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Well logging is a technique used in the oil and gas industry for recording rock and fluid properties to find hydrocarbon zones in the geological formations below the Earth's crust. A logging procedure consists of lowering a 'logging tool' on the end of a wireline into an oil well (or hole) to measure the rock and fluid properties of the formation. An interpretation of these measurements is then made to locate and quantify potential depth zones containing oil and gas (hydrocarbons). Logging tools developed over the years measure the electrical, acoustic, radioactive, electromagnetic, and other properties of the rocks and their contained fluids. Logging is usually performed as the logging tools are pulled out of the hole. This data is recorded to a printed record called a 'Well Log' and is normally transmitted digitally to office locations. Well logging is performed at various intervals during the drilling of the well and when the total depth is drilled, which could range in depths from 300 m to 8000 m (1000 ft to 25,000 ft) or more. Pumpjack pumping an oil well near Sarnia, Ontario Petroleum (from Greek petra – rock and elaion – oil or Latin oleum – oil ) or crude oil, sometimes colloquially called black gold, is a thick, dark brown or greenish liquid. ...
Many stoves use natural gas. ...
Rock is a naturally occurring aggregate of minerals and/or mineraloids. ...
Hydrocarbons are refined at oil refineries and processed at chemical plants In chemistry, a hydrocarbon is any chemical compound that consists only of the elements carbon (C) and hydrogen (H). ...
Earth (often referred to as The Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth in order of size. ...
Earth cutaway from core to exosphere. ...
An oil well is a term for any perforation through the Earths surface designed to find and release both petroleum oil and gas hydrocarbons. ...
A drill is a tool with a rotating drill bit used for drilling holes in various materials. ...
The metre, or meter, is a measure of length, approximately equal to 3. ...
A foot (plural: feet) is a non-SI unit of distance or length, measuring around a third of a meter. ...
Wireline and "While Drilling" Well Logging Well logging usually refers to downhole measurements made via instrumentation that is lowered into the well at the end of a wireline cable. The wireline consists of an outer wire rope and an inner group of wires. The outer rope provides strength for lowering and lifting the heavy insturments and the inner wiring provides for transmission of power to the downhole equipment and for data telemetry uphole to the recording equipment on the surface. This article refers to metallic wire. ...
Telemetry is a technology that allows the remote measurement and reporting of information of interest to the system designer or operator. ...
In recent years, a new technique, Logging While Drilling (LWD), has been introduced which provides similar information about the well. Instead of sensors being lowered into the well at the end of wireline cable, the sensors are integrated into the drill string and the measurements are made while the well is being drilled. While wireline well logging occurs after the drill string is removed from the well, LWD measures geological parameters while the well is being drilled. However, because there is no high bandwidth telemetry path available -- no wires to the surface -- data is either recorded downhole and retrieved when the drill string is removed from the hole, or the measurement data is transmitted to the surface via pressure pulses in the well's mud fluid column. This mud telemetry method provides a bandwidth of much less than 100 bits per second. Fortunately, drilling through rock is a fairly slow process and data compression techniques mean that this is an ample bandwidth for real-time delivery of critical information. Logging While Drilling is a technique of measuring geological formation properties in real-time while drilling an oil well. ...
In petroleum drilling technology, a drill string in an oil rig is the column, or string, of drill pipe with attached tool joints that transmits fluid and rotational power from the kelly or top drive to the drill collars and bit. ...
Mud Pulse Telemetry - The transmition of encoded data through a drilling rigs drilling mud system using rapid fluctuations in the pressure of a closed loop circulating system. ...
Drilling mud, also called drilling fluid, is a lubricant used while drilling oil and natural gas wells. ...
Telemetry is a technology that allows the remote measurement and reporting of information of interest to the system designer or operator. ...
Logging measurement types Logging measurements are quite sophisticated. The prime target is the measurement of various geophysical properties of the subsurface rock formations. Of particular interest is porosity and permeability. In the oilfield, formation porosity indicates the amount of space found between the granules that form the rock. It is this space that contains the oil and gas. Permeability is a measure of the interlinking of the rock pores, a description of the passages between the pores through which the oil and gas may pass. The higher the porosity, the higher the possible oil and gas content of a rock reservoir. The higher the permeability, the easier for the oil and gas to travel from far out in the formation toward the wellbore. While logging tools don't measure these quantities directly, they provide measurements that allow for the mathematical interpretation of these quantities. Geophysics, the study of the earth by quantitative physical methods, especially by seismic reflection and refraction, gravity, magnetic, electrical, electromagnetic, and radioactivity methods. ...
Used in geology, building science and hydrogeology, the porosity of a porous medium (such as rock or sediment) is the proportion of the non-solid volume to the total volume of material, and is defined by the ratio: where Vp is the non-solid volume (pores and liquid) and Vm...
Permeability has several meanings: In electromagnetism, permeability is the degree of magnetisation of a material in response to a magnetic field. ...
Interpretation, or interpreting, is an activity that consists of establishing, either simultaneously or consecutively, oral or gestural communications between two or more speakers who are not speaking (or signing) the same language. ...
Beyond just the porosity and permeability, various logging measurements allow the interpretation of what kinds of fluids are in the pores – oil, gas, brine. In addition, the logging measurements are used to determine mechanical properties of the formations. These mechanical properties determine what kind of enhanced recovery methods may be used (tertiary recovery) and what damage to the formation (such as erosion) is to be expected during oil and gas production.
The types of instrumentation deployed in well logging is quite broad. Historically, logging measurements consisted of basic electrical logs (resistivity) and spontaneous potential (SP) logs, introduced by the Schlumberger brothers in the 1920's. Tools later became available to estimate porosity via sonic velocity and nuclear measurements. Tools are now more specialized and better able to resolve fine details in the formation. Radiofrequency transmission and coupling techniques are used to determine fluid conductivity (brine is more conductive than oil or gas). Sonic transmission characteristics (pressure waves) determine mechanical integrity. Nuclear magnetic resonance can determine the properties of the hydrogen atoms in the pores (surface tension, etc.). Nuclear scattering ( radiation scattering ), spectrometry and absorption measurements can determine density and elemental analysis or composition. High resolution electrical or acoustical imaging logs are used to visualize the formation, compute formation dip, and analyze thinly-bedded and fractured reservoirs. Conrad and Marcel Schlumberger were brothers from Alsace, France (Conrad a physicist -gratuated from École Polytechnique (France) in 1900- and Marcel an engineer). ...
Radio frequency, or RF, refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current fed to an antenna. ...
Electrical conductivity is a measure of how well a material accommodates the transport of electric charge. ...
Sonic might refer to: A sonic boom If mach number equals 1, the flow is called sonic A nickname Supersonic and Hypersonic speeds. ...
Pacific Northwest National Laboratorys high magnetic field (800 MHz, 18. ...
Radiation scattering is the deflection of radiation (electromagnetic or products of nuclear decay) from its original path as a result of interaction or collisions with atoms, molecules, or larger particles in the atmosphere or other media between the source of radiation and an observation point some distance away. ...
Spectroscopy is the study of spectra, ie. ...
Density (symbol: Ï - Greek: rho) is a measure of mass per unit of volume. ...
Elemental analysis is a process where a sample of some material (eg. ...
In addition to sensor-based measurments above, robotic equipment can sample formation fluids which may then be brought to the surface for laboratory examination. Also, controlled flow measurements can be used to determine in situ viscosity, water and gas cut (percentage), and other fluid and production parameters.
Mud Logging Another kind of logging technique used is 'Mud Logging'. A Mud Logger works when drilling is going on. The Mud Logger analyzes the rock samples coming out of the circulating mud/fluids off 'flow line' from the drill string/pipe. Similar to a Well Log, a 'Mud Log' is prepared by the Mud logging company. A mud log displays the Gas present in the formation by using Gas Chromatograph techniques. A mud log also describes the formation geology. In petroleum drilling technology, a drill string in an oil rig is the column, or string, of drill pipe with attached tool joints that transmits fluid and rotational power from the kelly or top drive to the drill collars and bit. ...
Gas-liquid chromatography (GLC), or simply gas chromatography (GC) is a type of chromatography in which the mobile phase is a carrier gas, usually an inert gas such as helium or nitrogen, and the stationary phase is a microscopic layer of liquid on an inert solid support. ...
Petroleum geology is a term used to refer to the specific set of geological disciplines that are applied to the search for hydrocarbons (oil exploration). ...
Use of Information The well log and the mud log are usually transferred in 'real time' to the operating company, which uses these logs to make operational decisions about the well and to make interpretations about the quantity of hydrocarbons present.
Major well logging and mud logging companies Both these jobs are performed by Oil & Gas Service companies.
Well Logging companies are:
Some logging companies are: Schlumberger Limited is the worlds largest multinational oilfield services corporation, incorporated in the Netherlands Antilles. ...
Baker Hughes NYSE: BHI is the worlds third-largest oil-services company behind Schlumberger and Halliburton . ...
This article needs to be updated. ...
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