Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Earth science
Reexamination Certificate
1999-04-21
2001-12-11
Patidar, Jay (Department: 2862)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Earth science
C702S014000
Reexamination Certificate
active
06330513
ABSTRACT:
The present invention relates to mineral exploration and, and more particularly to methods of detecting massive sulphide deposits by the use of seismic reflection surveys.
BACKGROUND OF THE INVENTION
Multi-dimensional seismic reflection survey techniques, for example two dimensional (2-D) and three dimensional (3-D) seismic reflection survey techniques, have allowed the petroleum industry to generate remarkably accurate subsurface models to discover oil and gas deposits several thousand meters below the earth's surface, making deep oil drilling an economically viable procedure.
The minerals industry has made a considerable investment in multi-dimensional seismic reflection techniques to adapt the procedure for detecting the presence of massive sulphide deposits. However, the use of multi-dimensional seismic technologies by the minerals industry has thus far met with comparatively less success. In most cases, a massive sulphide will be extremely difficult to discern amongst the other strata of the geological region being explored.
To date, mineral exploration using seismic reflection surveys has been typically done on broad spectrum of geological terrain known to be potential sites for massive sulphides. Unfortunately, many of these regions exhibit poor signal to noise conditions. This relatively poor data has been found to be an inherent feature in multi-dimensional seismic exploration for massive sulphides. Experts in the field have worked diligently to overcome these problems by using state-of-the-art acquisition and processing strategies derived from the petroleum industry, hoping to filter out the noise and to generate an accurate, dependable subsurface geological model based on the remaining relatively poor acoustic signature of the massive sulphide deposit. With this goal in mind, experts have developed a number of sophisticated procedures which have been published in a number of leading mining journal articles.
However, these investigations have thus far not yielded significant useful results.
It is an object of the present invention to provide a novel technique for prospecting for massive sulphides.
SUMMARY OF THE INVENTION
Briefly stated, the invention involves a technique of prospecting for massive sulphide ore bodies, comprising the steps of:
selecting a geologic region which is substantially acoustically transparent;
directing seismic waves at the region and collecting reflected waves therefrom; and
analyzing the reflected waves for the presence of the massive sulphide ore bodies.
Preferably, the step of analyzing the reflected waves includes the step of generating a multi-dimensional seismic data set, which may be two dimensional, such as a that known as a 2-D section or three dimensional such as a 3-D volume or cube. The term multi-dimensional also includes the known 2-D technique referred to as vertical seismic profiling.
In another of its aspects, the present invention provides an exploration process which consists of evaluating a plurality of geological regions which are candidates for massive sulphide deposits, identifying a site with a host lithography which is essentially acoustically transparent and carrying out a seismic investigation on the site.
Rather than simply applying the latest multi-dimensional seismic modeling techniques on all geologic regions suspected of bearing massive sulphide deposits, the present technique involves selecting only those geologic regions which have a particular range of characteristics, primarily those suspected of having a local host stratigraphy which is essentially acoustically transparent, and then applying seismic survey techniques only on those selected geologic regions.
The term ‘acoustically transparent’ as a characteristic of a local host stratigraphy, refers to the ability of seismic waves to pass through the stratigraphy, while producing minimal or otherwise substantially non-interfering seismic reflections from geological boundaries which are not the boundaries of massive sulphide contacts. For example, an acoustically transparent local host stratigraphy may be one in which a massive sulphide deposit generates a recognizable peak on an acoustic impedance trace that exceeds the accumulation of noise from the survey, for example the noise originating from the local host itself, that is geologic noise, and the noise originating from the seismic survey instruments themselves. The local host stratigraphy, in this case, is that which is in the vicinity of the massive sulphide itself, that is above and below the massive sulphide and not necessarily the entire depth investigation range of the geological terrain. In this case, a major ‘marker’ may be above or below the local host stratigraphy and could present a significant peak in an impedance trace but not otherwise substantially interfere with the acoustic transparency of the adjacent local host stratigraphy itself.
REFERENCES:
patent: 4393488 (1983-07-01), Gassaway et al.
patent: 4878205 (1989-10-01), Gelchinsky
patent: 5170377 (1992-12-01), Manzur et al.
Adam et al., 3D Seismic Data Processing for Mineral Exploration, pp. 1-8, Apr. 1996.*
Keynote Session, Paper 7, “3-D Seismic Exploration”.
Seismic Methods in Mineral Exploration, Paper 49, “Physical Properties and Seismic Imaging of Massive Sulphides”.
Seismic Methods in Mineral Exploration, Paper 50, “Refection Seismics for Gold, Platinum and Base Metal Exploration and Mining in Southern Africa”.
Seismic Methods in Mineral Exploration, Paper 52, “Structurally Controlled Mineralization in Australia-How Seismic Profiling Helps Find Minerals: Recent Case Histories”.
Seismic Methods in Mineral Exploration, Paper 54, “Seismic Exploration for VMS Deposits, Matagami, Quebec”.
Seismic Methods in Mineral Exploration, Paper 55, “Development of 3-D Seismic Exploration Technology for NI-Cu Deposits, Sudbury Basin”.
Seismic Methods in Mineral Exploration, Paper 56, “Seismic Exploration of the Manitouwadge Greenstone Belt, Ontario”.
Seismic Methods in Mineral Exploration, Paper 59, “Seismic Refection Imaging of a Shallow, Fault-Controlled VMS Deposit in the Matagami Mining Camp, Quebec”.
Seismic Methods in Mineral Exploration, Paper 61, “Full Waveform Acoustic Logging Applications in Mineral Exploration and Mining”.
Seismic Methods in Mineral Exploration, Paper 53, “Sedimentary-Hosted Mineral Deposits: High-Resolution Seismic Survey in the Athabasco Basin”.
Katten Muchin & Zavis
Noranda Inc.
Patidar Jay
Taylor Victor J.
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