The Origins of Reservoir Overpressure in Kelasu Tectonic Zone

AbstractStress sensitivity in reservoirs is critical during the exploitation of oil and gas fields. As a deep clastic reservoir under strong tectonic compression, the Ahe Formation in the northern tectonic zone of the Kuqa depression exhibited strong stress sensitivity effect. However, the conventional evaluation method by using permeability damage rate as a constraint restricts the mechanistic understanding of the strong stress sensitivity effect. In this study, morphology of stress sensitivity test curve, coupled with rate change of permeability and extent of irreversible damage in actual sample measurement through micro-CT in-situ scanning, is used to characterize differentially. The strong stress sensitivity effects of the studied intervals can be divided into three types: (1) rapid change in permeability–weak irreversible damage, (2) moderate change in permeability–strong irreversible damage and (3) moderate change in permeability–moderate irreversible damage. The strong stress sensitivity is caused by the micro-pores and micro-fractures, which are widely developed in the studied reservoir. The mechanisms caused by the two types of pore are different. The stress sensitivity effects in micro-fracture-rich reservoirs are characterized by rapid change in permeability and weak irreversible damage. Meanwhile, the stress sensitivity effects in micro-pore-rich reservoirs are manifested as moderate change in permeability and strong irreversible damage. The study shows that the differences in the content of micro-pores and micro-fractures and their reverse mechanisms of stress sensitivity co-create different types of stress sensitivity within the samples. Accordingly, the differences of the stress sensitivity type in macroscopic samples are caused by the competition between the microscopic differences of pore types.

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Contribution to crustal strain accumulation of minor faults: a case study across the Niigata–Kobe Tectonic Zone, Japan

Earth Planets and Space ◽

10.1186/s40623-020-1132-5 ◽

2020 ◽

Vol 72 (1) ◽

Author(s):

Tomonori Tamura ◽

Kiyokazu Oohashi ◽

Makoto Otsubo ◽

Ayumu Miyakawa ◽

Masakazu Niwa

Keyword(s):

Strain Accumulation ◽

Tectonic Zone ◽

Crustal Strain

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Division Features of Coal-Bearing Tectonic Units in North China

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.737.827 ◽

2015 ◽

Vol 737 ◽

pp. 827-830

Author(s):

Kang Liu ◽

Guo Hong Qin ◽

Zhi Kai Ma

Keyword(s):

North China ◽

Tectonic Structure ◽

Tectonic Zone ◽

Coal Resources ◽

Tectonic Zones ◽

Potential Evaluation ◽

Basic Characteristics

Based on the new round of national potential evaluation on coal resources, and reference to the latest achievements about regional geological and energy basins, this article analyzed the main features of North China coalfield structure. According to the main features of North China coalfield structure and the distribution of North China coal series, the boundary of North China coal-bearing tectonic region and the division of North China coal-bearing tectonic units were identified. North China coalfield tectonic region can be divided into 5 coal-bearing tectonic sub-regions and 22 coal-bearing tectonic zones. The basic characteristics of the tectonic structure and its influence upon coal series distribution in each coal-bearing tectonic zone were systemically discussed.

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A Tectonic Zone in the Northwestern Part of Kinki District, Southwest Japan (2)

Zisin (Journal of the Seismological Society of Japan 2nd ser ) ◽

10.4294/zisin1948.38.2_243 ◽

1985 ◽

Vol 38 (2) ◽

pp. 243-249

Author(s):

Susumu NISHIMURA ◽

Tohru MOGI ◽

Kazuo MIND ◽

Osamu YAMADA

Keyword(s):

Northwestern Part ◽

Southwest Japan ◽

Tectonic Zone

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Delamerian Glenelg tectonic zone, western Victoria: Geology and metamorphism of stratiform rocks

Australian Journal of Earth Sciences ◽

10.1046/j.1440-0952.2002.00922.x ◽

2002 ◽

Vol 49 (2) ◽

pp. 187-200 ◽

Cited By ~ 8

Author(s):

C. M. Gray ◽

A. I. S. Kemp ◽

J. A. C. Anderson ◽

D. J. Bushell ◽

D. J. Ferguson ◽

...

Keyword(s):

Tectonic Zone ◽

Western Victoria

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A seismic-based cross-section of the Grenville Orogen in southern Ontario and western Quebec

Canadian Journal of Earth Sciences ◽

10.1139/e99-094 ◽

2000 ◽

Vol 37 (2-3) ◽

pp. 183-192 ◽

Cited By ~ 61

Author(s):

D J White ◽

D A Forsyth ◽

I Asudeh ◽

S D Carr ◽

H Wu ◽

...

Keyword(s):

Cross Section ◽

Seismic Refraction ◽

Shear Zones ◽

Tectonic Zone ◽

Grenville Province ◽

Crustal Layer ◽

Seismic Reflection Data ◽

Velocity Models ◽

Laurentian Margin ◽

Structural Boundary

A schematic crustal cross-section is presented for the southwestern Grenville Province based on reprocessed Lithoprobe near-vertical incidence seismic reflection data and compiled seismic refraction - wide-angle velocity models interpreted with geological constraints. The schematic crustal architecture of the southwest Grenville Province from southeast to northwest comprises allochthonous crustal elements (Frontenac-Adirondack Belt and Composite Arc Belt) that were assembled prior to ca. 1160 Ma, and then deformed and transported northwest over reworked rocks of pre-Grenvillian Laurentia and the Laurentian margin primarily between 1120 and 980 Ma. Reworked pre-Grenvillian Laurentia and Laurentian margin rocks are interpreted to extend at least 350 km southeast of the Grenville Front beneath all of the Composite Arc Belt. Three major structural boundary zones (the Grenville Front and adjacent Grenville Front Tectonic Zone, the Central Metasedimentary Belt boundary thrust zone, and the Elzevir-Frontenac boundary zone) have been identified across the region of the cross-section based on their prominent geophysical signatures comprising broad zones of southeast-dipping reflections and shallowing of mid-crustal velocity contours by 12-15 km. The structural boundary zones accommodated southeast over northwest crustal stacking at successively earlier times during orogeny (ca. 1010-980 Ma, 1080-1060 Ma, and 1170-1160 Ma, respectively). These shear zones root within an interpreted gently southeast-dipping regional décollement at a depth of 25-30 km corresponding to the top of a high-velocity lower crustal layer.

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Energy distribution of weak deformed rock mass and its influence on gas well productivity

Interpretation ◽

10.1190/int-2018-0083.1 ◽

2019 ◽

Vol 7 (2) ◽

pp. T423-T435 ◽

Cited By ~ 1

Author(s):

Shuai Yin ◽

Yi Wang ◽

Jingzhou Zhao ◽

Yan Wang ◽

Weitao Wu ◽

...

Keyword(s):

Energy Density ◽

Strain Energy Density ◽

Strain Energy ◽

Production Capacity ◽

Type I ◽

Tight Sandstone ◽

Tectonic Zone ◽

Gas Well ◽

Well Productivity ◽

Low Amplitude

Microfractures represent an important rupture type, but current studies on the construction of microscale rupture parameters and their impacts on oil and gas production capacity are relatively weak. Therefore, we constructed the strain energy density ([Formula: see text]) based on 3D finite-element method (FEM) for the tight sandstone reservoir of the Permian He8 segment in the western region of the Sulige gas field, Ordos Basin. It indicated that the [Formula: see text] values of the major production layers are mainly distributed between 0.12 and [Formula: see text]. High-[Formula: see text]-value regions ([Formula: see text]) are mainly distributed in local areas of the western, central, and eastern regions. The [Formula: see text] values are small in the northwestern part of the study area and are usually less than [Formula: see text]. There is a very good exponential correlation between the [Formula: see text] values and gas well productivity (the main controlling factor for the production capacity of the He8 tight sandstone is the gas content, and fracturing, as an engineering factor affecting capacity, has not been taken into account). The distribution of the strain energy densities also matches the low-amplitude tectonic zone well. We have developed the criterion for the discrimination of gas well productivity using the strain energy density. According to this criterion, the conformity rates of type I, type II, and type III wells are 92.3%, 73.0%, and 83.3%, respectively. The areas with [Formula: see text] values greater than [Formula: see text], especially for areas with [Formula: see text] values exceeding [Formula: see text], which should serve as the core exploration targets. The research results can effectively guide tight gas sandstone exploration in low-amplitude tectonic zones and reduce the risk of drilling.

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The Jurassic of Skåne, southern Sweden

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/geusb.v1.4682 ◽

2003 ◽

Vol 1 ◽

pp. 527-541 ◽

Cited By ~ 9

Author(s):

Anders Ahlberg ◽

Ulf Sivhed ◽

Mikael Erlström

Keyword(s):

Clay Mineralogy ◽

Depositional Environments ◽

Burial Diagenesis ◽

Sea Level Changes ◽

Humid Climate ◽

Alluvial Deposits ◽

Tectonic Zone ◽

Marine Strata ◽

Coal Beds ◽

Shallow Marine Sediments

In Sweden, Jurassic strata are restricted to Skåne and adjacent offshore areas. Jurassic sedimentary rocks predominantly comprise sandy to muddy siliciclastics, with subordinate coal beds and few carbonate-rich beds. During Mesozoic times, block-faulting took place in the Sorgenfrei– Tornquist Zone, a tectonic zone which transects Skåne in a NW–SE direction. The Jurassic depositional environments in Skåne were thus strongly influenced by uplift and downfaulting, and to some extent by volcanism. Consequently, the sedimentary record reveals evidence of numerous transgressions, regressions and breaks in sedimentation. Relative sea-level changes played a significant role in controlling the facies distribution, as deposition mainly took place in coastal plain to shallow shelf environments. The alluvial deposits in Skåne include floodplain palaeosols, autochthonous coals, overbank sandstones, and stream channel pebbly sandstones. Restricted marine strata comprise intertidal heteroliths with mixed freshwater and marine trace fossil assemblages, and intertidal delta distributary channel sandstones. Shallow marine sediments encompass subtidal and shoreface sandstones with herringbone structures, and bioturbated mudstones with tempestite sandstones. Offshore deposits typically comprise extensively bioturbated muddy sandstones. Floral remains, palaeopedology, clay mineralogy and arenite maturity indicate a warm and humid climate in Skåne throughout the Jurassic, possibly with slightly increasing aridity towards the end of the period. Most Jurassic strata in Skåne have been subjected to mild burial diagenesis, and the petroleum generative window has rarely been reached.

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