Conjugate Normal Faults Research Articles

Convex-up Style of Deformation within Grabens in Regions of Incomplete Crossing Conjugate Normal Faults: A Numerical Simulation Investigation and Case Study

Convex-up Style of Deformation within Grabens in Regions of Incomplete Crossing Conjugate Normal Faults: A Numerical Simulation Investigation and Case Study

A prospect analysis of the Upper Oligocene sandstone reservoirs of the Wenchang 9 block, Pearl River Mouth Basin, northern South China Sea margin

Faults can act as a migration pathway and/or a lateral seal in structural traps in the Wenchang 9 block (WC9B) oil field, affecting the potential for enhanced hydrocarbon recovery in the field. In this study, three-dimensional (3D) seismic survey and well data are used to characterize Upper Oligocene fan delta - tidal flat heterogeneous reservoirs and investigate fault seal potential in two new structural traps interpreted in the WC9B oil field. Five lithofacies are identified in the Upper Oligocene Zhuhai Formation based on the well log analysis and core description. The fan delta front and sand-rich tidal flat sandstone of facies F1 in reservoir unit A of the middle Zhuhai member is characterized by the best porosity and permeability. The RMS amplitude attribute analysis and facies modeling help to predict gradual upward progression of the F1 fan delta deposits from the proximity of the Shenhu Uplift to the NW into the basin for ∼ 7–8 km during accumulation of the middle member. The NE-dipping conjugate normal faults of lower throw in the hanging wall of the NW-dipping main normal basement faults contributed to the formation of hydrocarbon-bearing structural traps and side seals. Two new structural traps in the middle member of Zhuhai Formation interpreted in the WC9B oil field. The traps are 3-way dip closure bounded by the NE-dipping normal faults of the conjugate set that are characterized by good sealing potential in the interval of the middle member. The results of this study contribute to the optimization of the enhanced hydrocarbon recovery of the WC9B oil field.

Internal architecture and structural evolution of a horst relay zone from the northern Gulf of Suez rift, Egypt: Implications for syn-rift sedimentation

A remarkable outcrop of an extensional NW-oriented horst block takes place between conjugate normal fault segments at the Akheider-El Ramliya fault block (ARFB), along the northwestern termination of the Gulf of Suez rift. Detailed field geological mapping is accomplished to identify the architecture, linkage style as well as evolution of the encountered normal fault system at the ARFB. The resultant structural model revealed several geometries of normal faults interaction that form soft- and hard-linkage relay zones affecting pre- and syn-rift rock units. Such relay zones are well developed between the boundary faults of the ARFB. Additionally, three E-W oriented fault belts are mapped at the northern, central and southern parts of the ARFB enclosing left-stepping en echelon normal faults, where several relay zones are formed between the overlapped fault segments. Structural analysis and evolution of the mapped area revealed that the overall architecture of the ARFB representing a broad horst relay zone between the conjugate divergent boundary normal faults. Also, two sub-basins have been recognized at the downthrows of the border faults comprising syn-rift Oligocene and Miocene sediments. The results show that these faults are rejuvenated by a continued NE-SW extension through Late Eocene, Oligocene and Miocene times. Additionally, the formed relay zones via growth and propagation of such faults have main controls on syn-sedimentation at the northern Gulf of Suez rift. The results of the present study offer constraints on horst relay zones including, internal structural architecture, geometries and interaction of boundary faults as well as role of inherited structures. Also, it provides an outcrop model for architecture and evolution of similar structural styles (e.g., the Gulf of Suez rift) as well as for subsurface mapping and exploration in extensional relay zones.

Complex deformation history of the Keszthely Hills, Transdanubian Range, Hungary

Abstract We have investigated the deformation history of the Keszthely Hills (Transdanubian Range, W Hungary), which belongs to the uppermost slice of the Austroalpine nappe system. This Upper Triassic to Upper Miocene sedimentary rock sequence documented the deformation of the upper crust during repeated rifting and inversion events. We investigated the structural pattern and stress field evolution of this multistage deformation history by structural data collection and evaluation from surface outcrops. Regarding the Mesozoic deformations, we present additional arguments for pre-orogenic (Triassic and Jurassic) extension (D1 and D2 phases), which is mainly characterized by NE–SW extensional structures, such as syn-sedimentary faults, slump-folds, and pre-tilt conjugate normal fault pairs. NW–SE-striking map-scale normal faults were also connected to these phases. The inversion of these pre-orogenic structures took place during the middle part of the Cretaceous; however, minor contractional deformation possibly reoccurred until the Early Miocene (D3 to D5 phases). The related meso- and map-scale structures are gentle to open folds, thrusts and strike-slip faults. We measured various orientations, which were classified into three stress states or fields on the basis of structural criteria, such as tilt-test, and/or superimposed striae on the same fault planes. For this multi-directional shortening we presented three different scenarios. Our preferred suggestion would be the oblique inversion of pre-orogenic faults, which highly influenced the orientation of compressional structures, and resulted in an inhomogeneous stress field with local stress states in the vicinity of inherited older structures. The measured post-orogenic extensional structures are related to a new extensional event, the opening of the Pannonian Basin during the Miocene. We classified these structures into the following groups: immediate pre-rift phase with NE–SW extension (D6), syn-rift phase with E–W extension (D7a) and N–S transpression (D7b), and post-rift phase with NNW–SSE extension (D8).

Aftershocks triggering in a conjugate normal fault zone: a case study of the 2020 MW 5.7 Utah earthquake sequence

Aftershocks triggering in a conjugate normal fault zone: a case study of the 2020 MW 5.7 Utah earthquake sequence

High‐Resolution Seismic Imaging of Fault‐Controlled Basins: A Case Study From the 2009 Mw 6.1 Central Italy Earthquake

AbstractWe present the first seismic reflection images of the Paganica and Bazzano basins, two tectonic basins developed in the hanging wall of the Paganica‐San Demetrio Fault System, the causative fault of the 2009 Mw 6.1 L'Aquila earthquake, Italy. Five high‐resolution seismic profiles were acquired along a main, 7 km long transect cutting across the strands of an active fault system in urbanized areas with widespread sources of seismic noise. Three processing approaches were chosen to tackle a variable and site‐dependent data quality . To aid interpretation of this complex setting, we complemented seismic amplitude images with energy and similarity attributes as well with post‐stack acoustic impedance inversion. The final seismic sections expose, with unprecedented resolution, the basins' structure and the uppermost splays of the 2009 earthquake. The seismic data show fine details of the subsurface stratigraphic setting, revealing continental depocenters carved in the marine Meso‐Cenozoic substratum and displaced by a series of conjugate normal faults, mostly unknown before this study. Several of the imaged fault strands connect to the 2009 coseismic surface ruptures. Matching the seismic interpretation with constraints from surface geology and shallow boreholes, published data from field surveys and scientific drilling, we present a structural map of the Bazzano and Paganica basins with an estimation of the depth of the Meso‐Cenozoic substratum. This map highlights a different structure, evolution, and age of the two basins, with the older Bazzano basin that likely began to form in late Pliocene.

Investigation of the Thiva 2020–2021 Earthquake Sequence Using Seismological Data and Space Techniques

We investigate an earthquake sequence involving an Mw = 4.6 mainshock on 2 December 2020, followed by a seismic swarm in July–October 2021 near Thiva, Central Greece, to identify the activated structures and understand its triggering mechanisms. For this purpose, we employ double-difference relocation to construct a high-resolution earthquake catalogue and examine in detail the distribution of hypocenters and the spatiotemporal evolution of the sequence. Furthermore, we apply instrumental and imaging geodesy to map the local deformation and identify long-term trends or anomalies that could have contributed to stress loading. The 2021 seismic swarm was hosted on a system of conjugate normal faults, including the eastward extension of the Yliki fault, with the main activated structures trending WNW–ESE and dipping south. No pre- or coseismic deformation could be associated with the 2021 swarm, while Coulomb stress transfer due to the Mw = 4.6 mainshock of December 2020 was found to be insufficient to trigger its nucleation. However, the evolution of the swarm is related to stress triggering by its major events and facilitated by pore-fluid pressure diffusion. The re-evaluated seismic history of the area reveals its potential to generate destructive Mw = 6.0 earthquakes; therefore, the continued monitoring of its microseismicity is considered important.

Spatiotemporal evolution of transfer structures and linked fault systems in an extensional setting: Southwest Gebel Akheider, Cairo-Suez District, Egypt

Detailed geological field mapping of the area located to the southwest of Gebel Akheider, south-central part of the Cairo-Suez District (Egypt), was carried out to identify the geometry, structural style, and evolution of the normal fault systems in the study area. The present structural geometry of the study area is of Miocene age and is the result of the propagation, kinematic interaction, and eventual linkage of extensional fault segments. Eight mapped relay ramps formed between synthetic non-overlapping and overlapping normal faults. Fault displacement profiles showing variation in displacement along strike revealed steep displacement gradients and local displacement minima at the locations of these relay ramps. Conjugate normal faults in the area also showed signs of kinematic interaction. Fault displacement profiles revealed complimentary displacement distribution between interacting overlapping conjugate faults. In competent rock units (Middle Eocene limestone), this interaction resulted in the formation of horsts and grabens relay zones, while in incompetent rock units (Middle Miocene soft marl and sandy limestone), this interaction resulted in a series of en echelon plunging anticlines and synclines (accommodation folds). Several transfer faults marked by points of local displacement minima were also identified, forming a distinctive zigzag pattern in map view that is characteristic of the Cairo-Suez District. Curved fault traces represent another form of fault linkage in the study area. Fault displacement profiles indicated two different growth mechanisms, either as the result of bilateral growth of two along-strike faults, or the intersection of previously isolated and differently oriented fault segments.

Origin of two different deformation styles via active folding mechanisms of inverted Abu El Gharadiq Basin, Western Desert, Egypt

The Abu El Gharadiq Basin (AGB) is one of the largest Cretaceous rift basins in the northern district of the Western Desert of Egypt. The AGB underwent tectonic inversion in the Upper Cretaceous through horizontal shortening in the NW-SE direction. Detailed interpretation of seismic sections across discrete regions of this basin shows that the rocks deformed in two different depth-related deformation styles, which are partitioned across the base of the so called Bahariya Formation of Cenomanian age. The deeper, pre-Cenomanian rock units show contractional deformation forming tight folds and related fabrics while shallower, post-Cenomanian rock units display features of extensional deformation. These are essentially shallowly undulating open folds, associated with conjugate normal faults and tensional fractures. The deeper pre-Cenomanian tight anticlines pierce the upper rock units as diapiric-like intrusions that are seen on the seismic sections as hazy regions. We infer that the two different deformation styles above and below the Cenomanian rocks occurred simultaneously. The hazy regions on the seismic sections may result from lateral flow of shale rocks that give rise to chaotic structures near the anticlines. Mechanical anisotropy across the Cennomanian rock unit is inferred to be the main cause of simultaneous emergence of contractional and extensional deformations. Re-evaluation of fracture patterns of the northern rift basins in the Western Desert implies that the AGB originated in an extensional stepover region of a discrete, ENE-WSE trending, shear zone whose margins underwent inversions, developing two parallel thrust-dominated ridges, namely the crustal scale Kattaniya and Qattara-Alamein ridges.

Postmagmatic Tectonic Evolution of the Outer Izu-Bonin Forearc Revealed by Sediment Basin Structure and Vein Microstructure Analysis: Implications for a 15 Ma Hiatus Between Pacific Plate Subduction Initiation and Forearc Extension.

International Ocean Discovery Program Expedition 352 recovered sedimentary‐volcaniclastic successions and extensional structures (faults and extensional veins) that allow the reconstruction of the Izu‐Bonin forearc tectonic evolution using a combination of shipboard core data, seismic reflection images, and calcite vein microstructure analysis. The oldest recorded biostratigraphic ages within fault‐bounded sedimentary basins (Late Eocene to Early Oligocene) imply a ~15 Ma hiatus between the formation of the igneous basement (52 to 50 Ma) and the onset of sedimentation. At the upslope sites (U1439 and U1442) extension led to the formation of asymmetric basins reflecting regional stretch of ~16–19% at strain rates of ~1.58 × 10−16 to 4.62 × 10−16 s−1. Downslope Site U1440 (closer to the trench) is characterized by a symmetric graben bounded by conjugate normal faults reflecting regional stretch of ~55% at strain rates of 4.40 × 10−16 to 1.43 × 10−15 s−1. Mean differential stresses are in the range of ~70–90 MPa. We infer that upper plate extension was triggered by incipient Pacific Plate rollback ~15 Ma after subduction initiation. Extension was accommodated by normal faulting with syntectonic sedimentation during Late Eocene to Early Oligocene times. Backarc extension was assisted by magmatism with related Shikoku and Parece‐Vela Basin spreading at ~25 Ma, so that parts of the arc and rear arc, and the West Philippine backarc Basin were dismembered from the forearc. This was followed by slow‐rift to postrift sedimentation during the transition from forearc to arc rifting to spreading within the Shikoku‐Parece‐Vela Basin system.

Litho-structural controls on mineralisation at the Pillara carbonatehosted Zn-Pb Deposit, Lennard Shelf District, Western Australia

The Pillara Zn-Pb deposit is located on the northeast margin of the Canning Basin, Western Australia where it is hosted by a series north-northeast-trending, en echelon, conjugate normal faults tha...

Low-angle normal faults record Early Permian extensional tectonics in the Orobic Basin (Southern Alps, N Italy)

Well-preserved SSE-dipping low-angle normal faults (LANF) active during the Early Permian (Cisuralian) were recognized along the northern margin of the Orobic Basin (central Southern Alps, N Italy). These faults, which escaped most of the Alpine deformations, exhumed the Variscan basement during the deposition of the upperpart of the Lower Permian succession (Pizzo del Diavolo Formation).Fault planes show evidence of frictional processes typical of the upper crust associated with hydrothermal circulation, responsible for the deposition of cm to m thick tourmalinite and Uranium mineralization.The recognized LANFs interacted with high-angle normal faults producing half grabens that stored the Lower Permian deposits, where synsedimentary fault activity in their hangingwall is testified by abrupt vertical and lateral facies changes, thickness variations and by soft-sediment deformations. Mesoscopic structures, exposed in the hangingwall of a major LANF (the Aga-Vedello Fault system) along a synthetic high-angle normal fault, include conjugate normal faults, horst-and-graben, domino-style planar and listric faults, which clearly record synsedimentary deformations testified by liquefaction and dewatering structures, typical of pre-consolidation hydroplastic conditions. This exceptional record indicates deformations at shallow crustal level which occurred during the Early Permian along high-angle normal faults soling into the LANFs, forming the northern boundary of the Orobic Basin.The outcrop continuity, the perfectly preserved relationships among high- and low-angle normal faults together with the synsedimentary record of fault activity and the occurrence of mesoscopic faults developed during the deposition of the sediments, make this case-study an excellent reference for the analysis of extensional tectonics in synsedimentary conditions.In addition, the occurrence of large LANF systems, typical of a stress regime characterized by a vertical s1, suggests that the Lower Permian Orobic Basin was dominated by pure extension at least in the study area, alternatively to existing interpretations, which favor a transtensional origin of the basin. Strike-slip tectonics can be responsible for a later partial tectonic inversion of the basin, as testified by the angular unconformity with the overlying Upper Permian succession (Verrucano Lombardo), marking a Middle Permian stratigraphic gap.

Thrust to transpression and transtension tectonics during the Paleoproterozoic evolution of the Birimian Greenstone Belt of Mako, Kédougou-Kéniéba Inlier, Eastern Senegal

The structural cartography of the Birimian formations of the Mako area shows a polyphase deformation marked by variable structures such as imbricated shear zones, thrusts and reverse-shears, poly-folding, boudinage, normal faults. The multiscale analysis of the various mapped structures combined with the satellite images allowed us to distinguish three major phases of Eoeburnean and Eburnean deformation. The Eoeburnean D1 deformation phase is preserved through ductile structures in some lithologies (metabasalts, quartzites). It is composed of early thrusting and late sinistral reverse-shearing due to a NW-SE principal shortening direction, which involved large overturned folds verging northwestward and associated with thrust faults. It is also associated with the emplacement of early granitoids (c. 2200 Ma) followed by andesitic to felsic volcanic rocks around c. 2160 Ma. The Eburnean event is divided into two phases of deformation namely D2 and D3. The D2 phase is the early Eburnean event which involves a sinistral transpressive deformation. It is characterized by a NNE-SSW shortening direction which creates major NNW-SSE (N160°-170°) and NNE-SSW (N20°-30°) sinistral reverse-shear zones associated with ENE-WSW (N60°-70°) dextral reverse-shear zones. Interference between both major NNE-SSW and NNW-SSE reverse-shear zones involves an anatomizing pattern of deformation. The D3 phase is a transtensional deformation associated with a dextral movement which creates dextral shear zones and conjugate normal faults leading to graben depression. The D3 principal maximum stress is ENE-WSW oriented. The granitoids were emplaced during these Eoeburnean and Eburnean orogenic events.

Structural evolution of thrust-related folds and associated fault systems in the eastern portion of the deep-water Niger Delta

Abstract The geometry and kinematic evolution of a gravity-driven system consisting of thrust-related folds and associated fault systems located in the detachment fold province of the eastern portion of the deep-water Niger Delta were analyzed using a high-resolution 3D seismic dataset. This paper suggests that the structural evolution of delta progradational units can be divided into six episodes, which together represent a typical evolutionary cycle under gravity-driven processes that have resulted in the formation of distinct thrust-related folds and associated fault systems. An oblique anticline (Anticline E) trending NE-SW is subparallel to the regional transport direction (NNE-SSW) of the delta progradational units and sub-perpendicular to the main trend of the main structures (WNW-ESE). Before the shortening of the H4-H6 period, the region of this anticline was a half-graben associated with a normal fault (F0). Subsequently, during the shortening of the H2-H4 period, this normal fault acted as an oblique lateral ramp along which the half-graben sediments were shortened, forming an oblique anticline. Ultimately, growth of this anticline ceased during the H0-H1 period. The majority of faults associated with Anticline E can be divided into two types. (1) One type includes the domino normal faults generated during the H1-H4 period, these faults located in the west limb, were primarily caused by a secondary gravity-driven mechanism related to the dip of the anticline limb and gradually migrated as the crest or hinge line moved westward in subsequent intervals. The fault spacing and density are negatively and positively correlated, respectively, to the dip of the anticline limb. (2) The other fault type includes the conjugate normal faults generated during the H0-H1 period. These faults are located in the east limb and are related to the reactivated fault F0. These conjugate faults were primarily caused by a combination of local gravitational collapse resulting from the withdrawal of a mobile delta unit and the regional maximum horizontal stress caused by oblique sliding along the trend of F0. The reactivation of F0 was kinematically coupled with Anticline E and the conjugate normal faults through the delta units, and was a key factor in the origin of the anticline and faults.

The role of post-collisional strike-slip tectonics in the geological evolution of the late Neoproterozoic volcano-sedimentary Guaratubinha Basin, southern Brazil

The Guaratubinha Basin is a late Neoproterozoic volcano-sedimentary basin included in the transitional-stage basins of the South American Platform. The aim of this study is to investigate its tectonic evolution through a detailed structural analysis based on remote sensing and field data. The structural and aerogeophysics data indicate that at least three major deformational events affected the basin. Event E1 caused the activation of the two main basin-bounding fault zones, the Guaratubinha Master Fault and the Guaricana Shear Zone. These structures, oriented N20-45E, are associated with well-defined right-lateral to oblique vertical faults, conjugate normal faults and vertical flow structures. Progressive transtensional deformation along the two main fault systems was the main mechanism for basin formation and the deposition of thick coarse-grained deposits close to basin-borders. The continuous opening of the basin provided intense intermediate and acid magmatism as well as deposition of volcaniclastic sediments. Event E2 characterizes generalized compression, recorded as minor thrust faults with tectonic transport toward the northwest and left-lateral activation of the NNE-SSW Palmital Shear Zone. Event E3 is related to the Mesozoic tectonism associated with the South Atlantic opening, which generated diabase dykes and predominantly right-lateral strike-slip faults oriented N10-50W. Its rhomboidal geometry with long axis parallel to major Precambrian shear zones, the main presence of high-angle, strike-slip or oblique faults, the asymmetric distribution of geological units and field evidence for concomitant Neoproterozoic magmatism and strike-slip movements are consistent with pull-apart basins reported in the literature.

Temporal evolution of fault systems in the Upper Jurassic of the Central German Molasse Basin: case study Unterhaching

The structural evolution of faults in foreland basins is linked to a complex basin history ranging from extension to contraction and inversion tectonics. Faults in the Upper Jurassic of the German Molasse Basin, a Cenozoic Alpine foreland basin, play a significant role for geothermal exploration and are therefore imaged, interpreted and studied by 3D seismic reflection data. Beyond this applied aspect, the analysis of these seismic data help to better understand the temporal evolution of faults and respective stress fields. In 2009, a 27 km2 3D seismic reflection survey was conducted around the Unterhaching Gt 2 well, south of Munich. The main focus of this study is an in-depth analysis of a prominent v-shaped fault block structure located at the center of the 3D seismic survey. Two methods were used to study the periodic fault activity and its relative age of the detected faults: (1) horizon flattening and (2) analysis of incremental fault throws. Slip and dilation tendency analyses were conducted afterwards to determine the stresses resolved on the faults in the current stress field. Two possible kinematic models explain the structural evolution: One model assumes a left-lateral strike slip fault in a transpressional regime resulting in a positive flower structure. The other model incorporates crossing conjugate normal faults within a transtensional regime. The interpreted successive fault formation prefers the latter model. The episodic fault activity may enhance fault zone permeability hence reservoir productivity implying that the analysis of periodically active faults represents an important part in successfully targeting geothermal wells.

Theoretical and experimental estimation of geometric relationship of non-parallel conjugate normal faults

Intersecting and crossing conjugate normal faults develop at different scales. Equations of geometric parameters of non-parallel conjugate normal faults can be deduced from their trigonometric relations. Physical models can also be used to verify the theoretical calculations and compared with natural examples. In this study, we have used a theoretical approach to outline some key geometric parameters of conjugate normal faults (intersection angles, plunge of intersection line, and vertical and horizontal distances of the intersection point, etc.) and compared them to equivalent geometric values in scaled analogue models. The comparison shows that theoretical plots used for geometric estimation of conjugate normal faults constrain reasonably the geometric parameters in natural cases. Data from the Lufeng Sag of Pearl River Mouth Basin in the northern part of South China Sea, where conjugate non-parallel basement faults propagate and intersect in cover units are compatible with the theoretical geometric estimation.

Occurrence and development of folding related to normal faulting within a mechanically heterogeneous sedimentary sequence: a case study from Inner Moray Firth, UK

Abstract Folds associated with normal faults are potential hydrocarbon traps and may impact the connectivity of faulted reservoirs. Well-calibrated seismic reflection data that image a normal fault system from the Inner Moray Firth basin, offshore Scotland, show that folding was preferentially localized within the mechanically incompetent Lower–Middle Jurassic pre-rift interval, comprising interbedded shales and sandstones, and within Upper Jurassic syn-rift shales. Upward propagation of fault tips was initially inhibited by these weak lithologies, generating fault propagation folds with amplitudes of c. 50 m. Folds were also generated, or amplified, by translation of the hanging wall over curved, convex-upward fault planes. These fault bends resulted from vertical fault segmentation and linkage within mechanically incompetent layers. The relative contributions of fault propagation and fault-bend folding to the final fold amplitude may vary significantly along the strike of a single fault array. In areas where opposite-dipping, conjugate normal faults intersect, the displacement maxima are skewed upwards towards the base of the syn-rift sequence (i.e. the free surface at the time of fault initiation) and significant fault propagation folding did not occur. These observations can be explained by high compressive stresses generated in the vicinity of conjugate fault intersections, which result in asymmetric displacement distributions, skewed towards the upper tip, with high throw gradients enhancing upward fault propagation. Our observations suggest that mechanical interaction between faults, in addition to mechanical stratigraphy, is a key influence on the occurrence of normal fault-related folding, and controls kinematic parameters such as fault propagation/slip ratios and displacement rates.

Interpreting Seismic Profiles in terms of Structure and Stratigraphy, an Example from Lower Indus Basin Pakistan

Structural delineation and Stratigraphic evaluation of proven geological basins are of prime importance for hydrocarbon exploration and exploitation. The current study aims to map the subsurface geology in a part of Lower Indus basin of Pakistan in terms of structure and stratigraphy using seismic data with some borehole information. In this paper, conventional integrated geophysical technique has been used to analyze the seismic data to characterize reservoir formations. To pursue the interpretation, 2D seismic data in SEG-Y format was used along with velocity and well logs information. Visual interpretation of seismic profiles is transformed into 2D and 3D (Time and Depth domain) contour maps, which is the representation of true subsurface geology. Three promising closures at shallow time have been identified on structural contour maps which are indicative of possible prospects. A closure, covering approximately 1 Sq. Km area over Eocene aged Sui Main Limestone and further two over Cretaceous aged Lower Goru formation covering areas of 500 and 400 Sq. km along shot point 260 and 380-390, respectively. Conjugate normal fault system among the stratigraphic layers existing in the study area can smoothly provide the hydrocarbon trapping mechanism. In order to further confirm the probable future prospects and support the study, modeling of P and S wave Acoustic Impedance have also been done. The advance integrated study of AVO modeling and numerical rock physics analysis may be helpful in providing further insights into current research.

Interpreting Seismic Profiles in terms of Structure and Stratigraphy with Implications for Hydrocarbons Accumulation, an Example from Lower Indus Basin Pakistan

Structural delineation and Stratigraphic evaluation of proven geological basins are of prime importance for hydrocarbon exploration and exploitation. The current study aims to map the subsurface geology in a part of Lower Indus basin of Pakistan in terms of structure and stratigraphy using seismic data with some borehole information. In this paper, conventional integrated geophysical technique has been used to analyze the seismic data to characterize reservoir formations. To serve this purpose, 2D seismic data in SEG-Y format was used along with velocity and well logs information. Seismic profiles are interpreted and then transformed into 2D and 3D (Time and Depth domain) contour maps, which is the representation of true subsurface geology. Three promising closures at shallow time have been identified on structural contour maps which are indicative of possible prospects. A closure, covering approximately 1 Sq Km area over Eocene aged Sui Main Limestone and further two over Cretaceous aged Lower Goru formation covering areas of 500 and 400 Sq km along shot point 260 and 380-390, respectively. Conjugate normal fault system among the stratigraphic layers existing in the study area can smoothly provide the hydrocarbon trapping mechanism. In order to further confirm the probable future prospects and support the study, modeling of P and S wave Impedance have also been done. The advance integrated study of AVO modeling and numerical rock physics analysis may be helpful in providing further insights into current research.