scholarly journals Thrust Faults Promoted Hydrocarbon Leakage at the Compressional Zone of Fine-Grained Mass-Transport Deposits

2021 ◽  
Vol 9 ◽  
Author(s):  
Qiliang Sun ◽  
Xinong Xie ◽  
Shiguo Wu ◽  
Guorui Yin
Keyword(s):  
Fluid Flow ◽  
Mass Transport ◽  
Northern South China Sea ◽  
Coarse Grained ◽  
Thrust Faults ◽  
Borehole Data ◽  
Fine Grained ◽  
Hydrocarbon Reservoir ◽  
Effective Seal ◽  
Mass Transport Deposits

Fine-grained mass-transport deposits (MTDs), especially their compressional toe zones, are traditionally considered as effective seal in constraining the vertical fluid migration underneath. However, this study documents thrust faults at the compressional toe zone of fine-grained MTDs that could disaggregate the seal competence and promote vertical fluid flow. The investigated MTD referred to as MTD-a lies directly over a large hydrocarbon reservoir that is located within the Central Canyon of northern South China Sea, which is examined by using high-resolution 3D seismic and borehole data. Thrust faults and irregular blocks composed of coarse-grained sandstones are observed in the compressional zone of the MTD-a’s toe. More importantly, seismic evidence (e.g., enhanced seismic reflections) suggests that a large amount of hydrocarbons from the underlying reservoir penetrated through the MTD-a along these thrust faults and charged into the coarse-grained sandstone blocks. This clear evidence of thrust faults compromising the MTD’s seal effectiveness and thus facilitating the vertical fluid flow through the non-permeable strata demonstrate the importance of reassessing the seal capacity of MTD.

Mass transport deposits and processes in the north slope of the Xisha Trough, northern South China Sea

2015 ◽  
Vol 34 (9) ◽  
pp. 117-125 ◽  
Author(s):  
Zhiliang Qin ◽  
Shiguo Wu ◽  
Dawei Wang ◽  
Wei Li ◽  
Shaojun Gong ◽  
...  
Keyword(s):  
South China Sea ◽  
Mass Transport ◽  
South China ◽  
Northern South China Sea ◽  
North Slope ◽  
China Sea ◽  
The North ◽  
Mass Transport Deposits ◽  
Xisha Trough

Characteristics and origins of ridges and troughs on the top of the Middle Miocene strata in the Beijiao sag of the Qiongdongnan basin, northern South China Sea

2020 ◽  
pp. 1-57
Author(s):  
Yufeng Li ◽  
Renhai Pu ◽  
Gongcheng Zhang ◽  
Hongjun Qu
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Middle Miocene ◽  
Northern South China Sea ◽  
Qiongdongnan Basin ◽  
Coarse Grained ◽  
Bottom Currents ◽  
Fine Grained ◽  
Sediment Waves ◽  
History Of

Sedimentary structures generated by bottom currents are poorly understood worldwide. Ridges and troughs are imaged for the first time by 3D high-resolution seismic data and drilled by a well, YL19-1-1, in the Beijiao sag of Qiongdongnan basin (QDNB). Combined with 2D high resolution seismic data, they are analyzed in detail. The results show that ridges and troughs occur on the top of the Middle Miocene, dominantly present a wave-shaped structure. Their magnitudes are larger on the middle (regional) slope than on the upper and lower slope. They extend for tens of kilometers, dominantly parallel to one another, evenly spaced and nearly E-W directed distribution, some of which locally merge and bifurcate. They are aligned oblique to the regional slope. Both internal mounded reflections and parallel underlying-strata reflections, occur within ridges. The presence of polygonal faults and weak-to-moderate amplitudes within the ridges and troughs, suggests that they consist of fine-grained mudstones, as confirmed by well YL19-1-1. High amplitudes filled within troughs are probably composed of coarse-grained turbidite sandstones where polygonal faults are inhibited. Truncated reflections and onlaps occur along the thalweg of a trough, and are also clearly observed on the sides of ridges and troughs. We conclude the troughs are a product of erosion of bottom currents, and ridges are remnant underlying (sediment waves) strata as a result of this erosion. Besides, troughs are filled by turbidite sandstones with high amplitudes in the southwestern part of the study area, where ridges and troughs a combined result of early erosion by bottom currents and later reworking by turbidity flows. Conceptual schematic models are proposed to show the evolutionary history of ridges and troughs. This study provides new insights into further understanding of erosion and deposition of bottom currents.

Low permeability Neogene lithofacies in Northern Croatia as potential unconventional hydrocarbon reservoirs

2014 ◽  
Vol 6 (2) ◽  
Author(s):  
Tomislav Malvić ◽  
Antonija Sučić ◽  
Marko Cvetković ◽  
Filip Resanović ◽  
Josipa Velić
Keyword(s):  
Pannonian Basin ◽  
Interesting Case ◽  
Coarse Grained ◽  
Low Permeability ◽  
Water Contact ◽  
Fine Grained ◽  
Hydrocarbon Reservoir ◽  
Definition Of ◽  
Northern Croatia ◽  
Migration Pathways

AbstractWe present two examples of describing low permeability Neogene clastic lithofacies to outline unconventional hydrocarbon lithofacies. Both examples were selected from the Drava Depression, the largest macrostructure of the Pannonian Basin System located in Croatia. The first example is the Beničanci Field, the largest Croatian hydrocarbon reservoir discovered in Badenian coarse-grained clastics that consists mostly of breccia. The definition of low permeability lithofacies is related to the margins of the existing reservoir, where the reservoir lithology changed into a transitional one, which is mainly depicted by the marlitic sandstones. However, calculation of the POS (probability of success of new hydrocarbons) shows critical geological categories where probabilities are lower than those in the viable reservoir with proven reserves. Potential new hydrocarbon volumes are located in the structural margins, along the oil-water contact, with a POS of 9.375%. These potential reserves in those areas can be classified as probable. A second example was the Cremušina Structure, where a hydrocarbon reservoir was not proven, but where the entire structure has been transferred onto regional migration pathways. The Lower Pontian lithology is described from well logs as fine-grained sandstones with large sections of silty or marly clastics. As a result, the average porosity is low for conventional reservoir classification (10.57%). However, it is still an interesting case for consideration as a potentially unconventional reservoir, such as the ”tight” sandstones.

scholarly journals Geostatistical characterization of internal structure of mass-transport deposits from seismic reflection images and borehole logs

2019 ◽  
Vol 221 (1) ◽  
pp. 318-333
Author(s):  
Jonathan Ford ◽  
Angelo Camerlenghi
Keyword(s):  
Mass Transport ◽  
Internal Structure ◽  
Seismic Reflection ◽  
Slope Failure ◽  
Random Medium ◽  
Seismic Facies ◽  
Strain History ◽  
Borehole Data ◽  
Mass Transport Deposits ◽  
Scale Length

SUMMARY Seismic reflection images of mass-transport deposits often show apparently chaotic, disorded or low-reflectivity internal seismic facies. The lack of laterally coherent reflections can prevent horizon-based interpretation of internal structure. This study instead inverts for geostatistical parameters which characterize the internal heterogeneity of mass-transport deposits from depth-domain seismic reflection images. A Bayesian Markov Chain Monte Carlo inversion is performed to estimate posterior probability distributions for each geostatistical parameter. If the internal heterogeneity approximates an anisotropic von Kármán random medium these parameters can describe the structural fabric of the imaged mass-transport deposit in terms of lateral and vertical dominant scale lengths and the Hurst number (roughness). To improve the discrimination between vertical and lateral dominant scale lengths an estimate of the vertical dominant scale length from a borehole is used as a prior in the inversion. The method is first demonstrated on a synthetic multichannel seismic reflection image. The vertical and lateral dominant scale lengths are estimated with lower uncertainty when data from a synthetic borehole data are included. We then apply the method to a real data example from Nankai Trough, offshore Japan, where a large mass-transport deposit is imaged in a seismic profile and penetrated by a borehole. The results of the inversion show a downslope shortening in lateral scale length, consistent with progressive down-slope disaggregation of the mass-flow during transport. The dominant scale lengths can be used as a proxy for strain history, which can improve understanding of post-failure dynamics and emplacement of subacqueous mass-movements, important for constraining the geohazard potential from future slope failure.

scholarly journals Morphology and spatio-temporal distribution of lacustrine mass-transport deposits in Wörthersee, Eastern Alps, Austria

2019 ◽  
Vol 500 (1) ◽  
pp. 235-254 ◽  
Author(s):  
Christoph Daxer ◽  
Maddalena Sammartini ◽  
Ariana Molenaar ◽  
Thomas Piechl ◽  
Michael Strasser ◽  
...  
Keyword(s):  
Mass Transport ◽  
Temporal Distribution ◽  
Late Glacial ◽  
Eastern Alps ◽  
Excess Pore Pressure ◽  
European Alps ◽  
Fine Grained ◽  
Spatio Temporal ◽  
Morphological Differences ◽  
Mass Transport Deposits

AbstractIn lakes, landslides can be studied in high resolution due to their accessibility and limited size. Here, we investigate mass-transport deposits in glacigenic Wörthersee (Eastern European Alps) by integration of seismic, sediment core and multibeam bathymetric data. Two outstanding landslide events were revealed: the first occurred in the Late Glacial, leading to multiple deposits of up to 15 m thickness; they consist of sandy turbidites and mudclast conglomerates, which are overlain by a 2.5 m thick megaturbidite. The extensive, likely earthquake-triggered failure linked to this event was preconditioned by rapid sedimentation of fine-grained glaciolacustrine sediments and associated build-up of excess pore pressure. The second event was presumably triggered by a major earthquake (Mw≈7) in AD 1348 and comprises a mass-transport complex and several landslides, which led to a c. 30 cm thick turbidite. In total, 62 landslides are imaged in the multibeam map, 6 of which are most likely human-induced. Some of these show horseshoe-type compressional ridges and frontal breaching, whereas others exhibit an extensive zone of rafted blocks. We attribute these morphological differences to four main factors: (1) slope gradient and changes therein; (2) preconditioning of the impacted zone; (3) volume of remobilized sediment; and (4) type of impactor.

scholarly journals Exotic clasts, debris flow deposits and their significance for reconstruction of the Istebna Formation (Late Cretaceous – Paleocene, Silesian Basin, Outer Carpathians)

2017 ◽  
Vol 68 (6) ◽  
pp. 562-582 ◽  
Author(s):  
Piotr Strzeboński ◽  
Justyna Kowal-Kasprzyk ◽  
Barbara Olszewska
Keyword(s):  
Mass Transport ◽  
Carbonate Platform ◽  
Sedimentary Cover ◽  
Source Area ◽  
Transport Processes ◽  
Coarse Grained ◽  
Tectonic Activity ◽  
Depositional System ◽  
Outer Carpathians ◽  
Mass Transport Deposits

AbstractThe different types of calcareous exotic clasts (fragments of pre-existing rocks), embedded in the Paleocene siliciclastic deposits of the Istebna Formation from the Beskid Mały Mountains (Silesian Unit, Western Outer Carpathians), were studied and differentiated through microfacies-biostratigraphical analysis. Calcareous exotics of the Oxfordian- Kimmeridgian age prevail, representing a type of sedimentation comparable to that one documented for the northern Tethyan margin. The Tithonian exotic clasts (Štramberk-type limestones), which are much less common, were formed on a carbonate platform and related slope. The sedimentary paleotransport directions indicate the Silesian Ridge as a main source area for all exotics, which were emplaced in the depositional setting of the flysch deposits. The exotics constitute a relatively rare local component of some debrites. Proceedings of the sedimentological facies analysis indicate that these mass transport deposits were accumulated en-masse by debris flows in a deep-water depositional system in the form of a slope apron. Exotics prove that clasts of the crystalline basement and, less common, fragments of the sedimentary cover, originated from long-lasting tectonic activity and intense uplift of the source area. Mass transport processes and mass accumulation of significant amounts of the coarse-grained detrital material in the south facial zone of the Silesian Basin during the Early Paleogene was due to reactivation of the Silesian Ridge and its increased denudation. Relative regression and erosion of the emerged older flysch deposits were also forced by this uplift. These processes were connected with the renewed diastrophic activity in the Alpine Tethys.

Correlation between dislocation, grain boundary and interface of duplex SS in stress corrosion cracking(SCC)

1990 ◽  
Vol 48 (4) ◽  
pp. 928-929
Author(s):  
Wang Zheng-fang ◽  
Z.F. Wang
Keyword(s):  
Stainless Steel ◽  
Thermal Cycle ◽  
Secondary Phase ◽  
Corrosion Cracking ◽  
Coarse Grained ◽  
Test Environment ◽  
Fine Grained ◽  
Evaluation Test ◽  
Welding Thermal Cycle ◽  
Micro Analysis

The main purpose of this study highlights on the evaluation of chloride SCC resistance of the material,duplex stainless steel,OOCr18Ni5Mo3Si2 (18-5Mo) and its welded coarse grained zone(CGZ).18-5Mo is a dual phases (A+F) stainless steel with yield strength:512N/mm2 .The proportion of secondary Phase(A phase) accounts for 30-35% of the total with fine grained and homogeneously distributed A and F phases(Fig.1).After being welded by a specific welding thermal cycle to the material,i.e. Tmax=1350°C and t8/5=20s,microstructure may change from fine grained morphology to coarse grained morphology and from homogeneously distributed of A phase to a concentration of A phase(Fig.2).Meanwhile,the proportion of A phase reduced from 35% to 5-10°o.For this reason it is known as welded coarse grained zone(CGZ).In association with difference of microstructure between base metal and welded CGZ,so chloride SCC resistance also differ from each other.Test procedures:Constant load tensile test(CLTT) were performed for recording Esce-t curve by which corrosion cracking growth can be described, tf,fractured time,can also be recorded by the test which is taken as a electrochemical behavior and mechanical property for SCC resistance evaluation. Test environment:143°C boiling 42%MgCl2 solution is used.Besides, micro analysis were conducted with light microscopy(LM),SEM,TEM,and Auger energy spectrum(AES) so as to reveal the correlation between the data generated by the CLTT results and micro analysis.

Shelf-derived mass-transport deposits: origin and significance in the stratigraphic development of trench-slope basins

2021 ◽  
pp. 1-36
Author(s):  
Barbara Claussmann ◽  
Julien Bailleul ◽  
Frank Chanier ◽  
Geoffroy Mahieux ◽  
Vincent Caron ◽  
...  
Keyword(s):  
Mass Transport ◽  
Mass Transport Deposits ◽  
Trench Slope
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