Well-to-well tomography

• US 7,046,581 B2
• Filed: 11/24/2004
• Issued: 05/16/2006
• Est. Priority Date: 12/01/2003
• Status: Active Grant

• Current Assignee: Shell USA Incorporated (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Calvert, Rodney William
• Primary Examiner(s): Keith, Jack
• Assistant Examiner(s): Hughes, Scott A.
• Application Number:
  US10/997,205
• Publication Number:
  US 20050117452A1
• Time in Patent Office: 538 Days
• Field of Search: 367/38, 367/56, 367/57, 367/73
• US Class Current: 367/57
• CPC Class Codes: G01V 1/42 using generators in one well and receivers elsewhere or vice versa G01V1/52 takes precedence

Abstract

A method of obtaining a spatial model of a property of part of a subsurface formation located between underground seismic receivers in which at least two sets of pairs of seismic receivers are utilized and one pair of receivers is used to record a signal from a seimic source and obtaining a response by solving (s₁₁(−t){circle around (x)}s₂₁(t))=r_11,21(t){circle around (x)}(s₁₁(−t){circle around (x)}s21(t)), wherein the symbol {circle around (x)} denotes convolution and wherein s₁₁(−t) is the time-reverse of the signal s₁₁(t). A path-related attribute is selected from transmission response r_11,21(t) that corresponds to the property of the subsurface formation and a tomographic reconstruction technique is applied to the path-related attribute to obtain the spatial model of the property of part of the subsurface formation.

Claims

1. A method of obtaining a spatial model of a property of part of a subsurface formation located between underground spaced-apart seismic receivers, said method comprising the steps of:

(a) positioning in a borehole a first set of seismic receivers and positioning in a borehole a second set of seismic receivers;

(b) selecting at least one pair of seismic receivers, wherein each pair of seismic receivers consists of a seismic receiver i of the first set and a seismic receiver j of the second set;

(c) recording for the pair(s) of seismic receivers i and j signals s_i(t) and s_j(t) obtained from a seismic source;

(d) obtaining for each of the pair(s) a transmission response r_ij(t) of the formation between the two seismic receivers of the pair by solving (s_i(−

t){circle around (x)}s_j(t))=r_ij(t){circle around (x)}(s_i(−

t){circle around (x)}s_i(t)), wherein the symbol {circle around (x)} denotes convolution and wherein s_i(−

t) is the time-reverse of the signal s_i(t);

(e) selecting a path-related attribute of the transmission response r_ij(t) that corresponds to the property of the subsurface formation; and

(f) applying a tomographic reconstruction technique to the path-related attribute of the transmission response(s) r_ij(t) to obtain the spatial model of the property of part of the subsurface formation.

2. The method according to claim 1, wherein the first set of seismic receivers i is arranged in a first borehole and the second set of seismic receivers j is arranged in a second borehole, spaced apart from the first borehole.