Time‐lapse imaging at Bullwinkle field, Green Canyon 65, offshore Gulf of Mexico

Geophysics ◽  
2003 ◽  
Vol 68 (5) ◽  
pp. 1470-1484 ◽  
Author(s):  
Alastair M. Swanston ◽  
Peter B. Flemings ◽  
Joseph T. Comisky ◽  
Kevin D. Best
Keyword(s):  
Gulf Of Mexico ◽  
Time Lapse ◽  
Seismic Survey ◽  
Data Sets ◽  
Water Contact ◽  
Seismic Surveys ◽  
Fluid Properties ◽  
Induced Changes ◽  
Time Lapse Imaging ◽  
Difference Images

Two orthogonal preproduction seismic surveys and a regional seismic survey acquired after eight years of production from the Bullwinkle field (Green Canyon 65, Gulf of Mexico) reveal extraordinary seismic differences attributed to production‐induced changes in rock and fluid properties. Amplitude reduction (of up to 71%) occurs where production and log data show that water has replaced hydrocarbons as the oil–water contact moved upward. Separate normalizations of these surveys demonstrate that time‐lapse results are improved by using seismic surveys acquired in similar orientations; also, clearer difference images are obtained from comparing lower‐frequency data sets. Superior stratigraphic illumination in the dip‐oriented survey relative to the strike‐oriented surveys results in nongeological amplitude differences. This documents the danger of using dissimilar baseline and monitor surveys for time‐lapse studies.

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

Geophysics ◽  
2001 ◽  
Vol 66 (3) ◽  
pp. 836-844 ◽  
Author(s):  
Martin Landrø
Keyword(s):  
Seismic Data ◽  
Time Lapse ◽  
Seismic Survey ◽  
Baseline Survey ◽  
Water Contact ◽  
Data Set ◽  
Seismic Surveys ◽  
Fluid Saturation ◽  
Oil Water ◽  
Pressure Changes

Explicit expressions for computing saturation‐ and pressure‐related changes from time‐lapse seismic data have been derived and tested on a real time‐lapse seismic data set. Necessary input is near‐and far‐offset stacks for the baseline seismic survey and the repeat survey. The method has been tested successfully in a segment where pressure measurements in two wells verify a pore‐pressure increase of 5 to 6 MPa between the baseline survey and the monitor survey. Estimated pressure changes using the proposed relationships fit very well with observations. Between the baseline and monitor seismic surveys, 27% of the estimated recoverable hydrocarbon reserves were produced from this segment. The estimated saturation changes also agree well with observed changes, apart from some areas in the water zone that are mapped as being exposed to saturation changes (which is unlikely). Saturation changes in other segments close to the original oil‐water contact and the top reservoir interface are also estimated and confirmed by observations in various wells.

Time‐lapse (4-D) seismic monitoring of primary production of turbidite reservoirs at South Timbalier Block 295, offshore Louisiana, Gulf of Mexico

Geophysics ◽  
2000 ◽  
Vol 65 (2) ◽  
pp. 351-367 ◽  
Author(s):  
Tucker Burkhart ◽  
Andrew R. Hoover ◽  
Peter B. Flemings
Keyword(s):  
Reservoir Characterization ◽  
Water Saturation ◽  
Seismic Analysis ◽  
Time Lapse ◽  
Hydrocarbon Production ◽  
Seismic Surveys ◽  
Seismic Amplitude ◽  
Fluid Properties ◽  
Multiple Reservoir ◽  
Gas Drive

Two seismic surveys acquired over South Timbalier Block 295 field (offshore Louisiana) record significant differences in amplitude that are correlated to hydrocarbon production at multiple reservoir levels. The K8 sand, a solution‐gas‐drive reservoir, shows increases in seismic amplitude associated with gas exsolution. The K40 sand, a water‐drive reservoir, shows decreases in seismic amplitude associated with increases in water saturation. A methodology is presented to optimize the correlation between two seismic surveys after they have been individually processed (poststack) This methodology includes rebinning, crosscorrelation, band‐pass filtering, and cross‐equalization. A statistical approach is developed to characterize the correlation between the seismic surveys. This statistical analysis is used to discriminate seismic amplitude differences that record change in rock and fluid properties from those that could be the result of miscorrelation of the seismic data. Time‐lapse seismic analysis provides an important new approach to imaging hydrocarbon production; it may be used to improve reservoir characterization and guide production decisions.

Simulation of complete seismic surveys for evaluation of experiment design and processing

Geophysics ◽  
1996 ◽  
Vol 61 (2) ◽  
pp. 496-508 ◽  
Author(s):  
Turgut Özdenvar ◽  
George A. McMechan ◽  
Preston Chaney
Keyword(s):  
Composite System ◽  
Real Data ◽  
Seismic Survey ◽  
Data Sets ◽  
Seismic Surveys ◽  
Depth Migration ◽  
Data Line ◽  
Processing Algorithms ◽  
The Cost ◽  
Survey Designs

Synthesis of complete seismic survey data sets allows analysis and optimization of all stages in an acquisition/processing sequence. The characteristics of available survey designs, parameter choices, and processing algorithms may be evaluated prior to field acquisition to produce a composite system in which all stages have compatible performance; this maximizes the cost effectiveness for a given level of accuracy, or for targets with specific characteristics. Data sets synthesized for three salt structures provide representative comparisons of time and depth migration, post‐stack and prestack processing, and illustrate effects of varying recording aperture and shot spacing, iterative focusing analysis, and the interaction of migration algorithms with recording aperture. A final example demonstrates successful simulation of both 2-D acquisition and processing of a real data line over a salt pod in the Gulf of Mexico.

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.

From acquisition footprints to true amplitude

Geophysics ◽  
2002 ◽  
Vol 67 (3) ◽  
pp. 830-839 ◽  
Author(s):  
Stéphane Gesbert
Keyword(s):  
Time Lapse ◽  
Theoretical Framework ◽  
Data Sets ◽  
Variable Geometry ◽  
Quantitative Interpretation ◽  
Prestack Depth Migration ◽  
Seismic Surveys ◽  
Depth Migration ◽  
Minimal Data ◽  
Imaging Artifacts

This paper addresses the issue of the sensitivity of 3‐D prestack depth migration (PSDM) with respect to the acquisition geometry of 3‐D seismic surveys. Using the theoretical framework of PSDM, I show how acquisition‐related imaging artifacts—the acquisition footprints—can arise. I then show how the acquisition footprint can be suppressed in two steps by (1) partitioning the 3‐D survey into minimal data sets, each to be migrated separately, and (2) applying a robust variable‐geometry PSDM quadrature. The validity of the method is demonstrated on synthetic parallel and antiparallel multistreamer data and cross‐spread data. The proposed two‐step solution can play an important role in projects where amplitude integrity and fidelity are paramount, e.g., quantitative interpretation and time‐lapse surveying. The concept of minimal data also fills a gap in understanding the relation between acquisition and imaging.

scholarly journals Time-lapse CSEM: how important is survey repeatability?

2020 ◽  
Vol 223 (3) ◽  
pp. 2133-2147
Author(s):  
Daniil V Shantsev ◽  
Elias A Nerland ◽  
Leiv-J Gelius
Keyword(s):  
Measurement Errors ◽  
Time Lapse ◽  
Oil Field ◽  
Data Sets ◽  
Gas Field ◽  
Poor Knowledge ◽  
Controlled Source ◽  
Important Concern ◽  
Induced Changes ◽  
Contrast Measurement

SUMMARY An important concern for time-lapse studies using the controlled-source electromagnetic (CSEM) method is repeatability of acquisition parameters for the base and monitoring surveys. We consider a challenging case when variations in source and receiver positions, conductivity of seawater, etc. will lead to differences in the recorded EM fields that exceed EM response due to production-induced changes in the reservoir resistivity. We show that even in that case, 4-D response can often be clearly resolved if the base and monitor EM data sets are inverted to produce 3-D resistivity distributions. More precisely, for a synthetic model of the Snøhvit gas field, changes in the inverted resistivity maps caused by such non-repeatability will be at least 10 times smaller than the time-lapse differences in the reservoir resistivity. By contrast, measurement errors and poor knowledge of background resistivity may reduce the resolution of 4-D CSEM to a much stronger degree. Analysis of field CSEM data from the Wisting oil field supports our conclusion about strongly relaxed repeatability requirements when 4-D effects are established by examining inverted resistivity volumes rather than by looking at raw EM data.

Time-lapse seismic data registration and inversion for CO2 sequestration study at Cranfield

Geophysics ◽  
2013 ◽  
Vol 78 (6) ◽  
pp. B329-B338 ◽  
Author(s):  
Rui Zhang ◽  
Xiaolei Song ◽  
Sergey Fomel ◽  
Mrinal K. Sen ◽  
Sanjay Srinivasan
Keyword(s):  
Cross Sections ◽  
Seismic Data ◽  
Time Lapse ◽  
Seismic Survey ◽  
Rock Properties ◽  
Time Shift ◽  
Data Sets ◽  
Registration Method ◽  
Data Registration ◽  
Seismic Amplitude

The time-lapse seismic survey for [Formula: see text] sequestration study at Cranfield can be problematic because of misalignments between time-lapse data sets. Such misalignments can be caused by the seismic data processing workflow and may result in the wrong interpretation of time-lapse seismic amplitude differences. We propose an efficient local-correlation-based warping method of registering the time-lapse poststack data sets, which can align these data sets without changing original amplitudes. Application of our registration method to Cranfield time-lapse data demonstrates its effectiveness in separating time-shift character from seismic amplitude signature. After registration, time-lapse differences show an improved consistency in vertical cross sections and a more localized distribution of difference amplitudes along the horizon, allowing us to apply a high-resolution basis pursuit inversion (BPI) for acoustic impedances. Inversion results show that decreases in acoustic impedances occur mostly at the top of the injection interval, which can be used as an indicator of rock properties to detect a subsurface [Formula: see text] plume.

Rock physics modelling and analysis of time-lapse seismic response in the Pyrenees Field, offshore Western Australia

2015 ◽  
Vol 55 (2) ◽  
pp. 470
Author(s):  
Stanislav Kuzmin ◽  
Mauricio Florez ◽  
Guy Duncan ◽  
Konstantinos Kostas
Keyword(s):  
Seismic Response ◽  
Coming Out ◽  
Significant Risk ◽  
Rock Physics ◽  
Time Lapse ◽  
Seismic Survey ◽  
Water Contact ◽  
Fluid Saturation ◽  
Oil Water ◽  
4D Seismic

Rock physics modelling of the time-lapse seismic response of the Pyrenees Field was carried out to evaluate the feasibility of monitoring reservoir drainage and performance. Initially, the purpose of 4D seismic was to monitor the upward displacement of the oil-water contact. It was recognised that the likelihood of gas breakout imposed a significant risk to the feasibility of monitoring the oil-water contact. Models for different scenarios were used to assess this uncertainty and demonstrated that, in either case, an observable change in seismic properties would occur, providing technical support for 4D seismic acquisition. The monitor seismic survey acquired in 2013, showed detectable changes in both interval velocity and reflectivity that was associated with gas coming out of solution in the reservoir, where depletion occurred below the bubble point. This agrees with pre-acquisition predictions based on rock physics modelling. Additional rock physics analysis was carried out to calibrate the observed 4D response to changes in both fluid saturation and effective stress.

Target-oriented joint least-squares migration/inversion of time-lapse seismic data sets

Geophysics ◽  
2010 ◽  
Vol 75 (3) ◽  
pp. R61-R73 ◽  
Author(s):  
Gboyega Ayeni ◽  
Biondo Biondi
Keyword(s):  
Least Squares ◽  
Seismic Data ◽  
Time Lapse ◽  
Data Sets ◽  
Reservoir Properties ◽  
Phase Distortions ◽  
Time Lapse Imaging ◽  
Least Squares Migration ◽  
Seismic Images ◽  
Degradation Time

Two related formulations are proposed for target-oriented joint least-squares migration/inversion of time-lapse seismic data sets. Time-lapse seismic images can be degraded when reservoir overburden is complex or when acquisition geometries significantly differ, because the migration operator does not compensate for the resulting amplitude and phase distortions. Under these circumstances, time-lapse amplitudes are poor indicators of production-related changes in reservoir properties. To correct for such image degradation, time-lapse imaging is posed as joint inverse problems that utilize concatenations of target-oriented approximations to the linear least-squares imaging Hessian. In both formulations, spatial and temporal constraints ensure inversion stability and geologically consistent time-lapse images. Using two numerical time-lapse data sets, we confirmed that these formulations can attenuate illumination artifacts caused by complex overburden or geometry differences, and that they yield better-quality images than obtainable with migration.

scholarly journals Initial 4D seismic results after CO2 injection start-up at the Aquistore storage site

Geophysics ◽  
2017 ◽  
Vol 82 (3) ◽  
pp. B95-B107 ◽  
Author(s):  
Lisa A. N. Roach ◽  
Donald J. White ◽  
Brian Roberts ◽  
Doug Angus
Keyword(s):  
Root Mean Square ◽  
Time Lapse ◽  
Seismic Survey ◽  
Co2 Injection ◽  
Data Sets ◽  
Storage Site ◽  
Mean Square ◽  
Simultaneous Processing ◽  
Start Up ◽  
4D Seismic

The first post-[Formula: see text]-injection 3D time-lapse seismic survey was conducted at the Aquistore [Formula: see text] storage site in February 2016 using the same permanent array of buried geophones used for acquisition of three previous pre-[Formula: see text]-injection surveys from March 2012 to November 2013. By February 2016, 36 kilotons of [Formula: see text] have been injected within the reservoir between 3170 and 3370 m depth. We have developed time-lapse results from analysis of the first post-[Formula: see text]-injection data and three pre-[Formula: see text]-injection data sets. The objective of our analysis was to evaluate the ability of the permanent array to detect the injected [Formula: see text]. A “4D-friendly simultaneous” processing flow was applied to the data in an effort to maximize the repeatability between the pre- and post-[Formula: see text]-injection volumes while optimizing the final subsurface image including the reservoir. Excellent repeatability was achieved among all surveys with global normalized root-mean-square (Gnrms) values of 1.13–1.19 for the raw prestack data relative to the baseline data, which decreased during processing to Gnrms values of approximately 0.10 for the final crossequalized migrated data volumes. A zone of high normalized root-mean-square (nrms) values (0.11–0.25 as compared with background values of 0.05–0.10) is identified within the upper Deadwood unit of the storage reservoir, which likely corresponds to approximately 18 kilotons of [Formula: see text]. No significant nrms anomalies are observed within the other reservoir units due to a combination of reduced seismic sensitivity, higher background nrms values, and/or small quantities of [Formula: see text] residing within these zones.

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