The Westernmost Tethys Blog Geology mapping, basin analysis and 3D modeling

01/29/2020

Compactation in sedimentary basins

Filed under: basin analysis,simulation — Tags: , , — messinianalicante @ 8:59 AM

Subsidence analysis is an important technique in the study of sedimentary basins but the effects of compaction must be “backstripped”. The compaction of sediments is also of importance for petroleum and water reservoir research with very important economic derivations. Most methods for calculating compaction are based on empirically derived porosity-depth relationships from a variety of known sediment types. The challenge of this paper is to apply alternative methods for calculating compaction in sedimentary basins based on: physical calculation with elastic by Steinbrenner, oedometric and change of the specific weight of the sediment methods; and use of Loadcap software.

The Triassic to Lower Miocene 3025m thick succession of Sierra Espuña (SE Spain) is used as case study for the calculations. In this succession former mineralogical studies and apatite fission-track suggested an original thickness between 4 and 6km. The validity of each one of the proposed methods is discussed, as well as, compared for the whole succession compaction but also separately for hard vs soft sediments and for thick vs thin beds.

Accumulate thickness-age (My) graphic with the comparative of the measured thickness and the results of original accumulate thickness along time of the studied succession after decompaction with the whole methods. The mean thickness with the whole methods is also represented with dash line. Key: ESM: elastic by Steinbrenner; SWM: specific weight of the sediment methods; OM: oedometric method; PCM: porosity change method (Bond et al., 1983); LSM: use of Loadcap software method.

The compaction values obtained with the alternative methods are similar to those resulting with the lower-limit curves of the porosity-depth change method. The new methods have provided values slightly higher than 4km for the whole original thickness using the geotechnical software and the change of the sediments specific weigh methods; meanwhile values below 4km for other methods. So, in our opinion, the geotechnical software and the change of the specific weight of the sediment methods are compatible with mineralogical constraints and also, the input data are usually better known and easier to determinate. Otherwise, the elastic method seems only accurate for soft sediments; meanwhile the oedometric method is highly influenced by the thickness of the considered beds.

 

Cite as: Martín-Martín, M., and Robles-Marín, P. (2020): Alternative methods for calculating compaction in sedimentary basins. Mar. Pet. Geol. 113, 104132. doi: 10.1016/j.marpetgeo.2019.104132

11/19/2019

shallow water stratified simulation

Filed under: simulation — Tags: , — messinianalicante @ 2:28 PM

The computational simulation of shallow stratified fluids is a very active research topic because these types of systems are very common in a variety of natural environments. The simulation of such systems can be modeled using multilayer shallow-water equations but do impose important computational requirements, especially when applied to large domains.

General Purpose Computing on Graphics Processing Units (GPGPU) has become a vivid research field due to the arrival of massively parallel hardware platforms (based on graphics cards) and adequate programming frameworks which have allowed important speed-up factors with respect to not only sequential but also parallel CPU based simulation systems.

In this work we present simulation of shallow stratified fluids with an arbitrary number of layers using GPUs. The designed system does fully adapt to the many-core architecture of modern GPUs and several experiments have been carried out to illustrate its scalability and behavior on different GPU models. We propose a new multilayer computational scheme for an underlying 2D mathematical model. This scheme is capable of handling an arbitrary number of layers. The system adds no overhead when used for two-layer scenarios, compared to an existing 2D system specifically designed for just two layers.

In this image we show a scheme for the initial configuration of a 6 layers simulation, along with a screenshot of the program.

The GPU computes the evolution in time of the interfaces between several layered fluid types (for a given initial configuration) and displays those interfaces as solid surfaces, as soon as the output from each computing step is available. The user can rotate the view interactively, so he can better observe the layers’ evolution.

Here you can view two screen-shots taken from the simulation program while running. First one the initial layers configuration is shown.

Then It is shown the resulting layers configuration after the simulation has been running for some time.

These screen captured videos (see links below) show the simulation program running in real-time, for various scenerarios. You can observe how the user is able to manipulate the view:

https://youtu.be/MXl6b675uXQ

 

Cite as:  Miguel Lastra, Manuel J. Castro Díaz, Carlos Ureña, Marc de la Asunción (2017):  Efficient multilayer shallow-water simulation system based on GPUs. Mathematics and Computers in Simulation, Volume 148, 2018,  48-65. DOI: https://doi.org/10.1016/j.matcom.2017.11.008

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