Tripping (pipe)

Last updated March 22, 2019

Tripping pipe (or "Making a round trip" or simply "Making a trip") is the physical act of pulling the drill string out of the wellbore and then running it back in. This is done by physically breaking out or disconnecting (when pulling out of the hole) every other 2 or 3 joints of drill pipe at a time (called a stand) and racking them vertically in the derrick. When feasible the driller will start each successive trip on a different "break" so that after several trips fresh pipe dope will have been applied (when running back in the hole) to every segment of the drill string.

A drill string on a drilling rig is a column, or string, of drill pipe that transmits drilling fluid and torque to the drill bit. The term is loosely applied to the assembled collection of the drill pipe, drill collars, tools and drill bit. The drill string is hollow so that drilling fluid can be pumped down through it and circulated back up the annulus.

Drill pipe, is hollow, thin-walled, steel or aluminium alloy piping that is used on drilling rigs. It is hollow to allow drilling fluid to be pumped down the hole through the bit and back up the annulus. It comes in a variety of sizes, strengths, and wall thicknesses, but is typically 27 to 32 feet in length. Longer lengths, up to 45 feet, exist.

A stand is two or three joints of drill pipe connected and stood in the derrick vertically, usually while tripping pipe. A stand of collars is similar, only made up of collars and a collar head. The collar head is screwed into the collar to allow it to be picked up by the elevators.

The most typical reason for tripping pipe is to replace a worn-out drill bit. Though there are many problems that occur to warrant the tripping of pipe. Downhole tools such as MWD (measurement while drilling), LWD (logging while drilling) or mud motors break down quite often. Another common reason for tripping is to replace damaged drill pipe. It is important to get the pipe out of the wellbore quickly and safely before it can snap.

Drill bits are cutting tools used to remove material to create holes, almost always of circular cross-section. Drill bits come in many sizes and shapes and can create different kinds of holes in many different materials. In order to create holes drill bits are usually attached to a drill, which powers them to cut through the workpiece, typically by rotation. The drill will grasp the upper end of a bit called the shank in the chuck.

A drilling rig is used to create a borehole or well in the earth's sub-surface, for example in order to extract natural resources such as gas or oil. During such drilling, data is acquired from the drilling rig sensors for a range of purposes such as: decision-support to monitor and manage the smooth operation of drilling; to make detailed records of the geologic formations penetrated by a borehole; to generate operations statistics and performance benchmarks such that improvements can be identified, and to provide well planners with accurate historical operations-performance data with which to perform statistical risk analysis for future well operations. The terms measurement while drilling (MWD), and logging while drilling (LWD) are not used consistently throughout the industry. Although these terms are related, within the context of this section, the term MWD refers to directional-drilling measurements, e.g., for decision support for the smooth operation of the drilling, while LWD refers to measurements concerning the geological formation made while drilling.

Logging while drilling (LWD) is a technique of conveying well logging tools into the well borehole downhole as part of the bottom hole assembly (BHA).

Bit trip

Drill bits wear and tear like most any other piece of equipment. Once a bit becomes too worn to drill at an adequate rate or make a full-gauge hole, or if the bearings are thought to be near failure, a trip is undertaken to replace the bit. A trip is not considered a bit trip when the purpose of replacing the bit is to change sizes. This is only done when the crew "sets surface, intermediate or longstring" as appropriate.

Fishing trip

A fishing trip is when a crew is forced to trip pipe to retrieve loose items in the wellbore. This can result from something being dropped in the hole, i.e. a tool, that would cause damage to the bit if the crew attempted to drill with it on bottom.

Twisting off

Another major cause is known as a "twist off". Twisting off is when the drill string parts by failing catastrophically under the torsional stress. This may happen if the drill string below is pinched in the wellbore, or as the result of a structural weakening of the pipe caused by a washout or a crack in a threaded connection member.

Broken string or broken bit

When pipe snaps or a part of the bit breaks off, the crew has to recover all of the separated items from the wellbore. Recovering snapped pipe usually involves placing a specialized tool (an "overshot") with grips set inside of it over the broken pipe in an attempt to capture it. The grip works in a manner similar to Chinese fingercuffs. Sometimes the jagged top of the fish must be milled back to a round outside shape before the overshot can slip over it. The overshot contains a packoff device to make a pressure seal so circulation can be reestablished through the bit to facilitate recovery of the fish. For a broken bit, a magnet is commonly used to remove all of the broken parts.

Cracked pipe or collar

A cracked pipe can lead to a broken string. Extra care is taken when tripping for one so that too much pull does not cause the cracked pipe to snap. Cracked pipes (i.e., washouts) are usually noticed by a sudden drop in pressure. The crew will usually pump "fastline" (small lengths of manila rope taken from unraveled catline) down the drill string to make a temporary plug and time the pressure to see when it rises back to normal. This enables the crew to know how far down to expect the cracked pipe to be within a few stands; also strands of these rope segments may be seen at the point of washout. Most trips for a cracked pipe are not complete trips like a fishing trip or a bit trip. These can be as simple as only going a few stands down, to pulling the drill collars.

Logging

Logging of the open hole may take place at various depths while drilling, and almost always at the end of the drilling operation. The drill string will be removed from the wellbore to allow a logging crew to conduct a survey of the well. After the logging is completed at total depth, the crew will run the drill string back into the well and then proceed to lay it down when coming out of the hole prior to installing the final set of casing (the "production casing").

Well logging, also known as borehole logging is the practice of making a detailed record of the geologic formations penetrated by a borehole. The log may be based either on visual inspection of samples brought to the surface or on physical measurements made by instruments lowered into the hole. Some types of geophysical well logs can be done during any phase of a well's history: drilling, completing, producing, or abandoning. Well logging is performed in boreholes drilled for the oil and gas, groundwater, mineral and geothermal exploration, as well as part of environmental and geotechnical studies.

Setting surface, intermediate and longstring

These trips are routinely expected by the crew. Setting surface occurs after the wellbore is drilled to the predetermined surface depth (e.g., after drilling below fresh water strata). The crew will remove the entire drill string to allow surface casing to be emplaced. The procedure is similar for setting intermediate, only that it typically involves a much longer drill string to be removed. Setting longstring is usually a one time operation combining both surface and intermediate casing. This saves the time of only having to undertake one pipe trip as opposed to two pipe trips.

Related Research Articles

An oil well is a boring in the Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released along with the oil. A well that is designed to produce only gas may be termed a gas well.

In the oil and gas industry, the term wireline usually refers to a cabling technology used by operators of oil and gas wells to lower equipment or measurement devices into the well for the purposes of well intervention, reservoir evaluation, and pipe recovery.

Directional drilling is the practice of drilling non-vertical wells. It can be broken down into four main groups: oilfield directional drilling, utility installation directional drilling, directional boring, and surface in seam (SIS), which horizontally intersects a vertical well target to extract coal bed methane.

A drilling rig is a machine that creates holes in the earth's subsurface. Drilling rigs can be massive structures housing equipment used to drill water wells, oil wells, or natural gas extraction wells, or they can be small enough to be moved manually by one person and such are called augers. Drilling rigs can sample subsurface mineral deposits, test rock, soil and groundwater physical properties, and also can be used to install sub-surface fabrications, such as underground utilities, instrumentation, tunnels or wells. Drilling rigs can be mobile equipment mounted on trucks, tracks or trailers, or more permanent land or marine-based structures. The term "rig" therefore generally refers to the complex equipment that is used to penetrate the surface of the Earth's crust.

Well control is the technique used in oil and gas operations such as drilling, well workover, and well completions for maintaining the fluid column hydrostatic pressure and formation pressure to prevent influx of formation fluids into the wellbore. This technique involves the estimation of formation fluid pressures, the strength of the subsurface formations and the use of casing and mud density to offset those pressures in a predictable fashion. Understanding of pressure and pressure relationships are very important in well control.

In geotechnical engineering, drilling fluid, also called drilling mud, is used to aid the drilling of boreholes into the earth. Often used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are also used for much simpler boreholes, such as water wells.

In drilling technology, casing string is a long section of connected oilfield pipe that is lowered into a wellbore and cemented. The purpose of the casing pipe is as follows:

Underbalanced drilling, or UBD, is a procedure used to drill oil and gas wells where the pressure in the wellbore is kept lower than the static pressure then the formation being drilled. As the well is being drilled, formation fluid flows into the wellbore and up to the surface. This is the opposite of the usual situation, where the wellbore is kept at a pressure above the formation to prevent formation fluid entering the well. In such a conventional "overbalanced" well, the invasion of fluid is considered a kick, and if the well is not shut-in it can lead to a blowout, a dangerous situation. In underbalanced drilling, however, there is a "rotating head" at the surface - essentially a seal that diverts produced fluids to a separator while allowing the drill string to continue rotating.

In the oil and gas industries, coiled tubing refers to a very long metal pipe, normally 1 to 3.25 in in diameter which is supplied spooled on a large reel. It is used for interventions in oil and gas wells and sometimes as production tubing in depleted gas wells. Coiled tubing is often used to carry out operations similar to wirelining. The main benefits over wireline are the ability to pump chemicals through the coil and the ability to push it into the hole rather than relying on gravity. Pumping can be fairly self-contained, almost a closed system, since the tube is continuous instead of jointed pipe. For offshore operations, the 'footprint' for a coiled tubing operation is generally larger than a wireline spread, which can limit the number of installations where coiled tubing can be performed and make the operation more costly. A coiled tubing operation is normally performed through the drilling derrick on the oil platform, which is used to support the surface equipment, although on platforms with no drilling facilities a self-supporting tower can be used instead. For coiled tubing operations on sub-sea wells a mobile offshore drilling unit (MODU) e.g. semi-submersible, drillship etc. has to be utilized to support all the surface equipment and personnel, whereas wireline can be carried out from a smaller and cheaper intervention vessel. Onshore, they can be run using smaller service rigs, and for light operations a mobile self-contained coiled tubing rig can be used.

Slickline refers to a single strand wire which is used to run tools into wellbore for several purposes. It is used in the oil and gas industry, but also describes that niche of the industry that involves using a slickline truck or doing a slickline job.

See snubber for a device used to suppress ("snub") voltage transients in electrical systems

Well completion is the process of making a well ready for production. This principally involves preparing the bottom of the hole to the required specifications, running in the production tubing and its associated down hole tools as well as perforating and stimulating as required. Sometimes, the process of running in and cementing the casing is also included. After a well has been drilled, should the drilling fluids be removed, the well would eventually close in upon itself. Casing ensures that this will not happen while also protecting the wellstream from outside incumbents, like water or sand.

Oilfield terminology refers to the jargon used by those working in fields within and related to the upstream segment of the petroleum industry. It includes words and phrases describing professions, equipment, and procedures specific to the industry. It may also include slang terms used by oilfield workers to describe the same.

In the oil and gas industry, a drill bit is a tool designed to produce a generally cylindrical hole (wellbore) in the earth’s crust by the rotary drilling method for the discovery and extraction of hydrocarbons such as crude oil and natural gas. This type of tool is alternately referred to as a rock bit, or simply a bit. The hole diameter produced by drill bits is quite small, from about 3.5 inches (8.9 cm) to 30 inches (76 cm), compared to the depth of the hole, which can range from 1,000 feet (300 m) to more than 30,000 feet (9,100 m). Subsurface formations are broken apart mechanically by cutting elements of the bit by scraping, grinding or localized compressive fracturing. The cuttings produced by the bit are most typically removed from the wellbore and continuously returned to the surface by the method of direct circulation.

In oil or gas well drilling, lost circulation occurs when drilling fluid, known commonly as "mud", flows into one or more geological formations instead of returning up the annulus. Lost circulation can be a serious problem during the drilling of an oil well or gas well.

Oil well control is the management of the dangerous effects caused by the unexpected release of formation fluid, such as natural gas and/or crude oil, upon surface equipment of oil or gas drilling rigs and escaping into the atmosphere. Technically, oil well control involves preventing the formation fluid, usually referred to as kick, from entering into the wellbore during drilling.

Pipe recovery is a specific wireline operation used in the oil and gas industry, when the drill string becomes stuck downhole. Stuck pipe prevents the drill rig from continuing operations. This results in costly downtime, ranging anywhere from $10,000-1,000,000 per day of downtime, therefore it is critical to resolve the problem as quickly as possible. Pipe recovery is the process by which the location of the stuck pipe is identified, and the free pipe is separated from the stuck pipe. This allows fishing tools to subsequently be run down hole to latch onto and remove the stuck pipe.

References

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.