scholarly journals Modeling offset‐dependent reflectivity for time‐lapse monitoring of water‐flood production in thin‐layered reservoirs

Geophysics ◽  
2004 ◽  
Vol 69 (1) ◽  
pp. 25-36 ◽  
Author(s):  
Shelley J. Ellison ◽  
Matthias G. Imhof ◽  
Cahit Çoruh ◽  
Alan D. Fuqua ◽  
Stephen C. Henry
Keyword(s):  
Synthetic Data ◽  
Time Lapse ◽  
Amplitude Variation With Offset ◽  
Seismic Amplitude ◽  
Amplitude Correction ◽  
Full Waveform ◽  
Wireline Logs ◽  
Oil Gas

The objective of this case study is to predict whether 5 years of water‐flood production from a thinly layered Gulf of Mexico reservoir will change its seismic amplitude‐variation‐with‐offset (AVO) response in a detectable manner. Density and velocity profiles were computed from in situ wireline logs for 100% oil, gas, and brine saturations and for a 5‐year prediction that was based on a fluid‐flow and production simulation. Analytical AVO curves for simple half‐space models did not match AVO curves extracted from synthetic seismograms computed with a full‐waveform layer‐stack algorithm. Several different amplitude corrections were tried to reduce the AVO curves from the synthetic data to the analytical ones, but, ultimately, none was deemed satisfactory. Instead, AVO change attributes based on relative changes, polarity changes, or ratios were used. Attributes based on the change of AVO gradient were perceived to be most diagnostic of the water flood, but they were also overly sensitive to interference noise and amplitude correction errors. For field data from the study area, a large decrease in intercept magnitude may be the best indicator of the waterfront.

Time-lapse full waveform inversion based on curvelet transform: Case study of CO2 storage monitoring

2021 ◽  
Vol 110 ◽  
pp. 103417
Author(s):  
Dong Li ◽  
Suping Peng ◽  
Xingguo Huang ◽  
Yinling Guo ◽  
Yongxu Lu ◽  
...  
Keyword(s):  
Co2 Storage ◽  
Waveform Inversion ◽  
Curvelet Transform ◽  
Time Lapse ◽  
Full Waveform Inversion ◽  
Full Waveform

Estimating saturation and density changes caused by CO2 injection at Sleipner — Using time-lapse seismic amplitude-variation-with-offset and time-lapse gravity

2017 ◽  
Vol 5 (2) ◽  
pp. T243-T257 ◽  
Author(s):  
Martin Landrø ◽  
Mark Zumberge
Keyword(s):  
Gravity Data ◽  
Time Lapse ◽  
Co2 Injection ◽  
Injection Point ◽  
Amplitude Variation With Offset ◽  
Seismic Method ◽  
Seismic Amplitude ◽  
Gravity Measurements ◽  
Measured Time ◽  
Best Fit

We have developed a calibrated, simple time-lapse seismic method for estimating saturation changes from the [Formula: see text]-storage project at Sleipner offshore Norway. This seismic method works well to map changes when [Formula: see text] is migrating laterally away from the injection point. However, it is challenging to detect changes occurring below [Formula: see text] layers that have already been charged by some [Formula: see text]. Not only is this partly caused by the seismic shadow effects, but also by the fact that the velocity sensitivity for [Formula: see text] change in saturation from 0.3 to 1.0 is significantly less than saturation changes from zero to 0.3. To circumvent the seismic shadow zone problem, we combine the time-lapse seismic method with time-lapse gravity measurements. This is done by a simple forward modeling of gravity changes based on the seismically derived saturation changes, letting these saturation changes be scaled by an arbitrary constant and then by minimizing the least-squares error to obtain the best fit between the scaled saturation changes and the measured time-lapse gravity data. In this way, we are able to exploit the complementary properties of time-lapse seismic and gravity data.

Discrimination between pressure and fluid saturation changes from marine multicomponent time‐lapse seismic data

Geophysics ◽  
2003 ◽  
Vol 68 (5) ◽  
pp. 1592-1599 ◽  
Author(s):  
Martin Landrø ◽  
Helene Hafslund Veire ◽  
Kenneth Duffaut ◽  
Nazih Najjar
Keyword(s):  
Pore Pressure ◽  
Seismic Data ◽  
Water Saturation ◽  
Synthetic Data ◽  
Time Lapse ◽  
Seismic Survey ◽  
Data Sets ◽  
Amplitude Variation With Offset ◽  
Fluid Saturation ◽  
Pressure Changes

Explicit expressions for computation of saturation and pressure‐related changes from marine multicomponent time‐lapse seismic data are presented. Necessary input is PP and PS stacked data for the baseline seismic survey and the repeat survey. Compared to earlier methods based on PP data only, this method is expected to be more robust since two independent measurements are used in the computation. Due to a lack of real marine multicomponent time‐lapse seismic data sets, the methodology is tested on synthetic data sets, illustrating strengths and weaknesses of the proposed technique. Testing ten scenarios for various changes in pore pressure and fluid saturation, we find that it is more robust for most cases to use the proposed 4D PP/PS technique instead of a 4D PP amplitude variation with offset (AVO) technique. The fit between estimated and “real” changes in water saturation and pore pressure were good for most cases. On the average, we find that the deviation in estimated saturation changes is 8% and 0.3 MPa for the estimated pore pressure changes. For PP AVO, we find that the corresponding average errors are 9% and 1.0 MPa. In the present method, only 4D PP and PS amplitude changes are used in the calculations. It is straightforward to include use of 4D traveltime shifts in the algorithm and, if reliable time shifts can be measured, this will most likely further stabilize the presented method.

scholarly journals AVO as a fluid indicator: A physical modeling study

Geophysics ◽  
2007 ◽  
Vol 72 (1) ◽  
pp. C9-C17 ◽  
Author(s):  
Aaron Wandler ◽  
Brian Evans ◽  
Curtis Link
Keyword(s):  
Physical Model ◽  
Physical Modeling ◽  
Model Experiment ◽  
Close Agreement ◽  
Time Lapse ◽  
Amplitude Variation ◽  
Amplitude Variation With Offset ◽  
Zoeppritz Equations ◽  
Seismic Amplitude ◽  
Gradient Domain

Information on time-lapse changes in seismic amplitude variation with offset (AVO) from a reservoir can be used to optimize production. We designed a scaled physical model experiment to study the AVO response of mixtures of brine, oil, and carbon dioxide at pressures of 0, 1.03, and [Formula: see text]. The small changes in density and velocity for each fluid because of increasing pressure were not detectable and were assumed to lie within the error of the experiment. However, AVO analysis was able to detect changes in the elastic properties between fluids that contained oil and those that did not. When the AVO response was plotted in the AVO intercept-gradient domain, fluids containing oil were clearly separated from fluids not containing oil. This was observed in the AVO response from both the top and base of the fluids in the physical model. We then compared the measured AVO response with the theoretical AVO response given by the Zoeppritz equations. The measured and theoretical AVO intercept responses for the top fluid reflection agree well, although the AVO gradients disagree slightly. For the fluid base reflection, the measured and theoretical responses are in close agreement.

Time-lapse full-waveform inversion as a reservoir-monitoring tool — A North Sea case study

2016 ◽  
Vol 35 (10) ◽  
pp. 850-858 ◽  
Author(s):  
Erik Hicks ◽  
Henning Hoeber ◽  
Marianne Houbiers ◽  
Séverine Pannetier Lescoffit ◽  
Andrew Ratcliffe ◽  
...  
Keyword(s):  
North Sea ◽  
Waveform Inversion ◽  
Time Lapse ◽  
Full Waveform Inversion ◽  
Monitoring Tool ◽  
Full Waveform ◽  
Reservoir Monitoring

scholarly journals 3-D tomographic limb sounder retrieval techniques: irregular grids and Laplacian regularisation

2019 ◽  
Vol 12 (2) ◽  
pp. 853-872 ◽  
Author(s):  
Lukas Krasauskas ◽  
Jörn Ungermann ◽  
Stefan Ensmann ◽  
Isabell Krisch ◽  
Erik Kretschmer ◽  
...  
Keyword(s):  
Ad Hoc ◽  
Computational Cost ◽  
Synthetic Data ◽  
Computation Time ◽  
Physical Parameters ◽  
Modelling Problem ◽  
Tikhonov Regularisation ◽  
Grid Points

Abstract. Multiple limb sounder measurements of the same atmospheric region taken from different directions can be combined in a 3-D tomographic retrieval. Mathematically, this is a computationally expensive inverse modelling problem. It typically requires an introduction of some general knowledge of the atmosphere (regularisation) due to its underdetermined nature. This paper introduces a consistent, physically motivated (no ad-hoc parameters) variant of the Tikhonov regularisation scheme based on spatial derivatives of the first-order and Laplacian. As shown by a case study with synthetic data, this scheme, combined with irregular grid retrieval methods employing Delaunay triangulation, improves both upon the quality and the computational cost of 3-D tomography. It also eliminates grid dependence and the need to tune parameters for each use case. The few physical parameters required can be derived from in situ measurements and model data. Tests show that a 82 % reduction in the number of grid points and 50 % reduction in total computation time, compared to previous methods, could be achieved without compromising results. An efficient Monte Carlo technique was also adopted for accuracy estimation of the new retrievals.

Fitting top seal topography and CO2 layer thickness to time-lapse seismic amplitude maps at Sleipner

2015 ◽  
Vol 3 (2) ◽  
pp. SM47-SM55 ◽  
Author(s):  
Anders Fredrik Kiær
Keyword(s):  
Layer Thickness ◽  
Synthetic Data ◽  
Real Data ◽  
Time Lapse ◽  
Thin Layers ◽  
Storage Site ◽  
Seismic Amplitude ◽  
Reflection Amplitude ◽  
Flow Mechanisms ◽  
Cap Rock

Injected [Formula: see text] at the Sleipner storage site is migrating into several thin layers. Using a tuning relationship, two different layer thicknesses can give the same reflection amplitude, and it is then not possible to go from amplitudes to [Formula: see text] layer thicknesses without further constraints. Exploiting spatial and time-lapse dependencies in the reflection amplitude maps makes it possible to resolve this ambiguity and create layer thickness maps when the [Formula: see text] flow is gravity dominated. The topography of the sealing cap rock was used as an optimization parameter. Tests were done on synthetic data and real data from the Sleipner [Formula: see text] injection. The resulting topography map for the Sleipner case deviated by 5.3 m on average from simple time-depth mapping, which is within the mapping uncertainty. Although the predictive power is limited, outputs of the method can be used to check if the flow matches a gravity-dominated model or if other flow mechanisms are needed to explain the observations.

scholarly journals An estuarine-tuned quasi-analytical algorithm (QAA-V): assessment and application to satellite estimates of SPM in Galveston Bay following Hurricane Harvey

2018 ◽  
Vol 15 (13) ◽  
pp. 4065-4086 ◽  
Author(s):  
Ishan D. Joshi ◽  
Eurico J. D'Sa
Keyword(s):  
Ocean Color ◽  
Synthetic Data ◽  
Analytical Relationship ◽  
Galveston Bay ◽  
Water Absorption Coefficient ◽  
Color Sensor ◽  
Suspended Particulate ◽  
Analytical Algorithm

Abstract. The standard quasi-analytical algorithm (Lee et al., 2002) was tuned as QAA-V using a suite of synthetic data and in situ measurements to improve its performance in optically complex and shallow estuarine waters. Two modifications were applied to the standard QAA: (1) the semi-analytical relationship for obtaining remote sensing reflectance just below the water surface as a function of absorption and backscattering coefficients was updated using Hydrolight® simulations, and (2) an empirical model of the total non-water absorption coefficient was proposed using a ratio of green to red bands of an ocean color sensor, which is known to work well in various inland and estuarine environments. The QAA-V-derived total absorption and backscattering coefficients, which were evaluated in a variety of waters ranging from highly absorbing and turbid to relatively clear shelf waters, showed satisfactory performance on a Hydrolight-simulated synthetic dataset (R2 > 0.87, MRE < 17 %), an in situ estuarine and nearshore dataset (R2 > 0.70, MRE < 35 %), and the NOMAD (R2 > 0.90, MRE < 30 %). When compared to the standard QAA (QAA-v6), the QAA-V showed an obvious improvement with ∼ 30–40 % reduction in absolute mean relative error for the Hydrolight-simulated synthetic and in situ estuarine and nearshore datasets, respectively. The methodology of tuning QAA was applied to the VIIRS ocean color sensor and validation results suggest that the proposed methodology can also be applied to other ocean color and land-observing sensors. The QAA-V was also assessed on VIIRS imagery using a regional relationship between suspended particulate matter (SPM) and particulate backscattering coefficient at 532 nm (bbtnw532; R2 = 0.89, N = 33). As a case study, the QAA-V processing chain and VIIRS imagery were used to generate a sequence of SPM maps of Galveston Bay, Texas following the unprecedented flooding of Houston and the surrounding regions due to Hurricane Harvey in August 2017. The record discharge of floodwaters through two major rivers into the bay resulted in very high SPM concentrations over several days throughout the bay, with wind forcing additionally influencing its distribution into the coastal waters of the northern Gulf of Mexico. The promising results of this study suggest that the application of QAA-V to various ocean color and land-observing satellite imagery could be used to assess the bio-optical state and water quality dynamics in a variety of coastal systems around the world.

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