scholarly journals Sealing assessment of normal faults in clastic reservoirs. The role of fault geometry and shale smear parameters.

2002 ◽  
Vol 67 (6) ◽  
pp. 576-589 ◽  
Author(s):  
Rasoul Sorkhabi ◽  
Shutaro Hasegawa ◽  
Shoji Iwanaga ◽  
Masamichi Fujimoto
Keyword(s):  
Normal Faults ◽  
Fault Geometry ◽  
Clastic Reservoirs

Geometrical characterisation of fault arrays in three dimensions

2021 ◽  
Author(s):  
Vincent Roche ◽  
Giovanni Camanni ◽  
Conrad Childs ◽  
Tom Manzocchi ◽  
John Walsh ◽  
...  
Keyword(s):  
Full Range ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Normal Faults ◽  
Fault Geometry ◽  
Surface Geometry ◽  
Fault Surface ◽  
Mechanical Stratigraphy ◽  
Quantitative Basis ◽  
Geometry Analysis

<p>Normal faults are often complex three-dimensional structures comprising multiple sub-parallel segments separated by intact or breached relay zones. In this study we outline geometrical characterisations capturing this 3D complexity and providing a semi-quantitative basis for the comparison of faults and for defining the factors controlling their geometrical evolution. Relay zones are classified according to whether they step in the strike or dip direction and whether the relay zone-bounding fault segments are unconnected in 3D or bifurcate from a single surface. Complex fault surface geometry is then described in terms of the relative numbers of different types of relay zones to allow comparison of fault geometry between different faults and different geological settings. A large database of 87 fault arrays compiled primarily from mapping 3D seismic reflection surveys and classified according to this scheme, reveals the diversity of 3D fault geometry. Analysis demonstrates that mapped fault geometries depend on geological controls, primarily the heterogeneity of the faulted sequence and the presence of a pre-existing structure. For example, relay zones with an upward bifurcating geometry are prevalent in faults that reactivate deeper structures, whereas the formation of laterally bifurcating relays is promoted by heterogeneous mechanical stratigraphy. In addition, mapped segmentation depends on resolution limits and biases in fault mapping from seismic data. In particular, the results suggest that the proportion of bifurcating relay zones increases as data resolution increases. Overall, where a significant number of relay zones are mapped on a single fault, a wide variety of relay zone geometries occurs, demonstrating that individual faults can comprise segments that are both bifurcating and unconnected in three dimensions. Models for the geometrical evolution of fault arrays must therefore account for the full range of relay zone geometries that appears to be a characteristic of all faults.</p>

scholarly journals Superposition of two kinematically distinct extensional phases in southern Death Valley: Implications for extensional tectonics

Geosphere ◽  
2021 ◽  
Author(s):  
Z.D. Fleming ◽  
T.L. Pavlis ◽  
S. Canalda
Keyword(s):  
Early Period ◽  
Rock Avalanche ◽  
Strike Slip ◽  
Death Valley ◽  
Normal Faults ◽  
Geologic Mapping ◽  
The North ◽  
Transcurrent Deformation ◽  
Two Phases

Geologic mapping in southern Death Valley, California, demonstrates Mesozoic contractional structures overprinted by two phases of Neogene extension and contemporaneous strike-slip deformation. The Mesozoic folding is most evident in the middle unit of the Noonday Formation, and these folds are cut by a complex array of Neogene faults. The oldest identified Neogene faults primarily displace Neoproterozoic units as young as the Johnnie Formation. However, in the northernmost portion of the map area, they displace rocks as young as the Stirling Quartzite. Such faults are seen in the northern Ibex Hills and con­sist of currently low- to moderate-angle, E-NE– dipping normal faults, which are folded about a SW-NE–trending axis. We interpret these low-angle faults as the product of an early, NE-SW extension related to kinematically similar deformation recognized to the south of the study area. The folding of the faults postdates at least some of the extension, indicating a component of syn-exten­sional shortening that is probably strike-slip related. Approximately EW-striking sinistral faults are mapped in the northern Saddlepeak Hills. However, these faults are kinematically incompatible with the folding of the low-angle faults, suggesting that folding is related to the younger, NW-SE extension seen in the Death Valley region. Other faults in the map area include NW- and NE-striking, high-angle normal faults that crosscut the currently low-angle faults. Also, a major N-S–striking, oblique-slip fault bounds the eastern flank of the Ibex Hills with slickenlines showing rakes of <30°, which together with the map pattern, suggests dextral-oblique movement along the east front of the range. The exact timing of the normal faulting in the map area is hampered by the lack of geochronology in the region. However, based on the map relationships, we find that the older extensional phase predates an angular unconformity between a volcanic and/or sedimentary succession assumed to be 12–14 Ma based on correlations to dated rocks in the Owlshead Mountains and overlying rock-avalanche deposits with associated sedimentary rocks that we correlate to deposits in the Amargosa Chaos to the north, dated at 11–10 Ma. The mechanism behind the folding of the northern Ibex Hills, including the low- angle faults, is not entirely clear. However, transcurrent systems have been proposed to explain extension-parallel folding in many extensional terranes, and the geometry of the Ibex Hills is consistent with these models. Collectively, the field data support an old hypothesis by Troxel et al. (1992) that an early period of SW-NE extension is prominent in the southern Death Valley region. The younger NW-SE extension has been well documented just to the north in the Black Mountains, but the potential role of this earlier extension is unknown given the complexity of the younger deformation. In any case, the recognition of earlier SW-NE extension in the up-dip position of the Black Mountains detachment system indicates important questions remain on how that system should be reconstructed. Collectively, our observations provide insight into the stratigraphy of the Ibex Pass basin and its relationship to the extensional history of the region. It also highlights the role of transcurrent deformation in an area that has transitioned from extension to transtension.

scholarly journals Sealing assessment of normal faults in clastic reservoirs: Modeling the petrophysical and stress attributes of faults.

2003 ◽  
Vol 68 (4) ◽  
pp. 291-304 ◽  
Author(s):  
Rasoul Sorkhabi ◽  
Shoji Iwanaga ◽  
Masamichi Fujimoto ◽  
Shutaro Hasegawa
Keyword(s):  
Normal Faults ◽  
Clastic Reservoirs

The temporal evolution of syn-sedimentary normal faults and the possible role of tip retreat

2020 ◽  
Author(s):  
Bailey Lathrop ◽  
Christopher Jackson ◽  
Rebecca Bell ◽  
Atle Rotevatn
Keyword(s):  
Growth Model ◽  
Temporal Evolution ◽  
Fault Model ◽  
Normal Faults ◽  
Constant Length ◽  
Final Length ◽  
Fault Growth ◽  
Stratigraphic Evolution ◽  
The Relationship

<p>We need to understand how normal faults grow in order to better determine the tectono-stratigraphic evolution of rifts, and the distribution and size of potentially hazardous earthquakes. The growth of normal faults is commonly described by two models: 1) the propagating fault model (isolated growth model), and 2) the constant-length model. The propagating fault model envisages a sympathetic increase between fault lengthening (L) and displacement (D), whereas the constant-length model states that faults reach their near-final length before accumulating significant displacement (Walsh et al., 2002). Several relatively recent studies agree that faults generally follow a constant-length model, or a “hybrid model” of the two, where most faults reach their near final length within the first 20-30% of their lives, and accrue displacement throughout. Furthermore, in the past 20 years, much research has focused on how faults grow; relatively few studies have questioned what happens to the fault geometry as it becomes inactive, i.e. do faults abruptly die, or do they more gradually become inactive by so-called tip retreat. We here use a 3D seismic reflection dataset from the Exmouth Plateau, offshore Australia to support a hybrid fault growth model for normal faults, and to also determine the relationship between length and displacement as a fault dies. We show that the studied faults grew in three distinct stages: a lengthening stage (<30% of the faults life), a displacement accrual stage (30-75%), and a possible tip retreat stage (75%-end). This work has important implications in our understanding of the temporal evolution of normal faults, both how they grow and how they die.</p>

3D geometry of outcrop-scale normal faults from Taranaki, New Zealand

2020 ◽  
Author(s):  
Inbar Vaknin ◽  
Andy Nicol ◽  
Conrad Childs
Keyword(s):  
New Zealand ◽  
Fault Zone ◽  
Slip Surface ◽  
Geometric Model ◽  
Fault Zones ◽  
Normal Faults ◽  
Small Scale ◽  
Fault Geometry ◽  
Fault Rock ◽  
Fault Surface

<p>Fault surfaces and fault zones have been shown to have complex geometries comprising a range of morphologies including, segmentation, tip-line splays and slip-surface corrugations (e.g., Childs et al., 2009*). The three-dimensional (3D) geometries of faults (and fault zones) is difficult to determine from outcrop data which are typically 2D and limited in size. In this poster we examine the small-scale geometries of faults from normal faults cropping out in well bedded parts of the Mount Messenger and Mahakatino formations in Taranaki, New Zealand. We present two main datasets; i) measurements and maps of 2D vertical and horizontal sections for in excess of 200 faults and, ii) 3D fault model of a small-fault (vertical displacement ~1 cm) produced by serial fault-perpendicular sections of a block 10x10x13 cm. The sectioned block contains a single fault that offsets sand and silt layers, and comprises two main dilational bends; in the 3D model we map displacement, bedding and fault geometry for the sectioned fault zone. Faults in the 2D dataset comprise a range of geometries including, vertical segmentation, bends, splays and fault-surface corrugations. Although we have little information on the local magnitudes and orientations of stresses during faulting, geometric analysis of the fault zones provides information on the relationships between bed characteristics (e.g., thickness, induration and composition) and fault-surface orientations. The available data supports the view that the strike and dip of fault surfaces vary by up to 25° producing undulations or corrugations on fault surfaces over a range of scales from millimetres to metres and in both horizontal and vertical directions. Preliminary analysis of the available data suggests that these corrugations appear to reflect fault refractions due to changing bed lithologies (unexpectedly the steepest sections of faults are in mudstone beds), breaching of relays and development of conjugate fault sets. The relative importance of these factors and their importance for fault geometry will be explored further in the poster.</p><p> </p><p>*Childs, C., Walsh, J.J., Manzocchi, T., Bonson, C., Nicol A., Schöpfer, M.P.J. 2009. A geometric model of fault zone and fault rock thickness variations. Journal of Structural Geology 31, 117-127.</p>

scholarly journals Rifted margins: Ductile deformation, boudinage, continentward-dipping normal faults and the role of the weak lower crust

2018 ◽  
Vol 53 ◽  
pp. 20-40 ◽  
Author(s):  
Camille Clerc ◽  
Jean-Claude Ringenbach ◽  
Laurent Jolivet ◽  
Jean-François Ballard
Keyword(s):  
Lower Crust ◽  
Ductile Deformation ◽  
Normal Faults ◽  
Rifted Margins
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