Utilizing the onset of time-lapse changes: a robust basis for reservoir monitoring and characterization

Vasco, D. W.; Daley, Thomas M.; Bakulin, Andrey

doi:10.1093/gji/ggt526

Cited by 32 publications

(31 citation statements)

References 79 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We then present a brief outline of an iterative algorithm for estimating permeability given a collection of onset times. The general approach is similar to the inversion technique described in Vasco et al (2014). Therefore, we will abbreviate the initial discussion somewhat and focus on the application to the inversion of time-lapse amplitude changes.…”

Section: Methodsmentioning

confidence: 99%

“…We are assuming that the fluid viscosity μ n is constant and that the relative permeability function k rn ðS n Þ is known for the reservoir under study. As noted by Vasco et al (2004Vasco et al ( , 2014, the vector U n harbors an implicit dependence upon the flow properties. It is shown by Vasco et al (2004) that, as long as the pressure fields are recalculated for each iteration of the inversion algorithm given below, the implicit dependence may be neglected.…”

Section: Characterization Based On Onset Times M3mentioning

confidence: 99%

“…As we recompute U n at each iteration of our inversion algorithm, we neglect the effect of its perturbation upon the propagation time. As shown by Vasco et al (2014), under these restrictions, one may relate perturbations in τ to perturbations in the permeability via the integral…”

Section: Characterization Based On Onset Times M3mentioning

confidence: 99%

“…For example, one may take the time at which the observable quantity deviates from its background value in a statistically significant manner. Alternatively, as in Vasco et al (2014), one may define the onset time as the time at which the change in a quantity exceeds a preset percentage of the total change of the observed quantity. Here, we define the onset time as the calendar time at which the rate of change of the observed quantity is the greatest.…”

Section: M6mentioning

confidence: 99%

“…Our approach, based upon onset times, follows a recent generalization of techniques developed for the interpretation of geodetic data as described in Vasco et al (2014). In that paper, onset times were introduced in the context of seismic first-arrival times and crosswell imaging.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Reservoir characterization based upon the onset of time-lapse amplitude changes

et al. 2015

Self Cite

View full text Add to dashboard Cite

Time-lapse geophysical monitoring has potential as a tool for reservoir characterization, that is, for determining reservoir properties such as permeability. Onset times, the calendar times at which geophysical observations begin to deviate from their initial or background values, provide a useful basis for such characterization. We found that, in contrast to time-lapse amplitude changes, onset times were not sensitive to the exact method used to related changes in fluid saturation to changes in seismic velocities. As a consequence of this, we found that an inversion for effective permeability based upon onset times was robust with respect to variations in the rock-physics model. In particular, inversions of synthetic onset times calculated using Voigt and Reuss averaging techniques, but inverted using sensitivities from Hill's averaging method, resulted in almost identical misfit reductions and similar permeability models. All solutions based on onset times recovered the large-scale, resolvable features of the reference model. Synthetic tests indicated that reliable onset times can be obtained from noisy seismic amplitudes. Testing also indicated that large-scale permeability variations can be recovered even if we used onset times from seismic surveys that were spaced as much as 300 days apart.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Characterization Based On Onset Times M3mentioning

confidence: 99%

Section: Characterization Based On Onset Times M3mentioning

confidence: 99%

Section: M6mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Reservoir characterization based upon the onset of time-lapse amplitude changes

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

Trajectory‐based modeling of fluid transport in a medium with smoothly varying heterogeneity

Vasco

Pride

Commer

2016

Water Resources Research

Self Cite

View full text Add to dashboard Cite

Using an asymptotic methodology, valid in the presence of smoothly varying heterogeneity and prescribed boundaries, we derive a trajectory-based solution for tracer transport. The analysis produces a Hamilton-Jacobi partial differential equation for the phase of the propagating tracer front. The trajectories follow from the characteristic equations that are equivalent to the Hamilton-Jacobi equation. The paths are determined by the fluid velocity field, the total porosity, and the dispersion tensor. Due to their dependence upon the local hydrodynamic dispersion, they differ from conventional streamlines. This difference is borne out in numerical calculations for both uniform and dipole flow fields. In an application to the computational X-ray imaging of a saline tracer test, we illustrate that the trajectories may serve as the basis for a form of tracer tomography. In particular, we use the onset time of a change in attenuation for each volume element of the X-ray image as a measure of the arrival time of the saline tracer. The arrival times are used to image the spatial variation of the effective hydraulic conductivity within the laboratory sample.

show abstract

An Extended Trajectory Mechanics Approach for Calculating the Path of a Pressure Transient: Derivation and Illustration

Vasco

2018

Water Resources Research

Self Cite

View full text Add to dashboard Cite

Following an approach used in quantum dynamics, an exponential representation of the hydraulic head transforms the diffusion equation governing pressure propagation into an equivalent set of ordinary differential equations. Using a reservoir simulator to determine one set of dependent variables leaves a reduced set of equations for the path of a pressure transient. Unlike the current approach for computing the path of a transient, based on a high‐frequency asymptotic solution, the trajectories resulting from this new formulation are valid for arbitrary spatial variations in aquifer properties. For a medium containing interfaces and layers with sharp boundaries, the trajectory mechanics approach produces paths that are compatible with travel time fields produced by a numerical simulator, while the asymptotic solution produces paths that bend too strongly into high permeability regions. The breakdown of the conventional asymptotic solution, due to the presence of sharp boundaries, has implications for model parameter sensitivity calculations and the solution of the inverse problem. For example, near an abrupt boundary, trajectories based on the asymptotic approach deviate significantly from regions of high sensitivity observed in numerical computations. In contrast, paths based on the new trajectory mechanics approach coincide with regions of maximum sensitivity to permeability changes.

show abstract

Utilizing the onset of time-lapse changes: a robust basis for reservoir monitoring and characterization

Cited by 32 publications

References 79 publications

Reservoir characterization based upon the onset of time-lapse amplitude changes

Reservoir characterization based upon the onset of time-lapse amplitude changes

Trajectory‐based modeling of fluid transport in a medium with smoothly varying heterogeneity

An Extended Trajectory Mechanics Approach for Calculating the Path of a Pressure Transient: Derivation and Illustration

Contact Info

Product

Resources

About