Data processing: measuring – calibrating – or testing – Measurement system – Remote supervisory monitoring
Reexamination Certificate
2000-04-27
2003-05-06
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system
Remote supervisory monitoring
C702S189000
Reexamination Certificate
active
06560565
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to seismic operations. More particularly, the invention relates to seismic operations using satellites to provide communication between the field of operations and the office environment. Still more particularly, the invention relates to an integrated satellite-based seismic information system, facilitating efficient management of resources and assets in the field.
2. Background of the Invention
The field of seismology focuses on the use of artificially generated elastic waves to locate subsurface structures which may contain mineral deposits such as hydrocarbons, ores, water, and geothermal reservoirs. Seismology also is used for archaeological purposes and to obtain geological information for engineering. Exploration seismology provides data that, when used in conjunction with other available geophysical, borehole, and geological data, can provide information about the structure and distribution of rock types and their contents.
Most oil and gas companies rely on the interpretation of seismic data for selecting the sites in which to invest in drilling exploratory and production oil and gas wells. Despite the fact that seismic data is used to map geological structures rather than finding petroleum directly, the gathering of seismic data has become a vital part of selecting the site of an exploratory and/or development well. Experience has shown that the use of seismic data greatly improves the likelihood of a successful venture.
The process of designing, planning, taking seismic measurements, and processing the data generally is referred to as a “seismic project.” Although the scale of seismic projects vary depending on the depth of the subsurface structures, size of the area to be surveyed, and other factors, most seismic projects use a common set of equipment. A “source” device creates the energy that propagates into the earth. “Receivers” detect the energy after it reflects off subsurface interfaces between rock formations. The time between emitting the impulse from the source and detecting the reflected impulse by a receiver is used to determine the distance to the subsurface structure under investigation. At least several different energy sources have been used at times, but most large scale land-based projects (seismic projects can also be performed at sea) use either high amplitude explosives or lower amplitude vibrators as the source.
Explosives produce high-energy, short time duration impulses. The explosive source and the associated data acquisition and processing system are relatively simple. Explosive charges usually are placed into holes drilled in the ground by drilling trucks, portable drills and personnel, and subsequently detonated.
Seismic projects alternatively may use low magnitude, vibratory energy. Rather than imparting a high magnitude pressure pulse into the earth in a very short time period as with explosive charges, vibratory sources emit lower amplitude pressure waves over a longer time period typically between 5 and 7 seconds, but longer time periods are also possible. A total interval of 5 to 32 seconds is possible. Further, the frequency of the vibrating source varies from a low of about 5 to 10 Hz to a high of 100 to 150 Hz, although the specific low and high frequencies differ from system to system. The frequency of the source may vary linearly with respect to time or non-linearly. The frequency variations are commonly called a “frequency sweep.” The frequency sweep thus typically is between 5 and 150 Hz and on average 12 seconds in duration. The magnitude of the seismic wave oscillations may vary or remain at a constant amplitude.
Many other types of equipment are used in seismic projects. As noted above, drilling trucks are used to drill holes in the ground at predetermined locations for positioning and detonating explosive charges. Further, vibrator trucks are used to generate the vibratory energy. Recording equipment is used to record the seismic data. “Line cutters” are used to clear trees and other obstacles from the area in which the sources and receivers are to be placed. Transportation in the survey area is provided by trucks, buses, all terrain vehicles, and other types of vehicles. Helicopters are used to ferry people and equipment to the site of the project. In addition, large scale projects may require over one hundred personnel in the field to perform a myriad of tasks such as clearing the line, setting up and dismantling the equipment, locating the sites for placement of the sources and receivers, precisely determining the coordinates of source and receiver points, as well as numerous other tasks. Such personnel require food, water, lodging and other facilities and resources. Project critical vehicles such as vibrators require prompt fueling. Periodically, equipment malfunctions. Trouble shooting equipment including vehicles, testing and repair equipment is provided in the field along with skilled personnel to trouble shoot the malfunctions and effectuate any necessary repairs. A typical project may include over one hundred personnel and several hundred pieces of equipment, many of which are mobile, and vehicles. Accurately tracking and coordinating these resources is vitally important to increase the efficiency of the survey and thus lower the costs. Managing the field resources, however, becomes increasingly problematic as the size of the project area increases. Many projects may require field-based equipment and personnel spread out over several hundred square miles. Other equipment and personnel may be located in various sites, such as the surveying company's head office, around the globe.
A typical seismic project begins with a request to a seismic company to run a seismic project in a particular area of the world. The request, from the seismic company's client, initiates a planning phase in which seismic designers, typically geophysicists, design the project grid—made up of source and receiver points. The designed project grid is to be confirmed and modified in the surveying phase of the overall seismic process. The design activity involves reviewing maps of the area to be surveyed and determining where the seismic sources and receivers should be located. Usually, a series of measurements, or “shot records,” are performed in each survey and the sources and receivers must be relocated between each shot record.
Source and receiver locations are determined in three dimensions in terms of geodetic latitude, longitude and height. The height dimension is the distance from a source or receiver point to the surface of a reference ellipsoid. Thus, the height is the distance over or above the ellipsoid. The ellipsoid height is the sum of the geoid height and orthometric height (height above sea level). The ellipsoid is an industry standard whose geometric center is ideally at the center of gravity of the Earth, and whose minor axis coincides with the rotation axis of the Earth. The size and shape of the ellipsoid is chosen to best represent the Earth in the mean sense. The WGS84 (World Geodetic System 1984) is one such industry standard. The accuracy specifications for the coordinates of sources and receivers are generally specified in terms of meter or submeter accuracy. The maintenance and assessment of this accuracy is critical to seismic surveys.
Survey designers use digital maps to help them design the survey. These maps indicate the locations of ponds, roads or other obstructions that may interfere with the otherwise desirable location of the seismic equipment. Thus, the quality of the survey design at least partially is a function of the quality of the maps. Poor quality maps (i.e., inaccurate maps or maps which have not been recently updated) detrimentally impact the quality of seismic survey.
In addition to maps, survey designers must also consider local permitting regulations and surface and mineral rights ownership when designing the survey.
Krakiwsky Edward J.
Krakiwsky Sean E.
Portsmouth Jackie L. A.
Roy James
Barlow John
Conley & Rose, P.C.
Veritas DGC Inc.
Washburn Douglas N
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