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We use three-dimensional seismic reflection data and new map-based structural restoration methods to define the displacement history and characteristics of a series of tear faults in the deep-water Niger Delta. Deformation in the deep-water Niger Delta is focused mostly within two fold-and-thrust belts that accommodate downdip shortening produced by updip extension on the continental shelf. This shortening is accommodated by a series of thrust sheets that are locally cut by strike-slip faults. Through seismic mapping and interpretation, we resolve these strike-slip faults to be tear faults that share a common detachment level with the thrust faults. Acting in conjunction, these structures have accommodated a north –south gradient in westward-directed shortening. We apply a map-based restoration technique implemented in Gocad to restore an upper stratigraphic horizon of the late Oligocene and use this analysis to calculate slip profiles along the strike-slip faults. The slip magnitudes and directions change abruptly along the lengths of the tear faults as they interact with numerous thrust sheets. The discontinuous nature of these slip profiles reflects the manner in which they have accommodated differential movement between the footwall and hanging-wall blocks of the thrust sheets. In cases for which the relationship between a strike-slip fault and multiple thrust faults is unclear, the recognition of this type of slip profile may distinguish thin-skinned tear faults from more conventional deep-seated, throughgoing strike-slip faults.
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We present a method of using fault displacement-distance profiles to distinguish fault-bend, shear fault-bend, and fault-propagation folds, and use these insights to guide balanced and retrodeformable interpretations of these structures. We first describe the displacement profiles associated with different end-member fault-related folding models, then provide examples of structures that are consistent with these model-based predictions. Natural examples are imaged in high-resolution two- and three dimensional seismic reflection data sets from the Niger Delta, Sichuan Basin, Sierras Pampeanas, and Cascadia to record variations in displacement with distance updip along faults (termed displacement-distance profiles). Fault-bend folds exhibit constant displacement along fault segments and changes in displacement associated with bends in faults, shear fault-bend folds demonstrate an increase in displacement through the shearing interval, and fault-propagation folds exhibit decreasing displacement toward the fault tip. More complex structures are then investigated using this method, demonstrating that displacement-distance profiles can be used to provide insight into structures that involve multiple fault-related folding processes or have changed kinematic behavior over time. These interpretations are supported by comparison with the kinematics inferred from the geometry of growth strata overlying these structures. Collectively, these analyses illustrate that the displacement-distance approach can provide valuable insights into the styles of fault-related folding.

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Assets within the Appalachian Basin range from conventional clastic and carbonate reservoirs to source rocks of Devonian black shale and Pennsylvanian coal, all of which are fractured.

American Association of Petroleum Geologists (AAPG)
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The quest to establish a commercially viable thermogenic petroleum system in the Tobago Basin continues.

American Association of Petroleum Geologists (AAPG)
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Fracture zones can be critical to improving or creating sufficient porosity and permeability in hydrocarbon reservoirs – with strain, along with lithology and thickness being the major controls.

American Association of Petroleum Geologists (AAPG)
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The central Black Sea Basin of Turkey is filled by more than 9 km (6 mi) of Upper Triassic to Holocene sedimentary and volcanic rocks. The basin has a complex history, having evolved from a rift basin to an arc basin and finally having become a retroarc foreland basin. The Upper Triassic–Lower Jurassic Akgol and Lower Cretaceous Cağlayan Formations have a poor to good hydrocarbon source rock potential, and the middle Eocene Kusuri Formation has a limited hydrocarbon source rock potential. The basin has oil and gas seeps. Many large structures associated with extensional and compressional tectonics, which could be traps for hydrocarbon accumulations, exist.

Fifteen onshore and three offshore exploration wells were drilled in the central Black Sea Basin, but none of them had commercial quantities of hydrocarbons. The assessment of these drilling results suggests that many wells were drilled near the Ekinveren, Erikli, and Ballıfakı thrusts, where structures are complex and oil and gas seeps are common. Many wells were not drilled deep enough to test the potential carbonate and clastic reservoirs of the İnaltı and Cağlayan Formations because these intervals are locally buried by as much as 5 km (3 mi) of sedimentary and volcanic rocks. No wells have tested prospective structures in the north and east where the prospective İnalti and Cağlayan Formations are not as deeply buried. Untested hydrocarbons may exist in this area.

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Outcrops of the Cretaceous high-porosity sandstone of the Southeast Basin, France, show two main types of deformation structures: a large number of small-offset, shear-enhanced cataclastic deformation bands (DBs); and a small number of large (meters to decameters)-offset ultracataclastic fault zones. Microstructural analyses of the cataclastic DBs show that fragmentation produces strands of cataclastic fragment-supported matrix, separated by weakly fractured host rock, which cluster to form the DBs. The ultracataclastic fault zones, however, are composed of a matrix-supported ultracataclasite material. Permeability data show that the DBs reduce host-rock permeability by 0.5 to 2 orders of magnitude, whereas the ultracataclasites reduce permeability by approximately 4 orders. Simple calculations considering the structural frequency, thickness, and permeability of these faults suggest that, although the DBs may have an impact on single-phase flow, it is most likely to be less than a 50% reduction in flow rate in extensional contexts, but it may be more severe in the most extreme cases of structural density in tectonic shortening contexts. The larger ultracataclastic faults, however, despite their much lower frequency, will have a more significant reduction in flow rate, probably of approximately 90 to 95%. Hence, although they are commonly at or below the limit of seismic resolution, the detection and/or prediction of such ultracataclastic faults is likely to be more important for single-phase flow problems than DBs (although important two-phase questions remain). The study also suggests that it is inappropriate to use the petrophysical properties of core-scale DB structures as analogs to larger seismic-scale faults.
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We do not dispute that the pores shown in the photomicrograph of figure 8G of Beavington-Penney et al. (2008; reproduced here as Figure 1) could have formed at least partly by poststylolite dissolution, but we do not agree that this photomicrograph constitutes evidence for porosity creation by mesogenetic dissolution in the El Garia Formation of offshore Tunisia. Our skepticism is based on two main considerations: (1) that the multiple possible origins of the pores shown in Figure 1 cannot be determined with any meaningful degree of objective certainty and (2) that Figure 1 appears to be unrepresentative of pore types in the El Garia Formation, based on comparison with numerous other published images from this unit.
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In the rough terrain of overthrust settings, 2-D seismic data continues to be a standard tool for subsurface mapping – and not only because of economic reasons. Two-D and 3-D seismic surveys are complementary in land environments, because each data type has its own strength and weakness.

American Association of Petroleum Geologists (AAPG)
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Oil production in Nigeria started in 1958 after the discovery of Oloibiri oil field in 1956.

American Association of Petroleum Geologists (AAPG)
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In-Person Training
Vilnius Lithuania 24 October, 2016 25 October, 2016 32641 Desktop /Portals/0/PackFlashItemImages/WebReady/er-gtw-gtw-hydrocarbon-exploration-lithuania-hero.jpg?width=100&height=100&mode=crop&anchor=middlecenter&quality=75amp;encoder=freeimage&progressive=true Business and Economics, Economics, Reserve Estimation, Development and Operations, Engineering, Conventional Drilling, Coring, Production, Hydraulic Fracturing, Primary Recovery, Secondary Recovery, Gas Injection, Tertiary Recovery, Reservoir Characterization, Environmental, Natural Resources, Pollution, Geochemistry and Basin Modeling, Basin Modeling, Maturation, Migration, Oil and Gas Analysis, Oil Seeps, Petroleum Systems, Source Rock, Thermal History, Geophysics, Direct Hydrocarbon Indicators, Petrophysics and Well Logs, Sedimentology and Stratigraphy, Carbonates, Clastics, Conventional Sandstones, Deep Sea / Deepwater, Deepwater Turbidites, High Stand Deposits, Low Stand Deposits, Marine, Shelf Sand Deposits, Transgressive Deposits, Sequence Stratigraphy, Structure, Tectonics (General), Structural Analysis (Other), Salt Tectonics, Geomechanics and Fracture Analysis, Fold and Thrust Belts, Extensional Systems, Compressional Systems, Deep Basin Gas, Fractured Carbonate Reservoirs, Shale Gas, Stratigraphic Traps, Structural Traps, Subsalt Traps, Alternative Resources, Gas Hydrates
 
Vilnius, Lithuania
24-25 October 2016

AAPG Europe are excited to announce the first event to be held in the beautiful capital city of Vilnius, Lithuania. This Geosciences Technology Workshop will be based around the main theme "Hydrocarbon Exploration in Lithuania and the Baltic Region" and we expect interests from Latvia, Estonia, Poland and Kaliningrad.

Lithuania 26 October, 2016 26 October, 2016 33520 Desktop /Portals/0/PackFlashItemImages/WebReady/gtw-er-core-workshop-lithuanian-geological-society-2016-hero.jpg?width=100&height=100&mode=crop&anchor=middlecenter&quality=75amp;encoder=freeimage&progressive=true Alternative Resources, Gas Hydrates, Deep Basin Gas, Fractured Carbonate Reservoirs, Shale Gas, Stratigraphic Traps, Structural Traps, Subsalt Traps, Business and Economics, Economics, Reserve Estimation, Development and Operations, Engineering, Conventional Drilling, Coring, Production, Hydraulic Fracturing, Primary Recovery, Tertiary Recovery, Secondary Recovery, Gas Injection, Water Flooding, Reservoir Characterization, Environmental, Natural Resources, Pollution, Water Resources, Geochemistry and Basin Modeling, Basin Modeling, Migration, Oil and Gas Analysis, Oil Seeps, Petroleum Systems, Source Rock, Thermal History, Geophysics, Direct Hydrocarbon Indicators, Petrophysics and Well Logs, Sedimentology and Stratigraphy, Carbonates, Clastics, Conventional Sandstones, Deep Sea / Deepwater, Deepwater Turbidites, Low Stand Deposits, Marine, Shelf Sand Deposits, Transgressive Deposits, Sequence Stratigraphy, High Stand Deposits, Structure, Fold and Thrust Belts, Extensional Systems, Salt Tectonics, Tectonics (General), Geomechanics and Fracture Analysis, Structural Analysis (Other), Compressional Systems
 
Lithuania
26 October 2016

Join AAPG Europe and the Lithuanian Geological Survey for this exciting Core Workshop. This workshop will follow on from the 'Hydrocarbon Exploration in Lithuania and the Baltic Regions' event taking place at Vilnius University on 24th – 25th October.

The Early Palaeozoic Hydrocarbon System in the Baltic Basin and adjacent territories involves Middle-Late Cambrian, the Late Ordovician (Mossen & Fjacka Formations) and the Early Silurian Graptolitic Shales source rocks and the major complexes of reservoirs, associated with Middle Cambrian sandstones, Ordovician and Silurian reefogenic and carbonate build-ups.

The major reservoirs of the Baltic Basin are:

  • The Middle Cambrian (Deimena Fm). Sandstones - Producing
  • The Early Ordovician (Tremadoc, Salantai Fm.) sandstones
  • Late Ordovician (Early Ashgill) organogenic limestones/carbonate buildups
  • Late Silurian (Late Ludlow/Pridoli) reefogenic carbonate build-ups
Core Presentation:
Cores presented from the following 3 reference wells:

1. The Middle Cambrian - the Early Ordovician quartz sandstone reservoirs

The Middle Cambrian Deimena Group sandstones comprises all the major economically important oil fields located Lithuania, Latvia, Kaliningrad district and Polish onshore and Baltic Sea offshore. The other, much less significant, potential reservoirs are the Late Ordovician carbonate build-ups of Gotland (Sweden) and Southern part of Lithuania and the Late Silurian carbonate reefogenic buildups in South Lithuania (Zdanaviciute O., Sakalauskas J. eds., 2001, Zdanaviciute, Lazauskiene 2007; Kanev et al., 1994).

The reference sections would demonstrate core from fine-grained (dominated by 0.25-0.1 mm fraction (30-75%)) quartz sandstones containing thin clay and siltstone interlayers. The sandstones are to a different degree litified by compaction and predominantly cemented by quartz and diagenetic quartz cement that has the major control on reservoir properties.

The Early Ordovician

The early Ordovician Tremadoc age (Pakerort Regional Stage, Salantai Fm.) strata distributed rather locally are a reservoir unit at the base of the Ordovician succession, comprising quartz sandstones and quartz siltstones of only 0.5 to 4 m thick. It overlays directly to the Middle Cambrian Deimena Group sandstones and together form one reservoir unit with similar reservoir properties. The formation is overlain by the Early Ordovician shales. Several small oil fields are producing from this reservoir unit in the western part of Lithuania.


2. The Late Ordovician (Early Ashgill) and Late Silurian (Late Ludlow/Pridoli) organogenic limestone and reefogenic carbonate buildups reservoirs

The Late Ordovician - The Late Silurian

The reservoir rocks within the Silurian succession are the Wenlock - Early Ludlow and Pridolian reefogenic carbonates comprising secondary dolomites and reefal limestones with thicknesses of tens of meters. Silurian sequences are locally distributed along the Eastern slope of the Baltic Basin. The Wenlockian - Early Ludlow strata are up to 28 m thick; the effective porosity ranges from 12% to 17% and average permeabilities – 12-15 mD. The most favourable conditions for the formation of non-structural traps (reef-associated, lithologic-stratigraphic and combined) are associated with the carbonates (mainly stromoporoidal and crinoidal limestones) sucession of about 90 m thick of the late Ludlow- earliest Pridoli (Minija and Ventspils Formations). The reservoir rocks has mean porosities of 6-15 % and up to 26% and permeability ~465mD, reaching up to 2400mD. The Late Silurian reservoir rocks mainly occur in central and southern Lithuania in the central part of the basin.


3. Late Ordovician (Mossen & Fjacka Formations) and the Early Silurian Llandovery Black Shales

The Late Ordovician Shales

In the central and eastern part of the Baltic Basin the potential source rocks comprises dark grey and black shales of the Late Ordovician Late Caradoc-Early Asghill Fjacka and Mossen formations. Both units are generally thin, reaching only up to 5–10 m; the thicknesses of Fjack & Mossesn Formations are 6 m and 4 m respectively. TOC content are mostly in the 0.9 to 10 % range, with occasional higher values of up to 15 %. The source rock facies are kerogen type II and II-III.

The Early Silurian Shales

Potential source rocks in the Silurian succession are found within the Llandovery, Wenlock and, presumably, Ludlow-aged strata. The Silurian source rocks are composed of dark grey and black graptolite shales and dark grey and black clayey marlstones. Within the Baltic Basin organic matter content generally ranges from 0.7 to 9–11%, but can be as high as 16.46 % (fig. 5.5.b; Zdanaviciute, Lazauskiene, 2004). In terms of petrography, the organic matter is dominated by syngenetic, sapropelic and marine material, together with vitrinite-like particles and abundant faunal remains. Detrital sapropel is scattered as very fine-grained particles and lenses. Liptinite (up to 20%) generally occurs together with dispersed liptodetrinite in sapropelic organic matter, or more rarely as scattered particles. (Zdanavičiūtė, Swadowska 2002, Zdanaviciute, Lazauskiene, 2004, 2007, 2009).

Maturities in the area of interest attain at pre-Silurian level 1.3% Ro and around 1.0% Ro at Silurian source rock level, and reach 1.9% on the prominent West-Lithuanian local temperature high Zdanaviciute, Lazauskiene, 2004, 2007, 2009)

 

Please note registration for the Core Workshop is available to attendees of the upcoming GTW "Hydrocarbon Exploration in Lithuania and the Baltic Region" on the 24th - 25th October 2016. Please click here for information about the event.

 

 

Online Training
19 August, 2010 19 August, 2010 1462 Desktop /Portals/0/PackFlashItemImages/WebReady/oc-es-challenging-the-paradigm-missing-section-normal-fault.jpg?width=100&height=100&mode=crop&anchor=middlecenter&quality=75amp;encoder=freeimage&progressive=true
 
19 August 2010

This presentation will show where there are cases of missing sections, but none of them can be attributed to normal faulting.

14 February, 3000 14 February, 3000 7817 Desktop /Portals/0/PackFlashItemImages/WebReady/oc-es-generic-hero.jpg?width=100&height=100&mode=crop&anchor=middlecenter&quality=75amp;encoder=freeimage&progressive=true
 
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