Seismic Structural Interpretation Research Articles

Thin-skinned versus thick-skinned structural models for Apulian carbonate reservoirs: constraints from the Val d'Agri Fields, S Apennines, Italy

The Apulian Platform Carbonates form the reservoir unit in several major oil fields in the Val d'Agri area of southern Italy. Traps are formed by compressional fold structures developed in the hanging wall of major reverse faults. Published models for these structures emphasize a ‘thin-skinned’ tectonic style with a basal detachment located in Triassic evaporites. However, the generally poor quality of seismic data in the southern Apennines means that subsurface geometries are poorly constrained and seismic-structural interpretation becomes model-driven. The density of data associated with field development in the Val d'Agri area provides an opportunity to constrain structural models at a variety of scales. Good quality seismic data image the front of the Monte Alpi field and show involvement of the Base Apulian seismic reflection in compressional structures. Locally, well-defined fault plane reflectors image the moderate-steeply dipping, convex-up reverse faults that bound the structures. Integration of well, vertical seismic profiles and seismic data confirm the dominance within the reservoir of moderate-high angle reverse and normal faulting. Taken together these elements suggest that a thick-skinned structural model is most appropriate for the Val d'Agri Apulian structures, whilst the geometry of the main bounding faults suggests that they are inverted Permo-Triassic extensional faults.

Introduction to the structure and stratigraphy of rift systems

Bruce Trudgill has a B.Sc. degree in geology from Aberystwyth, University of Wales and a Ph.D. in structural geology from Imperial College, London. He was a geophysicist at Amerada Hess UK Ltd. before taking up a postdoctoral research fellow position back at Imperial College studying the growth of normal fault structures. From 1994 until the end of 1999 he was a research associate/professor at the University of Colorado in Boulder, investigating salt tectonics in the northern Gulf of Mexico. Bruce is now in his third stint at Imperial College, having rejoined the department as a lecturer in geology and geophysics. His main research interests lie in the tectonics of sedimentary basins and, in particular, the growth of normal fault structures and the role of salt in controlling basin evolution. Bruce teaches 3-D seismic interpretation and advanced structural interpretation of seismic data in the petroleum geoscience M.Sc. course. He is also a leader on the annual M.Sc. field trip to the Book Cliffs and Paradox basin in Utah.John Underhill has been a professor of stratigraphy at the University of Edinburgh since 1998. Prior to joining the faculty at Edinburgh in 1989, John worked for Shell International in The Hague and London as an exploration geoscientist. He was an AAPG Distinguished Lecturer in 1999 and was awarded their prestigious Matson Award for excellence in presentation in 1992. John has also been the recipient of the Geological Society's President's Award in 1990 and their Wollaston Fund in 1999. He was the European Association of Petroleum Geoscientists' Distinguished Lecturer in 1989 and 1992. In his spare time, John is a professional soccer referee and officiates in international (FIFA, UEFA) and Scottish Premier League competitions. The AAPG Hedberg Research Conferences were established in 1974 by the Committee on Research to promote the science of geology …

Model-inspired interpretation of seismic structures in the Central Alps: Crustal wedging and buckling at mature stage of collision

Research Article| July 01, 2002 Model-inspired interpretation of seismic structures in the Central Alps: Crustal wedging and buckling at mature stage of collision Jean-Pierre Burg; Jean-Pierre Burg 1Geologisches Institut, ETH-Zentrum and Universität Zürich, Sonneggstrasse 5, CH-8092 Zürich, Switzerland Search for other works by this author on: GSW Google Scholar Dimitrios Sokoutis; Dimitrios Sokoutis 2Department of Geology and Physical Geography, School of Geology, Aristotle University of Thessaloniki, 540 06 Thessaloniki, Greece Search for other works by this author on: GSW Google Scholar Marco Bonini Marco Bonini 3Consiglio Nazionale delle Ricerche, Istituto di Geoscienze e Georisorse, Sezione di Firenze, via G. La Pira 4, 50121 Firenze, Italy Search for other works by this author on: GSW Google Scholar Geology (2002) 30 (7): 643–646. https://doi.org/10.1130/0091-7613(2002)030<0643:MIIOSS>2.0.CO;2 Article history received: 13 Nov 2001 rev-recd: 28 Feb 2002 accepted: 03 Mar 2002 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Jean-Pierre Burg, Dimitrios Sokoutis, Marco Bonini; Model-inspired interpretation of seismic structures in the Central Alps: Crustal wedging and buckling at mature stage of collision. Geology 2002;; 30 (7): 643–646. doi: https://doi.org/10.1130/0091-7613(2002)030<0643:MIIOSS>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Analogue models of continental convergence inspire a new interpretation of the deep-seismic profile across the Central Alps, the classical collision belt of Western Europe. We conclude that active mountain-building processes involve wedging and crustal buckling and that seismic information does not reflect subduction-related orogeny, but documents recent crustal shortening. We also infer that present-day subduction of the delaminated European mantle lithosphere takes place below the northern side of the mountain belt. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The Challenge of Interpreting 3-D Seismic in Shaybah Field, Saudi Arabia

ABSTRACT The giant Shaybah field, situated in the northeastern Rub’ Al-Khali Desert in Saudi Arabia, was discovered in 1968. 2-D seismic and well control were used at the time to delineate the field. A 3-D seismic program was launched in 1993 to develop a detailed geological picture of the field. Over 120 million seismic traces, covering an area of about 1,100 square kilometers, were acquired in flat sabkhas and high sand dunes. The dunes, exceeding 200 meters in height in places, posed a severe statics correction problem. Up to 200 milliseconds of time correction was sometimes applied to the seismic traces in order to compensate for sand-related statics. Also, as verified by vertical seismic profiles, the reservoir level was severely obscured by strong multiples. In addition to complex topography and multiples, the 3-D structural seismic interpretation had to overcome two further problems. First, the lithology of the gas-capped Shu’aiba reservoir consists predominantly of carbonates which are sealed by a denser, compacted shale. The decrease in density and increase in velocity, at the top of the Shu’aiba reservoir, result in a weak reflection. Second, the top of the Shu’aiba reservoir undulates as a result of rudist build-ups and therefore is not conformable with its base. For these reasons, the top of the Shu’aiba reservoir cannot be mapped as a “phantom” of the much better reflection from the base of the reservoir. To resolve the uncertainties described above, borehole seismic measurements (specifically offset and zero-offset vertical seismic profiles in vertical wells) were incorporated. These additional measurements provided the required calibration of the seismic, and hence the validation of the structural interpretation. These borehole surveys continue to serve as a reference for on-going efforts to further improve the data quality using more advanced processing techniques.

KTB — The structure of a Variscan terrane boundary: seismic investigation — drilling — models

On October 12, 1994, the Hauptbohrung (main hole) of the German Continental Deep Drilling Program (KTB) in the Oberpfalz/NE Bavaria reached its final depth of 9101 m. The drilling results provide a test of the validity of the initial structural concept for the KTB location in the boundary zone between the Saxothuringian and Moldanubian terranes of the Variscan orogen. This paper outlines some of the geological results as well as additional information from seismic investigations, and discusses briefly alternative structural models. The interpretation of local and regional seismic structures leads, in connection with the drilled profile, to the conclusion that the ZEV (Zone Erbendorf-Vohenstrauss, with the KTB drill-site) is derived from and linked with the ‘Erbendorf Body’ and equivalents of the Mariánské Lázně Complex and/or the Bohemicum in the middle and lower crust. Instead of a rootless klippe resting on the Saxothuringian-Moldanubian suture, the ZEV appears to be a part of the suture itself. The present position of the ZEV is tied to the junction of the ENE-WSW suture with the NNW-SSE Oberpfalz Block as a part of a large wrench system, and developed, probably, by a two-stage transpressive exhumation process prior to and during the Variscan collision.

Stress Regime and Structural Style: A New Classification for Seismic Structural Interpretation: ABSTRACT

The total stress tensor (effective stresses), which acts in rock deformation, is usually divided into a geostatic component (including pore pressure) and a tectonic component. Change in tectonic stress magnitude (negative, nil, or positive) inverts the relative position of the effective main stress axes. Microtectonic data, mechanical laws, structural field geology, and seismic reflection data are compared. These studies show a close relationship between tectonic style, strike of the structures, fault movements, and regional tectonic regime, i.e., orientation, relative position of the main stress axes at the time of deformation, and magnitude of the tectonic stress. Thus, the structural styles in a sedimentary basin can be classified as a function of the tectonic regime in the absence or presence of shale or salt tectonics. These styles are illustrated with strike and dip seismic sections, which allow us to predict the style and evolution of structures in petroleum sedimentary basins.

Modeling the three‐dimensional structure of macroscopic magma transport systems: Application to Kilauea Volcano, Hawaii

We report the results of modeling the three‐dimensional internal structure of Kilauea's magmatic passageways. The approach uses a clear plexiglass model containing equally‐spaced levels upon which well‐located seismic hypocenters are plotted. Application of constraining geologic and geophysical criteria to this distributed volume of earthquakes permits the interpretation of seismic structures produced by fracturing in response to locally high fluid pressures. Four magma transport and storage structures have been identified within and beneath Kilauea: (1) Primary conduit. The conduit transporting magma into Kilauea's summit storage reservoir rises from the model base (14.6 km) to the 6.5 km depth level. It is a zone of intense fracturing and inferred intrusion, whose horizontal sections are elliptical in planform. Over its height, the average major axis of the component horizontal sections is 3.3 km, with an average minor axis of 1.7 km. This yields an aspect ratio of ξ = 0.52. At the 14.6 km level, the strike of the major axis is N67°E. During passage from the upper mantle through the oceanic crust, this axis rotates in a right‐handed sense, until the strike is N41°W at the 6.5 km level. (2) Magma chamber complex floor. The interval from 6.5 to 5.7 km, immediately over the primary conduit, is aseismic. This suggests differentially high fluid‐to‐rock ratios, and relatively weak pathways for further vertical transport into higher levels of the storage complex, as well as lateral leakage eastward into the Mauna Ulu staging area—for later vertical ascent beneath the upper east rift zone. Seismicity within the immediately subjacent rocks that form the top of the primary conduit (at 6.5 km) suggests that this inferred magma‐rich horizon forms the effective floor of the summit storage complex. (3) Magma chamber crown. Intense seismicity over the 1.1–1.9 km depth interval defines an elliptical region in plan view. The top of this region has a broad apex with an average major axis of 1.5 km, and an average minor axis of 1.1 km producing an aspect ratio of ξ = 0.73. This region coincides with the epicentral position of summit vertical displacement maxima during inflationary deformation and is interpreted as a region of intense diking, crowning the summit storage complex. (4) Upper east rift zone pipe. From a depth of 5.7 km, a cylindrical region of seismicity rises beneath the upper east rift zone, to the 1.9 km level, where it merges with the subhorizontal upper east rift zone duct. This pipe‐like zone has a mean diameter of 1.4 km and a vertical axis that pierces the surface of the volcano at the intersection of the Koae fracture system and the upper east rift zone. We suggest this pipe forms a principal connection between the base of the summit storage reservoir, and near‐surface storage compartments and ducts in the upper east rift zone. In this role, the pipe is suggested to have contributed heavily to Mauna Ulu's magma supply during 1969–1974. The model of magma transport and storage thus constructed provides a context in which other types of data (e.g., ground deformation and electrical conductivity) may be interpreted as well as a means of refining petrological inferences based on lava chemistry.

ON THE THEORY OF GROWTH FAULTING*: GENESIS OF THE “UNIT”

A detailed and rigorous geomechanical analysis of the stability of overpressured, gently sloping, sediment layers is presented that underlies the Multi‐Unit Delta Model described in Part I (Crans, Mandl and Haremboure, Journ. Petrol. Geol., 2, 3, 1980). That delta model explains and permits quantitative reproduction of main features associated with growth faulting. Starting from the equilibrium equations, the Coulomb‐Mohr yield criterion and the proper initial and boundary conditions, the elastic and plastic stress fields in the sloping, overpressured layer are derived. The plastic stress field is calculated on the grid generated by the “characteristics” of the hyperbolic partial differential equation for the plastic stress state. These characteristics, being called in stress analyses “slip lines”, are potential faults. In the case considered, a parameter equation is derived for one set of slip lines, (potential growth faults), which may simplify into cycloids under special conditions. Once the plastic stress field has been generated, the plastic deformation of the layer can be calculated by introducing the proper boundary conditions to the flow rules or plastic “velocity equations” being discussed extensively. To complete the rheological description, the behavior of the sediment layer is described by attributing also thixotropic properties to the sediment. Although the case discussed is a very specific one, it illustrates how structural geological phenomena can be modeled on the computer in an appropriate geomechanical way. Such a numerical computer model shows the unique relation between plastic stress state and fault pattern, and the non‐unique relation between plastic stress state and deformation pattern, being typical for the theory of plasticity. Generally, the unique relation between stress state and fault pattern is of utmost importance for the seismic interpreter in judging the feasibility of fault patterns. Inversely, one may deduce the stress state in the formation from a convincing fault pattern obtained from structural seismic interpretation which is, among others, important for the evaluation of acoustic properties of the sedimentary sequence used for the probabilistic assessment of seismic amplitude anomalies in the search for hydrocarbons (Crans and Berkhout, 1979, 1980; Crans and Ausburn, 1980).