EP-4740046-A2 - CONSTRAINED SIMULTANEOUS SOURCE SHOOTING

Abstract

System and techniques to fire a first source array at a first time of a first shot timing distribution comprising first time values according to a firing schedule and fire a second source array at a second time of a second shot timing distribution comprising second time values subsequent to firing the first source array and prior to another firing of the first source array according to the firing schedule. Additionally, at least a portion of the second shot timing distribution overlaps with the first shot timing distribution or the at least a portion of the second shot timing distribution is separated from the first shot timing distribution by less than a predetermined period of time and the first time and the second time of the firing schedule are separated by at least the predetermined period of time.

Inventors

• ETGEN, John Theodore
• FU, Kang

Assignees

• BP Corporation North America Inc.

Dates

Publication Date

20260513

Application Date

20240701

Claims (1)

1. CLAIMS What is claimed is: 1. A method, comprising: firing a first source array at a first time of a first shot timing distribution comprising first time values according to a firing schedule; and firing a second source array at a second time of a second shot timing distribution comprising second time values subsequent to firing the first source array and prior to another firing of the first source array according to the firing schedule, wherein at least a portion of the second shot timing distribution overlaps with the first shot timing distribution or the at least a portion of the second shot timing distribution is separated from the first shot timing distribution by less than a predetermined period of time, wherein the first time and the second time of the firing schedule are separated by at least the predetermined period of time. 2. The method of claim 1, comprising firing the first source array at a third time of the first shot timing distribution comprising the first time values subsequent to firing the second source array at the second time according to the firing schedule, wherein the third time and the second time of the firing schedule are separated by at least the predetermined period of time. 3. The method of claim 1, comprising firing a third source array at a third time of a third shot timing distribution comprising third time values subsequent to firing the second source array and prior to the another firing of the first source array according to the firing schedule, wherein at least a portion of the third shot timing distribution overlaps with the second shot timing distribution or the at least a portion of the third shot timing distribution is separated from the second shot timing distribution by less than the predetermined period of time, wherein the third time and the second time of the firing schedule are separated by at least the predetermined period of time. 4. The method of claim 3, wherein the first time, the second time, and the third time of the firing schedule comprise a constrained vector of timing values. 5. The method of claim 3, wherein the first shot timing distribution, the second shot timing distribution, and the third shot timing distribution share the same probability distribution function. 6. The method of claim 3, wherein the first shot timing distribution, the second shot timing distribution, and the third shot timing distribution share different probability distribution functions. 7. The method of claim 1, wherein the firing schedule is loaded into a controller of a vessel towing the first source array and the second source array prior to movement of the vessel along a shot line of a seismic acquisition. 8. The method of claim 1, wherein the firing schedule is calculated in conjunction with movement of a vessel along a shot line of a seismic acquisition. 9. The method of claim 8, comprising towing the first source array and the second source array behind the vessel. 10. The method of claim 1, comprising: positioning the first source array at a fixed first distance from a vessel towing the first source array and the second source array; and positioning the second source array at a fixed second distance from the vessel, wherein the fixed second distance differs from the fixed first distance. 11. The method of claim 10, comprising: utilizing a tether having a first length to position the first source array at the fixed first distance from the vessel; and utilizing a second tether having a second length to position the second source array at the fixed second distance from the vessel. 12. The method of claim 10, comprising altering a length of a tether coupled to the second source array to position the second source array at the fixed second distance from the vessel. 13. The method of claim 10, comprising altering a length of a tether coupled to a third source array to position the third source array at a fixed third distance from the vessel. 14. The method of claim 10, comprising: selecting a first group of seismic sources within the first source array that have a first offset distance from a center of the first source array along the shot line direction; and selecting a second group of seismic sources within the second source array that have a second offset distance from a center of the second source array along the shot line direction. 15. The method of claim 14, wherein the second offset distance from the center of the second source array is different from the first offset distance from the center of the first source array. 16. The method of claim 1, comprising: disposing the first source array comprising a plurality of seismic sources over a seismic survey region prior to firing the first source array; and disposing the second source array comprising a second plurality of seismic sources over the seismic survey region prior to firing the second source array. 17. A tangible and non-transitory machine readable medium, comprising instructions to: generate a first shot timing distribution comprising first time values to fire a first source array; generate second shot timing distribution comprising second time values to fire a second source array, wherein at least a portion of the second shot timing distribution overlaps with the first shot timing distribution or the at least a portion of the second shot timing distribution is separated from the first shot timing distribution by less than a predetermined period of time; generate a time adjustment series comprising a plurality of pairs of timing values selected from each of the first time values and the second time values; compare each pair of timing values of the plurality of pairs of timing values against a threshold value; and generate a finalized time adjustment series comprising selected pairs of timing values of the plurality of pairs of timing values that exceed the threshold value. 18. The tangible and non-transitory machine readable medium of claim 17, comprising instructions to delete any pairs of timing values of the plurality of pairs of timing values that are less than the threshold value or are less than or equal to the threshold value. 19. The tangible and non-transitory machine readable medium of claim 17, comprising instructions to modify any pairs of timing values of the plurality of pairs of timing values that are less than the threshold value or are less than or equal to the threshold value by adjusting at least one of a respective first time value of the first time values and a respective second time value of the second time values of each of the any pairs of timing values of the plurality of pairs of timing values to generate modified pairs of timing values. 20. The tangible and non-transitory machine readable medium of claim 19, comprising instructions to: compare the modified pairs of timing values against the threshold value; and generate the finalized time adjustment series as additionally comprising selected modified pairs of timing values of the modified pairs of timing values that exceed the threshold value. 21. The tangible and non-transitory machine readable medium of claim 17, comprising instructions to transmit the finalized time adjustment series as a firing schedule of a vessel corresponding to the first source array and the second source array. 22. A tangible and non-transitory machine readable medium, comprising instructions to: select timing values as a set of timing values together taken as a vector, wherein a number of timing values in the set of timing values corresponds to a number of seismic sources of a seismic acquisition; apply a predetermined constraint to the vector to determine whether the set of timing values meet or exceed a predetermined threshold; and generate a finalized time adjustment series comprising the vector when the set of timing values meet or exceed the predetermined threshold. 23. The tangible and non-transitory machine readable medium of claim 22, comprising instructions to apply the predetermined constraint to the vector by determining whether pairs of timing values of the set of timing values have a difference therebetween that meet or exceed the predetermined threshold as a predetermined amount of time. 24. The tangible and non-transitory machine readable medium of claim 22, comprising instructions to select second timing values as a second set of timing values together taken as a second vector; apply the predetermined constraint to the second vector to determine whether the second set of timing values meet or exceed the predetermined threshold; and generate the finalized time adjustment series as additionally comprising the second vector when the second set of timing values meet or exceed the predetermined threshold. 25. The tangible and non-transitory machine readable medium of claim 22, comprising instructions to delete the vector when the set of timing values are less than the predetermined threshold.

Description

CONSTRAINED SIMULTANEOUS SOURCE SHOOTING CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Patent Application No. 63/511,996 filed on July 5, 2023 and titled “Constrained Simultaneous Source Shooting,” which is hereby incorporated herein by reference in its entirety for all purposes. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not applicable. BACKGROUND [0003] The present disclosure relates generally to seismic data acquisition, and more specifically, to simultaneous source shooting techniques to increase the separability of overlapping shots. [0004] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. [0005] A seismic survey includes generating an image or map of a subsurface region of the Earth by sending acoustic energy down into the ground and recording the reflected acoustic energy that returns from the geological layers within the subsurface region. During a seismic survey, an energy source is placed at various locations on or above the surface region of the Earth, which may include hydrocarbon deposits. Each time the source is activated, the source generates a seismic (e.g., acoustic wave) signal that travels downward through the Earth, is reflected, and, upon its return, is recorded using one or more receivers disposed on or above the subsurface region of the Earth. The seismic data recorded by the receivers may be used to create an image or profile of the corresponding subsurface region. [0006] Seismic data acquisition can be a time consuming and expensive process. One technique to reduce the time and cost required to acquire seismic data is the use of two or more sources that are fired close in time to one another (i.e., multiple sources are sequentially activated during a single recording period). However, while this technique may decrease the amount of time and cost associated with seismic acquisition, the resultant seismic data may include noise. One example of this noise is blending noise, which refers to signals received during data collection periods that interfere with a current data collection period and may be read as noise (e.g., weak- coherence energy or signal) despite being part of a primary signal (e.g., coherent energy or signal) for a subsequent input data (e.g., input seismic data) collection period corresponding to another source activation. It may be desired to develop and/or improve techniques associated with seismic acquisition that increase the incoherency of the resultant noise generated from the firing of two or more sources during a data collection period such that the resultant noise may be separated effectively by data processing. SUMMARY [0007] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. [0008] Seismic acquisition utilizing sources and receivers may be useful in the generation of, for example, seismic images. Seismic images may be used, for example, in the determination of hydrocarbon deposits (e.g., areas within a subsurface that contain hydrocarbons) and/or subsurface drilling hazards. Seismic images are generally produced using seismic waveforms produced by a source, reflected off regions within a subsurface, and received by one or more receivers. However, noise associated with the seismic acquisition can render portions of the gathered data unusable. [0009] Accordingly, present techniques include towing multiple source arrays to increase data density and/or reduce operation run time and cost. Additionally, present techniques allow for the increase of the number of sampling of source positions. Additionally, present techniques address some of the limits to increasing the number of sampling of source positions in a seismic survey that would otherwise be capped, for example, due to interference between samples. One technique to alleviate and/or eliminate overlap in reflected wave reception with subsequent shot firing times includes adjusting the timing of shot timings to include adjusted (e.g., dithered) by, for example, a random amount of time. Moreover, the present techniques include determination of the adjusted shot timings so that they do not conflict with one another. In this manner, sequential shots that have been adjusted will