1. A method for mapping the open fractures in a subsurface formation using two compressional seismic waves (signals) transmitted from the surface into the subsurface formations and recording the reflected signals from the formation boundaries by using multiple receivers located on the surface, the receivers laid out in a pattern to provide three dimensional (3-D) seismic coverage; the 3-D seismic coverage designed to provide a predetermined range of sourcereceiver offset distances and azimuthal angle distribution. One of the transmitted signals is a swept frequency seismic signal and the other a mono-frequency seismic signal, both signals transmitted from the same surface location. Both the seismic signals are synchronized with each other and have the same start-up time and the duration of transmission period. The frequencies of both signals are pre-selected.
2. The method in claim 1 further comprising:
Recording the 3-D seismic data, with both the surface sources transmitting their signals simultaneously, in a manner that the recorded data will provide adequate and required subsurface coverage of the particular subsurface formation that is to be mapped for open fractures, data recorded using the two surface vibratory sources that transmit the swept frequency and the mono-frequency signals, both sources moving together in a source pattern that is designed to provide the necessary subsurface coverage of the fractured formation to be mapped.
3. The method in claim 1 further comprising:
Since there are two sets of data that have been superimposed due to two seismic sources transmitting two different seismic signals simultaneously, separating one set of data by cross-correlating the recorded data with the swept frequency signal, and using this cross-correlated data for conventional and standard 3-D seismic reflection processing.
4. The method in claim 1 further comprising:
Synthetically computer generating two additional swept frequency signals, one swept frequency signal by the frequency addition of the mono-frequency signal to the swept frequency signal, and the second swept signal generated by the frequency subtraction of the mono-frequency signal from the swept frequency signal, and cross-correlating the recorded data with these two synthetically generated sweep signals, in this manner generating two additional sets of cross-correlated seismic reflection data that have new frequenciesnot transmitted from the surface, but generated when the transmitted seismic signals nonlinearly interact with each other as they intersect the fractures at right angles. There will be no nonlinear interaction and no new frequencies will be generated when the two transmitted signals do not intersect the fractures, either due to the absence of the fractures or due to their propagation in the same plane as the fractures so the transmission path is parallel to the fractures.
5. The method in claim 1 further comprising:
The said cross-correlated data generated using synthetic sweeps analyzed to detect the fractures’ location and orientation, this cross-correlated data represents and consists of the full volume of 3-D seismic information that has a full range of sourcereceiver offset distances and sourcereceiver azimuthal angle distribution, this data to be sorted according to different sourcereceiver azimuthal angles, so that it is sliced as two dimensional (2-D) seismic lines, each representing a particular sourcereceiver azimuthal angle, these 2-D seismic lines processed for subsurface reflection imaging, using processing parameters that have been established by processing the standard 3-D data set that was created by cross-correlating with the swept signal that was transmitted from the surface source.
6. The method in claim 1 further comprising:
Identifying the sourcereceiver azimuthal angle that provides the most coherent reflected image of the fractured subsurface formation in the processed results of the 2-D seismic lines that have been sliced according to different azimuthal angles, this sourcereceiver azimuthal angle intersects the fractures at right angles, use this azimuthal angle information to determine the orientation of the open fractures, further confirm the results by analysis of the reflection image of the fractured formation at the sourcereceiver azimuthal angle that is parallel to the fractures, there should be no reflection image of the said formation, the location of the open fractures is defined by the reflection image of the said fractured formation, the presence of the reflected image indicates the presence of fractures, and the common mid-point of the imaged reflection identifies the subsurface location.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A current limiting system for current control of light fixtures comprising:
a light source;
a sensor adapted to sense the electrical current flow passing to said light source and to communicate an input signal associated with the sensed current flow;
a variable switch adapted to regulate the current flow to said light source; and
a controller in communication with said sensor and said variable switch, said controller being adapted to monitor said input signal from said sensor and being adapted to compare said input signal to a predetermined current value, said controller actuates said variable switch to reduce the current passing to said light source upon said input signal associated with the sensed current exceeding said predetermined current value.
2. The system of claim 1, wherein the controller is further structured to be in communication with and at least partially operated via a remote control.
3. The system of claim 1 wherein the variable switch comprises at least one of a triac, a diode, or a semi-conducting switch device.
4. A method of limiting current to a light fixture comprising the steps of:
(A) providing a light source;
(B) providing a sensor adapted to sense the electrical current passing to the light source and to communicate an input signal associated with the sensed current flow;
(C) providing a variable switch adapted to regulate the current flow to said light source; and
(D) providing a controller in communication with the sensor and the variable switch;
(E) monitoring the input signal from the sensor with the controller and comparing the input signal to a predetermined current value, and
(F) actuating the variable switch to reduce the current passing to the light source upon the input signal associated with the sensed current exceeding the predetermined current value.
5. The method of claim 4 wherein the controller is further structured to be in communication with and at least partially operated via a remote control.
6. The method of claim 4 wherein the variable switch comprises at least one of a triac, a diode, or a semi-conducting switch device.