derrick floor versus kelly bushing in stock

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).

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.

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).

The term "subsea" (SS) by itself should not be used, as it is ambiguous. It could mean: below sea floor or bottom, below mean sea level (MSL), below lowest astronomical tide (LAT), etc.

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.

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.

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).

Every signed oil well drilling contract includes some form of conditions and agreements. For example, the drilling rig contractor will agree to a specific drilling depth, financial obligations, or where the well will be drilled. Once everything has been agreed upon, the drilling rig will be moved in to prepare for drilling. This is most commonly referred to as the MIRU, or the “Move In and Rig Up”; and in most cases, will include drilling with a jackknife rig instead of the derricks that are built in place. Other important personnel often comprise of:

Commonly referred to as the derrick man, a derrick worker cannot be afraid of heights. This position requires working high above the floor, and is used during regular operations to help when the pipe is being pulled or run. In many of the modern rigs, a rack will vertically hold various sections of drill pipe along the side of the derrick. Each is then added to the drilling string as the bit makes it way deeper and deeper into the ground.

One of the common duties of derrick workers is to add (or remove) sections of pipe from the drill string. During drilling, the pipe is added the deeper into the ground they drill; while sections are removed from the drill string and pulled out of the ground once the drilling has been complete. Sections of pipe are also removed for replacement, or to deal with any drilling issues.

While running and pulling pipe, there are always two floor workers. These two personal are generally referred to as either roughnecks or floor hands, with the more experienced worker being referred to as the lead. The lead operates the lead tong, while the other floor worker operates the back-up tong (or back-up). In most cases, these workers are the most inexperienced members of the rig crew.

As the crew drills the well, the distances are calculated starting from the top of kelly bushing (refers to the sliding bushing located on the drilling rig floor on top of the rotary table that permits the drill kelly  to go down through it when the pipe is turning and the hole is drilled.

Once the casing pipe is permanently cemented into the hole (or set) and either the braiden head or wellhead installed, the measurements from the top of the wellhead to the top of the kelly bushing are calculated and subtracted from all drilling records. This allows precise well records for once the drilling rig is no longer there.

A pit in the ground to provide additional height between the rig floor and the well head to accommodate the installation of blowout preventers, ratholes, mouseholes, and so forth. It also collects drainage water and other fluids for disposal.†

A small enclosure on the rig floor used as an office for the driller or as a storehouse for small objects. Also, any small building used as an office or for storage.†

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 portable derrick capable of being erected as a unit, as distinguished from a standard derrick, which cannot be raised to a working position as a unit.†

The derrickman"s working platform. Double board, tribble board, fourable board; a monkey board located at a height in the derrick or mast equal to two, three, or four lengths of pipe respectively.†

Shallow bores under the rig floor, usually lined with pipe, in which joints of drill pipe are temporarily suspended for later connection to the drill string.†

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.†

Shallow bores under the rig floor, usually lined with pipe, in which joints of drill pipe are temporarily suspended for later connection to the drill string.†

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.†

A vertical pipe rising along the side of the derrick or mast. It joins the discharge line leading from the mud pump to the rotary hose and through which mud is pumped going into the hole.†

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.†

n: a large load-bearing structure, usually of bolted construction. In drilling, the standard derrick has four legs standing at the corners of the substructure and reaching to the crown block. The substructure is an assembly of heavy beams used to elevate the derrick and provide space to install blowout preventers, casingheads, and so forth.

n: all members in the assembly used for rotary drilling from the swivel to the bit, including the kelly, the drill pipe and tool joints, the drill collars, the stabilizers, and various specialty items. Compare drill string.

n: the column, or string, of drill pipe with attached tool joints that transmits fluid and rotational power from the kelly to the drill collars and the bit. Often, the term is loosely applied to include both drill pipe and drill collars.

The monkey board is a platform about halfway up the derrick. The board is essentially a rack that is used to secure the upper end of a stand of pipe when it is removed from the well. The worker who guides pipes into the board is called the derrickman.

The floor of the drill rig, where most drilling operations occur. Typically contains a rotary table, control systems, tongs, and other operational equipment. Is elevated above the ground by the substructure.

The swivel allows the kelly to rotate while suspended from the travelling block. Importantly, it allows drilling fluid to flow from the stationary standpipe to the rotating drill string.

The tongs are essentially large hydraulic pipe wrenches that can grip pipe joints when making up (screwing together) and breaking out (unscrewing) drilling pipe. After the floorhand tightens the tongs on the pipe, a cat-head built into the draw works pulls on a cable, turning the tongs and tightening (or loosening) the pipe. The tongs are pushed back into neutral position by workers.

An indoor shelter containing coffee, personal storage space, meeting rooms, communications equipment, etc. It is typically installed to be level with the rig floor.

A hole drilled in the ground beneath the rig floor. It is lined with pipe, including an extension that brings it up to the rig floor. The mousehole holds lengths of drilling pipe in preparation for adding them to the drill string.

This blowout preventer consists of rubber “wedges” that can be extruded into the wellbore by hydraulic pistons. These wedges can create a powerful seal around drill-string pipes as well as irregularly shaped pipes like kellys. Importantly, the pipe can be moved up and down while the preventer is engaged. Annular BOPs are not as effective at closing an open hole as the other types of BOPs.

A high pressure, flexible pipe with an interior diameter of 3-5 inches that carries drilling mud from the standpipe to the kelly or topdrive. The pipe is longer than the distance between these parts in order to accommodate the up-down movement of the kelly or topdrive.

Instead of rotating the drill string with a kelly and rotary table, top drive systems use an electrically powered drive shaft that screws directly into the top of the drill string (kind of like an electric screwdriver or drill). As drilling progresses, the top drive system is lowered deeper into the hole.

A system for providing rotation to a drill string. A non-circular pipe known as a kelly is rotated by an adapter called a kelly bushing, which is in turn rotated by the master bushing and rotary table. The square or hexagonal cross section of the pipe allows it to be rotated while sliding up and down. This allows powered rotation and drilling to occur simultaneously.

The powered mechanism that provides rotational force to the kelly. It is a round table set into the floor of the rig containing a master bushing, which in turn contains the kelly bushing.

The master bushing sits right inside the rotary table. It often contains a bowl shaped depression that allows drillers to insert wedges, which hold up the drill string while it is unscrewed from the kelly. It is also designed to engage the kelly bushing, which is placed inside.

The kelly bushing is essentially an adapter that fits inside the master bushing and transmits rotation to the kelly, which will likely vary in size as drilling progresses and the diameter of the hole decreases.

A rectangular or hexagonal pipe that is screwed into the top of the drill string and transmits the rotation of the rotary table and kelly bushing to the string.

In a kelly drive system, the swivel allows drilling fluid to pass from the static standpipe into the rotating kelly. In a topdrive system, it does essentially the same thing at the top of the drill string.

The stairway allows workers to ascend from ground level to the rig floor. The pipe ramp provides a sloped surface along which drill pipe and casing can be pulled during hoisting operations. This allows pipes to be raised to the rig floor from the pipe rack safely.

A high pressure, flexible pipe with an interior diameter of 3-5 inches that carries drilling mud from the standpipe to the kelly or topdrive. The pipe is longer than the distance between these parts in order to accommodate the up-down movement of the kelly or topdrive.

The NOV CUL & CB Casing Bushings are inserted directly into the rotary table and insure that the casing being run is perfectly aligned with the center of the hole. Model CU is a solid bushing and model CB is a split bushing. All of the bushings accept bowls of different sizes to accommodate a wide range of casing. Using CMS-XL or CP-S slips, since these bushings fit into the rotary table, the casing string can be easily rotated during cementing operations.

This invention relates to a rotary drilling accessory and particularly to a rotary drilling rig used to drill or dig a hole in the ground next to an oil well for storing the rotary Kelly joint or drill stem of a string of drill pipe in the oil well.

Heretofore, operators of rotary rigs to drill or dig such a Kelly joint store hole or Rat Hole as it is commonly called, slide the rotary drill table across the derrick floor to a position above where the Rat Hole is to be drilled, raise up one side of the table to a desired angle and then provide a power take-off connection by running a drive chain from the source of power or draw works to a special line shaft and from this shaft to the rotary table. On some draw works there is a special sprocket on a jack shaft that enables a chain drive to be run direct from the draw works to the rotary table in its moved over position. However, by either process the rotary table must be moved out of its regular position, and entails time and extra manpower.

The principal object of this invention therefore is to provide as an article of manufacture, an accessory for oil well drilling rigs comprising a separate hole digger for digging or drilling"Kelly joint store holes or Rat Holes so that the main rotary drill table may be left in its regular position, whereby much time and labor is saved.

Another object is to provide a Rat Hole digger constructed to fit the usual standard Kelly bushings or couplings used to connect with the "usual Kelly joint.

" A further object is to provide in combination with a novel Rat Hole digger, a novel quick attachable power take-off drive means adapted to be drivably connected with the rotary part of the hole digger, to thereby rotate the Kelly drilling members mounted in the Kelly drive of the digger.

Figure 1 is a general perspective View of the floor of an oil well derrick and rotary table with our novel power take-off sprocket inserted in the Kelly drive thereof with our novel Rat Hole digger in driving connection therewith.

Figure 4 is aside elevation partly in cross section of the digger with the parts assembled and ready for the insertion therein of the usual Kelly drill members.

Figure 7 is a top plan in elevation of the split Kelly drive socket adapted to be driven from the driven sprocket carrying part shown in Figures "5 and 6.

Figure 9 is an elevational view of one half section of the Kelly drive, showing one of the clutch projections or lugs adapted to engage with and between similar lugs on the sprocket carrying part.

Figure 10 is a fragmentary view of one side of the digger with the Kelly drive removed to show the bearing mountings between the rotary sprocket carrying part and the fixed base or outer shell of the digger.

Referring in detail to the drawings and first with, particular reference to Figure 1, there is "shown the derrick floor I 0 of an oil well derrick This table is revolved by the usual power source or draw works, not shown. Centrally located in the table II is the usual opening for receiving drive bushings for connecting with the Kelly joint, not shown. In place ofthe usual Kelly joint there is mounted in the table opening I2 a sprocket shaft I4 having a round plate I5, which fits in the tapered opening I 2 in table "I I. This is shown in more detail in Figure 2 and also includes a relatively larger square plate I 6 machined to fit in the square part of opening I2 in the top of the table I I. Keyed or welded on the end of the sprocket shaft I4 is a sprocket wheel I8 connected with an endless drive chain I9.

The drive chain I9 connects with another sprocket wheel 22, which is carried by the driven part 23, see Figures 5" and 6, of our novel accessory drill rig for drilling or digging Kelly joint store holes or Rat Holes. This digger or drilling unit comprises a hollow shell 24 supported on a base 25 and extending at an oblique angle therefrom and also oblique to the plane of the derrick floor to which the base is attached by bolts 26. This angle or tilt of the base serves to direct or pilot the drill pipe into the ground at a slant, so as to drill a slanting store hole or "Rat Hole, asit is commonly called in the oil country.

The hollow driven part 23 in turn mounts a Kelly drive 50 formed in two halves 5| and 52. These half sections when put together form a closed hollow body with an outer cylindrical lower skirt portion 53 topped by an annular flange 54. Above the flange the interior bore of the drive 50 is substantially square to drive the Kelly drive bushings, not shown, connected to the -usual kelly, likewise not shown. Insertion of the Kelly drive sections 5| and 52 is facilitated by the pick-up handles 55 and 56 carried by each section. When the Kelly drive 50 has been inserted in the driven part, it appears as shown in Figure 4. Mounted on the underside of the flange 54 of the Kelly drive are clutch lugs 58 and 59 similar to the clutch lugs 30 and 3| on the top side of the flange 29 of the driven part 23. These "lugs30, 3| onthe part 23 and 58 and 59 on the Kelly drive 50 are spaced and proportioned so as to fit between each other to provide a clutch drive connection between the driven part 23 and the Kelly drive 50.

We have in the foregoing description referred by reference numeral to each constituent part of our accessory drill rig and although the operation should be obvious from the description, we will briefly summarize its operation. For example, assume it is desired to drill or dig a store hole for a Kelly joint or the like. The first step is to remove the oil well drill pipe from the Kelly drive |2 of the table II and insert in place thereof the sprocket l8 and its shaft l4. Then after securing the accessory drill rig shell 24, with the driven hollow body 23, to the jderrick floor l over an opening therethrough to the ground, the-Kelly. drive D-is inserted in the shell and the sprocket I8 is connected with the sprocket 22. Next a Kelly joint is mounted in the drilling rig 4 and power is supplied to rotate the table H and sprocket 22.

As sprocket 22 is revolved the engaging clutch lugs of the driven part 23 and the Kelly joint 50 will rotate the Kelly joint to drill the hole. Usually these holes are drilled to a depth of about 30 feet and at an angle, this angular pitch of the hole being provided by the tilt of the hollow base 24 of the accessory drilling rig,

Thus we have provided a novel article of manufacture which can be sold as an accessory to all standard oil well drilling rigs for digging or drill ing the necessary Kelly joint-store hole or Rat Hole. Also, this accessory is simple and economical to use and manufacture, and saves many hours of labor as hereinbefore explained.

1. Means for drilling a hole to store a Kelly joint or the like, comprising a hollow shell fixed to the derrick floor of an oil well, bearing members around the inner circumference of said shell, a driven part rotatably journalled in said shell, a flange carried by said driven part, means for applying rotary driving power thereto, a bearing groove around the underside of said flange, said groove registering with a similar groove in the top rim of said shell to form a bearing race between said driven part and said fixed shell, spaced lugs on the upperside of said flange, and a drive bushing having a flange around its outer circumference with spaced lugs adapted to fit between said lugs on said flange of the driven part, whereby the drive bushing is rotatable with said driven part when power is applied to said flange.

2. A rotary drilling rig for drilling Kelly joint store holes comprising a fixed hollow member having a base secured to the derrick fioor of an oil well, a driven member journalled for rotation .in said fixed member, means for retainingv said driven member in said fixed member, .a flange carried by said driven member, clutch lugs on the upper surface of said flange, a drive bushing telescopically mounted in said driven member, clutch lugs carried by said drive bushing adapted to fit between each of the clutclilugs on said driven members flange, and means for establishing a driving connection between the regular rotary drill table of an oil well and said driven member and said drive bushing.

3. The drilling rig as described in claim 2, wherein the drive bushing comprises two half sections adapted to telescopically nest within the top of said driven member, each of said sections having handle members.

4. An accessory drilling rig for drilling holes in the earth inclined to the vertical to store Kelly joints or the like, comprising an upright rounding flange having a raceway in its under surface for coaction with the last mentioned bearing raceway, bearing balls within the coacting raceways, upstanding clutch lugs formed upon the top of said flange coengageable with lugs carried by a drive bushing, a drive bushing insertable in said cylindrical member, clutch lugs carried by the drive bushing coengageable with the lugs of said flange, and means coengaging and encircling the lower end of said cylindrical member and coengageable with an element of the lower one of said pair of bearing races for maintaining the cylindrical member within the cylindrical base.

RF2HB7M7M–Oilman released excess pressure of gas into oil pipeline and watching as oil pump working. Worker ensuring safe extraction of oil. Oil drilling derrick at oilfield for petroleum production from ground