A methodology for 7D warping and deformation monitoring using time-lapse seismic data

Abstract

A methodology is presented for vector analysis of the image displacements ͑warping͒ between successive 3D seismic image volumes that provides 7D analysis ͑including lateral and vertical displacements͒ of in situ subsurface deformation around hydrocarbon reservoirs. The key challenges are ͑1͒ assessment of just vertical shifts is insufficient, and vector displacements should be determined; ͑2͒ robust vertical displacements can usually be derived, but lateral shifts are less well defined because of the generally smooth data character in a horizontal/horizon plane; ͑3͒ subvoxel resolution is necessary for correct matching and deformation analysis; ͑4͒ velocity and strain effects are intrinsically combined in timelapse seismic images; ͑5͒ separation of accumulated and local effects is necessary; ͑6͒ apparently coherent and smooth displacement fields do not necessarily provide good strain analysis; ͑7͒ warping is easily degraded by noise, and good cross-matching is a prerequisite. To address these challenges, a full 3D, local warp vector derivation methodology is proposed, which involves ͑1͒ constraint using prior estimates, ͑2͒ local refinement with subvoxel resolution, and ͑3͒ 3D and vectorial conditioning using a deformable mesh with sensitivity to image-match quality. The warping approach is extended to separate accumulated from local effects and to analyze in situ deformation based on the displacement vector volume. This is achieved by a finite-element approach to determine an elemental pseudostrain tensor field and an iterative procedure to separate the pseudostrain into velocity and strain components. The approach up to the strain analysis, is demonstrated using a real data example, which indicates the potential of the methodology ͑accumulated overburden effects are separated to reveal a local compaction signature in the reservoir͒, but realistic, quantitative values of strain have not yet been realized.

Soil deformation around a penetrating cone in silt

“…TomoWarp calculates the strains from the derived displacements under continuum assumptions. Further details regarding the calculation procedure are given by Hall (2006).…”

“…(e 1 is the major, e 2 the intermediate and e 3 the minor principal strain) was derived using the 3D-DIC code TomoWarp (Hall, 2006;Hall et al, 2010). TomoWarp calculates the strains from the derived displacements under continuum assumptions.…”

Reservoir monitoring and characterization using satellite geodetic data: Interferometric synthetic aperture radar observations from the Krechba field, Algeria

“…These studies utilized geodetic data, such as leveling measurements, in order to quantify surface deformation related to fluid production or injection. Currently, time-lapse seismic surveys are providing additional deformation measurements, distributed throughout the overburden (Guilbot and Smith 2002, Landro and Stammeijer 2004, Tura et al 2005, Hatchell and Bourne 2005, Barkved and Kristiansen 2005, Hall 2006, Roste et al 2006, Rickett et al 2007, Staples et al 2007). Recently, the observed deformation has been used to better understand fluid flow and the heterogeneity of flow properties within the reservoir (Vasco et al 2000a, Vasco et al 2001, Du et al 2005, Vasco and Ferretti 2005, Hodgson et al 2007, Vasco et al 2008.…”

Estimating permeability from quasi-static deformation: Temporal variations and arrival-time inversion

“…InSAR observations may be used to image fluid-induced deformation over regions tens to hundreds of square kilometers in extent (Fielding et al 1998, Galloway et al 1998, Amelung et al 1999, Hoffmann et al 2001, Schmidt and Burgmann 2003, Colesanti et al 2003, Vasco and Ferretti 2005. Second, recent developments in the processing of time-lapse seismic data allow for estimates of deformation in the overburden and within the reservoir (Guilbot and Smith 2002, Landro and Stammeijer 2004, Tura et al 2005, Hatchell and Bourne 2005, Barkved and Kristiansen 2005, Hall 2006, Roste et al 2006, Staples et al 2007, Hawkins et al 2007). Such estimates offer high resolution, three-dimensional sampling of deformation over a producing reservoir.…”