tripping pipe on a workover rig brands

The Attorneys at Spurgeon Law Firm know what it’s like to spend countless hours tripping pipe on a drilling rig. Stephen and Sam both have experience working on drilling rigs where they have roughnecked on Kelly and rotary drilling rigs.

Running in the hole or pulling out of the hole (aka tripping pipe) is one of the most labor intensive job tasks a worker will engage in while on a drilling rig. Long hours of throwing the slips in, breaking or making connections, and racking back stands of pipe in the derrick is mentally and physically exhausting whereby your brain will start to populate abnormal thoughts. Your mind will start to drift due to fatigue and exhaustion and thus cause you to lose focus on the job at hand. Because of this, people are more susceptible of making mistakes, which in turn will cause injury to themselves or someone else. This is why it is imperative that companies have adequate personnel on the job and to allow that personnel to take breaks as needed. Your safety should be priority and always put your health first and the company’s profit second.

All oilfield workers have the right to work in a safe environment. The oilfield is governed by rules, laws, and guidelines to keep workers safe. However, these rules and laws are not always followed and often lead to serious injury. If you have sustained injuries in the oilfield contact our experienced oilfield lawyers at 318-224-2222. Attorneys, Stephen and Sam, have both worked in the oilfield and know the ins and outs. Prior to becoming an attorney, Stephen worked offshore as a Petroleum Engineer gaining valuable experience which he uses to get his clients maximum compensation. Their experience can make the difference when it comes to getting the payment you deserve. Contact Spurgeon Law Firm today for a free consultation.

Tripping refers to the process of removing and/or replacing pipes from the well when it is necessary to change the bit or other piece of the drill string, or when preparing to run certain tests in the well bore.

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The act of pulling the drillstring out of the hole or replacing it in the hole. A pipe trip is usually done because the bit has dulled or has otherwise ceased to drill efficiently and must be replaced.

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.

Manufacturer of standard & mobile rigs & carriers for oilfield applications. Includes well servicing from 14,000 ft. to 22,000 ft., workovers from 10,000 ft. to 16,000 ft. & drilling from 6000 ft. to 10,000 ft. Specifications include brakes range from 28 in. dia. x 8 in. wide to 42 in. dia. x 12 in. wide, barrels from 12 3/4 in. x 38 in. to 18 in. x 43 in., chains from 1 1/4 in. to 1 3/4 in., clutches of 24 in. with single & 2 plate air friction outboards, shafts of 5 in. dia. to 6 1/2 in. dia. & gross weights from 63,200 lbs. to 115,000 lbs. Also includes forged steel, demountable options, mufflers with spark arrestors, dry type air cleaners, transmissions with torque converters, water splash brake cooling & up to 6 axles.

Operators working in shallow resource plays, such as shallow oil, unconventional shale gas and coalbed methane (CBM), just can’t get enough of a good thing. At their request, rig manufacturers are expanding the operating and mobility features of the industry’s rigs to a new level of sophistication – the highly or ultra-mobile rig. Highly mobile drilling rigs bring increased agility, automation, safety focus and cost savings, and are being used in deeper oil plays to perform top-hole work. Additionally, highly mobile rigs are carving niches for themselves in workover operations from offshore platforms, as well as geothermal applications.

Mobile and highly mobile rigs are different from their predecessor, the heliportable rig, which is used to access locations where no infrastructure exists, such as Siberia and the Amazon region. Heliportable rigs, which first appeared about 30 years ago, are capable of being broken down into a minimum number of loads, with each load weighing three tons, depending on the type of rig.

“Ironically, the helirig concept has not evolved very much, I suppose due to low-volume demand for these units. However, modular highly portable rigs have taken off, and the demand is very high for the foreseeable future,” Ray Pereira, vice president of North America sales for Drillmec, said.

For the purpose of this article, highly or ultra-mobile rigs are defined as small or medium-size self-driving rigs with wheels, mounted on either a substructure or trailer, and quite often their substructure and mast are self-erecting. How is this different from mobile rigs? According to rig manufacturers, features such as a heightened ability to be broken down and reassembled and still retain full functionality, increased use of automation for added safety and operational ability, and a reduction in crew size all set highly mobile rigs apart from mobile rigs.

“A fully engineered drilling system is even more important in highly mobile rigs given the trend toward more factory-styled well construction and automated drilling,” Eric Quinlan, LOC product manager for Huisman, commented. “The complete integration of third-party equipment into the rig design will further reduce the number of loads required, the rig-up and rig-down times, as well as improve on automation.”

“High mobility allows more wells to be drilled in a year,” he continued. Particularly for pad drilling in the shale plays, rigs must not only be able to skid or walk but also move quickly and safely to the next pad.

“There is a stronger focus on self-erecting components in highly mobile designs, for instance slingshot-type substructure and self-elevating or self-erecting masts,” Thomas Janowski, sales manager for Herrenknecht Vertical, said. The advent of portable top drives, iron roughnecks, as well as casing-running tools, have added to efficiencies of highly mobile rigs, he noted.

The design and construction of these highly mobile rigs have become very sophisticated, as with the case of the Drillmec HH Series rig, where the main rig components, such as the mast and part of the drill floor, are fused to the specially designed trailer. This allows the top drive and iron roughneck to be transported without being removed from the mast. The trailer concept has improved the mobility of mud pumps, mud tanks, variable frequency drive houses and pipe bins for the automatic racking system.

“A key limitation to current rigs is the available resources (people, trucks, etc) that enable the rig move. Location of the wells also plays a role and adds constraints, both geographic and regulatory,” Mr Quinlan said.

Therefore, there is a major push to reduce load weights and dimensions of all modules that are required to erect a highly mobile rig on location while at the same time reducing the number of loads required to fully assemble the rig on site, according to Mr Pereira.

It all comes down to the challenge of how to rethink components, such as a 40-ton mud pump, to make them more easily and economically transportable. “There is no standard solution at all,” Mr Janowski said. “How do you make 40 tons highly mobile? You can put wheels on it, but there are limits as to weight and size of components. It is challenging to design the components on the one hand lighter by using different compound materials like glass-reinforced plastic, and on the other hand, these heavy components like mud pumps, diesel generators and electrical cabinets and steel structures, such as the mast and substructure, have to be able to be broken down into smaller pieces but retain the same operational features.”

Equipment advances have brought challenges to highly mobile rig designs as well. “We are seeing a lot more wires and sensors being installed along with measurement equipment and video cameras,” Mr Quinlan remarked.

According to Atlas Copco, mobile rigs got their start in the energy industry when operators started using water-well rigs to drill for oil and gas. “The industry sort of evolved into using mobile rigs for oil and gas drilling rather than actually beginning at a definitive time. The Atlas Copco RD20 rig was borne out of the need for a mobile rig designed specifically for oil and gas drilling,” Alex Grant, well drilling product line manager for Atlas Copco, recalled. The rig was conceived from the T4 water-well rig and has received several technology upgrades since it was introduced in 1986.

The 120,000-lb hookload RD20 rig now has a sister rig, the highly mobile 200,000-lb hookload Predator, which took five years to develop and is just now finishing field trials. The first production unit is expected to begin work in September this year in a Texas shale play.

“We saw a definite need to get into the bigger fields with the bigger players. That’s where Predator came in. We took a clean sheet of paper and asked the question, ‘What does the oil and gas market need?’ ” Mr Grant said. “Because we desired to have an API 4F rating, we probably spent about two years getting our suppliers lined up…. Structures are designed to three times the loading capacity; that’s something you can’t just evolve from a rig that you already have. In 2010, we built two prototypes and put them in the field in an extensive testing program.”

Recognizing that more operators are performing directional drilling, Atlas Copco also added more pullback capacity to the Predator design. The RD20 rig had a pullback capacity of about 5,500 ft; the Predator has about 8,000 ft to 10,000 ft of pullback capacity.

For Drillmec, the Drillmec HH Series rig saw its evolution from a simple hydraulic rig for water wells upgraded to oil well standards in 1990. The first built-for-purpose HH rig was delivered to Eni in 1994. Since then, each generation of the rig has been improved to include enhanced automatic controls for the pipe handler using programmable logic controllers (PLCs) and advances to the hoisting and hydraulic systems. The latest generations include joystick controls and cyber control touchscreen features. The company offers up to 375-ton HH Series rigs for land applications and up to 600-ton rigs for offshore platforms.

Also on the HH Series rig, the vertical pipe-racking system is assembled in a semi-circular array around the rig floor to contribute to quick rig-up and rig-down. Further, containers can be transported and handled full of drill pipe to save time and to reduce risks associated with pipe handling.

“For us, the challenge in the beginning was to develop a rig that provided very safe working conditions for the crew, a small environmental footprint and a high level of operating efficiency,” Mr Pereira said. “Our extensive knowledge of hydraulics enabled us to effectively use a purpose-made cylinder for the hoisting aspect of the rig, thereby eliminating the need for mechanical drawworks and the operational and transport complexities that it brings. The rigs do not have a conventional mast structure nor drawworks and long wires or traveling equipment as the hydraulic cylinder replaces those items and is the main hoisting element of the rig.”

Safety has become a paramount driver alongside economics for highly mobile rigs. “Try to remove personnel from unsafe areas is what we’ve done,” Atlas Copco’s Mr Grant said.

“From a mechanical standpoint to achieve safety, we’re getting into more computer-controlled systems, such as a wireless pipe-handling system where the operator can stand away from the whole operation, observe from a distance and still control the unit. We’re bringing computers more into it. It’s the same with the driller; with the use of electronics, we’re able to stand away from the drill table, stand back in the doghouse even and operate the rig from back there, out of the area where injuries typically occur,” Mr Grant said.

“Drillmec uses single 45-ft joints of range 3 drill pipe that is transported in pipe bins and ready to be used,” Mr Pereira said. “There are no delays waiting to make up stands and set them in fingerboards. Stand-building operations can take days. With the HH Series rig, there is no need to touch the pipe, thereby increasing safety parameters.”

The LOC 250, Huisman’s first highly mobile rig, is a containerized rig, meaning that all elements of the rig fit into standard ISO containers, and has casing-while-drilling capabilities. Since introducing the LOC 250 in 2005, the company has upgraded its design to include AC drive, a higher hookload and an expanded mud system, and the LOC 400 was introduced in 2009. The next generation of the LOC 400, to be introduced in late 2012 or early 2013, will feature a higher level of automation, even quicker rig moves and enhanced skidding capabilities.

“We’re conducting a study on rig moves, finding the weak links and engineering the process to improve it, and preparing recommendations for field personnel to accomplish rig moves quicker,” Mr Quinlan said.

Increased rig safety features desired by operators have brought about another benefit – a reduction in the number of crews needed to run the rig. “The more features you have, such as self-erecting masts, self-erecting substructures and highly mobile components, the less the risk of accidents related to these activities. In Herrenknecht Vertical’s case, a high level of automation, together with the concept of mobility, eliminates almost all of the dangerous jobs on the rig,” Mr Janowski explained. “The number of people involved in tripping pipe in and out is limited to two persons.”

The Drillmec HH Series rig advanced automation concept requires few crew members as well. The concept “allows it to perform most of the routine drilling operations, including tripping in and out the drill string, with an almost unmanned drill floor where worker presence is basically limited to thread doping and handling the bottomhole assembly,” Mr Pereira said. “No one is exposed to direct contact with rotating tubulars, tongs and wrenches or to falling objects.”

“With the latest Atlas Copco rig, the Predator, we’ve got it down to the minimum amount where we can have three people operating a rig as opposed to the six or seven people that would be on a conventional rig,” Mr Grant said.

With Herrenknecht Vertical’s Terra Invader rig, only two people are involved in tripping pipe in and out. The rig came onto the work scene in a geothermal application in Germany in 2006, just one year after the company was established. This rig, which has a box-on-box substructure, is tailored to the Western European market, where cranes are readily available.

“The design criteria are different in that the situation regarding cranes and heavy trucks in Europe is slightly different from the rest of the world,” Mr Janowski noted. “It’s cheaper to install a crane because it’s available and you can rig-up in two days with a crane.”

“There has always been a demand for high mobility in this industry, but the higher the costs are for drilling and transportation, the higher the demand to make the equipment more mobile than before,” Mr Janowski noted. According to him, exploration drilling in remote places, on artificial islands, in the Brazilian Amazonas region and in Siberia has prompted the increased demand for highly mobile units. Crane and truck load capacities are limited. Cost levels are quite high, and the need to reduce crew cost is an issue.

An economic boost has been a huge plus for operators choosing highly mobile rigs. In addition to the shale plays in North America, key markets are North Africa and the Middle East. “In the Middle East, you have only to drill 700 to 900 meters (2,297 to 2,953 ft) to access resources. Drilling takes only five or six days,” Mr Janowski commented. “There must be a relation between the drilling time and the moving time. When you drill five days, no one would accept a rig move time of five days.”

“It is not just the rig design that enables high portability,” Mr Quinlan remarked. “The contractor must also have the right procedures and systems in place and have a dedicated rig-moving team that knows the rig and how to move it. It’s no use having a rig that can move in two days and be waiting for trucks for three days before it can move.”

“With the Huisman LOC rigs, we wanted a rig that could be moved anywhere on the planet with the same ease as moving a few miles on the road. In this regard, we have been very successful. To move the LOC rigs overseas is very cost effective and can be cheaper than rig moves over land.”

Also regarding improved economics, Mr Grant pointed out that “in addition to the rig’s ability to be broken down into manageable pieces that can be rolled down the road to the next site, the pieces are smaller and the capital outlay is a lot less to achieve the same result as that achieved by drilling with a conventional rig. We run less crew; staff overhead is a lot less. Ultimately, if you’re going for the shallower stuff, the overall cost of ownership is a lot less … roughly two-thirds of the cost of a big conventional rig.”

Rig manufacturers believe there is savings to be realized from use of a highly mobile rig to drill the top-hole section when an operator is targeting deeper reserves. The conventional rig doesn’t need to stay on-site as long. There’s also savings to be realized from reducing nonproductive time.

“It’s about decreasing nonproductive time and increasing safety,” Mr Pereira remarked. “The correct application of a fast-moving or portable rig can save the operator days in mobilization and demobilization between wells. Depending on the distance to the next well location, the Drillmec HH Series rig can be ready for drilling within 72 hours. A well-trained crew can do it in less than 48 hours.”

According to Drillmec, one of its expanded rig capabilities as a result of the design was for the rig to become an integral part of the substructure. “We figured, wouldn’t it be great if you could run the hydraulics of the substructure from the rig itself and offer connections on the substructure to quickly connect an air or mud pump system and reduce the downtime for setup,” Mr Grant said. “The other part was to have the pipe-handling on the back of that.” The Drillmec rigs have the main rig components fused to the specially designed trailer.

With Atlas Copco, Mr Grant said they’re expanding the operational ability of their highly mobile rigs by taking manual labor out of the scenario where possible. For example, “with the Predator rig, the driller has the more accurate ability to dial-in to a computer what he is trying to accomplish; for instance, establish weight on bit by dialing it in,” Mr Grant said. “Before, the driller had to watch the pressure gauge and dial-in weight-on-bit information as the formation changed.”

Highly mobile rigs are meeting diverse global drilling requirements as well. Drillmec’s HH Series rigs are currently operating in shale plays in North America, in the deserts of Egypt and the Middle East, in remote locations in Peru, Colombia, Venezuela and Australia, as well as in geothermal projects in Iceland and Chile. Further, the company recently announced the sale of 25 hydraulic rigs, with an option for an additional 125 rigs, to Chinese drilling company Greka Drilling. The units will work in CBM and shale-gas applications in China’s Shanxi Province.

Huisman’s LOC rigs have drilled oil, gas and geothermal wells in the US and Europe. Although the LOC rigs were designed for onshore drilling, the company has developed a concept and performed basic engineering on a LOC rig for offshore application.

“We have worked on a very interesting concept for using our LOC rig as a modular platform rig with a unique installation procedure onto the platform. This solution would see platform installation in a few days as compared with the several weeks required for similar modular rigs,” Mr Quinlan said.

In addition to shallow-resource development, Atlas Copco has found success using its highly mobile units to do top-hole drilling and set the casing so that conventional double or triple rigs can go in later to drill the deeper sections.

“We can use a top head drive to push the head down onto the drill bit to create weight on bit,” Mr Grant said. “The conventional rigs are not top head drive; they’re relying on collars and sticks of steel to give them weight on bit, making it harder there at the top of the hole.”

As operators expand their search for resources across the globe, rig manufacturers are keeping pace, delivering innovations in operation and transportability.

With more advances already on the drawing board, rig manufacturers are confident that the next generation of highly mobile rigs will continue to meet operator expectations.

Annular BOP: A Bop with a full opening elastomer element that has the ability to seal on virtually any shape, as well as seal on itself in and emergency situation.

Balance Point: This term refers to the condition during a trip in or out of the hole where the pipe weight and the lift force exerted by the well acting on the cross-sectional area of the pipe being tripped is at or near equal.

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.

Staging tubing: Is the process of moving tubing into or out of a live or underbalanced well by using different sections of the BOP stack to insert or extract tubing connections or larger diameter tool assemblies. I.e. annular and a set of stripping pipe rams or two sets of stripping rams. The preventers are closed and opened in sequence allowing for tubing connections or larger diameter tools to be staged in with at least one preventer being closed to contain well bore pressures.

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 automatic operation equipment for minor workover is mainly composed of a wellhead operation device, hydraulic elevator, pipe and rod transmission and arrangement device and electro-hydraulic control system.

Each part of the device has different structural forms and can be selected arbitrarily for personalized configuration according to the needs of users.

The device adopts the structural form of dispersing the functional modules and integrated installation on the workover rig: with the hydraulic tong, manipulator and anti splash snap device set on the derrick of the workover rig, which can expand and rotate, and the safety slip is installed above the BOP.

The device only needs to install safety slips, which realizes rapid installation and migration and shortens the auxiliary working time. The device has the function of moving back and forth, left and right, which is convenient to align the wellhead. The height of the hydraulic tong is adjustable and can adapt to the wellhead with different heights. Hoisting equipment and special transport vehicles are not required for the installation and removal of the device.

In addition to its main function of suspending the pipe string, it also has the functions of automatic tubing mouth match, make-up and break-out, and is also equipped with a guide device bearing reverse torque, which can realize the functions of automatic well washing, sand flushing, drilling, grinding and milling.

Main function: connect to the wellhead flange and clamp the pipe string. Slip teeth are common with other manufacturers for easy replacement. The hydraulic cylinder is clamped and the pipe string is forced to be centered. The clamping is reliable and convenient for automatic operation. Open and close state detection, and realize safety interlock with other equipment.

The main electric control box can be installed on the operation vehicle or integrated into the modular wellhead operation device. The make-up torque of various oil pipes is set on the touch screen to realize automatic make-up and break-down. Equipped with video monitoring, process prompt, safety alarm, etc. The control system has a perfect action interlocking function to ensure the safety and reliability of the workover operation process. All of the electric cabinets, sensors, connectors meet the requirement of Explosion-proof on field.

The hydraulic system includes hydraulic source, wellhead automatic operation device control valve group, hydraulic elevator, hydraulic slip valve group, conveyor control valve group and pipeline, etc.

This paper documents the results of a new stage of development in the application of coiled-tubing drilling (CTD). Combining CTD technology with a conventional jointed-pipe workover capability represents the next-step change in providing low-cost reserves access solutions through selection of the most efficient tool for the application.

Drilling sidetracks using coiled tubing is an established practice in Alaska"s North Slope oil fields. During these operations, the use of jointed pipe was avoided, except for running liners, with the CTD rig. A conventional workover rig was the preferred approach to prepare the coiled-tubing candidate well when it required a changeout of production tubing or other workover activity.

In 2001, a North Slope operator evaluated the opportunity to utilize one rig to perform both operations. In 2002, a workover rig was modified to fit the need.

Integrating two established technologies presented many challenges. Specialized equipment, multidisciplinary personnel, and control of overall well cost are just a few of the many parts of the operation to be planned. This paper details the results, problems encountered, solutions, and a quantification of the real benefits achieved combining CTD with a jointed pipe workover.

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