Topic
Depth conversion
About: Depth conversion is a research topic. Over the lifetime, 376 publications have been published within this topic receiving 2891 citations.
Papers published on a yearly basis
Papers
TL;DR: In this paper, a first-order linear velocity-depth trend line has been estimated from published velocity data, but the data analyzed in this study show significant variations from this trend line, indicating that no general velocitydepth function can be used when performing more accurate analyses like depth conversion of seismic data, pore pressure prediction, or basin modeling.
Abstract: Sonic velocity, density, and resistivity log data from 60 wells on the Norwegian Shelf have been used to investigate velocity-depth trends in sedimentary rocks as a function of sediment composition, porosity, pore-pressure, burial-history, and compaction processes. A first-order linear velocity-depth trend line has been estimated from published velocity data. The data analyzed in this study, however, show significant variations from this trend line, indicating that no general velocity-depth function can be used when performing more accurate analyses like depth conversion of seismic data, pore-pressure prediction, or basin modeling. Lower Tertiary smectitic sediments from the northern North Sea and Haltenbanken are characterized by relatively low velocities compared to the overlying Pliocene and Pleistocene sediments, causing a distinct velocity inversion. A significant velocity increase at a burial depth corresponding to 70–100C was found and may reflect the alteration of smectite to illite and the initial precipitation of quartz cement in both sandstones and shales. Overpressured Jurassic sediments from Haltenbanken have lower velocities than equivalent hydrostatically pressured sequences but no significant porosity difference. The reduced velocities may be a direct response to lower effective stresses and, thus, reduced elastic compaction. Low velocities in source rocks are mainly attributed to the relatively soft kerogen and resulting velocity anisotropy. The high velocity/depth ratio of Barents Sea sediments (after correcting for Tertiary exhumation) is explained by the burial history of the area, the subsequent thermal exposure of the sediments over time, and thus, the amount of quartz cementation.
124 citations
TL;DR: In this paper, a new velocity parameter, the velocity anomaly (dV) is defined as the deviation between a velocity measurement and a linear velocity-depth function for a formation.
Abstract: A new velocity parameter, the velocity anomaly (dV), is defined as the deviation between a velocity measurement and a linear velocity-depth function for a formation. The variation of the velocity anomaly of the lowermost Jurassic claystones in northern Denmark is interpreted as the combined effect of three types of uplift movements, and the magnitude of these are estimated. It is concluded that the pre-Quaternary surface in northern Denmark is an erosional surface, created by up to 1000 m of Neogene uplift and subsequent erosion. The Upper Cretaceous Danian Chalk Group and the Tertiary sequence must thus have been deposited far beyond their present extensions. Consequences of Neogene uplift for the source rock potential of the area are discussed. In the Danish Central Trough, North Sea, the velocity anomaly of the Lower Cretaceous is shown to reflect lithological variations related to differential subsidence and to characterize the geological regions better than the interval velocity. Since the primary influence of depth on velocity is removed, the velocity anomaly is an expression of physical factors such as lithology, overpressure, and gas content as well as uplift and erosion. Contoured maps based on well data of the velocity anomaly of a formation may thus be used to estimate the velocity anomaly at arbitrary locations. The velocity anomaly map, the seismic time maps, and the linear velocity parameters for each layer constitute the input for velocity-anomaly depth conversion. This depth-conversion method results in depth maps with perfect well ties and geologically reasonable depth estimates away from wells.
110 citations
1 Jan 2010
TL;DR: In this paper, a detailed 3D history-matching of the topmost layer of the CO 2 plume at Sleipner has been performed, showing a multi-tier feature of high reflectivity, suggesting either pathway transmissivities are increasing with time and/or the pathways are becoming more numerous.
Abstract: Since its inception in 1996, the CO 2 injection operation at Sleipner has been monitored by 3D time-lapse seismic surveys. Striking images of the CO 2 plume have been obtained showing a multi-tier feature of high reflectivity. In the medium to longer term, the topmost layer of CO 2 , accumulating and migrating directly beneath the topseal, is the main determinant of storage site performance. Fortunately it is this topmost layer that can be most accurately characterized, its rate of growth quantified, and CO 2 flux arriving at the reservoir top estimated. The latter is mostly controlled by pathway flow through thin intra-reservoir mudstones. This has increased steadily with time, suggesting either that pathway transmissivities are increasing with time and/or the pathways are becoming more numerous. Detailed 3D history-matching of the topmost layer cannot easily match the observed rate of spreading. Isotropic permeabilities result in a stronger radial component than observed and a degree of anisotropic permeability, higher in a north–south direction, is possible. The main contributor to the mismatch, however, is likely to be small but significant uncertainty in the depth conversion. Irrespective of uncertainty, the observed rate of lateral migration seems to require very high permeabilities, and is, moreover, suggestive of a topseal which behaves like a ‘hard’ impermeable flow barrier. Detailed studies such as this will provide important constraints on longer term predictive models of plume evolution and storage performance which are key regulatory requirements.
88 citations
TL;DR: In this paper, a panel of 20 interpreters, with different geoscientific backgrounds, interpreted faults in modern conventional and high-resolution P-Cable 3D seismic data from the Hoop area, SW Barents Sea.
80 citations
29 Jun 2013
TL;DR: A new algorithm for calibrating a Kinect sensor that achieves high accuracy using only 6 to 10 image-disparity pairs of a planar checkerboard pattern is described, and several modifications to this estimation pipeline are proposed that dramatically improve stability, usability, and runtime.
Abstract: The article describes a new algorithm for calibrating a Kinect sensor that achieves high accuracy using only 6 to 10 image-disparity pairs of a planar checkerboard pattern. The method estimates the projection parameters for both color and depth cameras, the relative pose between them, and the function that converts kinect disparity units (kdu) into metric depth. We build on the recent work of Herrera et. al [8] that uses a large number of input frames and multiple iterative minimization steps for obtaining very accurate calibration results. We propose several modifications to this estimation pipeline that dramatically improve stability, usability, and runtime. The modifications consist in: (i) initializing the relative pose using a new minimal, optimal solution for registering 3D planes across different reference frames, (ii) including a metric constraint during the iterative refinement to avoid a drift in the disparity to depth conversion, and (iii) estimating the parameters of the depth distortion model in an open-loop post-processing step. Comparative experiments show that our pipeline can achieve a calibration accuracy similar to [8] while using less than 1/6 of the input frames and running in 1/30 of the time.
69 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 8 |
| 2020 | 9 |
| 2019 | 15 |
| 2018 | 25 |
| 2017 | 14 |
| 2016 | 16 |