Seniorforsker
Pål Dahle
- Avdeling Statistisk modellering av geologi
- Telefonnummer +47 22 85 26 41
- E-post pdahle@nr.stage.dekodes.no
Prosjekter
Publikasjoner
- 92 publikasjoner funnet
Abrahamsen, Petter; Dahle, Pål; Nevjen, Fredrik; Kvernelv, Vegard; Sektnan, Audun; Vazquez, Ariel Almendral; Waade, Bendik Skundberg og Aarnes, Ingrid. (2025).
COHIBA User Manual Version 7.2.1.
Vis sammendrag
This user manual describes the COHIBA surface modeling software. It consists of:
Part I Introduction: Basic ideas and terminology
Part II User manual: Usage, input data, and results
Part III Tutorials: Special topics such as volumes, simulation, and faults
Part IV Reference manual: Descriptions of all COHIBA model file elements
Part V Theory: Methods used by COHIBA
Part VI Appendix: Release notes, known issues, references, list of acronyms,
tables and figures, and an index
Abrahamsen, Petter; Dahle, Pål; Nevjen, Fredrik; Kvernelv, Vegard; Sektnan, Audun; Vazquez, Ariel Almendral; Waade, Bendik Skundberg og Aarnes, Ingrid. (2025).
Cohiba User Manual Version 7.2.
Vis sammendrag
This user manual describes the COHIBA surface modeling software. It consists of:
Part I Introduction: Basic ideas and terminology
Part II User manual: Usage, input data, and results
Part III Tutorials: Special topics such as volumes, simulation, and faults
Part IV Reference manual: Descriptions of all COHIBA model file elements
Part V Theory: Methods used by COHIBA
Part VI Appendix: Release notes, known issues, references, list of acronyms,
tables and figures, and an inde
Dahle, Pål; Waade, Bendik Skundberg; Vazquez, Ariel Almendral og Ohlsen, F.. (2025).
Geosteering: Continuous Surface Model Updates Using Gamma Log.
Vis sammendrag
Abstract Logging-while-drilling (LWD) tools transmit formation data in real-time to the surface as the drill bit moves through the subsurface. LWD is particularly valuable in horizontal wells where it minimizes the risk of getting off course and drilling into undesired formations. The introduction of ultra-deep azimuthal resistivity (UDAR) technology has improved the process of drilling horizontal wells (Antonsen et al. 2022), but its value is limited to reservoirs where important resistivity contrasts are observed. When this is not the case, a classical LWD measure like gamma ray, becomes crucial for well placement. The interpretation of well logs is difficult, however, and error prone whenever manual work is involved. In this paper, we present a method for consistently integrating the structural model with LWD measurements while drilling. This approach enables estimation of the distance between the drill bit and nearby constraining zone boundaries, allowing for continuous updates of the surface model during drilling operations. By avoiding manual operations, the risk of getting a structural model that has diverged from real-time measurements is reduced.
Vazquez, Ariel Almendral; Dahle, Pål; Abrahamsen, Petter og Sektnan, Audun. (2024).
Consistent prediction of well paths and geological surfaces.
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We propose a smooth stochastic process for modeling the vertical well path uncertainty. This process describes the accumulation of measurement errors along the well path. We combine the stochastic process with a stochastic model for surfaces into a consistent framework for simultaneous prediction of well paths and surfaces. We show properties of the proposed stochastic process and provide examples of interaction between wells and surfaces.
Dahle, Pål; Vigsnes, Maria og Syversveen, Anne Randi. (2024).
Seismic Forward User Manual v4.3.
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Rapport
Vazquez, Ariel Almendral; Dahle, Pål; Abrahamsen, Petter og Sektnan, Audun. (2022).
Conditioning geological surfaces to horizontal wells.
Løland, Anders; Abrahamsen, Petter og Dahle, Pål. (2021).
Fra verdifulle oljefelt til farlige løsmasser med COHIBA.
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Programdeltagelse
Sektnan, Audun; Abrahamsen, Petter og Dahle, Pål. (2020).
Dip point coordinates in COHIBA.
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Rapport
Abrahamsen, Petter; Dahle, Pål; Kvernelv, Vegard Berg; Sektnan, Audun; Vazquez, Ariel Almendral og Aarnes, Ingrid. (2020).
COHIBA User Manual Version 6.1.
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Vazquez, Ariel Almendral; Dahle, Pål og Abrahamsen, Petter. (2020).
Compendium of Linvel formulas used in Cohiba.
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Rapport
Dahle, Pål. (2019).
Choosing depth-conversion models using cross validation of wells. Norsk Regnesentral
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Faglig foredrag
Vis sammendrag
Choosing the best depth conversion model for an oil or gas reservoir can be difficult. One of the best ways to choose between two competing models is to use cross-validation of wells. This means that both models are estimated from all observation except one, and then the prediction error for the observation left out is measured. By doing this successively for all observations, a root-mean-square-error (RMSE) can be estimated for both depth-conversion models. The model with the lowest RMSE is the better. The RMSE does not suffer from over-fitting.
Sektnan, Audun; Dahle, Pål; Vazquez, Ariel Almendral og Abrahamsen, Petter. (2019).
Getting the zonation right. A synthetic real-time case study. Norsk Regnesentral
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Faglig foredrag
Vis sammendrag
A COHIBA case study investigating a synthetic model for depth conversion, with focus on how to get the zonation right and the impact of different modelling settings on the estimation of volume distributions.
Dahle, Pål; Abrahamsen, Petter og Vazquez, Ariel Almendral. (2019).
Handling true vertical depth (TVD) uncertainty in wells. Norsk Regnesentral
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Faglig foredrag
Vis sammendrag
We have developed a model for the true vertical depth (TVD) uncertainty in wells. The model allows well positions to be predicted given the well uncertainty and surface uncertainties. From this, we can predict the most likely position of the well.
Vazquez, Ariel Almendral; Abrahamsen, Petter; Dahle, Pål og Sektnan, Audun. (2019).
A novel implementation of the LinVel model. Norsk Regnesentral
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Faglig foredrag
Vazquez, Ariel Almendral; Abrahamsen, Petter; Dahle, Pål og Sektnan, Audun. (2019).
Getting the most out of your deep directional resistivity data. Norsk Regnesentral
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Faglig foredrag
Kolbjørnsen, Odd; Dahle, Pål; Bjerke, Morten D.; Bakke, Beate A. og Straith, Knut Richard. (2019).
Using Deep Directional Resistivity for Model Selection and Uncertainty Reduction in the Edvard Grieg Depth Conversion.
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Vitenskapelig foredrag
Dahle, Pål; Aarnes, Ingrid; Abrahamsen, Petter; Vazquez, Ariel Almendral og Sektnan, Audun. (2019).
Increasing subsurface accuracy with COHIBA by taking advantage of resistivity contrasts.
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Rapport
Sektnan, Audun; Vazquez, Ariel Almendral og Dahle, Pål. (2019).
Correlating intervals that share common reference surface.
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Rapport
Aarnes, Ingrid; Vazquez, Ariel Almendral og Dahle, Pål. (2019).
COHIBA in fault blocks on Valhall.
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Rapport
Abrahamsen, Petter; Dahle, Pål; Kvernelv, Vegard Berg; Sektnan, Audun; Vazquez, Ariel Almendral og Aarnes, Ingrid. (2019).
COHIBA User Manual Version 6.0.
Vis sammendrag
This user manual describes the COHIBA surface modeling software. It consists of:
Part I Introduction: Basic ideas and terminology
Part II User manual: Usage, input data and results
Part III Tutorials: Special topics such as volumes, simulation and faults
Part IV Reference manual: Descriptions of all COHIBA model file elements
Part V Theory: Methods used by COHIBA
Part VI Appendix: Release notes, known issues, references, list of acronyms,
tables and figures, and an index
Advanced topics and technicalities are marked by the warning symbol in the right margin. COHIBA model file elements marked by this warning symbol should be used with some care. The latest version of this document is available at: www.nr.no/COHIBA. For COHIBA support contact Pal.Dahle@nr.no or Ariel.Almendral.Vazque@nr.no.
The following scientists at Norwegian Computing Center has contributed to the development of
COHIBA:
Petter Abrahamsen
Pål Dahle Frode Georgsen
Vera Louise
Hauge Gudmund Hermansen
Odd Kolbjørnsen
Lars Bakke Krogvik
Vegard Berg Kvernelv
Inge Myrseth
Audun Sektnan
Arne Skorstad
Harald Soleng
Ariel Almendral Vazquez
Maria Vigsnes
Ingrid Aarnes
The front page shows two fences along well paths on top of a faulted surface on the Valhall carbonate field in the North Sea. The illustration is made by Ingrid Aarnes. We thank Aker BP for permission to publish the illustration.
Abrahamsen, Petter; Vazquez, Ariel Almendral; Dahle, Pål; Kvernelv, Vegard Berg og Sektnan, Audun. (2018).
Cohiba User Manual Version 5.6.
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Rapport
Aarnes, Ingrid; Vazquez, Ariel Almendral og Dahle, Pål. (2018).
Valhall structural model with COHIBA.
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Rapport
Dahle, Pål; Vazquez, Ariel Almendral og Abrahamsen, Petter. (2018).
COHIBA and velocity models linear in depth.
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Rapport
Vazquez, Ariel Almendral; Dahle, Pål og Sektnan, Audun. (2018).
Valhall study using Cohiba.
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Rapport
Abrahamsen, Petter; Dahle, Pål; Kvernelv, Vegard Berg; Sektnan, Audun og Vazquez, Ariel Almendral. (2017).
Cohiba User Manual Version 5.5.
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Rapport
Vigsnes, Maria; Kolbjørnsen, Odd; Hauge, Vera Louise; Dahle, Pål og Abrahamsen, Petter. (2017).
Fast and Accurate Approximation to Kriging Using Common Data Neighborhoods.
Vis sammendrag
Unknown values of a random field can be predicted from observed data using kriging. As data sets grow in size, the computation times become large. To facilitate kriging with large data sets, an approximation where the kriging is performed in sub-segments with common data neighborhoods has been developed. It is shown how the accuracy of the approximation can be controlled by increasing the common data neighborhood. For four different variograms, it is shown how large the data neighborhoods must be to get an accuracy below a chosen threshold, and how much faster these calculations are compared to the kriging where all data are used. Provided that variogram ranges are small compared to the domain of interest, kriging with common data neighborhoods provides excellent speed-ups (2–40) while maintaining high numerical accuracy. Results are presented both for data neighborhoods where the neighborhoods are the same for all sub-segments, and data neighborhoods where the neighborhoods are adapted to fit the data densities around the sub-segments. Kriging in sub-segments with common data neighborhoods is well suited for parallelization and the speed-up is almost linear in the number of threads. A comparison is made to the widely used moving neighborhood approach. It is demonstrated that the accuracy of the moving neighborhood approach can be poor and that computational speed can be slow compared to kriging with common data neighborhoods.
Aker, Eyvind; Røe, Per; Kjøsnes, Øyvind; Hauge, Ragnar; Dahle, Pål; Ahmadi, Gholam Reza og Sandstad, Odd Arne. (2017).
Probabilistic prediction of lithology-fluid-classes from seismic - A North Sea case study. NTNU
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Vitenskapelig foredrag
Aker, Eyvind; Dahle, Pål; Hauge, Ragnar og Røe, Per. (2016).
PCube inversion study in the greater Alvheim area.
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Rapport
Abrahamsen, Petter; Dahle, Pål; Hauge, Vera Louise; Hermansen, Gudmund Horn; Kvernelv, Vegard Berg og Vazquez, Ariel Almendral. (2016).
Cohiba User Manual Version 5.4.
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Rapport
Abrahamsen, Petter; Dahle, Pål; Hauge, Vera Louise; Hermansen, Gudmund Horn; Vigsnes, Maria og Almendral-Vazquez, Ariel. (2015).
Cohiba User Manual
Version 5.3.
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Rapport
Abrahamsen, Petter; Dahle, Pål; Hauge, Vera Louise; Hermansen, Gudmund Horn; Vigsnes, Maria og Vazquez, Ariel Almendral. (2015).
Cohiba User Manual, Version 5.1.
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Rapport
Abrahamsen, Petter; Dahle, Pål; Hauge, Vera Louise; Hermansen, Gudmund Horn; Vigsnes, Maria og Almendral-Vazquez, Ariel. (2015).
Cohiba User Manual
Version 5.2.
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Rapport
Dahle, Pål; Abrahamsen, Petter og Almendral-Vazquez, Ariel. (2015).
Simultaneous prediction of geological surfaces and well paths. European Association of Geoscientists and Engineers (EAGE)
Dahle, Pål; Abrahamsen, Petter og Almendral-Vazquez, Ariel. (2015).
Simultaneous prediction of geological surfaces and well paths. Roxar
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Faglig foredrag
Abrahamsen, Petter; Dahle, Pål; Hauge, Vera Louise; Vazquez, Ariel Almendral og Vigsnes, Maria. (2015).
Surface prediction using rejection sampling
to handle non-linear constraints.
Vis sammendrag
We demonstrate accurate prediction of geological surfaces by imposing consistent physical and stochastic relationships between surfaces. The accuracy is improved by using all relevant information collected in wells: well points, zonation in horizontal sections, and gas/fluid content along wells. The conditioned surfaces are used to provide estimates of gross rock volumes of oil and gas reservoirs. In particular, it is shown how knowledge of spill point and zonation along well paths affect trapped volumes. A plain rejection sampling technique is used to deal with the highly non-linear relationships between a surface and its spill point. For well path conditioning, an extension of kriging to treat inequality constraints is proposed. It is based on efficient rejection sampling from a high dimensional truncated multivariate Gaussian distribution. The impact on gross rock volume distributions from different assumptions and data types is demonstrated by examples and the uncertainties in all the involved data types are consistently handled and quantified.
Almendral-Vazquez, Ariel; Abrahamsen, Petter; Dahle, Pål og Hermansen, Gudmund Horn. (2015).
A continuous model for well depths: theory and application to well repositioning. Norsk statistikk forening
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Vitenskapelig foredrag
Dahle, Pål; Abrahamsen, Petter og Almendral-Vazquez, Ariel. (2015).
Surface modelling in fault blocks using COHIBA: A feasibility study.
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Rapport
Abrahamsen, Petter; Dahle, Pål; Hauge, Vera Louise; Almendral-Vazquez, Ariel og Vigsnes, Maria. (2014).
Surface prediction using rejection sampling to handle non-linear relationships. Canadian Society of Petroleum Geologists (CSPG)
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Vitenskapelig foredrag
Vis sammendrag
We demonstrate accurate surface predictions by imposing consistent physical and stochastic relationships between surfaces. The accuracy is improved by using all relevant information collected in wells: well markers, zone logs in horizontal sections, and gas/fluid content along wells. The conditioned surfaces are used to provide estimates of gross rock volumes of oil and gas reservoirs. In particular, we show how spill point and zone log information affect trapped volumes. We apply plain rejection sampling techniques to deal with the highly non-linear relationships between a surface and its spill point. For well path conditioning we build upon an extension of kriging to treat inequality constraints, based on an efficient rejection sampling from a high dimensional truncated multivariate Gaussian distribution. A fast approximate approach to simulating surfaces is presented and successfully applied to estimate volumes. The impact on gross rock volume distributions from different assumptions and data types is demonstrated by several examples and the uncertainties in all the involved data types are consistently handled and quantified.
Abrahamsen, Petter; Dahle, Pål; Hauge, Vera Louise og Vigsnes, Maria. (2014).
Impact on Gross-Rock Volume Distributions from Uncertainties in Surfaces and Hydrocarbon Contacts. European Association of Geoscientists and Engineers (EAGE)
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Vitenskapelig foredrag
Vis sammendrag
The gross-rock volume often accounts for the largest uncertainty in reserves. It is therefore important to obtain a correct gross-rock volume distribution and to reduce the uncertainty by using all available data. We demonstrate a way of obtaining accurate volume estimates by imposing realistic and consistent physical and stochastic relationships between the surfaces and hydrocarbon contacts that define the reservoir rock volume. The uncertainty is reduced by using all relevant information collected in wells; well markers, zone logs in horizontal sections, and gas/fluid content along wells. Uncertainties in all these data types are handled. The impact on volume distributions from different assumptions and data types are demonstrated by several examples. We will in particular demonstrate how restrictions on the possible spill point depth have impact on the potential trap size and the trapped volume. Some of the results are obtained using standard stochastic simulation (Monte Carlo) techniques but in particular the highly non-linear relationship between a surface and its spill point requires rejection sampling techniques. Rejection sampling is simple but very inefficient so a fast approximate approach to simulating surfaces is investigated. The conclusion is that the approximation works for calculating volumes but individual surface realizations have unacceptable artefacts.
Aidas, Kestutis; Angeli, Celestino; Bak, Keld L.; Bakken, Vebjørn; Bast, Radovan; Boman, Linus; Christiansen, Ove; Cimiraglia, Renzo; Coriani, Sonja; Dahle, Pål; Dalskov, Erik K.; Ekström, Ulf Egil; Enevoldsen, Thomas; Eriksen, Janus J.; Ettenhuber, Patrick; Fernández, Berta; Ferrighi, Lara; Fliegl, Heike; Frediani, Luca; Hald, Kasper; Halkier, Asger; Hattig, Christof; Heiberg, Hanne; Helgaker, Trygve; Hennum, Alf Christian; Hettema, Hinne; Hjertenæs, Eirik; Høst, Stine; Høyvik, Ida Marie; Iozzi, Maria Francesca; Jansik, Brannislav; Jensen, Hans-Jørgen Aa.; Jonsson, Dan Johan; Jørgensen, Poul; Kauczor, Johanna; Kirpekar, Sheela; Kjærgaard, Thomas; Klopper, Wim; Knecht, Stefan; Kobayashi, Rika; Koch, Henrik; Kongsted, Jacob; Krapp, Andreas; Kristensen, Kasper; Ligabue, Andrea; Lutnæs, Ola B.; Melo, Juan I.; Mikkelsen, Kurt V.; Myhre, Rolf Heilemann; Neiss, Christian; Nielsen, Christian B.; Norman, Patrick; Olsen, Jeppe; Olsen, Jogvan Magnus H.; Osted, Anders; Packer, Martin J.; Pawlowski, Filip; Pedersen, Thomas Bondo; Provasi, Patricio F.; Reine, Simen Sommerfelt; Rinkevicius, Zilvinas; Ruden, Torgeir A.; Ruud, Kenneth; Rybkin, Vladimir V.; Salek, Pawel; Samson, Claire C. M.; Meras, Alfredo Sanchez de; Saue, Trond; Sauer, Stephan P. A.; Schimmelpfennig, Bernd; Sneskov, Kristian; Steindal, Arnfinn Hykkerud; Sylvester-Hvid, Kristian O.; Taylor, Peter R.; Teale, Andrew M.; Tellgren, Erik; Tew, David P.; Thorvaldsen, Andreas J.; Thøgersen, Lea; Vahtras, Olav; Watson, Mark A.; Wilson, David J. D.; Ziolkowski, Marcin og Ågren, Hans. (2014).
The Dalton quantum chemistry program system.
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Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational self-consistent-field, Møller–Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantum-mechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from http://www.daltonprogram.org for a number of UNIX platforms.
Abrahamsen, Petter; Dahle, Pål; Georgsen, Frode; Hermansen, Gudmund Horn og Myrseth, Inge. (2013).
Cohiba User Manual Version 4.1.
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Rapport
Dahle, Pål; Nesvold, Erik; Fjellvoll, Bjørn; Georgsen, Frode; Hauge, Ragnar; Kolbjørnsen, Odd; Syversveen, Anne Randi og Ulvmoen, Marit. (2013).
CRAVA User Manual version 2.0.
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Rapport
Abrahamsen, Petter; Dahle, Pål; Hauge, Vera Louise; Hermansen, Gudmund Horn og Vigsnes, Maria. (2013).
COHIBA technical manual (SAND/12/13).
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Rapport
Abrahamsen, Petter; Dahle, Pål; Hermansen, Gudmund Horn; Hauge, Vera Louise og Vigsnes, Maria. (2013).
COHIBA user manual version 4.2 (SAND/10/13).
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Rapport
Stenerud, Vegard Røine; Kallekleiv, Hans Ivar; Abrahamsen, Petter; Dahle, Pål; Skorstad, Arne og Viken, May Hege Aalmen. (2012).
Added Value by Fast and Robust Conditioning of Structural Surfaces to Horizontal Wells for Real-World Reservoir Models.
Vis sammendrag
Structural updates for a complex reservoir model require time-consuming manual work, therefore, updates are rarely performed. This leads to an outdated model that gradually loses its predictability. Eventually, this results in model breakdown, and a new model must be built from scratch. Continuously updatable reservoir models avoid this and increase the value of models as a tool in decision making. In addition, easily updateable structural surfaces enable several structural realizations for spanning the uncertainty.
We present the use of a method for fast and robust updates of structural surfaces in reservoir models. We will focus on updates using zone data from horizontal wells (zone-log conditioning), since this traditionally has been a bottleneck that needs tedious manual work prone to error. In zone-log conditioning, we try to generate horizon surfaces that honor the geological zonation along the well paths. This is important for property modeling, and is crucial for fluid-flow simulations. Our method is robust, fully automated, and is built on a consistent mathematical framework that includes specified input-data uncertainties. It has provided satisfactory results for large real-world reservoir models where standard methods and work processes have failed. The field example presented shows a reduction from 22.9 % to 0.9 % in incorrectly honoring of the zone logs by applying this method rather than the standard approach. The remaining 0.9 % is due to conflicting data, gridding errors, and is difficult to get rid of even with manual editing. We consider this a large step forward with respect to providing an up-to-date basis for decisions that also can account for structural uncertainties.
Dahle, Pål; Fjellvoll, Bjørn; Georgsen, Frode; Hauge, Ragnar; Kolbjørnsen, Odd; Syversveen, Anne Randi og Ulvmoen, Marit. (2012).
CRAVA User Manual version 1.2.
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Rapport
Almendral-Vazquez, Ariel; Dahle, Pål; Abrahamsen, Petter; Georgsen, Frode og Myrseth, Inge. (2012).
Cohiba User Manual Version 3.1.1.
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Rapport
Abrahamsen, Petter; Dahle, Pål; Georgsen, Frode og Myrseth, Inge. (2012).
Cohiba User Manual Version 4.0.
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Rapport
Dahle, Pål; Fjellvoll, Bjørn; Georgsen, Frode; Hauge, Ragnar; Kolbjørnsen, Odd; Syversveen, Anne Randi og Ulvmoen, Marit. (2012).
CRAVA User Manual version 1.1.
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Rapport
Abrahamsen, Petter; Dahle, Pål og Skorstad, Arne. (2012).
A Fast and Consistent Geostatistical Approach for Constraining 3D Structural Models to Horizontal Wells. EAGE - European Association of Geoscientists & Engineers
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Vitenskapelig foredrag
Vis sammendrag
The use of horizontal well data in 3D reservoir modeling has become an increasingly important task as the use of horizontal wells has become common practice. Standard gridding approaches are based on the use of well picks to define the positions of stratigraphic surfaces along well bores. Horizontal wells however, are often drilled almost parallel to the stratigraphic layering so the number of horizons intersected along a horizontal well can be relatively few. Therefore, horizontal sections of the well can be used to constrain the structural position of reservoir zones. A robust, geostatistical approach has been developed to ensure consistent use of horizontal well data in the construction of 3D structural models. Kriging is used for prediction of surface location based on well picks and constraints obtained from zone logs along horizontal wells. In contrast to standard approaches, all well data (picks and constraints) from all surfaces are treated simultaneously and will have impact on all surfaces above and below. The geostatistical approach is fast and reproducible, and allows structural models to be updated continuously as new wells are drilled. The uncertainty can be evaluated by kriging error maps or by generating stochastic realizations that honor all the well data.
Almendral-Vazquez, Ariel; Dahle, Pål; Abrahamsen, Petter; Georgsen, Frode og Myrseth, Inge Bjørn. (2011).
Cohiba user manual Version 2.5.
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Rapport
Almendral-Vazquez, Ariel; Abrahamsen, Petter; Dahle, Pål; Georgsen, Frode og Myrseth, Inge Bjørn. (2011).
COHIBA user manual - Version 2.4.
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Rapport
Almendral-Vazquez, Ariel; Dahle, Pål; Abrahamsen, Petter; Georgsen, Frode og Myrseth, Inge Bjørn. (2011).
COHIBA user manual - Version 2.3.
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Rapport
Dahle, Pål; Fjellvoll, Bjørn; Georgsen, Frode; Hauge, Ragnar; Kolbjørnsen, Odd; Syversveen, Anne Randi og Ulvmoen, Marit. (2011).
CRAVA User Manual version 1.1.
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Rapport
Abrahamsen, Petter; Almendral-Vazquez, Ariel; Dahle, Pål; Georgsen, Frode og Myrseth, Inge. (2011).
Cohiba user manual version 3.0.
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Rapport
Almendral-Vazquez, Ariel; Dahle, Pål; Abrahamsen, Petter; Skorstad, Arne; Georgsen, Frode og Myrseth, Inge. (2010).
COHIBA user manual — Version 2.1.
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Rapport
Nivlet, Phillippe; Ng, Sebastian; Hetle, Mari -Anne; Hauge, Ragnar; Dahle, Pål og Kolbjørnsen, Odd. (2010).
Integration of seismic data and uncertainties in the facies model; application to the Snorre field.
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Vitenskapelig foredrag
Abrahamsen, Petter; Dahle, Pål; Georgsen, Frode og Skorstad, Arne. (2010).
A Consistent Geostatistical Approach for Constraining Multiple Surfaces to Horizontal Wells.
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poster
Almendral-Vazquez, Ariel; Dahle, Pål; Abrahamsen, Petter; Skorstad, Arne; Georgsen, Frode og Myrseth, Inge. (2010).
COHIBA user manual - Version 2.0.
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Rapport
Dahle, Pål; Fjellvoll, Bjørn; Hauge, Ragnar; Kolbjørnsen, Odd; Syversveen, Anne Randi og Ulvmoen, Marit. (2010).
CRAVA USer Manual version 0.9.6.
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Rapport
Almendral-Vazquez, Ariel; Dahle, Pål; Abrahamsen, Petter; Skorstad, Arne; Georgsen, Frode og Myrseth, Inge. (2010).
COHIBA user manual — Version 2.2.
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Rapport
Abrahamsen, Petter; Almendral-Vazquez, Ariel; Dahle, Pål; Skorstad, Arne og Georgsen, Frode. (2009).
COHIBA — Technical Documentation.
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Rapport
Almendral-Vazquez, Ariel; Dahle, Pål; Abrahamsen, Petter; Skorstad, Arne og Georgsen, Frode. (2009).
COHIBA user manual version 1.4.1.
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Rapport
Dahle, Pål; Helgaker, T; Jonsson, Dan Johan og Taylor, PR. (2008).
Second-order Moller-Plesset calculations on the water molecule using Gaussian-type orbital and Gaussian-type geminal theory.
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The Gaussian-type orbital and Gaussian-type geminal (GGn) model is applied to the water molecule, at the level of second-order Møller–Plesset (MP2) theory. In GGn theory, correlation factors are attached to all doubly-occupied orbital pairs (GG0), to all doubly-occupied and singly-excited pairs (GG1), or to all orbital pairs (GG2). Optimizing the GG2 model using a weak-orthogonality functional, we obtain the current best estimate of the all-electron MP2 correlation energy of water, −361.95 mEh. In agreement with previous observations, the GG1 model performs almost as well as the GG2 model (−361.26 mEh), whereas the GG0 model is poorer (−351.36 mEh). For the barrier to linearity of water, we obtain an MP2 correlation contribution of −463 ± 5 cm−1.
Ng, Sebastian; Dahle, Pål; Hauge, Ragnar og Kolbjørnsen, Odd. (2008).
Estimation of facies probabilities on the Snorre field using AVA inversion.
NVA
Vitenskapelig foredrag
Abrahamsen, Petter; Almendral-Vazquez, Ariel; Dahle, Pål og Skorstad, Arne. (2008).
COHIBA - Technical Documentation.
NVA
Rapport
Dahle, Pål og Almendral-Vazquez, Ariel. (2008).
Surface modelling of the Troll field using COHIBA.
NVA
Rapport
Abrahamsen, Petter; Vazquez, Ariel Almendral og Dahle, Pål. (2008).
COHIBA course.
NVA
Faglig foredrag
Helgaker, Trygve; Dahle, Pål; Jonsson, Dan og Taylor, Peter R.. (2007).
Explicit Correlation by a Combined Use of Gaussian-Type Orbitals and Gaussian-Type Geminals.
NVA
Vitenskapelig foredrag
Helgaker, Trygve; Helgaker, Trygve; Dahle, Pål; Jonsson, Dan og Taylor, Peter R.. (2007).
Quantum-Chemical Calculations Using Gaussian-Type Orbital and Gaussian-Type Geminal Basis Sets. Quantum Theory Project, University of Florida
NVA
Vitenskapelig foredrag
Dahle, Pål; Helgaker, T; Jonsson, D og Taylor, PR. (2007).
Accurate quantum-chemical calculations using Gaussian-type geminal and Gaussian-type orbital basis sets: applications to atoms and diatomics.
Dahle, Pål; Helgaker, Trygve; Jonsson, Dan og Taylor, Peter R.. (2007).
Accurate quantum-chemical calculations using Gaussian-type geminal and Gaussian-type orbital basis sets: application to atoms and diatomics.
NVA
Vitenskapelig artikkel
Dahle, Pål; Hauge, Ragnar; Kolbjørnsen, Odd; Rossa, Ernesto Della; Luoni, Fabio og Marini, Alfonso Junio. (2007).
Geostatistical AVO Inversion on a Deep-water Oil Field.
NVA
Vitenskapelig foredrag
Almendral-Vazquez, Ariel; Dahle, Pål; Abrahamsen, Petter og Skorstad, Arne. (2007).
COHIBA user manual.
NVA
Rapport
Helgaker, Trygve; Helgaker, Trygve; Dahle, Pål; Jonsson, Dan og Taylor, Peter R.. (2007).
Quantum-chemical calculations with Gaussian-type orbital and geminal basis sets. Dansk Kemisk Forening
NVA
Vitenskapelig foredrag
Dahle, Pål; Hauge, Ragnar; Kolbjørnsen, Odd og Pham, Nam Hoai. (2006).
Geostatistical AVO inversion on Smørbukk Sør.
NVA
Vitenskapelig foredrag
Abrahamsen, Petter; Almendral-Vazquez, Ariel; Dahle, Pål; Skorstad, Arne og Soleng, Harald Heimtun. (2006).
Cohiba 0.2 Specification and design document.
NVA
Rapport
Dahle, Pål; Hauge, Ragnar og Kolbjørnsen, Odd. (2006).
Geostatistical Inversion Using the CRAVA Program.
NVA
Rapport
Dahle, Pål; Kolbjørnsen, Odd og Abrahamsen, Petter. (2005).
When can shape and scale parameters of a 3D variogram be estimated?
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Vitenskapelig Kapittel/Artikkel/Konferanseartikkel
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We have used a method of least squares to fit full 3D variogram models to data, and have tested it on data taken from Gaussian random fields. The empirical variogram estimates are made using various lag grid definitions and the best of these grids is identified. Our results suggest that some 200 vertical wells are needed for obtaining reliable estimates of the azimuth and dip anisotropy angles, while some 50 wells seem sufficient for the horizontal ranges and the sill. For the vertical range 10 wells are sufficient.
Soleng, Harald Heimtun; Dahle, Pål og Sperre, Thomas. (2005).
Structural Uncertainty Modelling using Havana, Horizon and RMS: a Field Study.
NVA
Rapport
Pham, Nam Hoai; Basire, Christophe; Lia, Oddvar; Dahle, Pål og Hauge, Ragnar. (2005).
CRAVA inversion and its application into geomodelling: Experiences and recommendations from a case study on the Smørbukk field.
NVA
Fagartikkel
Dahle, Pål; Hauge, Ragnar; Kolbjørnsen, Odd og Pham, Nam Hoai. (2005).
Bayesian AVO Inversion and Application to a Case Study.
NVA
Vitenskapelig foredrag
Dahle, Pål. (2004).
Uncertainty modelling og the Vilje oil reservoir usign the Horizon program.
NVA
Rapport
Dahle, Pål. (2004).
Surface modelling of the Oseberg field using the HORIZON program: A technical documentation.
NVA
Rapport
Dahle, Pål. (2003).
Uncertainty modelling og the Ormen Lange gas reservoir: Technical documentation.
NVA
Rapport
Dahle, Pål; Hauge, Ragnar og Skorstad, Arne. (2002).
Optimizing geological input to Eclipse: Ranking 3D model realizations using well pressures in Lunde fm., Snorre field.
NVA
Rapport