Electricity: measuring and testing – Of geophysical surface or subsurface in situ – With radiant energy or nonconductive-type transmitter
Reexamination Certificate
2000-03-10
2002-01-15
Snow, Walter (Department: 2862)
Electricity: measuring and testing
Of geophysical surface or subsurface in situ
With radiant energy or nonconductive-type transmitter
Reexamination Certificate
active
06339333
ABSTRACT:
BACKGROUND OF THE INVENTION
I have been interested in finding a direct means fox prospecting far oil for some time, although I have spent my entire career of nearly a half century in geophysical prospecting for oil, including the most widely used methods of seismic prospecting for oil. All geophysical is methods including the must used seismic reflection method have been indirect, i.e., aiming at finding structures, stratigraphic traps, or inferring lithological characteristics only. The chance of finding oil for the seismic techniques is about one in six to seven. In the present invention, the chance of finding oil will be about one in two to three.
The electromagnetic (EM) wave propagation depends primarily an the electric permittivity of the earth materials of rocks, while the conductivity of these earth materials is very low and the magnetic permeability is virtually constant. How the dynamic electromagnetic wave methods of this provisional application differ from any other methods lies in the fact using the physical properties of the oil itself in contrast to surrounding rocks of geological formations, gas, and water. Oil has an extremely low electric permittivity or dielectric constant, which is about 4 with an electromagnetic wave velocity of 50 m/us while fresh or salt water has a value of permittivity
81
with an electromagnetic wave velocity of 33 m/us. Surrounding sediments, usually say limestone, which has a value of permittivity
7
-
16
with an electromagnetic wave velocity of 75-113 m/us and that for sandstone
5
-
15
with an electromagnetic wave velocity of 77-134 m/us. It is these ideal electric permittivity contrasts that provide a means to use dynamic electromagnetic method for direct prospecting for oil.
FIELD OF THE INVENTION
The present invention relates to direct prospecting for oil in any environment worldwide at various depths. Using an extremely broad band of electromagnetic waves, this electromagnetic wave prospecting method should penetrate various depths which could be comparable to the penetration of seismic waves. Most importantly it would provide a means to directly identifying where the oil is and find the interfaces between the water and oil, as the permittivity of the water is
81
with an electromagnetic wave velocity 300 m/us.
BACKGROUND ART
During the last two decades, ground penetrating radar has been employed in shallow depth ranging from the surface to about 50 to 100 meters, which are operated in the radar frequency ranges of 50 to 1,000 mHz solely based on antenna source and antenna receivers.
This patent application is solely for prospecting for oil directly using frequency range from as low as DC to radar frequency, covering from the surface to a depth of greater than 3,000 meters or more for deep seated oil deposits. The art of achieving such a depth penetration must rely upon the design of the sources as well as the receivers, which will be expounded in the following section.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The essential part of this patent application is divided into two designing sections of the source and receiver, and one section on practice in the field.
1. The Source
In order to have the electromagnetic waves to penetrate to a depth of 3,000 m or more, a very low-frequency in the radio LF to UHF frequency range type of electromagnetic source is required, which would have the capability of delivering the power in the range of at least 10 to 100 kw or more with a voltage of 1,000 volts or more and a current of 10 to 100 Amperes or more.
1.) Pulse Excitation
An electric pulse of 1-ms pulse width or wider pulse width so that the one-sided positive excitation of the source arid one-sided negative excitation can be used as shown in
FIG. 1
a
. The first derivatives of these two pulses are the Gaussian functions as shown in
FIG. 1
b
. The second derivatives are the typical wave forms of one peak and one trough shown in
FIG. 1
c
. The Gaussian-function source in the form of (a/), ½ exp [-a(t-to)2], where the time is so chosen such that the function normalized by its peak value is nearly zero shown to
FIG. 2
a
the pulse width of which is defined as w=4 o where o=(
2
a
) ½ is the standard deviation of the Gaussian-pulse, which represents the decay time of the electric current; their amplitude spectrum is also a Gaussian which is in the form of exp(-2f2/a), where f is the frequency in Hz and fc is the cut-off-frequency as shown an
FIG. 2
b
is defined here as the frequency at which the amplitude has decayed to e-1 or 0.3679 times the peak value. All the derivative sources are continuous.
The return reflections at the depth of 3,000 m or deeper reach the surface by only the one-sided positive excitation and would be approximately 60 us or 30 us each way or longer, i.e., downward and upward of the pulse, before the one-sided negative pulse excites the source mechanism, which will be described in the sequel.
2.) Chirping or Sweeping Source:
Another source excitation can be easily achieved by means of a chirping or sweeping frequencies. The sweeping- frequency source can be from the low to high frequency or from the high to the low frequency. The near-vertical reflections from the depth can be processed by means of correlation techniques.
Frequency range would be from 0.10 to 100 mHz, corresponding to the wavelength fox a high-end average limestone velocity of 100 m/us from 1,000 m to 1 m. Despite the radio LF frequency, the high contrast of the impedance at the oil/salt water interface would produce a strong reflection.
Apparatus
Now the invention of the apparatus of the source and receiver is described in the following;
1.) The Source Apparatus
The source apparatus consists of an electromagnetic pulse, impulsive or chirping, generated multi-turn coil, which would in turn generate magnetic field the capacity to produce the power, in turn, the field will be directed by a parabolic directional reflector into the earth as shown in FIG.
3
. The source multi-turn-coil/parabolic-reflector does not need to be limited to only single one source but it could be a multi-source consisting of a number of multi-turn-coil/parabolic-reflectors which could be steered to give a boon-forming synchronization.
A current is introduced to the mild-turn coil, where the terminal of the incoming current is designated as positive and the terminal of the outgoing current is designated as the negative, there is an applied voltage across these two terminals. For the present application, the voltage will be about 1,000 volts or more and the current be between 10 to 100 Amperes or more to provide adequate power for electromagnetic wave propagation into a greater depth in the earth. The present source is geometrically symmetrical with respect to the center of the well and the vortex of the parabolic reflector.
2.) The Receiver Apparatus
The receiver apparatus consists of a multi-channel data acquisition system. Each channel is equipped by a directional impedance-matched antenna, which is capable of receiving wide-band electromagnetic signals. Receivers are formed in a variety of patterns with respect to the location of the source(s), namely a linear or areal coverage, or a radial coverage.
The number of channels depends on the subsurface coverage for the electromagnetic imagery. Normally, at least a 48 or 96 channels are required for such an electron wave reflection prospecting for oil directly.
SUMMARY OF THE INVENTION
The present invention fundamentally differs from any prior-art patents to be cited below owing to the fact that I discovered first the fact that the propagating part of the electromagnetic wave primarily depends on the electric permittivity of the medium which for the oil is extremely low. The interface between the geological formation including sedimentary rocks, namely, sandstone, shale, limestone, and any other rocks as a upper medium, and the sedimentary rocks containing oil as a lower medium provides strong reflection and refraction of electromagnetic waves. Upon this discovery, I then searched
Hughes Robert B.
Hughes & Schacht, PLLC
Profile Technologies, Inc.
Snow Walter
LandOfFree
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