A geostatistical approach to integrating data from multiple and diverse sources: An application to the integration of well data, geological information, 3d/4d geophysical and reservoir-dynamics data in a north-sea reservoir

2007 ◽  
pp. 61-71
Author(s):  
Jef Caers ◽  
Scarlet Castro
Keyword(s):  
North Sea ◽  
Geostatistical Approach ◽  
Geological Information ◽  
Well Data

scholarly journals Geological evolution of the Chalk Group in the northern Dutch North Sea: inversion, sedimentation and redeposition

2018 ◽  
Vol 156 (07) ◽  
pp. 1265-1284
Author(s):  
EVA VAN DER VOET ◽  
LEONORA HEIJNEN ◽  
JOHN J. G. REIJMER
Keyword(s):  
North Sea ◽  
Late Cretaceous ◽  
Seismic Survey ◽  
Structural Elements ◽  
The North ◽  
Show Evidence ◽  
New Finding ◽  
The North Sea ◽  
Thickness Variations ◽  
Well Data

AbstractIn contrast to the Norwegian and Danish sectors, where significant hydrocarbon reserves were found in chalk reservoirs, limited studies exist analysing the chalk evolution in the Dutch part of the North Sea. To provide a better understanding of this evolution, a tectono-sedimentary study of the Late Cretaceous to Early Palaeogene Chalk Group in the northern Dutch North Sea was performed, facilitated by a relatively new 3D seismic survey. Integrating seismic and biostratigraphic well data, seven chronostratigraphic units were mapped, allowing a reconstruction of intra-chalk geological events.The southwestward thickening of the Turonian sequence is interpreted to result from tilting, and the absence of Coniacian and Santonian sediments in the western part of the study area is probably the result of non-deposition. Seismic truncations show evidence of a widespread inversion phase, the timing of which differs between the structural elements. It started at the end of the Campanian followed by a second pulse during the Maastrichtian, a new finding not reported before. After subsidence during the Maastrichtian and Danian, renewed inversion and erosion occurred at the end of the Danian. Halokinesis processes resulted in thickness variations of chalk units of different ages.In summary, variations in sedimentation patterns in the northern Dutch North Sea relate to the Sub-Hercynian inversion phase during the Campanian and Maastrichtian, the Laramide inversion phase at the end of the Danian, and halokinesis processes. Additionally, the Late Cretaceous sea floor was characterized by erosion through contour bottom currents at different scales and resedimentation by slope failures.

scholarly journals Velocity-attenuation model from check-shot drift trends in North Sea well data

Geophysics ◽  
2020 ◽  
Vol 85 (2) ◽  
pp. D65-D74 ◽  
Author(s):  
Andrew J. Carter ◽  
Veronica A. Torres Caceres ◽  
Kenneth Duffaut ◽  
Alexey Stovas
Keyword(s):  
North Sea ◽  
Velocity Dispersion ◽  
Seismic Attenuation ◽  
P Wave ◽  
Linear Wave ◽  
Velocity Models ◽  
Velocity Attenuation ◽  
Attenuation Models ◽  
Well Data ◽  
Attenuation Values

Seismic attenuation distorts phase and narrows bandwidth in seismic surveys. It is also an exploration attribute, as, for example, gas or overpressure, may create attenuation anomalies. Compensating attenuation in imaging requires accurate models. Detailed attenuation models may be obtained using full-waveform inversion (FWI) or attenuation tomography, but their accuracy benefits from reliable starting models and/or constraints. Seismic attenuation and velocity dispersion are necessarily linked for causal linear wave propagation such that higher frequencies travel faster than lower frequencies in an attenuative medium. In publicly released well data from the Norwegian North Sea, we have observed systematic positive linear trends in check-shot drift when comparing (lower frequency) time-depth curves with (higher frequency) integrated sonic transit times. We observe velocity dispersion consistent with layers having constant seismic attenuation. Adapting a previously published method, and assuming an attenuation-dispersion relationship, we use drift gradients, measured over thick stratigraphic units, to estimate interval P-wave attenuation and tentatively interpret its variation in terms of porosity and fluid mobility. Reflectivity modeling predicts a very low attenuation contribution from peg-leg multiples. We use the attenuation values to develop a simple regional relationship between P-wave velocity and attenuation. Observed low drift gradients in some shallower units lead to an arch-shaped model that predicts low attenuation at both low and high velocities. The attenuation estimates were broadly comparable with published effective attenuation values obtained independently nearby. This general methodology for quickly deriving a regional velocity-attenuation relationship could be used anywhere that coincident velocity models are available at seismic and sonic frequencies. Such relationships can be used for fast derivation (from velocities) of starting attenuation models for FWI or tomography, constraining or linking velocity and attenuation in inversion, deriving models for attenuation compensation in time processing, or deriving background trends in screening for attenuation anomalies in exploration.

Extensive, Gas-charged Quaternary Sand Accumulations of the Northern North Sea and North Sea Fan

2020 ◽  
Author(s):  
Benjamin Bellwald ◽  
Sverre Planke ◽  
Sunil Vadakkepuliyambatta ◽  
Stefan Buenz ◽  
Christine Batchelor ◽  
...  
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Data Sets ◽  
3D Seismic ◽  
Fine Grained ◽  
The North ◽  
Northern North Sea ◽  
Well Data ◽  
Sea Fan ◽  
3D Seismic Data

<p>Sediments deposited by marine-based ice sheets are dominantly fine-grained glacial muds, which are commonly known for their sealing properties for migrating fluids. However, the Peon and Aviat hydrocarbon discoveries in the North Sea show that coarse-grained glacial sands can occur over large areas in formerly glaciated continental shelves. In this study, we use conventional and high-resolution 2D and 3D seismic data combined with well information to present new models for large-scale fluid accumulations within the shallow subsurface of the Norwegian Continental Shelf. The data include 48,000 km<sup>2</sup> of high-quality 3D seismic data and 150 km<sup>2</sup> of high-resolution P-Cable 3D seismic data, with a vertical resolution of 2 m and a horizontal resolution of 6 to 10 m in these data sets. We conducted horizon picking, gridding and attribute extractions as well as seismic geomorphological interpretation, and integrated the results obtained from the seismic interpretation with existing well data.</p><p>The thicknesses of the Quaternary deposits vary from hundreds of meters of subglacial till in the Northern North Sea to several kilometers of glacigenic sediments in the North Sea Fan. Gas-charged, sandy accumulations are characterized by phase-reserved reflections with anomalously high amplitudes in the seismic data as well as density and velocity decreases in the well data. Extensive (>10 km<sup>2</sup>) Quaternary sand accumulations within this package include (i) glacial sands in an ice-marginal outwash fan, sealed by stiff glacial tills deposited by repeated glaciations (the Peon discovery in the Northern North Sea), (ii) sandy channel-levee systems sealed by fine-grained mud within sequences of glacigenic debris flows, formed during shelf-edge glaciations, (iii) fine-grained glacimarine sands of contouritic origin sealed by gas hydrates, and (iv) remobilized oozes above large evacuation craters and sealed by megaslides and glacial muds. The development of the Fennoscandian Ice Sheet resulted in a rich variety of depositional environments with frequently changing types and patterns of glacial sedimentation. Extensive new 3D seismic data sets are crucial to correctly interpret glacial processes and to analyze the grain sizes of the related deposits. Furthermore, these data sets allow the identification of localized extensive fluid accumulations within the Quaternary succession and distinguish stratigraphic levels favorable for fluid accumulations from layers acting as fluid barriers.</p>

High-resolution reservoir characterization by an acoustic impedance inversion of a Tertiary deltaic clinoform system in the North Sea

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. O57-O67 ◽  
Author(s):  
Daria Tetyukhina ◽  
Lucas J. van Vliet ◽  
Stefan M. Luthi ◽  
Kees Wapenaar
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Reservoir Characterization ◽  
Structural Information ◽  
Sampling Rate ◽  
Seismic Inversion ◽  
Acoustic Properties ◽  
The North ◽  
The North Sea ◽  
Well Data

Fluvio-deltaic sedimentary systems are of great interest for explorationists because they can form prolific hydrocarbon plays. However, they are also among the most complex and heterogeneous ones encountered in the subsurface, and potential reservoir units are often close to or below seismic resolution. For seismic inversion, it is therefore important to integrate the seismic data with higher resolution constraints obtained from well logs, whereby not only the acoustic properties are used but also the detailed layering characteristics. We have applied two inversion approaches for poststack, time-migrated seismic data to a clinoform sequence in the North Sea. Both methods are recursive trace-based techniques that use well data as a priori constraints but differ in the way they incorporate structural information. One method uses a discrete layer model from the well that is propagated laterally along the clinoform layers, which are modeled as sigmoids. The second method uses a constant sampling rate from the well data and uses horizontal and vertical regularization parameters for lateral propagation. The first method has a low level of parameterization embedded in a geologic framework and is computationally fast. The second method has a much higher degree of parameterization but is flexible enough to detect deviations in the geologic settings of the reservoir; however, there is no explicit geologic significance and the method is computationally much less efficient. Forward seismic modeling of the two inversion results indicates a good match of both methods with the actual seismic data.

Variation of velocity with effective stress in chalk:null result from North Sea well data

2002 ◽  
Vol 19 (8) ◽  
pp. 921-927 ◽  
Author(s):  
M. Lubanzadio ◽  
N.R. Goulty ◽  
R.E. Swarbrick
Keyword(s):  
North Sea ◽  
Effective Stress ◽  
Well Data

scholarly journals Construction of 3D geological models in glacial deposits to characterise migration of pollution

2006 ◽  
Vol 10 ◽  
pp. 21-24
Author(s):  
Knud E.S. Klint ◽  
Frants Von Platen-Hallermund ◽  
Mette Christophersen
Keyword(s):  
Cost Benefit Analysis ◽  
Cost Benefit ◽  
Raw Material ◽  
Major Advance ◽  
Material Resources ◽  
Multiple Data ◽  
Geological Models ◽  
Geological Information ◽  
Well Data ◽  
Gis System

The National geological database at the Geological Survey of Denmark and Greenland (GEUS) is based on an extensive well database Jupiter, a geophysical database Gerda (Tulstrup 2003) and a recently established database for various types of geological models. These databases are integrated in a GIS system. The integration of this data enables new possibilities of constructing improved geological models. GIS systems offer a powerful tool for the geologist not only in combining multiple data, but also in visualising the model and hence presenting the final product in a simple and understandable way. 3D geological models will become increasingly important for the execution of improved cost-benefit analysis and risk assessment of contaminated sites, as well as strategic evaluation of groundwater and raw material resources in general. The possibility of storing such models on a public platform will be a major advance for future users of geological databases. The primary goal of this paper is to demonstrate the potential of an integrated GIS system, with an example of how traditional geological information may be combined in new ways in order to improve the correlation of well data in multiple directions. The application is demonstrated for a highly contaminated industrial site in the town of Ringe, Denmark (Fig. 1).

Improving porosity and gamma ray prediction for the Middle Jurassic Hugin sandstones in southern Norwegian North Sea with the application of deep neural networks

2021 ◽  
pp. 1-46
Author(s):  
Satinder Chopra ◽  
Ritesh Sharma ◽  
Kurt J. Marfurt ◽  
Rongfeng Zhang ◽  
Renjun Wen
Keyword(s):  
Neural Network ◽  
North Sea ◽  
Seismic Data ◽  
Deep Neural Network ◽  
Gamma Ray ◽  
Accurate Determination ◽  
Empirical Relation ◽  
Reservoir Property ◽  
Well Data

The complete characterization of a reservoir requires accurate determination of properties such as porosity, gamma ray and density, amongst others. A common workflow is to predict the spatial distribution of properties measured by well logs to those that can be computed from the seismic data. Generally, a high degree of scatter of data points is seen on crossplots between P-impedance and porosity, or P-impedance and gamma ray suggesting large uncertainty in the determined relationship. Although for many rocks there is a well established petrophysical model correlating P-impedance to porosity, there is not a comparable model correlating P-impedance to gamma ray. To address this issue, interpreters can use crossplots to graphically correlate two seismically derived variables to well measurements plotted in color. When there are more than two seismically derived variables, the interpreter can use multilinear regression or artificial neural network (ANN) analysis that uses a percentage of the upscaled well data for training to establish an empirical relation with the input seismic data and then uses the remaining well data to validate the relationship. Once validated at the wells, this relationship can then be used to predict the desired reservoir property volumetrically. We describe the application of deep neural network (DNN) analysis for the determination of porosity and gamma ray over the Volve Field in the southern Norwegian North Sea. After employing several quality-control steps in the deep neural network workflow and observing encouraging results, we validate the final prediction of both porosity and gamma ray properties using blind well correlation. The application of this workflow promises significant improvement to the reservoir property determination for fields that have good well control and exhibit lateral variations in the sought properties.

scholarly journals Pleasant Bayou Geopressured-Geothermal Reservoir Analysis—October 1991

1992 ◽  
Vol 114 (4) ◽  
pp. 315-322 ◽  
Author(s):  
T. D. Riney
Keyword(s):  
Gulf Coast ◽  
Sedimentary Basins ◽  
Department Of Energy ◽  
Well Test ◽  
Deep Wells ◽  
Geological Information ◽  
Fluid Properties ◽  
Southeast Texas ◽  
Reservoir Simulation Model ◽  
Well Data

Many sedimentary basins contain formations with pore fluids at pressures higher than hydrostatic value; these formations are called geopressured. The pore pressure is generally well in excess of hydrostatic and the fluids are saline, hot, and contain dissolved methane. The U.S. Department of Energy (DOE) has drilled and tested deep wells in the Texas-Louisiana Gulf Coast region to evaluate the geopressured-geothermal resource. Geological information for the Pleasant Bayou geopressured resource in southeast Texas is most extensive among the reservoirs tested. Testing of the DOE well (Pleasant Bayou No. 2) was conducted during 1979–1983; testing resumed in May 1988. A numerical simulator is employed to synthesize and integrate the geological information, formation rock and fluid properties data from laboratory tests, and well data from the earlier (1979–1983) and the ongoing testing (1988–1991) of the well. A reservoir simulation model has been constructed which provides a detailed match to the well test history to date.

A hydrodynamic model and associated spill-point map for the Huntington Field, UK Central North Sea

2016 ◽  
Vol 8 (1) ◽  
pp. 399-412 ◽  
Author(s):  
Sam Green ◽  
Stephen O'Connor ◽  
Richard Swarbrick ◽  
Kester Waters
Keyword(s):  
North Sea ◽  
Hydrodynamic Model ◽  
Published Data ◽  
Pressure Data ◽  
Seismic Attribute ◽  
Direct Pressure ◽  
Competing Models ◽  
Well Data ◽  
The Uk ◽  
Central North Sea

AbstractThe Huntington Field is located in Block UK 22/14b in the UK Central North Sea. The reservoir is the Tertiary Forties Formation (a deep-sea fan interval), which has been produced since 2013. Pre-production well data indicate that hydrocarbons (oil) are present outside structural closure as recorded by direct pressure data and wireline-derived fluid contacts, and indicated by seismic attribute data. These observations in other parts of the world (e.g. Mad Dog Field, Miocene Gulf of Mexico) have been attributed to the presence of a hydrodynamic reservoir. This paper aims to reconcile these observations from seismic data, logs and pressure data with competing models to explain the hydrocarbon distribution.Combining the interpretations above with the additional observations that (a) there are no sedimentological barriers or identifiable faulting between wells, (b) the surrounding fields (Everest and Forties) have been actively producing for decades, but that calculated flow rates in the Huntington Field agree with published data for other virgin hydrodynamic systems, and (c) measured regional and local overpressure gradients indicate fluid flow to the NW where hydrocarbons are present outside the structure indicates that a hydrodynamic model is the most probable solution to explain the fluids and their present distribution.

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