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Wednesday 18 April 2018  17:00

Monthly Lecture: Petroleum Geology of Trinidad

Organiser: PGK
Lecturer: Harry Doust

Program:
17:00 - 18:00: Social hour
18:00 - 19:00: Lecture by Harry Doust
19:00 onwards (after drinks at own expense at Cafe Hathor)

Abstract:
Trinidad-all geology is there!
How is it that in spite of its small size (barely 5000km2!) the island of Trinidad, situated at the southeastern corner of the Caribbean Sea, has punched so far above its weight in the development of so many geological concepts? From the 16th century onwards natural scientists have been fascinated by its geology and, through the 20th century generations of outstanding geologists, driven by the imperatives of petroleum exploration have worked on unravelling the complex stratigraphy and tectonics: Their success made Trinidad a hugely important strategic source of petroleum in the early part of the century, not least during World-War II. Among the most creative and celebrated of geologists to have worked there were Hans Kugler and Hans Bolli who, in the post-war years made ground-breaking advances in stratigraphic correlation based on planktonic foraminifera, which they then applied to interpreting the complex subsurface thrust structures. In their hands Trinidad became a classic geological laboratory, producing innovative concepts, many of which were years ahead of their time. What impresses the new-comer to the island is how closely structural and stratigraphic developments are linked. Following Mesozoic to Early Tertiary rifting and passive margin cycles, Late Tertiary to Quaternary development has been dominated by compression and wrenching as the eastward progressing collision zone between the South American and Caribbean plates impinged on the area. As a result we see a whole range of geologically young tectonic and  sedimentary features, freshly served for us to examine. In this talk I will review the basin evolution in its regional context and, making use of subsurface interpretations based on surface geology, seismic and well data from petroleum exploration, examine the variety of basin cycle types seen in the country and its surrounding offshore area. Naturally, we will not forget to highlight Trinidad's most famous landmark, the La Brea pitch lake, perhaps the most celebrated oil seepage of all.

Location

KIVI
Prinsessegracht 23
2514 AP
Den Haag
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Wednesday 11 April 2018  18:30

PGK-AAPG YP Lecture: How sweet is your shale?

Organiser: PGK-AAPG YP
Lecturer: Jan ter Heege (TNO)

PGK-AAPG YP event. See YP page for more details.

How sweet is your shale? A story about the uncertain potential, problematic recovery and public concerns of shale gas development in Europe.

Location

Shell HQ
Carel van Bylandtlaan 16
Den Haag
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Downloads

AbstractApr11.docx
excursion
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excursion · lecture · drinks

Wednesday 11 April 2018 - Thursday 24 May 2018  

PGK-AAPG YP - Activities in April & May 2018

Organiser: PGK-AAPG YP

See YP pages for details.

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Wednesday 21 March 2018  17:00

Monthly Lecture: Rock fracturing in the laboratory: Results on fracture propagation in layered media and predicting the onset of fracturing

Lecturer: Auke Barnhoorn

Program:
17:00-18:00 - social drinks
18:00-19:00 - Lecture by Auke Barnhoorn
19:00 onwards (after drinks at own expense at Cafe Hathor)

Auke Barnhoorn is Assistant Professor in Applied Geophysics and Petrophysics, Department of Geoscience and Engineering, Delft University of Technology

Abstract:

Fractures play an important role in the subsurface because they potentially are preferential pathways for fluid flow in naturally fractured reservoirs, they can compartmentalise reservoirs and they play an important role in seismic events. In addition, fractures can be created during well stimulation. In order to accurately predict the efficiency of flow along fractures the characteristics of the formed fracture networks is required. Characteristics such as fracture apertures and fracture orientations are important, but also the connectivity of the formed network. In Delft we focus in our laboratory research on the evolution of the fracture network to predict how fractures grow and connect through heterogeneous rocks and whether we can use seismic monitoring techniques to determine when and where these fractures start to grow.

In this presentation I will show two aspects of the research we are currently performing at TU Delft on experimental rock fracturing. In the first part of the presentation I will show the results on fracture propagation in layered siliciclastic rocks. We have selected various quartz-rich rock types which exhibit a large range of rock strength. By combining those samples we created layered samples in which a large range of mechanical contrast between the layers is present. We show that fractures formed in the weak layer sometimes propagate into the strong layer even at stress conditions in which fracturing of the strong layer was not expected. At other conditions, fractures remain contained within the weak layer. We can know predict at what depths in layered reservoirs this occurs. This has consequences for increased connectivity between layers in a reservoir or in other circumstances loss of integrity of the sealing layer.

The second part of the presentation shows how we use the analysis of the wave forms of acoustic waves that we send through the rock samples while they are fracturing. By analysing the change in wave amplitude of the wave and the scattering potential of the wave, we show that the technique is sensitive enough to detect the formation of the first microfractures in the samples. These first microfractures precede the formation of the large failure planes which are accompanied by the release of seismic energy. It may thus have the potential to be used as a predicting tool to determine the onset of seismicity in materials and reservoirs.

Location

KIVI
Prinsessegracht 23
2514 AP
Den Haag
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Thursday 8 March 2018

PGK/AAPG YP Marcella Dean: Science, Rocks and Roll

Organiser: PGK / AAPG YP
Lecturer: Marcella Dean

See the YP page for details.

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Wednesday 7 March 2018  17:00 - 19:00

PGK Utrecht (Mara van Eck van der Sluijs & Peter Fokker @ EBN office)

Lecturer: Mara van Eck van der Sluijs and Peter Fokker

Program:

17:00 - 18:00: registration and drinks at EBN bar
18:00 - 19:00: lectures by Mara van Eck van der Sluijs and Peter Fokker
19:00 onwards: drinks at a nearby location (TBD)

Lectures:

Mitigation of induced seismicity in Dutch geothermal systems - Presented by Mara van Eck van der Sluijs, DAGO

Abstract
Induced seismicity is a hot topic in the Netherlands, especially in the Groningen gas field. Here seismicity is caused by pressure depletion due to gas extraction. In geothermal energy, the overall pressure in the subsurface doesn't change due to the mining of energy, but there are other mechanisms which can induce seismicity. The lack of interwell pressure communication, injection of water in active fault zones and fraccing are all threats which can lead to induced seismicity. Mitigation of these threats is essential to prevent damage. These mitigation barriers can be preventive or a responsive management system.
In this talk I will guide you through the threats and mitigation measures, but will also discuss the knowledge gap we still have.

Harmonic pulse testing as a monitoring tool during hydraulic stimulation of an EGS - Presented by Peter Fokker (TNO)

Abstract
Reliable monitoring techniques are essential both for the economics of geothermal operations and for their safety. Classical examples are seismic monitoring of induced (micro-)seismicity, and well testing. Seismicity is related to the production and injection dynamics during operations. Well testing is related to the static flow properties of a reservoir and its interpretation is usually limited to the period that flow rates are zero. In this presentation I will discuss harmonic pulse testing, a technology that has similar capabilities as regular well testing but that can be employed during ongoing operations. A test of this technique was carried out during an EGS stimulation operation in Pohang, South Korea. No seismicity was observed during the test, but we did see an increase of injectivity during the stimulation treatment. The main value was the demonstration of harmonic pulse testing as a monitoring technology.

Location

EBN head office
Daalsesingel 1
3511 SV
Utrecht
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Wednesday 21 February 2018  17:00 - 19:00

PGK Lecture and AGM: Peter Mesdag - CGG GeoSoftware - A new approach to quantitative azimuthal inversion for stress and fracture detection. Working with effective elastic parameters in anisotropic media.

Organiser: PGK
Lecturer: Peter Mesdag CGG Geosoftware

Programme 21st February 2018:
17:00 - 18:00: Social hour
18:00 - 18:30: Lecture
18:30 - 19:00: AGM
19:00 onwards buffet reception at Hathor

A new approach to quantitative azimuthal inversion for stress and fracture detection.
Working with effective elastic parameters in anisotropic media.

Peter Mesdag - CGG GeoSoftware, The Hague, Netherlands

Exploration and development of unconventional reservoirs, where fractures and in-situ stress play a key role, calls for improved characterization workflows. The effects of anisotropy on the estimated reservoir parameters can no longer be ignored. In this work, we present a method for quantitative estimation of anisotropic parameters related to stress and fracture detection that makes use of standard isotropic modeling and inversion techniques in anisotropic media. Based on reflectivity equations for TI media, we build a set of transforms that map the elastic parameters used in prestack inversion into effective anisotropic elastic parameters. When used in isotropic forward modeling and inversion, these effective parameters accurately mimic the anisotropic reflectivity behavior of the seismic data, thus closing the loop between well log data and seismic inversion results in the anisotropic case.
Here we show that using these effective elastic parameters in isotropic modeling we produce exactly the same synthetics as when using more complex anisotropic modeling.
When estimates of the Thomsen parameters are known at well control, isotropic well measurements can be transformed into effective elastic parameters. This allows for more accurate well tying and wavelet estimation, and also for quantitative post-inversion analysis.
Results from azimuthally sectored inversions are analyzed through Fourier techniques to produce measures of anisotropy magnitude and orientation. Assuming an underlying model these quantitative measures can be transformed into measures of fracture density, rock weakness or stress.
After a brief introduction the power of this proposed method will be illustrated by means of a feasibility study. Here the importance of an Azimuthal Low Frequency Model (ALFM) will become evident.

Biography

Dr Ir P.R. Mesdag received a B.Sc (1980), M.Sc (1980) and Ph.D (1985) in Physics from the Delft University of Technology in the Netherlands. He started working for Jason Geosystems in 1986 and has over 32 years experience in the development and application of advanced, quantitative data analysis techniques including inversion, geostatistics, wavelet estimation, modelling and reservoir characterization. In his 32 year career with Jason he has undertaken a wide range of on-site and off-site client projects with oil and gas companies throughout the world, utilizing the full range of technologies available in the Jason Geoscience Workbench. Currently he is technical product manager for Deterministic Reservoir Characterization at CGG.

Location

KIVI
Prinsessegracht 23
2514 AP
The Hague
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Wednesday 17 January 2018  17:00 - 19:00

PGK Monthly Lecture: Unfaulting, unfolding and unconformities in the Schoonebeek Oil Field, the Netherlands

Lecturer: Kees W. Rutten

Program Wednesday 17th January, 2018 : 17:00-18:00 Social hour; 18:00-19:00 Lecture

Unfaulting, unfolding and unconformities in the Schoonebeek Oil Field, the Netherlands

Kees W. Rutten Slokkert Consultancy; slokkert@xs4all.nl

Abstract
We have applied the Landmark ezValidator software on the 2005 NAM high-resolution seismic survey of the Schoonebeek oil field to clarify the stratigraphic relationships of the Early Cretaceous Bentheim Sandstone Member reservoir unit to its underlying and overlying successions. ezValidator (www.slokkert.nl) provides a view of the seismic after restoration, i.e. unbroken by faults, and unfolded on one or more horizons. Unconformities can be shown as gaps representing missing section.

The original seismic survey was post-processed using a Structural Oriented Filter for noise reduction (Fig. 1). Three major unconformities are shown in the restored section (Fig. 2). The unconformity gaps are determined by the unfolding of seven horizons, using a top and a base horizon for each unconformity. This display can be interpreted like a Wheeler diagram.

The deepest, Late Jurassic unconformity (Weiteveen-C; Atlantic break-up) shows little missing section in the center and major erosion on the sides. The center part apparently subsided prior to the unconformity, protecting the sediments locally. In addition, there might be several other unconformities just above and below the mapped Weiteveen-C level.

The base-Bentheim unconformity shows substantial erosion of the underlying Coevorden Formation towards the NE side and limited erosion on the SW flank. The Coevorden Formation was protected by subsidence on the SW flank prior to unconformity time. On the NE side, above the unconformity, sediment formed a wedge onlapping onto the unconformity.

Two complementary displays provide more detail of the base-Bentheim unconformity. The first display (Fig. 3) highlights the paleostructure by unfolding the unconformity itself, assuming that the unconformity peneplenated the underlying succession. This shows the paleostructure of the subsided SW flank of the Coevorden Formation. The second display (Fig. 4) highlights the interaction of the stratigraphy by unfolding on a horizon above and a horizon below, while the unconformity itself is shown as a gap determined by the unfolding space requirements. This shows the onlapping wedge on the NE side really well. By mapping thickness variations and seismic reflection terminations in these structural and stratigraphic displays the relative timing and onlap/offlap/erosion relationships of the sediments above and below the unconformity can be defined.

The Paleocene unconformity (Fig. 1) shows the Late Cretaceous uplift and Early Tertiary erosion in the center. Towards both flanks the earlier sediments were protected. The bowl-shaped unconformity gap is the opposite of the butterfly-shaped gap of the Weiteveen-C unconformity.

Location

KIVI
Prinsessegracht 23
2514 AP
Den Haag
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