kelly bushing depth in stock

Kelly bushing is that elevated device positioned right on top of the rotary table and used to transmit torque from the rotary table to the kelly. The kelly bushing is designed to be the connection between the rotary table and the kelly. The kelly is a 4 or 6 sided steel pipe.

The purpose of the rotary table is to generate the rotary action (torque) and power necessary to rotate the drillstring and drill a well. The torque generated by the rotary table is useless if it is not transferred to the kelly (the drillstring is connected to the kelly).

Hence, through the kelly bushing the torque generated at the rotary table is transferred to the kelly. To achieve this connection, the inside profile of the kelly bushing matches the outer profile of the kelly so that the kelly fits or “sits” comfortably in the kelly bushing.

There are various designs for the kelly bushing including the split type, the pin-drive type and the square-drive type. Each of these designs has different ways in which they are connected and disconnected from the rotary table.

The internal diameter of the kelly bushing can be cut into the shape of a square (4-sided) or a hexagon (6-sided) depending on the outer shape of the kelly that will be used. The internals of a Kelly bushing is designed to resemble the outer shape of a Kelly just like the insides of a key lock is cut to exactly match the outer shape of the key.

The kelly bushing is not designed to hold tightly onto the Kelly; the kelly is still permitted to move up and down through the kelly bushing. This requirement is a must since drilling cannot progress if the kelly remains on a fixed spot. As the well is drilled deeper, the kelly also moves downward through the Kelly bushing.

The kelly bushing is sometimes used as a reference point from which depth measurements can be taken. All depths must be recorded with respect to a reference point; the kelly bushing (KB) is one of the depth references used in the oil and gas industry.

The top of the kelly bushing is normally used as the depth reference.For example, 7500ft KB means 7500ft below the kelly bushing or 7500ft measured from the top of the kelly bushing down to that point in the well.

In some other cases, depths could be recorded as 7500ft MDBKB meaning 7500ft measured depth below the kelly bushing. This is mostly used when the measured depth is different from the true vertical depth of the well, common with deviated and horizontal wells.

In the oil and gas industry, depth in a well is the measurement, for any point in that well, of the distance between a reference point or elevation, and that point. It is the most common method of reference for locations in the well, and therefore, in oil industry speech, “depth” also refers to the location itself.

Because wells are not always drilled vertically, there may be two “depths” for every given point in a wellbore: the measured depth (MD) measured along the path of the borehole, and the true vertical depth (TVD), the absolute vertical distance between the datum and the point in the wellbore. In perfectly vertical wells, the TVD equals the MD; otherwise, the TVD is less than the MD measured from the same datum. Common datums used are ground level (GL), drilling rig floor (DF), rotary table (RT), kelly bushing (KB) and mean sea level (MSL). [1]

Kelly Bushing Height (KB):The height of the drilling floor above the ground level. Many wellbore depth measurements are taken from the Kelly Bushing. The Kelly bushing elevation is calculated by adding the ground level to the Kelly bushing height.

Driller’s Depth below rotary table (DDbrt): The depth of a well or features within the wellbore as measured while drilling. The measured length of each joint of drillpipe or tubing is added to provide a total depth or measurement to the point of interest. Drillers depth is the first depth measurement of a wellbore and is taken from the rotary table level on the rig floor. In most cases, subsequent depth measurements, such as those made during the well completion phase, are corrected to the wellhead datum that is based on drillers depth (reference: Schlumberger Oilfield Glossary).

Although depth calculation is an intuitive concept, it is the source of much confusion because it is frequently not specified correctly. Absolute depth should always be specified with three components:

True vertical depth is obtained from a record of the deviation survey report. These surveys are generally run on deviated wellbores. It records measured depth (MD), inclination (deviation angle), azimuth angle, true vertical depth, and dogleg severity at various increments. To obtain a TVD, simply obtain a measured depth, go to the survey, and read off the TVD. If the desired measured depth is not in the survey, then extrapolate between the two closest points.

An adapter that serves to connect the rotary table to the kelly. The kelly bushing has an inside diameter profile that matches that of the kelly, usually square or hexagonal. It is connected to the rotary table by four large steel pins that fit into mating holes in the rotary table. The rotary motion from the rotary table is transmitted to the bushing through the pins, and then to the kelly itself through the square or hexagonal flat surfaces between the kelly and the kelly bushing. The kelly then turns the entire drillstring because it is screwed into the top of the drillstring itself. Depth measurements are commonly referenced to the KB, such as 8327 ft KB, meaning 8327 feet below the kelly bushing.

This is the brief explanation of a Kelly rotating system on the rig. Kelly rig is on an old style rigs and  nowadays it is mostly used on land operations. For offshore operation, a top drive system is used instead.

The upper end of the drill pipe is screwed onto the saver sub. The saver sub is used to protect and minimize wearr and tear on the threads at the bottom of the Kelly. The Kelly is about 40 ft in length with a square or hexagonal shape and it is hollow throughout in order to transport the drilling mud.  Kelly moves freely through a Kelly bushing even though the drill stem is rotated.

A Kelly cock valve is located at the top of a Kelly and it is a safety valve which can be closed to stop back pressure from coming back to damage other surface equipment.

A swivel attached to the hook does not rotate, but at the bottom part it supports the Kelly which is being rotated while drilling.  Drilling mud is pumped from a mud pump to a stand pipe manifold, Kelly hose and then to a gooseneck connection at a swivel.

A rotary table rotates a Kelly bushing and it simultaneously rotates a Kelly and a drill string and a drill bit. A rotary table has two main functions. The first one is to provide rotation to a drill stem and a bit and the second function is to hold slip in order to support the weight of a drill stem when it is not connected to a Kelly.

A master bushing severs its function as a rotary motion transmission from a rotary table to a Kelly. Additionally, it is a link between a slip and a rotary table.

A Kelly bushing (some people call “rotary Kelly bushing”) engages a master bushing via four pins and rollers inside a Kelly bushing to allow a Kelly to move up or down freely while it is rotated or in a static mode.

At a previous employer a coworker came to me and told me that a group within our company had asked for all the KB (kelly bushing) elevations for every well in Colorado. I replied that it made no sense and asked my coworker to see if the reference elevations were what they really wanted. The coworker returned the next day and indicated that they had insisted on the KB elevations. We supplied the KB elevations and sure enough, about a week later they came back and asked for the reference elevations.

Yes, most logs are measured from the KB. No, never use just the KB. Some logs are measured from the DF (derrick floor), GR (ground), or CHF (casing head flange), and there are a few other strange places logs are measured from. In today’s world, where multiple rigs can drill multiple sections of a well, the KB can have different elevations depending on the run of the log. It’s really important to put things back together on a common reference point so the logs aren’t off and formations can be correlated and depth corrected. (Side note: the definition of MSL, mean sea-level, is also probably a good topic of future discussion. It’s probably not what or where you think it is).

Well depth is a very important piece of information. There are several TDs and several ways to measure them. The major TDs we deal with are the driller’s total depth (DTD) and the logger’s total depth (LTD). In general, the DTD is considered to be the official depth of the well.

A couple of other TDs come into play when you are drilling directional or horizontal wells. MTD is the measured total depth, which is the distance along the wellbore. The other piece of information is the true vertical depth (TVD), which is the distance of the well from the surface. There is actually one other measurement, called true vertical depth subsea (TVDSS), which is the TVD as referenced from the reference elevation. In many instances this ends up with data below the sea level and the values are negative. Think of this like a thermometer, where some values are below zero (below sea-level).

In the oil and gas industry, depth in a well is the measurement, for any point in that well, of the distance between a reference point or elevation, and that point. It is the most common method of reference for locations in the well, and therefore, in oil industry speech, "depth" also refers to the location itself.

By extension, depth can refer to locations below, or distances from, a reference point or elevation, even when there is no well. In that sense, depth is a concept related to elevation, albeit in the opposite direction. Depth in a well is not necessarily measured vertically or along a straight line.

Because wells are not always drilled vertically, there may be two "depths" for every given point in a wellbore: the borehole, and the datum and the point in the wellbore. In perfectly vertical wells, the TVD equals the MD; otherwise, the TVD is less than the MD measured from the same datum. Common datums used are ground level (GL), drilling rig floor (DF), Rotary table (RT), kelly bushing (KB or RKB) and mean sea level (MSL).

Although it is an intuitive concept, depth in a well is the source of much confusion because it is frequently not specified correctly. Absolute depth should always be specified with three components:

Example: the top of a reservoir may be found at 1,500 mMDRT in a particular well (1,500 m measured depth below the rotary table), which may be equal to 1,492 mTVDMSL (1,492  m true-vertical-depth below mean sea level) after correction for deviations from vertical.

Well depth values taken during the drilling operation are referred to as "driller"s depth". The "total depth" for the well, core depths and all analysis of core / mud and other materials from the drilling hole are measured in "drillers depth".

Well depth values from the wireline loggers operation are referred to as "logger"s depth". The loggers depth are typically considered more reliable than the drillers depth.

The differences between loggers and drillers depths are due to different stretch in the drilling string when drilling, and the wire line entered into the bore hole during wireline logging operations. This difference is estimated and referred to as "core shift". A core from a certain drillers depth is lined up with a wireline log (loggers depth) and structures in the core are compared with the log and matched.

Sign Convention - Depth increases positive in the downward direction. This may seem intuitive but confusion can arise when using certain references while integrating data from different sources. Workers mapping surfaces typically use elevation which, by convention, increases positive in the upward direction. Be mindful when integrating depth and elevation. For example, shallow wells drilled onshore often encounter reservoir at negative depths when referenced to sea level, mappers would define these same reservoirs at positive elevations when referenced to sea level.

The acronym TVDSS is commonly used in the oil industry to represent TVD minus the elevation above mean sea level of the depth reference point of the well. The depth reference point is the kelly bushing in the United States and a few other nations, but is the drill floor in most places.

Differential (or relative) depths or thicknesses should generally be specified with at least two components: a unit and a path, plus any eventual specifiers to remove any possible ambiguity. No specifier should ever be left "implicit" or "understood". There are cases where a path is not needed and in fact should not be specified, because it is defined by the specifier, e.g. isochore (true stratigraphic thickness, independent of well path or inclination).

The distinction between "loggers" depth" and "drillers" depth" is becoming blurred due to the increasing use of logs acquired while drilling (LWD). At the time of writing, the common practice remains that the petrophysicists or geologists define the "official depths" in a well, and these depths are frequently different from the "drillers" depth", after various corrections, tie-ins, etc., have been applied.

Petrophysicists and drilling operations tend to express depths with reference to the rotary table or the original drill floor; geologists tend to use a common datum such as the mean sea level; geophysicists use the mean sea level. This can introduce much confusion when a unit is not specified with all 3 components: unit, path, and reference.

Special consideration must be given to depth measurement in toe-up laterals (J-profile). In these cases the measured depth will continue to increase while true vertical depth will decrease toward the toe of the wellbore.

Path: common expressions of path are measured depth (MD) – elsewhere often known as along hole depth (AHD) – and true vertical depth (TVD). Note that using TV for true vertical depth is not consistent with the use of MD for measured depth, hence the recommended TVD.

the legal datum offshore Australia is Lowest Astronomical Tide (LAT) – (Ref. 1 & 2). Note that this requirement in itself can cause difficulties as it is difficult to measure offshore and can vary greatly between locations and even with time. There is, however, an advantage to this convention: tidal corrections should always be of the same sign (negative depth), i.e. the sea level is always higher than or equal to LAT.

Common references used in operations include: Rotary Table (RT), Drill Floor (DF), Kelly Bushing (KB), Sea Bottom (SB), Ground Level (GL), Casing Bowl Flange (CBF).

Any combination of unit, path, and reference can be used, as long as they result in fully specified, unambiguous depths. A well may reach to many kilometers.

Specification of an absolute depth: in Figure 1 above, point P1 might be at 3207 mMDRT and 2370 mTVDMSL, while point P2 might be at 2530 mMDRT and 2502 mTVDLAT.

Specification of a differential depth or a thickness: in Figure 2 above, the thickness of the reservoir penetrated by the well might be 57 mMD or 42 mTVD, even though the reservoir true stratigraphic thickness in that area (or isopach) might be only 10 m, and its true vertical thickness (isochore), 14 m.

The global kelly drive market was valued at $1.6 billion in 2021, and is projected to reach $2.3 billion by 2031, growing at a CAGR of 3.7% from 2022 to 2031.

Report Key HighlightersThe kelly drive market is consolidated in nature with few players such as NOV Inc., SANY Group, BAUER Maschinen GmbH (Subsidiary of BAUER Group), Jereh Global Development LLC (As a Subsidiary of Jareh Group) and Liebherr-International Deutschland GmbH. that hold significant share of the market.

The study covers in-depth analysis of 16 countries from different regions including North America, Europe, Asia-Pacific, and LAMEA. In addition, country-wise data of every country has been provided for better understanding of kelly drive market dynamics in every country.

A kelly drive is a particular kind of well drilling tool which uses a section of pipe with a polygonal or splined outer surface and feeds it through a rotary table and matching kelly (mating) bushing which have the same shape or splines. The Kelly is a long, four- or six-sided steel bar having a hole bored through the center to allow drilling fluid to pass through. The kelly bushing allows the drill string to be lifted or lowered while it rotates by transferring rotating motion from the rotary table or kelly bushing to the drill string. Crewmembers make up several attachments to the kelly. The attachments include the upper kelly cock, the lower kelly cock (drill pipe safety valve), and the kelly saver sub.

Kelly drilling is one of the most used dry rotary drilling techniques. The kelly drive is used to create large-diameter bored piles (from a size of approx. 500 mm). With the increasing drilling activities is booting the kelly drive market share in coming year. The kelly drive works with almost any kind of rock and soil. According to kelly drive market forecast, the demand for short rotary drilling instruments, such as augers, core barrels, buckets, and specialized drilling tools which are used to move the dirt will be more in the market. The drill rod which is also known as a kelly bar, is a typical component of this drilling technique. The strong kelly bars enables deep drilling and help in boosting the kelly drive market trend in forecast period.

Globally, there has been a surge in oil exploration activity, which is driving the demand for kelly drive in rig and drilling industry. Apart from the pandemic time, a boom in exploration has tripled over the last five years. Kelly drive market analysis showcase the owing to a global boom in exploration of oil reserves, several oil companies are getting into the rig sector. With the ongoing expansion in petroleum products, large oil extraction companies are contracting with drilling equipment manufacturers for the rent and sale of drilling equipment. Oil exploration companies and equipment companies collaborate to provide offshore support services that can increase production. Factor such as oil exploration activities is likely to boost the market for kelly drive in near future.

Advances in technology and equipment have enabled more oil and natural gas to be recovered from the length of each well, improving production and reducing the environmental footprint of energy production. Kelly drive is cheaper however, technology is slow, inefficient, and unsafe as compared to the other technology which are present or coming in the market. These factors may restrain customers from using kelly drive; thus, hampering the market growth.

With combination of seismic surveys and drilling wells, companies are doing the search of oil reserve and deposits beneath the surface of the earth. Exploration projects can be expensive, time-consuming, and risky, drilling a well may cost tens of millions of dollars. Several factors are considered the number of wells to be drilled, recovery method, type of installation to be used, separation systems for the gas & fluids, and how the oil and gas will be transported to a processing facility. High demand for the petroleum products in the market resulting into several new excavations projects in different regions. This factor is anticipated to increase the sales of kelly drive; thus, creating lucrative kelly drive market opportunities.

The kelly drive market is segmented into product type, and region. On the basis of product type, the market is bifurcated into cleaners, braking oil, grease and lubes, degreaser, and others. Region-wise, the market is studied across North America, Europe, Asia-Pacific, and LAMEA.

In 2021, the square kelly segment was the largest revenue generator, and is anticipated to grow at a CAGR of 3.6% during the forecast period. With the increasing horizontal drilling operations result in increasing demand for square kelly in the market. To increase the output from a single well, drilling square kelly equipment are being used frequently in the market. Square Kelly is advantageous for end-users, however equipment can be used for both onshore and offshore drilling operations. Drilling activities are becoming more challenging which are demanding the high quality of kelly equipment. Several oil firms engage in new types of drilling on land, such as horizontal well drilling which covers a significantly larger area under the earth. With the increasing horizontal well drilling creates the opportunity for square kelly segment in global kelly drive market.

In 2021, the kelly bar segment was the largest revenue generator, and is anticipated to grow at a CAGR of 4.0% during the forecast period. With the increasing number of excavation projects and finding of deep oil reserves will increase the demand for kelly bars in the market. Companies are entering into the agreement for the drilling operations which is driving the kelly bars market. Today, reserves are found very deep under the land of sea which require the high strength bars for handling the pressure. Vertical and horizontal drilling activities are increasing which is increasing the demand for different shapes of kelly bars.

The North America kelly drive market size is projected to grow at the highest CAGR during the forecast period. The region is experiencing more drilling activities of oil and gas extraction as the demand for oil-related goods rises worldwide. Kelly drive equipment is particularly helpful for drilling through hard rock and getting to the oil deposits. The Kelly Drive can be used to reduce operational expenses in drilling operations. For field operators and engineers, it ensures long-term project success and a high rate of return.

LAMEA was the second-largest contributor in terms of revenue in the global kelly drive market in 2021, and is anticipated to grow at a CAGR of 3.8% during the forecast period. Accelerated investment across the upstream sector along with crude oil price recovery will foster the drilling activities in the region. Robust growth in petrochemical products demand along with increase in industrial and commercial activities across the developing economies will boost the kelly drive market growth in LAMEA region.

The leading players operating in the global kelly drive market include, NOV Inc., SANY Group, BAUER Maschinen GmbH (Subsidiary of BAUER Group), Jereh Global Development LLC (As a Subsidiary of Jareh Group) and Liebherr-International Deutschland GmbH, Bridges Equipment LTD, Lake Petro., TEXAS INTERNATIONAL OILFIELD TOOLS, LTD, Goldman, Tianhe Oil Group Co. Ltd., XI"AN KINGWELL OILFIELD MACHINERY CO.,LTD, El Didi Group.

It outlines the current Kelly drive market trends and future estimations from 2021 to 2031 to understand the prevailing opportunities and potential investment pockets.

The invasion of Russia has further worsened an already precarious scenario for the energy and drilling markets, notably in Europe. To minimize the possibility of an interruption in Russian oil and gas supply, oil and gas corporations must collaborate with governments. In longer term, the sector needs to increase its adaptability and relevance in a rapidly evolving energy environment. The scenario brought about by the conflict between Russia and Ukraine influences the Kelly Drive market as well. Many projects that were previously underway in the nations are now on hold, and new projects are being delayed, which has slowed the market"s expansion in recent years.

Bushing that rotationally connects the rotary table to the drill string kelly bar, the top of which is commonly used as vertical reference for the drill floor.

It is possible to develop the hydrostatic pressure equation as we know it:[6] P = ρgz , (Eq 2.4) P: Pressure[Pa]ρ: Density of fluid [kg/m3]g: Gravitational acceleration≈ 9,8 m/s2 z: True vertical depth, TVD [m] For convenience sake, the drilling industry have made their own way of denoting pressure, often using the mud density as a reference.

The unit will provide continuous 24-hour surveillance of drilling operations including the minimum:• Total gas detection• Chromatographic gas analysis• Continuous CO2 detection• Continuous H2S detection• Measured depth• True vertical depth as calculated from surveys• Rate of penetration• Weight on bit• RPM• Pump stroke rate• Mud pit levelsBefore surface casing is set, a single H2S sensor will be mounted in the possum belly and used to continuously monitor ditch gases for H2S.

A device fitted to the rotary table through which the kelly passes. It is the means by which the torque of the rotary table is transmitted to the kelly and to the drill stem. Also called the drive bushing.†

A hole in the rig floor 30 to 35 feet deep, lined with casing that projects above the floor. The kelly is placed in the rathole when hoisting operations are in progress.†

The hose on a rotary drilling rig that conducts the drilling fluid from the mud pump and standpipe to the swivel and kelly; also called the mud hose or the kelly hose.†

The principal component of a rotary, or rotary machine, used to turn the drill stem and support the drilling assembly. It has a beveled gear arrangement to create the rotational motion and an opening into which bushings are fitted to drive and support the drilling assembly.

Wedge-shaped pieces of metal with teeth or other gripping elements that are used to prevent pipe from slipping down into the hole or to hold pipe in place. Rotary slips fit around the drill pipe and wedge against the master bushing to support the pipe. Power slips are pneumatically or hydraulically actuated devices that allow the crew to dispense with the manual handling of slips when making a connection. Packers and other down hole equipment are secured in position by slips that engage the pipe by action directed at the surface.†

The top drive rotates the drill string end bit without the use of a kelly and rotary table. The top drive is operated from a control console on the rig floor.†

Alternatively, the depth reference is the point at which the depth is defined as being zero. it is typically the top of the kelly bushing or the level of the rig floor on the rig used to drill the well.

A 27-year-old gas drilling rig worker died on May 23, 2003 from blunt force trauma to the head, neck, and chest during a cleanout operation at the well. At the time of the incident, the victim was working within eight feet of the kelly on the drilling rig floor. Compressed air was used to blow out the conductor pipe, but due to a lack of communication, the compressor was turned on before the valves were prepared to control the flow of debris out of the hole. The excess pressure caused the kelly bushing, drillpipe slips, and debris to be blown out of the rotary table. The victim was struck by these objects and was pronounced dead on arrival to the hospital.

A 27-year-old gas drilling rig worker died on May 23, 2003 from blunt force trauma to the head, neck, and chest after he was struck by the kelly bushing and drillpipe slips. OKFACE investigators reviewed the death certificate, related local news articles, and reports from the sheriff’s office, Medical Examiner, Occupational Safety and Health Administration (OSHA),

At the time of the incident, the rig floor and working surfaces were level and dry; the weather was warm with light to no wind. The victim was working with four other crew members on a gas drilling rig, wearing the necessary personal protective equipment (e.g., steel toe boots, hard hat, eye protection). Prior to the incident, the decedent was assigned the task of driller and was asked to find the bottom of the conductor hole with the kelly (Figure 2). The kelly is used to transmit power (rotary motion) from the rotary table and kelly bushing to the drillstring (Table 1). After unlatching the brake handle, the driller allowed the kelly to free fall to the bottom. The uncontrolled fall caused the kelly to become jammed with debris, such as water, mud, and other material, that had collected in the conductor hole since the time it was originally drilled for the well. As a result, a cleanout operation became necessary. Cleanout procedures involving air or mud drilling fluid are acceptable norms in the oil and gas drilling industry; however, drilling fluid is more commonly used than compressed air.

a large diameter hole, lined with pipe, that varies in depth depending on the local geology; the hole where the crew starts the top of the well; also called a starter hole

a long square or hexagonal steel bar with a hole drilled through the middle for a fluid path; goes through the kelly bushing, which is driven by the rotary table

After the kelly became jammed, a senior driller was assigned to take over the brake handle and kelly; however, the decedent remained approximately eight feet away on the rig floor. A newly hired, yet experienced, derrickman had the job of running the air compressor. While the drillers were switching positions, the derrickman realized that he had not started that particular type of compressor in quite some time and left the rig floor to seek help from another driller onsite.

In normal cleanout operation procedures, certain valves are closed prior to turning on the compressed air, which allows control over the flow of debris out of the hole and into a catch pond. Once the valves are prepared, the driller indicates to the derrickman that the area is ready for the compressed air. At some point between the senior driller preparing for cleanout and the derrickman leaving the floor to turn on the air compressor, there was a lack of communication and the air compressor was activated without the senior driller’s knowledge, prior to the prescribed valves being shut. After starting the air compressor, the derrickman returned to the rig floor and, as he walked to his next assignment, the rotary table erupted. The pressure normally used to complete the cleanout work is a minimum of 20 pounds per square inch. Within minutes, the kelly had pressurized well beyond this point to 150 pounds per square inch. The victim, who was still on the rig floor in close proximity to the kelly, was also unaware that the air compressor had been turned on. The compressed air, at full pressure with no valves closed to control or direct the flow, blew the kelly bushing, drillpipe slips, and debris out of the rotary table; all of which struck and landed on the victim.