Seismic data imaging system

• US 5,991,235 A
• Filed: 01/29/1997
• Issued: 11/23/1999
• Est. Priority Date: 01/29/1996
• Status: Expired due to Fees

• Current Assignee: Subsurface Exploration Company
• Original Assignee: Subsurface Exploration Company
• Inventors: Allen, Samuel J.
• Primary Examiner(s): Oda, Christine K
• Assistant Examiner(s): JOLLY, ANTHONY S
• Application Number:
  US08/792,684
• Time in Patent Office: 1,028 Days
• Field of Search: 340/15.5, 367/13, 367/21, 367/38, 367/41, 367/40, 181/113, 181/114, 181/119
• US Class Current: 367/40
• CPC Class Codes: G01V 1/005 with exploration systems emitting special signals, e.g. frequency swept signals, pulse sequences or slip sweep arrangements

Abstract

A system for seismic prospecting by using reflections of acoustic waves and an operation method thereof. Unprocessed raw data from a plurality geophone sensors and other processed data are stored in a storage unit further processing and analysis. The preferred operation comprises four stages, performing test sweeps no and analyzing results thereof (testing stage), determination of control parameters for the spatial distribution of sensor array and data-collection sweeps based on the analysis of test sweeps (parameter-determination stage), performing data-collection sweeps (data collecting stage), and analysis and processing of the data-collection sweeps (data processing stage). Test sweeps and availability of unprocessed raw data allow optimization of the system to achieve maximal resolution and signal-to-noise ratios.

Claims

1. A method of seismic prospecting a region using seismic waves and a plurality of sensors, comprising:

distributing multiple seismic sensors in the region under survey relative to one another in a predetermined test pattern around one or more source points where seismic waves are generated, wherein at least a portion of the seismic sensors are located near the surface of the region, and a spread and spacing of the predetermined test pattern being determined based on prior seismic data of the region;

performing a plurality of test sweeps in said region by generating testing seismic waves of different sweep frequency ranges that have test parameters selected based on the prior seismic data;

obtaining test seismic data from said test sweeps by collecting signals from the multiple seismic sensors;

producing correlation signals from collected signals obtained from the seismic sensors corresponding to each testing seismic wave and a respective reference signal;

summing the correlation signals based on collected signals of each seismic sensor corresponding to different testing seismic waves to produce a testing composite correlation signal;

determining a data-acquisition operating condition of the region based on analysis of said testing composite correlation signals from the seismic sensors in order to enhance resolution and signal-to-noise ratio, wherein said data-acquisition operation condition is determined by at least selecting parameters for a set of seismic probe waves to be launched or changing said predetermined test pattern of the seismic sensors to a data-acquisition pattern with different spread and spacing of the seismic sensors;

performing a plurality of data-acquisition sweeps under said data-acquisition operating condition in said region by generating said set of seismic probe waves;

saving unprocessed raw data generated from said sensors from said data-acquisition sweeps;

processing said raw data by at least one selected correlation operation to produce a global seismic map of said region; and

selecting and further processing a subset of unprocessed data from the saved raw data to provide seismic information of a location in said global seismic map that is not revealed by said global seismic map.

2. A method as in claim 1, further comprising determining the source point locations for initiating said test sweeps, and testing spatial distribution of said sensors.

3. A method as in claim 1, wherein said data-acquisition operating condition further comprises source point locations for initiating said data-acquisition sweeps.

4. A method as in claim 1, wherein said sensors have a varying spatial spacing between two adjacent sensors at different locations in said data-acquisition pattern of the multiple seismic sensors.

5. A method as in claim 1, wherein said global seismic map is generated by

producing correlation signals from the raw data obtained from the seismic sensors corresponding to each data-acquisition seismic wave;

then summing the correlation signals for each seismic sensor corresponding to different data-acquisition seismic waves to produce a composite correlation signal; and

producing the global seismic map based on the composite correlation signals.

6. A method as in claim 1, wherein said global seismic map is generated by

producing a summation signal by summing signals from the raw data obtained from the seismic sensors corresponding to each data-acquisition seismic wave;

then correlating different summation signals for different seismic sensors corresponding to different data-acquisition seismic waves with different reference signals to produce different correlation signals; and

producing the global seismic map based on the different correlation signals.

7. A method as in claim 1, wherein said subset of unprocessed data from the saved raw data includes raw data points from one or more selected seismic sensors at a selected location within the region.

8. A method as in claim 1, wherein said subset of unprocessed data from the saved raw data includes raw data points at a specified frequency range obtained from at least one seismic sensor.

9. A method as in claim 1, wherein said subset of unprocessed data from the saved raw data includes raw data points obtained from at least one seismic sensor with signal amplitudes within a specified amplitude range.

10. A method as in claim 1, wherein said at least a portion of the seismic sensors are distributed at different depths under the surface of the region so as to produce a three-dimensional seismic map.