TERRASYS Geophysics


TERRASYS Geophysics

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Geisler O.,TERRASYS Geophysics | Smilde P.,TERRASYS Geophysics | Ballesteros R.,Geoprocesados | Garcia I.,Geoprocesados | Salazar H.,PEMEX
1st EAGE/ACGGP Latin American Geophysics Workshop | Year: 2012

For an integrated multi-technology interpretation study in the Gulf of Mexico aiming to increase imaging quality and geological reliability, 2D/3D gravity and magnetic modeling, inversion and joint visualization of seismic and additional constraining data is applied. In a combined interpretation approach existing depth models are updated, refined and improved regarding geometries and geophysical properties as velocity, density and susceptibility, with focus on salt features as main imaging problem zones. As a result of this study an improved salt geometry could be delivered for PSDM, optimizing the seismic imaging on the 2D profiles. Also areas of differing model conceptions in gravity/magnetic and seismic interpretation were identified and adjusted. Thus a more reliable regional structural concept was achieved.

Mueller C.,Terrasys Geophysics | Smilde P.L.,Terrasys Geophysics | Krieger M.H.,Terrasys Geophysics
74th European Association of Geoscientists and Engineers Conference and Exhibition 2012 Incorporating SPE EUROPEC 2012: Responsibly Securing Natural Resources | Year: 2012

Limited calculation ranges induce errors in gravity modelling that may become quite large by disadvantageous (but still likely) density distributions. Generally valid statements regarding the required calculation range always have to be based on the density distribution with the strongest differential effect possible. With the methodology presented, the necessary calculation range can be determined for a specific density distribution of a project. This is done by determining the differential gravity effect of the external volume on any pair of points within the area of interest. If long wavelength components of these differences can be assimilated by a regional trend, they do not have to be eliminated by an increased calculation range. To shorten calculation times, with a similar approach a limiting distance and depth can be determined, for calculating gravity by line or point masses instead of prisms. With these controlled simplifications, even large model areas can be computed with the required accuracy within acceptable times; especially for joint forward and inverse modelling of Gz and gravity gradient data in the context of complex geological models and/or finely discretised density distributions.

Geisler O.,TERRASYS Geophysics | Muller C.,TERRASYS Geophysics | Krieger M.H.,TERRASYS Geophysics | Ballesteros R.,Geoprocesados | Salazar H.,PEMEX
75th EAGE Conference and Exhibition Incorporating SPE EUROPEC 2013 | Year: 2013

Within the scope of multi-technology interpretation projects in Mexico and the Gulf of Mexico, gravity, gravity gradient and magnetic data are jointly modelled and inverted. This iterative seismic and non-seismic interpretation process improves the geological depth model, focusing on salt features as main imaging problem zones. Analysing well logging data results in regionally valid, layer specific density-velocity relations which enable an independent gravity-based control of the seismic velocity model. This results in a final increase of seismic imaging quality.

Krieger M.H.,Terrasys Geophysics | Becker V.,Terrasys Geophysics | Petersen S.,Terrasys Geophysics
EAGE/SPE Subsalt Imaging Workshop 2014: Challenges of Subsalt Exploration and Imaging in the Middle East and North Africa Deep Water | Year: 2014

For successful salt and subsalt modeling in complex geological settings a flexible multidisciplinary approach is required that integrates all information available. Because of the often significant density (and velocity) contrasts between salt and sediment, gravity (gradient) modeling and inversion tools are favorable. The paper highlights some of the necessary ingredients and the respective interactions between the gravity model and its constraints during interpretation, aiming to achieve a quantitative optimization of the salt/subsalt model as well as improved imaging quality of the seismic cube. Results are encouraging to further develop advanced interpretation techniques.

Smilde P.L.,Terrasys Geophysics | Mueller C.,Terrasys Geophysics | Krieger M.H.,Terrasys Geophysics
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

A method for removing the (regional) trend from gravity data is proposed. Firstly the optimal way of separating the strictly regional trend from the trend of a locally defined model in case of a general filtering method is discussed. Secondly the special application of trend separation by layers of point masses is proposed, to preserve some important properties of the Newtonian law of gravity inside this filtering process. Finally the inherent limitations of trend separation are discussed.

Smilde P.L.,TERRASYS Geophysics | Krieger M.H.,TERRASYS Geophysics
72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010 | Year: 2010

Fully Bouguer reduced gravity data cannot be assumed to be located at the reduction level. After the effect of the topography has been removed by Bouguer and terrain reduction, performing the normal field reductions may be interpreted as a virtual movement inside the normal field down to the reduction level. But this movement does not take into account the effect of the mass anomaly. There are two ways to handle this issue: Either by modelling at original varying observation heights or by applying a vertical field continuation to a constant level. Advantages and disadvantages of different approaches are discussed. © 2010, European Association of Geoscientists and Engineers.

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