Vertical seismic profiling is one of the rapidly developing areas geophysical technology for exploring in mature basins. The measurement basically involves recording total upgoing and downgoing wave fields propagating through a stratigraphic section by means geophones clamped to wall drilled well.

A bottom-simulating reflection (BSR) is a seismic reflectivity phenomenon that widely accepted as indicating the base of gas-hydrate stability zone. The acoustic impedance difference between sediments invaded with gas hydrate above BSR and without hydrate, but commonly free below, are conditions create this reflection. relationship BSRs marine has become so well known since 1970s investigators, when asked to define most important attribute systems, usually reply, “a event.” Research...

Recent research at the Bureau of Economic Geology (BEG) has focused on probing deeply buried rocks with shear-wave illumination. The challenge been that seismic data were available to team generated by vertical-vibrators and recorded vertical geophones. This BEG now demonstrated important, but conflicting, facts: (1) vibrators geophones can produce excellent quality SV-P data, (2) in some instances, do not usable data. paper focuses what causes such dramatic differences vibrator/vertical...

The seismic body wave radiation pattern of a working roller‐cone drill bit can be characterized by theoretical modeling and field data examples. Our model drill‐bit signal generation is pseudo‐random series bit‐tooth impacts that create both axial forces tangential torques about the borehole axis. Each tooth impact creates an extensional travels up string waves radiate into earth. predicts P‐waves primarily along axis borehole, shear perpendicular to In vertical hole, largest will recorded...

More robust seismic interpretation can be done when an project uses both compressional (P) and shear (S) data rather than using only one mode, whether that mode a P or S mode. Unfortunately, this fundamental principle is frustrated by the cost difficulty of deploying S-wave sources limited availability direct-S sources. We introduce new option based on direct-P modes generated vertical-force To explain potential method for acquiring data, we evaluate real-data examples illustrate physics...

Tube waves act as noise that camouflages upgoing and downgoing body wave events which are the fundamental seismic data measured in vertical profiling (VSP). In two onshore profiles, principal source of tube is shown to be surface ground roll sweeps across well head. Secondary sources revealed these VSP downhole geophone tool itself bottom borehole. Body signals also create when they arrive at significant impedance contrasts borehole such changes casing diameter. Computer simulated arrays...

We conducted a study at Stratton Field, large Frio gas‐producing property in Kleberg and Nueces Counties South Texas, to determine how best integrate geophysics, geology, reservoir engineering technologies detect thin‐bed compartmented reservoirs fluvially deposited system. This documents that narrow, meandering, channel‐fill as thin 10 ft (3 m) narrow 200 (61 can be detected with 3-D seismic imaging depths exceeding 6000 (1800 if the data are carefully calibrated using vertical profile...

We inverted P-wave amplitude variation with offset and azimuth (AVOAz) data from the Marcellus Shale to obtain fracture parameters that can fully describe elastic behavior of fractured rocks overall symmetry orthorhombic or monoclinic. AVOAz two interfaces, (1) upper interface between top Stafford limestone (2) lower base Onondaga limestone, were used for inversion. To check validity our inversion results, each using Monte Carlo simulation include uncertainty in a priori information, i.e.,...

Application of multicomponent seismic exploration produces multiple images the same subsurface. For a successful interpretation images, it is crucially important to register them in coordinate frame. Accurate registration time‐domain im‐ages also provides an effective estimate interval ratio, major petrophysical attribute. We propose multistep approach im‐age registration, which consists initial interpretation, amplitude and frequency balancing, scan, least‐squares optimization. The applied...

We show that SV-P reflectivity closely matches P-SV reflectivity; thus, in concept, an image should be as informative and valuable a for seismic interpretation purposes. If the dip of rock layering is not severe, length SV raypath involved imaging approximately same imaging; important lithology-sensitive [Formula: see text] velocity ratio determined with data data. compare velocities used to emphasize equivalence stacking velocities, therefore seismic-derived ratios, obtained both...

We show examples of S-S images created from multicomponent seismic data generated by vertical-force sources that can be quite useful to interpreters. Two source types are used: vertical vibrators and shot-hole explosives. first discuss made a vibrator recorded with receiver arrays 3C geophones. next extracted surface-based geophones deployed around this VSP well as 3D grid. The energy used generate these surface were In all examples, we observe each type (vertical explosive) produces...

Multicomponent seismic data have unique value for studying near-seafloor geology in deepwater environments. When properly processed, PP (compressional) and PS (converted-shear) images made from multicomponent acquired with seafloor sensors show impressive detail. These high-resolution are invaluable gas-hydrate systems.

Seismic technology will be of key importance for evaluating gas-hydrate resources, particularly across the Gulf Mexico (GoM) where many seismic surveys have been acquired and continue to acquired. To apply studies in gulf an optimal manner, it is essential understand target that has analyzed.

Estimates of worldwide hydrate resources are large, but they also uncertain because inherent difficulties in determining the amount gas present ocean sediments. gas-hydrate concentrations across a deepwater site can vary widely. For example, estimates volume existing hydrates and as free on Blake Ridge offshore South Carolina (USA) range from about 70 trillion m3 over an area 26 000 km2 (Dickens et al., 1997) to 80 for larger 100 (Holbrook 1996). Discrepancies between some partly be...

Using a data set from the Marcellus Shale, we evaluated advantages of multicomponent seismic for fracture and anisotropy studies over conventional P-wave data. traveltime amplitude analysis on pre- poststack data, concluded that PS-waves can provide more accurate information about location, orientation, intensity natural fractures stress than P-waves. Our indicated regional was main cause velocity anisotropy. Amplitude variation with offset azimuth appeared to be useful studies, whereas...

We have analyzed vertical seismic profile (VSP) data acquired across a Marcellus Shale prospect and found that SV-P reflections could be extracted from far-offset VSP generated by vertical-vibrator source using time-variant receiver rotations. Optimal rotation angles were determined dynamic steering of geophones to the time-varying approach directions upgoing reflections. These then imaged common-depth-point transformation based on ray tracing. Comparisons our image with P-P P-SV images...

In previous unpublished work, we found that anomalous values of instantaneous frequency (that is, are negative or have positive magnitudes greater than Nyquist limit) valuable indicators alterations in reflection waveshape occur commonly at stratigraphic terminations. Inspection 3-D seismic data across Nash Draw Field on the northwest slope Delaware Basin showed appreciable wavelet occurred boundaries distinct facies within targeted Brushy Canyon reservoirs being produced this field. Based...

A multidisciplinary team, composed of stratigraphers, petrophysicists, reservoir engineers, and geophysicists, studied a portion Boonsville gas field in the Fort Worth Basin North‐Central Texas to determine how modern geophysical, geological, engineering techniques could be combined understand mechanisms by which fluvio‐deltaic depositional processes create compartmentalization low‐ moderate‐accommodation basin. An extensive database involving well logs, cores, production, pressure data from...

Multicomponent seismic data, combining P-wave and converted P-to-SV wave (C-wave) wavefields, provide independent measurements of rock fluid properties. Unlike P waves, C waves are minimally affected by changes in pore fluids, cases azimuthal anisotropy, will be split into two modes (fast slow) with differing polarization. The 4C, 3D ocean-bottom cable (OBC) multicomponent data discussed here were acquired shallow water (<300 ft) offshore Louisiana over approximately 455 miles2 (Figure 1)....

The world's offshore continental margins contain vast reserves of gas hydrate, a frozen form natural that is embedded in cold, near-seafloor strata. Published estimates suggest the energy represented by hydrate may exceed available from conventional fossil fuel factor 2 or more. Understanding marine systems has become critical for long-term worldwide planning. Groups several nations are attempting to evaluate resource and define seafloor stability problems across accumulations.

Summary Multicomponent 2D (9C2D) seismic data were acquired in Wellington field, south central Kansas with an aim to improve the understanding of Ordovician-aged, fractured carbonate formation that is being considered for CO2 storage. This study demonstrates how P-P and S-S wave modes can be employed characterize spatial variability lithofacies fracture-related anisotropy. Details 9C2D interpretation workflow are discussed including well-to-seismic ties, polarity, P S-wave velocity models,...