2C: Two-Component. Shorthand for seabed seismic imaging using a hydrophone and single component geophone.
2-D Seismic Data: A vertical section of seismic data consisting of numerous adjacent traces acquired sequentially.
3C: Three-Component. Shorthand for multicomponent (full-wave) seismic imaging, as well as the notation for the orthogonal geometry associated with the VectorSeis sensor.
3-D Seismic Data: A set of numerous closely-spaced seismic lines that provide a high spatially sampled measure of subsurface reflectivity. Typical receiver line spacing can range from 80 m to over 600 m, and typical distances between shotpoints and receiver groups is 25 m (offshore and internationally) and 34 m to 67 m (onshore USA). The resultant data set can be "cut" in any direction but still display a well sampled seismic section. Computer-based interpretation and display of 3-D seismic data allow for more thorough analysis than 2-D seismic data.
4C: Four-Component. When full-wave data is acquired in the marine environment, a fourth receiver (a hydrophone) is added to the three-component sensor package.
4-D Seismic Data: 3-D seismic data acquired at different times (time-lapse) over the same area to assess changes in a producing hydrocarbon reservoir with time. Changes may be observed in fluid location and saturation, pressure and temperature.
A/C: Analog Cable. The geophone-equipped version of System Four, Scorpion, etc.
Accelerometer: A device used during surveying to detect ground acceleration in the Earth's surface produced by acoustic (seismic) vibrations.
Acquisition: The generation and recording of seismic data.
Aliasing: The distortion of frequency introduced by inadequately sampling a signal, which results in ambiguity between signal and noise. An unaliased image is an undistorted image provided by a robust sampling.
Anisotropy: Predictable variation of a property of a material with the direction in which it is measured, which can occur at all scales. In rocks, variation in seismic velocity measured parallel or perpendicular to bedding surfaces is a form of anisotropy (non-uniformity).
Array: A geometrical arrangement of seismic sources (a source array, with each individual source being activated in some fixed sequence in time) or receivers (a geophone array) that is recorded by one channel.
ASIC: Application Specific Integrated Circuit. The integrated circuit in VectorSeis that converts the sensor’s movement into a digital signal.
Attenuate: The removal of undesirable features, such as multiple events, from seismic data.
A-unit: Analog Unit. Component of System Four that collects information from 3 geophone strings, digitizes the information and sends it to the central recording truck.
AU2: Analog Unit. Component of Scorpion that collects information from 3 geophone strings, digitizes the information and sends it to the central recording truck.
AVA: Amplitude Variation with Angle (or Azimuth). Variation in seismic reflection amplitude with change in azimuth between a common shot point and the receivers.
AVO: Amplitude Variation with Offset. Variation in seismic reflection amplitude with change in distance between a common shot point and the receivers. AVO analysis is a technique by which geophysicists attempt to determine thickness, porosity, density, velocity, lithology and fluid content of rocks. AVO analysis is more successful in young, poorly consolidated rocks, such as those in the Gulf of Mexico, than in older, well-cemented sediments.
Azimuth: The compass direction of a directional survey. The azimuth is usually specified in degrees with respect to the geographic or magnetic north pole The angle that characterizes a direction or vector relative to a reference direction (usually True North) on a horizontal plane.
Backscatter: A reflection phenomenon of energy in which a non-reflective surface, which is a surface that does not reflect energy coherently, randomly scatters energy.
BBL: Barrels, in the context of a reserve measurement. Often used with M (Million) or B (Billion).
BBU: Battery Booster Unit. A component of System Four and Scorpion that ensures consistent levels of power across a cable-based land spread.
BLM: Bureau of Land Management. The steward of government lands in the U.S., controlling access to approximately 40% of all acreage in the West.
BOM: Bill of Materials, describing a product in terms of its sub-assemblies and basic parts.
BOPD or BOD: Barrels of Oil Per Day. Often used with k (thousand) or M (Million).
Bright Spot: A seismic amplitude anomaly or high amplitude that can indicate the presence of hydrocarbons. Bright spots result from large changes in acoustic impedance and tuning effects, such as when a gas sand underlies a shale, but can also be caused by phenomena other than the presence of hydrocarbons, such as a change in lithology. The term is often used synonymously with hydrocarbon indicator.
CIS: Commonwealth of the Independent States (of the FSU).
CPU: Central Processing Unit. A programmable logic device that performs all the instruction, logic, and mathematical processing in a computer.
CSL: Concept Systems Limited.
C-wave: A “converted” wave. Refers to the shear wave that is naturally created when an acoustic pressure wave hits off a reflector in the subsurface. Differentiated in geophysics from a shear wave, which is generally associated with a Vibroseis source that creates both P- and S-waves on the surface.
Deconvolution: A step in seismic signal processing to recover high frequencies, attenuate multiples, equalize amplitudes, produce a zero-phase wavelet or for other purposes that generally affect the waveshape. Deconvolution, or inverse filtering, can improve seismic data that were adversely affected by filtering, or convolution that occurs naturally as seismic energy is filtered by the Earth.
DHI: Direct Hydrocarbon Indicator. The Holy Grail of exploration, associated with detecting hydrocarbons in advance of any drilling activity.
DP: Data Processing.
D-unit: Digital Unit. Component of System Four and Scorpion that collects information from 3 VectorSeis (SVSM) sensors and sends it to the central recording truck.
EAGE: European Association of Geoscientists and Engineers.
EAME: Europe, Africa, and the Middle East.
EM: Electro-magnetic, generally referring to controlled-source, electro-magnetic surveys in the marine environment (conducted by firms like EMGS and OHM) to identify hydrocarbons in the sub-surface before any wells are drilled. Works on the same principles as an induction log in well-logging, just at a larger scale.
EMI: Electro-magnetic interference. The interference in signal transmission or reception caused by the radiation of electrical and magnetic fields.
E&P: Exploration and Production.
FSE: Field Service Engineer.
FSU: 1) Former Soviet Union; 2) Field Service Unit (the FireFly “yellow box”).
GIS: Geographical Information System. In its simplest form, a map; but generally refers today to an electronic spatial database that might be used in GM’s OnStar or for FireFly navigation.
GoM: Gulf of Mexico.
GMG: GMG/Axis, a software subsidiary of ION based in Denver and part of the GXT organization. Previously called “Green Mountain Geophysics”. Provides MESA and Millennium software for seismic survey design, illumination modeling, acquisition project tracking, and near-surface refraction statics.
GPS: Global Positioning System. A method of triangulating the latitude, longitude, and vertical position of an object using a series of geo-synchronous orbiting satellites.
GXT: GX Technology Corporation.
Full-Wave Digital (FWD) Imaging: A seismic survey where single-point multi-component MEMS based sensors are deployed in a wide-azimuth design to record the full seismic wave field with high accuracy, the maximum frequency bandwidth and the long off-set information is captured and processed. Enough equipment must be used in order to ensure that the reservoir image is unaliased.
Geophone: A device used in surface seismic acquisition, both onshore and on the seabed, that detects ground velocity produced by seismic waves and transforms the motion into electrical impulses. Geophones detect motion in only one direction. Conventional seismic surveys on land use an array of geophones per receiver location to detect motion in the vertical direction.
Geophysics: The study of the physics of the Earth, especially its electrical, gravitational and magnetic fields and propagation of elastic (seismic) waves within it. Geophysics plays a critical role in the petroleum industry because geophysical data are used by exploration and development personnel to make predictions about the presence, nature and size of subsurface hydrocarbon accumulations.
Ground Roll: A type of coherent noise generated by a surface wave, typically a low-velocity, low-frequency, high-amplitude Rayleigh wave. Ground roll can obscure signal and degrade overall data quality.
Hertz (Hz): The unit of measurement of frequency, equivalent to one cycle per second. The unit is named after German physicist Heinrich Hertz (1857 to 1894), who discovered electromagnetic waves.
HSE: Health, Safety, and Environmental. Sometimes pre-fixed with a “Q” (for Quality).
IAGC: International Association of Geophysical Contractors. The HSE standards of this industry organization are used as a model for ION Solutions’ QHSE management system.
Image: The apparent source of a received wave. The image is the point in the subsurface that the rays would appear to have come from if they were not reflected, but were shot up from below.
Interpretation: Analysis of data to generate reasonable models and predictions about the properties and structures of the subsurface. Interpretation of seismic data is the primary concern of geophysicists.
ISO: International Standardization Organization, as in ISO-9001 quality standards.
Isotropy: A quality of directional uniformity in material such that physical properties do not vary in different directions.
LIDAR: Light Detection and Ranging.
Lithology: The macroscopic nature of the mineral content, grain size, texture and color of rocks.
LMO: Linear Moveout. A seismic processing step whereby a single refraction or reflection event is flattened in a common midpoint gather in preparation for stacking.
LTI: Lost Time Incident. An industry standard industry HSE metric/term used to track any work related injuries or illnesses which prevent a person from doing any work.
MEMS: Micro-electro-mechanical systems. The ‘technology of the very small,’ associated with the three accelerometers that are mounted orthogonally within the VectorSeis sensor.
MENA: Middle East and North Africa.
METF: Middle East Technology Forum.
Multi-component: Sensors with the ability to capture seismic signals in all three dimensions rather than just one. As more data is recorded, the chances of determining where the reflected energy came from in the subsurface is improved, and a more accurate image can be developed.
M/V: Merchant Vessel. For example, M/V Ocean Pearl is a vessel that RXT uses in its seabed operations.
NMO: Normal Moveout. A seismic processing step whereby reflection events are flattened in a common midpoint gather in preparation for stacking.
Noise: Anything other than desired signal. Cultural noise is that generated by human activity, such as automobile traffic that interferes with seismic surveying, or electrical power lines or the steel in pipelines that can adversely affect electromagnetic methods.
OBC: Ocean-Bottom Cable. A method of seismic application involving the placement of receivers and cabling on the seabed.
Offset: The horizontal displacement between points on either side of a fault, which can range from millimeters to kilometers.
OPEC: Organization of Petroleum Exporting Countries.
OVT: Offset Vector-Tile. An advanced processing technique that can be used with FireFly. OVTs are single-fold subsets of an orthogonal survey and can be extracted for near, mid- and far offsets. OVT-sorted data groups like offsets and azimuths, thereby optimally preserving offset and azimuth integrity. Sorting and processing the data in this manner allows for robust methods of interpolating for missed shots, statics processing, noise attenuation, data migration and AVO analysis.
Pressure Wave (P-wave): A compression wave also known as a primary wave, a P-wave is a seismic wave that pushes and pulls rocks, contracting and expanding them as it moves through them.
Pre-Stack Depth Migration (PreSDM): The process of transforming seismic data from a scale of time (the domain in which they are acquired) to a scale of depth to provide a picture of the structure of the subsurface independent of velocity. Depth conversion, ideally, is an iterative process that begins with proper seismic processing, seismic velocity analysis and study of well data to refine the conversion.
Pre-Stack Time Migration (PreSTM): A migration technique for processing seismic data in areas where lateral velocity changes are not too severe, but structures are complex. Time migration has the effect of moving dipping events on a surface seismic line from apparent locations to their true locations in time. The resulting image is shown in terms of travel-time rather than depth, and must then be converted to depth (PSDM) with an accurate velocity model to be compared to well logs.
Processing: Alteration of seismic data to suppress noise, enhance signal and migrate seismic events to the appropriate location in space. Processing steps typically include analysis of velocities and frequencies, static corrections, deconvolution, normal moveout, dip moveout, stacking, and migration, which can be performed before or after stacking. Seismic processing facilitates better interpretation because subsurface structures and reflection geometries are more apparent.
PZ summation: A technique for processing 2C and 4C seabed data. The data recorded by the pressure-detecting hydrophone (the P in PZ) is summed with the z-component (vertical component - the Z in PZ) of the geophone to attenuate unwanted, water-borne multiple energy.
QA: Quality Assurance.
QC: Quality Control.
Resolution: The ability to distinguish between separate points or objects, such as sedimentary sequences in a seismic section. High frequency and short wavelengths provide better vertical and lateral resolution. Seismic processing can greatly affect resolution: deconvolution can improve vertical resolution by producing a broad bandwidth with high frequencies and a relatively compressed wavelet.
RF: Radio Frequency. That portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alternating current which is fed to an antenna.
RMAG: Rocky Mountain Association of Geologists.
RSR: Remote Seismic Recorder. A “wireless” precursor to FireFly and the first system to be VectorSeis capable in the ION acquisition system portfolio.
RTM: Reverse Time Migration. An advanced, compute-intensive migration technique that runs the wave equation forward in time for the source and backwards in time for the receiver. Used in the most complex velocity regimes, including sub-salt, for structures having dips in excess of 70 degrees, and in the presence of reflection boundaries that may generate internal multiples.
RXT: Reservoir Exploration Technology AS. A publicly-traded Norwegian company that is our exclusive acquisition contractor for VSO applications.
SEG: Society of Exploration Geophysicists.
SEG-Y: One of several tape standards developed by the Society of Exploration Geophysicists and the most common format used for seismic data in the exploration and production industry.
Seismic: Pertaining to waves of elastic energy, such as that transmitted by P-waves and S-waves. Seismic energy is studied by scientists to interpret the composition, fluid content, extent and geometry of rocks in the subsurface.
Seismic Wave: Wave of energy that travels through the Earth as a result of seismic activity.
Seismograph: An instrument that measures and records vibrations within the Earth and of the ground.
Shear Wave (S-wave): Also known as converted wave and transverse, a shear wave is a seismic wave that moves rocks from side to side as it moves through them.
SM-24: SeisMometer, the industry standard-setting geophone element from Sensor b.v.
SMT-300: The industry standard-setting geophone tester from Sensor b.v.
SPE: Society of Petroleum Engineers.
SRME: Surface-Related Multiple Elimination. A processing technique that is designed to minimize secondary reflections, most commonly in marine acquisition, between a) the interface of the base of water and the seabed; or b) the air-water interface at the ocean’s surface.
Stack: A processed seismic record that contains traces that have been added together from different records to reduce noise and improve overall data quality.
Statics: A bulk shift of a seismic trace in time during seismic processing. A common static correction is the weathering correction, which compensates for a layer of low seismic velocity material near the surface of the Earth. Other corrections may compensate for differences in topography among others.
SVSM: Standard VectorSeis Sensing Module. The three-component digital seismic receiver designed to operate with the System Four, Scorpion, and FireFly seismic recording systems.
TFlop: A trillion floating-point computing instructions per second. A measure of the number of operations carried out by advanced supercomputers.
TIM: Truck Interface Module. Timing device for FireFly, Scorpion and System Four.
TZ: Transition Zone. The somewhat nebulously defined area between the onshore and marine environments in which neither land, OBC, nor streamer acquisition systems are ideally suited. Often delineated in the region between the shoreline and 50 meters of water depth.
UHF: Ultra High Frequency. Television broadcasts, microwave ovens, mobile phones, wireless LAN, Bluetooth, and Two-Way Radios at 300-3000 MHz.
V/C: VectorSeis Cable. The VectorSeis-equipped version of System Four, Scorpion, etc.
VHF: Very High Frequency. FM, television broadcasts and line-of-sight ground-to-aircraft and aircraft-to-aircraft communications at 30-300 MHz.
Vib: Vibroseis. A method used to propagate energy signals into the earth over an extended period of time (using a mobile hydraulic vibrator or shaker) as opposed to the near instantaneous energy provided by an impulsive source such as explosives.
Vector Fidelity: A multi-component sensors ability to make equal measurements on all three axes and to limit signal cross contamination between the three axes.
VOR: Vertical Orientation Rotation. The initial processing step used with VectorSeis, to align the three orthogonal sensors to a perfect vertical orientation, regardless of the sensor plant.
VRSR: VectorSeis Remote Seismic Recorder. A “wireless” precursor to FireFly and the first system to be VectorSeis capable in the ION acquisition system portfolio.
VSO: VectorSeis Ocean. ION’s redeployable system for full-wave acquisition from the seabed.
VSSN: VectorSeis Sub-Sea Network. The ‘brand name’ given to our concept for permanent seismic data recording from the seabed.
WATS: Wide Azimuth Towed Streamer. An advanced acquisition technique for imaging complex structures (e.g., subsalt) in the marine environment, generally implemented with multiple source vessels that shoot at some distance from the streamer recording vessel.
Wave: A disturbance that moves through a medium, transporting energy from one location to another as it goes.
Wavelet: A one-dimensional pulse, usually the basic response from a single reflector. Its key attributes are its amplitude, frequency and phase. The wavelet originates as a packet of energy from the source point, having a specific origin in time, and is returned to the receivers as a series of events distributed in time and energy. The distribution is a function of velocity and density changes in the subsurface and the relative position of the source and receiver.
Wave Velocity: The rate at which a wave travels through a medium, or the rate at which a body is displaced in a given direction. Its usage in geophysics is as a property of a medium-distance divided by travel time.
XLU: Cross-Line Unit. A component of Scorpion and System four that allows individual cable lines in the spread to exchange data and power with other cable lines, providing an element of redundancy.
