Length is a measure of distance. In the International System of Quantities, length is a quantity with dimension distance. In most systems of measurement a base unit for length is chosen, from which all other units are derived. In the International System of Units (SI) system the base unit for length is the metre.
In petroleum exploration and development, formation evaluation is used to determine the ability of a borehole to produce petroleum. Essentially, it is the process of "recognizing a commercial well when you drill one".
Directional drilling is the practice of drilling non-vertical bores. 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 bore target to extract coal bed methane.
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.
A mud engineer works on an oil well or gas well drilling rig, and is responsible for ensuring the properties of the drilling fluid, also known as drilling mud, are within designed specifications.
In geophysics, vertical seismic profile (VSP) is a technique of seismic measurements used for correlation with surface seismic data. The defining characteristic of a VSP is that either the energy source, or the detectors are in a borehole. In the most common type of VSP, hydrophones, or more often geophones or accelerometers, in the borehole record reflected seismic energy originating from a seismic source at the surface.
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).
Geosteering is the optimal placement of a wellbore based on the results of realtime downhole geological and geophysical logging measurements rather than three-dimensional targets in space. The objective is usually to keep a directional wellbore within a hydrocarbon pay zone defined in terms of its resistivity, density or even biostratigraphy. In mature areas, geosteering may be used to keep a wellbore in a particular reservoir section to minimize gas or water breakthrough and maximize economic production from the well. In the process of drilling a borehole, geosteering is the act of adjusting the borehole position on the fly to reach one or more geological targets. These changes are based on geological information gathered while drilling.
In the oil and gas industry, depth in a well is the distance along a well between a point of interest and a reference point or surface. 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.
A caliper log is a well logging tool that provides a continuous measurement of the size and shape of a borehole along its depth and is commonly used in hydrocarbon exploration. The measurements that are recorded can be an important indicator of wash-outs, cave ins or shale swelling in the borehole, which can affect the results of other well logs.
In the oil industry measured depth is the length of the drilled borehole. In conventional vertical wells, this coincides with the true vertical depth, but in directional or horizontal wells, especially those using extended reach drilling, the two can deviate greatly. For example, at the time of writing (2012) a borehole in Odoptu field, Sakhalin-I, has the greatest measured depth of any borehole at 12,345 m, but most of this is horizontal, giving it a true vertical depth of only 1,784 m. For comparison, the Kola Superdeep Borehole has a slightly shorter measured depth at 12,262 m, but since this is a vertical borehole, this is also equal to the true vertical depth, making the Kola Superdeep Borehole deeper by a factor of 6.9.
A directional well is the oil industry term for an oil well with a borehole that deviates from a vertically straight line. This is normally done with the intention of hitting several target sands, for instance.
Estimated pore pressure, as used in the oil industry and mud logging, is an approximation of the amount of force that is being exerted into the borehole by fluids or gases within the formation that has been penetrated.
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 industry, a deviation survey, or simply a survey, is the measurement of a borehole's departure from the vertical, expressed in degrees (°).
A conductor Pipe is a large diameter pipe that is set into the ground to provide the initial stable structural foundation for a borehole or oil well. The Conductor pipe is the first string of casing and is the largest diameter casing to be installed in a well. It can also be referred to as a drive pipe because it is often driven into the ground with a pile driver.
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 gas or fluid (hydrocarbons), usually referred to as kick, from entering into the wellbore during drilling or well interventions.
Vertical position or vertical location is a position along a vertical direction above or below a given vertical datum . Vertical distance or vertical separation is the distance between two vertical positions. Many vertical coordinates exist for expressing vertical position: depth, height, altitude, elevation, etc. Points lying on an equigeopotential surface are said to be on the same vertical level, as in a water level.
Ice drilling allows scientists studying glaciers and ice sheets to gain access to what is beneath the ice, to take measurements along the interior of the ice, and to retrieve samples. Instruments can be placed in the drilled holes to record temperature, pressure, speed, direction of movement, and for other scientific research, such as neutrino detection.
