are done with a workover rig simply because it is the most cost-effective technique, even if other methods might be faster, or involve fewer people. The relatively high cost of a rig for offshore facilities means that in most cases every effort short of getting a rig is tried first. Then a catalogue or list of operations to be conducted by a rig at a given facility will be gradually built up over time until they reach a critical level. At that point, a rig will be sent out to conduct all the operations which only it can perform, moving from one well another to save costs by making the work repeatable.

BHA: Bottom hole assembly. Describes the production or workover tools used for completion or workover operations. (i.e. packers, bridge plugs, fishing tools, etc).

BOP stack: A series of blow out preventers stacked together using an equalizing and bleed of spool. Stack normally consists of an annular; equalize spool and a set of stripping rams. In snubbing operations the BOP stack is considered a secondary BOP. When working in conjunction with a workover, service or drilling rig the rig supplies the primary BOP’s.

Counter Balance Winches: A winch that can hydraulically counter balance the weight it is picking up. This gives the winch the ability to automatically feed off should the load placed upon it become greater than the actual weight being held via the hydraulics. Typically the snubbing unit will have two of these winches.

Equalize line: High pressure line pipe, chick sans (swivels) and valves for use during a snubbing operation to equalize or bleed off pressures within different chambers in a snubbing BOP stack.

Equalize spool: A ported spool for use in a snubbing operations allowing the operator the ability to equalize or bleed off certain sections of the BOP stack.

Gas well snubbing: Workover or completion work on a gas well which is either live or underbalanced with a rig assist or self-contained snubbing unit. Many gas well formations are fluid sensitive making a snubbing operation ideal for maximum production of the well. Eliminates the need for expensive kill fluids.

Guide Tube: Any arrangement of support system that prevents columnar buckling of the pipe being snubbed. Typical arrangements can be telescopic or static depending on the design of the snubbing unit structure.

Hydraulic Workover Unit: A unit that competes directly with conventional work over rigs. By utilizing hydraulic cylinders instead of a traditional draw-works arrangement, the unit maintains a small footprint allowing rig up in tight areas such as on offshore platforms.

Live well completions: A well condition where tubulars and tools are pulled or inserted into a well with the use of a rig assist snubbing unit or self-contained snubbing unit. The well has surface pressure from the down hole formations. Wells can be either gas or oil.

Live well workovers: Describes the condition of a gas or oil well is in when tubulars are snubbed in or out of well. There is pressure at surface in these wells making them ideal candidates for snubbing operations.

Lower snubbing basket: The work floor area which allows access to the snubbing crew to the BOP stack components and stationary snubbing and heavy slips.

Passive Rotary: A turn-table integrally mounted in the snubbing unit traveling plate which allows the rotation of the string with the slips closed on the pipe in either the snub mode or pipe heavy mode. This rotary must be driven with an external force be it by hand or with a power swivel rigged above the unit.

Pipe Heavy: In regards to snubbing, this is a pipe condition in which the tubing has sufficient string weight to overcome the forces acting on its cross-sectional area. Once the weight is sufficient, it overcomes the force applied by the pressure in the well and will fall under its own weight into the well.

Pipe Light:  In regards to snubbing, this term describes the condition when the well bore forces acting on the cross-sectional area of the pipe being snubbed are greater than string weight; if tubing is not controlled, the snubbing unit will eject itself from the well.

Power-Pack: This is the prime mover that provides the force needed to turn hydraulic pumps which allow the operation of the snubbing jack and BOP systems. Diesel engines are the most common form, although electric drives are also utilized in special circumstances.

Powered Rotary: A turn-table integrally mounted in the snubbing unit traveling plate which allows the rotation of the string with the slips closed on the pipe in either the snub mode or pipe heavy mode. This rotary is driven with hydraulic motors, allowing the unit to perform string rotation without external support equipment.

Rig assist snubbing: A mobile snubbing unit, either truck-mounted or skid-mounted, that works in conjunction with a workover, service or drilling rig for workover or completions work on a live well or underbalanced well. Unit is capable of running or pulling tubulars and tools under pressure.

Scalloped spool: A spacer spool modified for snubbing to allow well bore pressures to equalize or bleed off around the tubing hanger when landing or pulling the hanger.

Self contained snubbing:A snubbing unit which stands alone by itself with no need of a service, workover or drilling rig. A self-contained unit is capable of workover or completion work on a live well or underbalanced well or indirect.

Snubbing: A procedure in which tubing is run or pulled from a well, which is in an underbalanced or live well condition. Snubbing units have specialized pressure control devices which permit them to deliver drilling, completion and workover services while there is pressure in the wellbore. Snubbing units eliminate the need to neutralize well pressure prior to servicing and therefore avoid the formation damage which neutralizing pressure can have on a well’s ability to produce.

Snubbing Assistant: This person’s position is primarily focused on taking direction from the snubbing operator, and entails routine maintenance, pipe handling and power tong operation.

Snubbing jack: The structure of the unit designed to withstand engineered ratings for both the pipe weight and the force applied by the unit’s hydraulic cylinders. The hydraulically operated equipment which enables crews to work on underbalanced or live well.

Snubbing Operator:Equivalent to a driller position, the snubbing operator physically operates the snubbing unit and takes direction from the snubbing supervisor. The operator is responsible for managing the daily activities of the rest of the snubbing crew, and ensuring that the equipment is functioning as designed.

Snubbing slips: A set of hydraulically actuated slips which can be run either inverted or right side up to control the movements of pipe in conjunction with a snubbing jack to insert or extract tubulars under live well or underbalanced conditions.

Snubbing Supervisor:Equivalent to a rig manager or tool push, the snubbing supervisor is responsible for all aspects of the snubbing unit and its operations. He/she is the direct liaison to the oil company representative he/she is working for. All members of the snubbing crew are subordinate to the snubbing supervisor. Typically the supervisor will have in excess of 10 years’ experience in snubbing operations.

Snubbing unit: A hydraulically actuated unit with slips, BOP stack and hydraulic jack for inserting or pulling tubing and BHA’s from underbalanced or live well conditions.

Stand alone snubbing (see self contained unit): Use of a snubbing unit by itself without the aid of a service, workover or drilling rig. Unit is capable of workover or completion work on a live well or underbalanced well.

Stationary snubbing slips: A set of snubbing slips that are typically mounted on top of a BOP stack which will hold pipe that is in a pipe light or neutral state.

Stripping: : During snubbing operations this is the procedure where you move pipe through a closed preventer (pipe rams or annular) on a live or underbalanced well containing pressure from the well bore with a closed preventer.

Stripping on: : The procedure in which a snubbing unit is rigged onto a service, workover or drilling rig, which is holding the pipe heavy tubing string with their tubing slips and not with a tubing hanger landed.

Stripping Ram: A hydraulically operated ram style BOP used during snubbing and stripping operations. Typically the ram front insert is a sacrificial material that is easily replaced for extended stripping. Materials for the inserts can be custom ordered for the application at hand.

TEP: A type of tubing plug developed for snubbing to control well bore pressures inside the tubing. Only viable for snubbing in operations. The plug is a machined collar with a removable disc and “o” ring. Once the tubing string has been snubbed in, the disc can be knocked out by equalizing the tubing string and flowing the casing. Once an overbalanced condition has been achieved inside the tubing string, the disc will fall out. Disc may also be removed by sand line or wire line tapping down on the disc once tubing string has been equalized with casing pressures.

Traveling plate: The plate which connects the rods from the hydraulic cylinders together on a snubbing unit where the traveling and heavy slips are attached. There are many cylinder configurations and stroke lengths possible depending on job requirements.

Traveling snubbing slips: A set of slips mounted upside down on a snubbing jacks traveling plate, which controls the movement of tubing in or out of a well. Slips will hold tubing only when tubing is in the pipe light state.

Underbalanced:A term to describe the pressure conditions in a well. Formation pressure is greater than the hydrostatic pressure of fluid, mud, etc… exerted on the formation causing pressure to migrate to surface in a well. A well in an underbalanced state is a prime candidate for snubbing.

Underbalanced completions: The condition of a well when completion services such as snubbing are performed. Formation pressure is greater than the hydrostatic pressure inside the well bore causing pressure to be at surface in the well. Underbalanced completions are prime candidates for snubbing. Typically wells have been perforated before snubbing unit arrives and the unit snubs in a production string to allow the well to be produced.

Underbalanced drilling: This term describes the condition of the well when drilling operations are ongoing. Snubbing units are used to snub out drill strings, i.e. bit changes and then snub in the drill string again or run productions strings.

Underbalanced workovers: The well is live with pressure to surface when workover operations are performed. Rig assist snubbing or self-contained snubbing units are used for the running or pulling of tubulars and BHA’s. Typically the snubbing unit pulls pipe from the well, the original zone is worked over, abandoned, or a new zone perforated and the snubbing unit snubs the production string back into the well.

Well control:In regards to snubbing, well control is the operation of containing well bore pressure with the use of a blowout preventer stack and tubing pressure by the use of a plugging system.

The act of putting drillpipe into the wellbore when the blowout preventers (BOPs) are closed and pressure is contained in the well. Snubbing is necessary when a kick is taken, since well kill operations should always be conducted with the drillstring on bottom, and not somewhere up the wellbore. If only the annular BOP has been closed, the drillpipe may be slowly and carefully lowered into the wellbore, and the BOP itself will open slightly to permit the larger diameter tool joints to pass through. If the well has been closed with the use of ram BOPs, the tool joints will not pass by the closed ram element. Hence, while keeping the well closed with either another ram BOP or the annular BOP, the ram must be opened manually, then the pipe lowered until the tool joint is just below the ram, and then closing the ram again. This procedure is repeated whenever a tool joint must pass by a ram BOP. In snubbing operations, the pressure in the wellbore acting on the cross-sectional area of the tubular can exert sufficient force to overcome the weight of the drillstring, so the string must be pushed (or "snubbed") back into the wellbore. In ordinary stripping operations, the pipe falls into the wellbore under its own weight, and no additional downward force or pushing is required.

Major players in the hydraulic workover unit market are Archer limited, Basic Energy Services, Inc. , Canadian Energy Equipment Manufacturing FZE, Cudd Energy Services, Easternwell Group, Elnusa, Halliburton Company, High Arctic Energy Services Inc, Key Energy Services, LLC, NOV Inc.

New York, March 24, 2022 (GLOBE NEWSWIRE) -- Reportlinker.com announces the release of the report "Hydraulic Workover Unit Global Market Report 2022" - https://www.reportlinker.com/p06247583/?utm_source=GNW

The global hydraulic workover unit market is expected to grow from $8.65 billion in 2021 to $9.58 billion in 2022 at a compound annual growth rate (CAGR) of 10.7%. The growth is mainly due to the companies resuming their operations and adapting to the new normal while recovering from the COVID-19 impact, which had earlier led to restrictive containment measures involving social distancing, remote working, and the closure of commercial activities that resulted in operational challenges. The market is expected to reach $12.40 billion in 2026 at a CAGR of 6.7%.

The hydraulic workover unit market consists of sales of hydraulic workover unit services by entities (organizations, sole traders, and partnerships) that utilize versatile, cost-saving, and safe techniques for the repair and maintenance of all types of wells.Hydraulic workover is a well intervention technique used for installing or removing tubes (pipes) in and out of dead wells (the well with zero surface pressure).

The main services in the hydraulic workover unit are workover and snubbing.The snubbing services are used to install or eliminate tubular from a well while the well is pressurized.

Snubbing has the advantage of allowing work to be done without dying the well, which eliminates reservoir formation damage and costly stimulation procedures.The various installation types include skid mounted, trailer mounted and has a capacity in different ranges such as 0-50 tonnes, 51-150 tonnes, above 150 tonnes.

North America was the largest region in the hydraulic workover unit market in 2021. The regions covered in this report are Asia-Pacific, Western Europe, Eastern Europe, North America, South America, Middle East and Africa.

The increasing shale gas production is projected to propel the growth of the hydraulic workover unit market in the coming years.Shale gas is natural gas generated from a type of sedimentary rock called shale that is formed from clastic origins such as sedimentary rock or siltstone.

The most adaptable technology available in the upstream oil and gas industry is the snubbing unit, which is a type of hydraulic workover unit. According to the United States Energy Information Administration, shale gas production in the USA is expected to increase from 27.90 trillion cubic feet in 2021 to 32.50 trillion cubic feet by 2025. Therefore, the increasing shale gas production drives the growth of the hydraulic workover unit market.

The introduction of multiphase projects is a key trend gaining popularity in the hydraulic workover unit market.Major players operating in the hydraulic workover unit sector are launching multiphase projects in collaboration with technology players to set a new offshore snubbing unit or hydraulic workover world record.

For instance, in September 2020, SBS Energy Services (SBS), a US-based provider of snubbing, hydraulic workover services entered into a strategic partnership with Helix Solutions to complete a multi-phase project that deactivates roughly 29,000 feet of 10 inches by 6 inches insulated pipeline in the Gulf of Mexico.

In April 2019, High Arctic Energy Services Inc., a Canada-based drilling oil and gas wells company acquired assets of snubbing services equipment from Precision Drilling for $8.5 million. The acquisition provides the High Arctic with additional quality snubbing equipment and access to experienced personnel and crews. Precision Drilling is a Canada-based drilling rig contractor involved in offering snubbing services, oil field rental, and supplies.

The countries covered in the hydraulic workover unit market report are Australia, Brazil, China, France, Germany, India, Indonesia, Japan, Russia, South Korea, UK and USA.

The most critical factors in snubbing is knowing how much pipe can be pushed in a hole at a time without buckling and how much collapse and burst pressure the pipe can handle.

To most longtime oil and gas field professionals, the word "snubbing" means trouble. It means a well somewhere is dangerously close to being out of control. "Everyone connected it with that forever," said Cudd Pressure Control vice-president, Ron Jackson. "Twelve to fourteen years ago a snubbing unit was the last thing you wanted to see come on your location."

"[Snubbing units] are used in situations such as when you are off bottom with drill pipe and you take a kick in the hole, particularly in an oil mud where the kick is not going to migrate so you have to get the pipe back to bottom," explained Larry Flak, Engineering Manager of well control specialists and well firefighters, Boots & Coots.

Once the kick is under control, that is being flowed harmlessly to a pipeline or flare in what is often referred to as a diverted blowout, the drill pipe must be sent back to bottom before the crew can regain complete control. It is the classic snubbing unit task because often the upward pressure of the flowing well is greater than the downward force created by the available drill pipe weight.

"If you are pipe light, meaning you don"t have enough weight for the drill pipe to combat the pressure, you may have to get a snubbing unit rigged up on the well to push it back in the hole because it won"t fall."

"With snubbing you have the ability to work on the well without killing it with heavy fluid that can be damaging to the formation," Jackson said. "So we can do workovers and completions without killing the well."

So popular has the practice become that Jackson estimates more than 80% of all snubbing jobs performed today are planned workovers, completions, or other type well interventions performed to protect the formation from fluid damage.

"Well control [snubbing] activities are very unusual," said Flak. "If [snubbing companies] had to depend on diverted blowouts to earn a living today, they would go bankrupt."

Offshore, doing a workover operations with a snubbing unit rather than a traditional rig is referred to as a "hydraulic workover", likely because of the old connotations industry veterans associate with the term snubbing. In the US Gulf of Mexico, it has become a common practice for the same reason underbalanced drilling has become popular in many onshore applications—re-entering depleted or partially depleted reservoirs.

While avoiding damage to older formations is a prime driver of the proliferation of hydraulic workovers, Jackson says the growing popularity of underbalanced drilling just naturally raises demand for underbalanced completions. "Brand new wells are good candidates [for snubbing completions] because they don"t have any damage yet," he said. "A lot of wells are drilled underbalanced with a little positive flow. But just because you drilled underbalanced, if you can"t complete it underbalanced you really haven"t accomplished as much as you might. We can run casing, cement, and perforate underbalanced and never hurt the formation. We can run up to 13-in. casing and handle a hook load of 600,000 pounds."

Snubbing"s reputation as a dangerous way to make a living, say today"s proponents of the process, has also been mitigated by changing technologies and applications when indeed the call does come for a well control situation. Much as operators now routinely drill in a situation once considered highly dangerous, so have they come to view completions and workovers done under pressure as not only safe, but as optimum and even routine under the proper circumstances and when properly planned.

As with so many older technologies, computer software is being brought to bear on the planning and executing of snubbing operations. The most critical factors in snubbing is knowing how much pipe can be "grabbed" and pushed in the hole at a time without buckling and how much collapse and burst pressure that pipe can handle. Cudd is in the midst of refining their proprietary program to better define those numbers and will possibly make them commercially available in the future.

"If you are on a well with 5,000 psi, and you are injecting tubing into it, you have to know the maximum unsupported length [of tubing] you can stuff in at a time and the forces exerted on the tube," said Jackson, explaining the theory behind the computer program. "You put in all the known parameters such as type of unit and power pack size, and it tells you the hydraulic settings and the maximum [length of tubing] you can take."

In addition to the immediate savings on high-cost jackups, when working over a well under pressure, there are costs savings in heavy muds and their handling. (Heavy kill muds with exotic additives designed to protect producing formations are often expensive to recycle and transport in the environmentally sensitive offshore.) Also, rig up and down is faster than with traditional workover rigs and production can be brought back on line more reliably and quicker when muds need not be cleaned from the well bore first—an operation that can take several days.

While some of the traditional snubbing market such as wellbore fluids clean-out or spotting acid or cement in live wells, have in recent years become the province of coiled tubing, demand for the staid old units is likely to remain high. For one thing, CT units have size limits, snubbing units do not. Above about a 3 ½-in diameter, particularly offshore, their weight and space requirements are a liability. And CT is not available in production casing sizes, which are often the section operators are most intent on protecting from fluid invasion.

And finally, one of the most prolific areas of development in the world today, is in the older fields of the US Gulf of Mexico, where independent operators are re-entering partially depleted zones to recover hydrocarbons left behind by majors seeking bigger targets. The depleted nature of these zones means they are highly susceptible to fluid invasion damage during recompletion and workover operations, in many cases the least expensive, most efficient method for handling them: hydraulic workovers.

Industry retooling is no longer confined to new high-spec drilling rigs. The well service/workover market has embarked on a newbuild cycle with 2014 manufacturing capacity essentially sold out.

A Hart Energy survey of equipment manufacturers in the well service/workover segment found respondents reporting strong demand for newbuild workover rigs. The newfound interest points to change underway in the completions side of the business. As operators push lateral lengths beyond a mile, coil tubing has become less effective, and oil and gas operators are expressing renewed interest in the tried and true workover rig with or without a snubbing unit.

That trend is pushing demand for beefier workover rigs at the high-spec end of the market as the industry transitions into the resource harvest phase of the tight formation hydrocarbon development cycle.

Manufacturers participating in the Hart Energy survey identified recent technological improvements in rig braking systems and demand for specialized workover rigs suited to pad drilling and batch completions as the main drivers in the newbuild cycle. Multiple innovations are under development that will allow workover rigs to adapt to multiwell pads, including removing the need to reset guy wires around the location when transitioning from well to well on pads. In a few cases, rigs are sporting outriggers in a fit-for-purpose design custom configured for multiwell pads.

Manufacturers cited rising delivery times for newbuild workover units, and a few larger manufacturers are expanding production capacity to meet rising demand. Both trends illustrate a healthy market in the well services/workover segment.

In all, manufacturers contacted in the Hart Energy survey reported 316 well service/workover rigs on order in 2014, with 285 destined for the domestic market. Most manufacturers noted their 2014 order books are filled—or close to it—and a few commented that they were taking orders for 2015 delivery.

Customer interest is generally centered on higher-spec well service equipment in the 500 and 600 series range. Orders are rising for 600-series units with 116-foot masts capable of incorporating top drives.

The demands of pad drilling and batch completions are prompting contractors to expand the utility of the formerly humble workover unit. Some larger series rigs have adjustable-height rig floors—up to 34 feet—and can trip pipe as a doubles unit. In other cases manufacturers report that customers are adding rotary tables so the rig can double as a top hole drilling unit.

New rig demand is broad across the spectrum. Manufacturers point to growing international interest in newbuild workover rigs, although the current crop of equipment undergoing manufacture in the U.S. is weighted to domestic deliveries. For international orders, manufacturers are building masts and components in the U.S. and shipping them overseas, where customers assemble them into units that will meet destination-specific transportation standards.

Pricing for newbuild units varies depending on how the units are finished out. Baseline 500-series units averaged $734,000 across manufacturers in the survey, with the highest price reported at $1.2 million for a specially equipped model. Average baseline pricing for 600-series units came to $800,000, though most topped $1 million once customers added ancillary equipment.

The big difference between this type of flush-by rig and conventional flush-by unit is drawworks. Mechanical drawworks are adopted on ourflush-by rig.

The global hydraulic workover unit market size is predicted to grow at a 3.84% CAGR in the forecast period (2020- 2027), states the current Market Research Future (MRFR) report. A hydraulic workover unit is the perfect well intervention solution for re-entry operations, well interventions, and well maintenance. This unit uses hydraulic cylinders for lifting the tubular or out of the well. The hydraulic cylinders enable complete control over tubular movements and helps in eliminating the need for a huge mast construction that is present on conventional drilling rigs.

According to the MRFR report, there are numerous factors that are propelling the global hydraulic workover unit market share. Some of these entail technological advances in oil and gas well production, increasing offshore production post decline in oil prices, the burgeoning need for hydraulic workover units in the offshore oil and gas industry, the rising electricity demand, increasing focus on offshore exploration, the production of E&P of oil and gas, the rising efforts by upstream companies to improve the production from the mature fields, and the increasing oil and gas production. The additional factors adding to the global hydraulic workover unit market value includes the growing development of natural gas resources, the rising focus on mature oil and gas fields with the implementation of digital technologies which are the latest hydraulic workover unit market trends, rising energy demand in developing economies, increasing number of exploration activities, well drilling activities, and hydraulic fracturing, growing demand for snubbing services, and rising number of mature oil and gas fields.

On the contrary, stringent environmental regulations, lack of skilled workforce, problems related to the use of hydraulic workover unit like long rig-up time, and problems in transport for its heavy weight may impede the global hydraulic workover unit market revenue over the forecast period.

The oil and gas sector unfortunately has faced the brunt of the ongoing COVID-19 crisis which in turn has impacted the hydraulic workover unit market. Owing to the present scenario, several oil and gas companies across regions were compelled to shut down their services and producing assets as countries practiced complete or partial lockdown strategy for dealing with the pandemic. Across the region, companies has either delayed or suspended the key oil and gas projects. Besides, the crisis has also impacted the rig count for oil and gas, well drilling and production activities, and also crude oil prices. All these factors have negatively impacted the global hydraulic workover unit market growth.

The MRFR report highlights an inclusive analysis of the global hydraulic workover unit industry based on application, installation, service, and capacity.

By capacity, the global hydraulic workover unit market is segmented into above 150 tonnes, 50 to 150 tonnes, and up to 50 tonnes. Of these, the above 150 tonnes capacity segment will lead the market over the forecast period.

By service, the global hydraulic workover unit market is segmented into snubbing and workover. Of these, the workover service segment will dominate the market over the forecast period.

By installation, the global hydraulic workover unit market is segmented into trail mount and skid mount. Of these, the trail mount installation segment will spearhead the market over the forecast period.

By application, the global hydraulic worker unit market is segmented into offshore and onshore. Of these, the onshore application segment will have the lions share in the market over the forecast period.

Geographically, the global hydraulic workover unit market is bifurcated into Europe, North America, South America, the Asia Pacific, & the Middle East and Africa (MEA). Of these, North America will have the lions share in the market over the forecast period. Per capita consumption, production, and exploration of oil and gas, advances in upstream operations, high production of crude oil produced from tight oil resources in the US, the rise in the production and extraction of oil and gas increases the need for hydraulic workover units to perform routine well maintenance for offshore installations, inland waters, and land, increase in the need for cost-efficient method to repair leading to the installation of hydraulic workover units, the growth in unconventional resources in Canada and the US, and the demand for intervention operations in the maturing offshore fields in the Gulf of Mexico and other onshore fields in the US are adding to the global hydraulic workover unit market growth in the region.

In Europe, the global hydraulic workover unit market is predicted to hold the second-largest share over the forecast period for technological advances and increasing exploration and production of oil and gas.

In the APAC region, the global hydraulic workover unit market is predicted to have admirable growth over the forecast period. Rise in demand for energy in emerging economies of India and China are adding to the global hydraulic workover unit market growth in the region.

In the MEA and South America, the global hydraulic workover unit market is predicted to have sound growth over the forecast period. The presence of large untapped energy reserves is adding to the global hydraulic workover unit market growth in the region.

The prominent players profiled in the global hydraulic workover unit market report include ZYT Petroleum Equipment Co., Ltd (China), Uzma Berhad (Malaysia), PT Elnusa Tbk (Indonesia), Canadian Energy Equipment Manufacturing FZE (UAE), Velesto Energy (Malaysia), Superior Energy Services (US), Basic Energy Services (US), High Arctic Energy Services Inc. (Canada), Precision Drilling Corporation (Canada), Cudd Energy Services (US), Archer (Norway), National Oilwell Varco (US), and Halliburton (US), among others.

The global hydraulic workover unit market is fragmented and also competitive with the presence of many domestic as well as international industry players. They have incorporated assorted strategies to stay at the forefront and also cater to the surging needs of the customers, including collaborations, partnerships, contracts, geographic expansions, new product launches, joint ventures, and more. Additionally, these players are also making heavy investments in research and development activities for strengthening their portfolios and also creating a hold in the market.

Snubbing is a process that controls the pressure of oil or gas in order to run or pull tubing, drill pipe, or casing. These applications use the standard snubbing unit to complete or re-complete wells in a “live well” condition. Any type of workover application can be performed utilizing quick jacks.

Snubbing units are often used in place of workover units for offshore applications. Snubbing can offer the same services at a greatly reduced cost to the customer. Snubbing can be performed on live and dean wells. Milling operations can be faster and more precise with snubbing units due to infinite control of torque and speed of the rotary mounted on the snubbing jack.   Snubbing is versatile alternative that can overcome the limitations of other workover systems - wireline, coiled tubing and conventional workover rigs.  It eliminates the use of kill fluids that can damage the producing formation and require costly disposal. Snubbing is also a faster solution.  Snubbing units can often have the task completed before a conventional workover operation is even rigged up.

Snubbing is your best choice when conventional draw works are absent.  The self-contained equipment requires little space and can finish the job quickly.  The hydraulic system"s precise control over force protects against overload and allows responsive tool manipulation.

The use of hydraulic long stroke work over rigs for light drilling and work over applications is a phenomenon made possible by the development of a number of enabling technologies. These include enhanced rig designs, pipe handling systems to aid in tripping efficiencies with hydraulic long stroke work over rigs, top drive systems with torques reaching 30,000 ft/lbs and tailor-made window cutting systems among others. In addition, there is an increasing business imperative to maximize recoveries from existing assets and to develop technologies that will make marginal fields economic.

This has challenged the service industry and operators to develop and utilize non-conventional drilling and completion techniques. The expansion of underbalanced thru-tubing interventions, work over’s and re-entry drilling has led to a need for multi-purpose rig specifically designed to perform traditional underbalanced rig-less well operations combined with standard work over rig work.

A hydraulic long stroke rig specifically designed to conduct traditional rig operations combined with the ability to switch to underbalanced thru-tubing applications is offered by Nortech. The concept of the hydraulic long stroke rig evolved from innovative engineers in conjunction with experiences drilling, work over and snubbing personnel from Nortech. By combining underbalanced horizontal drilling experience and mobile land-based rig design expertise with snubbing and well controlled know how, a specialized hydraulic long stroke rig has been developed.

With a unique modular concept, Nortech has bridged the gap between a drilling rig and a hydraulic well intervention unit. Up till now, the use of single joints (i.e., 30 ft or greater) for well intervention and/or snubbing operations has been restrictive due to design of standard units and the prohibitive cost effectiveness of handling larger diameter drill pipe sizes. The hydraulic long stroke rig design developed by Nortech, is allowing a rig up time of 10 to 12 hours and a tripping speed of 2000 ft per hour in live wells.

This document describes a modular rig that has been manufactured specifically for bridging the gap between a traditional drilling rig and a Hydraulic intervention unit. The unique design allows the Super Single rig to perform all aspects of a work over operation and snubbing/well intervention work.

The hydraulic long stroke rig will provide the following scope of work for re-entry drilling and side-tracking operations both overbalanced and underbalanced:

Nortech offers a proprietary designed snubbing units for its Clients. The snubbing package will move in 12 loads and rig up in 6 to 8 hours. Pipe handlings is done with a new and revolutionary dual pole handling system a capable of handling 30 to 40 double joints per hour and allow the rig to trip pipe at up to 2400 ft per hour making this snubbing units the most efficient snubbing unit on the market. The snubbing unit has a set back capacity of 14,000 ft

This snubbing unit design allows tubing deployment into wells under pressure and allows the wells to be safely serviced without having to use kill fluids. The process of tubing developments involve the insertion and removal of pipe into and out of a well with positive well head pressure.

An increasing number of oil and gas companies are using snubbing units as a routine procedure for completions and work-over. The main advantage is that the well does not need to be killed during well operations making it a safe and easy alternative. These are highly mobile and very easy to mobilize both offshore and onshore.

An increasing number of oil and gas companies are using snubbing & work over rigs as a routine procedure for P&A, well completions, remedial fishing operations, stimulation and frac operations and general work-overs. The main advantage is that the well does not need to be killed prior to commencement of operation and the snubbing & work over rig offers a safe and easy alternative. These are highly mobile and very easy to mobilize both offshore and onshore.

Unique short design that places BOP"s inside the hydraulic cylinders making the rig assist unit highly compatible to all sizes of service, drilling rigs and coiled tubing units