The backlimb trishear velocity field is compared to that of mechanical models of fault-bend folds in an incompressible anisotropic viscous media to determine the relationship between the magnitude and orientation of mechanical anisotropy and the kinematic parameters of the trishear model. The trishear model can describe the velocity field of the mechanical model, at least to first order approximation for some cases. We find that the apical angle, asymmetry angle and overall geometry of the hanging-wall syncline above the ramp depend on the magnitude and orientation of the planar anisotropy inherent in stratigraphic sequences. The asymmetry of trishear zone in the backlimb region mimics that of the planar anisotropy. In general, as the magnitude and inclination of the anisotropy increase, the trishear apical angle decreases. The trishear parameters that describe physical models of fault-bend folds with different magnitudes of anisotropy also show a decrease in apical angle with an increase in magnitude of anisotropy. Yet the apical angles of the backlimb of physical models generally are less than these predicted by the mechanical model for the same magnitude of anisotropy. In addition, the physical models display significantly more negative asymmetry than predicted by the mechanical model. The results of this study may be used to determine the conditions under which the trishear model is an acceptable approximation to natural formation and help guide the selection of trishear parameters for subsurface structural interpretations in fault-fold terrains.

We present a method for detecting and correcting poor coupling in an Ocean Bottom Seismic (OBS) experiment. The basic idea of our method is that the normal component (with respect to the seafloor) of particle velocity is continuous at the water-solid interface. A comparison of the normal component of particle velocity just above and below the seafloor allows us to assess poor coupling. In other words, our method for detecting poor coupling consists of analyzing vertical particle velocities measured just above and below the seafloor. The normal component of particle velocity above the water is measured using either a vertical receiver array or a vertical source array (dipole source), whereas the normal component of particle velocity below the water is directly measured in this OBS experiment.

In general, the quantities recorded in the OBS experiment are vertical and horizontal components of particle velocity, but continuity of the boundary is based on the normal component of particle velocity being oriented perpendicularly to the seafloor. For a flat seafloor, the vertical component of particle velocity values just above and below the seafloor must be almost equal according to the continuity condition at the water-solid boundary. However, for a dipping seafloor this is not the case. We have established that we can differentiate a poor coupling effect from a dipping-seafloor effect by using the vertical component of particle velocity.

We have tested our method on real (Eugene Island) data and synthetic (finite-difference) data. For finite-difference synthetics, we have used a grid spacing 0.25 meters to properly simulate the water-solid interface. By examining the uniformity (with respect to offset) of cross-correlation between the vertical component of particle velocity just above and below the seafloor, we were able to detect poor coupling and to differentiate it with any dipping effect at the seafloor. The energy of data just above and below the seafloor were also used for detecting poor coupling and for differentiating it from dipping-seafloor effect.

This study describes the structural and depositional evolution in the KH field in West Natuna Basin, Indonesia. Data for the study were acquired by three-dimensional (3D) seismic reflection volume and a complete suite of well logs.

The regional basin underwent transtensional, sinistral shear during the rift phase that reactivated during the early to middle Miocene inversion as a traspressional, dextral shear. The study identified four periods of tectonic activity in the area which are extension, quiescence, compression and another period of quiescence.

A structural closure developed along a series of north-south trending, normal splay faults defines the area’s trap play. Understanding how this structural play fits into the regional tectonic picture may suggest new approaches to hydrocarbon exploration in the area.

Interpretation of 900 km of a closely spaced grid of high-resolution seismic profiles over the northwestern margin of South Caspian Basin (SCB) allows recognition and study of six late Pleistocene - Holocene depositional sequences.

Sequence stratigraphy analysis of sedimentary strata from 117,000 years B.P. to present led to the identification of a highstand systems tract, two transgressive systems tracts and six lowstand systems tracts. Each systems tract is characterized by specific seismic facies. Diverse depositional processes on the northwestern margin of the SCB are suggested by the thirteen seismic facies patterns recognized in the study area. Two distinct progradational complexes were interpreted within Sequence III and Sequences IV and V in the northeastern and northwestern parts of the study area, respectively. Stratigraphic interpretation of the sequences provided important information on parameters that control depositional architectures, such as lake level fluctuations, tectonic dynamics, and sediment supply.

High sedimentation rates combined with a series of high-frequency and high-amplitude lake-level fluctuations, abrupt changes at the shelf edge, abnormally high formation pressure, and high tectonic activity during Quaternary time resulted in the development of a variety of complex geologic drilling hazards. I distinguished three types of hazards as a result of this study: mud volcanoes, sediment instability, and shallow gas.

The 2D high-resolution seismic dataset from the northwestern margin of the SCB allowed more detailed seismic sequence stratigraphic analysis in the study area than has previously been attempted. In particular, it has a clear application in deciphering sediment supply and relative lake level changes as well as tectonic relationship of the northwestern shelf margin of the SCB.

Results of this work led us towards better understanding of recent depositional history, improved our knowledge of the nature of the basin tectonics, climate history and styles of and controls on sedimentation processes within a sequence stratigraphic framework during the late Pleistocene-Holocene time.

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The South Marsh OCS Blocks, located approximately 150 miles southwest of New Orleans, Louisiana, contain a 100 million barrels oil field. In recent years, exploration in this area has focused on plays in Pleistocene salt-related rollover structures with reservoirs of fluvial-deltaic sandstones and proven high oil producing potential. After more than twenty years of exploration, exploitation and producing, this area remains an attractive target for exploration target due to its potentially high quality reservoirs that have not been drilled.

The I, K and L reservoirs of the Pleistocene have contributed to the majority of the production of over 100 million barrels of oil and near 200 billion cubic feet natural gas.There are more than 90 well penetrations in these sands that show great stratigraphic diversity within short distances. The ability to accurately determine whether sand lenses have been adequately produced or bypassed represents great production opportunity for operators. New 3D seismic processing and interpretation techniques, such as 3D Pre-Stack depth migration, PostStack ESP (PostStack Event Similarity Prediction), Spectral decomposition, have been applied to interpret 3D seismic data with significantly improved accuracy. This has led to a renewed interest in the South Marsh area in an attempt to identify new plays and prospects.

An interactive 3D seismic interpretation has been carried out for the entire area. The objectives of this study are: 1) 3D seismic Interpretation, 2) build a depositional environment model that encompasses the different sedimentary facies and sequence stratigraphic framework by using the prestack time migrated 3D volume and existing well control, 3) study rock properties using seismic modeling and well data to explain seismic attribute response, and 4) study the hydrocarbon potential of the area.

Well correlations were investigated prior to 3D seismic interpretation. Reprocessing and special processing of data from the target area did not start until most of seismic interpretation had been completed, which significantly lowered the cost of special data processing and shortened the prospect evaluation time.

Three horizons were mapped based on well, seismic, and petrophysical data for I, K and L formation tops respectively. Structure styles were well defined based on 3D seismic interpretation. Wells correlation has been completed for I, K and L formations throughout the study area. A sequence stratigraphy framework was built based on seismic interpretation, well and petrophysical data, which led to the identification of reservoir types in different formations.

Reservoirs were studied vertically and horizontally. Reservoir types and properties were identified.

One prospect related to the proven play of fault bounded anticline structures was identified within the area. The plays involve the stratigraphic pinch out of basal transgressive sands deposited in the flank of the structure.