Downhole seismic sensing synchronization systems and methods

Patent metadata

Field	Value
Publication number	US-10935682-B2
Application number	US-201715712546-A
Country	US
Kind code	B2
Filing date	Sep 22, 2017
Priority date	Oct 3, 2016
Publication date	Mar 2, 2021
Grant date	Mar 2, 2021

Abstract

A seismic system that includes a seismic source configured to generate a first seismic signal and a second seismic signal in a formation adjacent the seismic source. A first downhole sensing device disposed in a first borehole configured to detect the first seismic signal and the second seismic signal in the formation; and a first surface acquisition system is in communication with the first downhole sensing device. The first surface acquisition system is configured to: determine a first reference transit time based at least in part on detection of the first seismic signal by the first downhole sensing device; a first subsequent transit time based at least in part on detection of the second seismic signal by the first downhole sensing device; and
whether a synchronization variation is expected to be present based at least in part on the first reference transit time and the first subsequent transit time.

First claim

What is claimed is:

1. A seismic system, comprising:
a seismic source configured to generate a first seismic signal and a second seismic signal in a formation adjacent the seismic source;
a first downhole sensing device disposed in a first borehole configured to detect the first seismic signal and the second seismic signal in the formation; and
a first surface acquisition system in communication with the first downhole sensing device, wherein the first surface acquisition system is configured to:
determine a first reference transit time based at least in part on detection of the first seismic signal by the first downhole sensing device;
determine a first subsequent transit time based at least in part on detection of the second seismic signal by the first downhole sensing device; and
determine whether a synchronization variation is expected to be present based at least in part on the first reference transit time and the first subsequent transit time;
wherein the seismic system is configured to determine whether an anticipated synchronization variation is occurring at the surface, downhole, or both, via one or more processors based on time-stamping the first and second seismic signals in the first surface acquisition system and in the first downhole sensing device.

2. The seismic system of claim 1 , wherein the first surface acquisition system is further configured to define a threshold synchronization variation, and wherein the expectation of the presence of the synchronization variation is determined based at least in part on whether a difference between the first reference transit time and the first subsequent transit time is greater than the threshold synchronization variation.

3. The seismic system of claim 2 , wherein the threshold synchronization variation is dynamically adjusted to account for sensor error.

4. The seismic system of claim 2 , wherein the threshold synchronization variation is dynamically adjusted to improve synchronization relative to the threshold synchronization variation.

5. The seismic system of claim 1 , wherein to determine whether an anticipated synchronization variation is occurring is further based on the first surface acquisition system time-stamping an absolute transmission time of the first reference transit time.

6. The seismic system of claim 1 , further comprising:
a second downhole sensing device disposed in a second borehole different from the first borehole, wherein the second downhole sensing device is configured to detect the first seismic signal and the second seismic signal in the formation; and
a second surface acquisition system in communication with the second downhole sensing device, wherein the second surface acquisition system is configured to:
determine a second reference transit time based at least in part on detection of the first seismic signal by the second downhole sensing device;
determine a second subsequent transit time based at least in part on detection of the second seismic signal by the second downhole sensing device; and
determine whether the synchronization variation is expected to be present based at least in part on the second reference transit time and the second subsequent transit time.

7. A method of performing a seismic operation, comprising:
generating a first seismic signal and a second seismic signal in a formation adjacent a seismic source;
detecting the first seismic signal and the second seismic signal in the formation with a first downhole sensing device, the first downhole sensing device in communication with a first surface acquisition system;
determining a first reference transit time based at least in part on detection of the first seismic signal;
determining a first subsequent transit time based at least in part on detection of the second seismic signal;
determining whether a synchronization variation is expected to be present based at least in part on the first reference transit time and the first subsequent transit time; and
determining whether an anticipated synchronization variation is occurring at the surface, downhole, or both, via one or more processors based on time-stamping the first and second seismic signals in the first surface acquisition system and in the first downhole sensing device.

8. The method of claim 7 , further comprising defining a threshold synchronization variation, wherein the expectation of the presence of the synchronization variation is determined based at least in part on whether a difference between the first reference transit time and the first subsequent transit time is greater than the threshold synchronization variation.

9. The method of claim 8 , wherein the threshold synchronization variation is dynamically adjusted to account for sensor error.

10. The method of claim 8 , wherein the threshold synchronization variation is dynamically adjusted to improve synchronization relative to the threshold synchronization variation.

11. The method of claim 7 , wherein determining whether an anticipated synchronization variation is occurring is further based on time-stamping an absolute transmission time of the first reference transit time.

Assignees

• Schlumberger Technology Corp

Inventors

• Underhill William Brian
• Le Calvez Joel Herve
• Denaclara Herve

Classifications

• G01V1/26 Primary

  Reference-signal-transmitting devices, e.g. indicating moment of firing of shot · CPC title

• G01V1/40 Primary

  specially adapted for well-logging · CPC title

• G01V2210/1429

  Subsurface, e.g. in borehole or below weathering layer or mud line · CPC title

• G01V1/301

  for determining seismic cross-sections or geostructures · CPC title

• G01V2210/1295

  Land surface · CPC title