Browsing ERL Industry Consortia Technical Reports by Author "Cheng, C. H."
Now showing items 1-20 of 101
-
Acoustic Logging Guided Waves In Transversely Isotropic Formations
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1988)We have studied the velocity dispersion of guided waves in transversely isotropic formations. Theoretical velocity dispersion curves were calculated with elastic constants based on laboratory and field measurements and ... -
Acoustic Logging In Randomly Stratified Formations
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1993)The propagation of borehole acoustic waves in the presence of various types of heterogeneous formations is investigated by modeling them as stratified media with varying velocity-depth distributions. Two types of formations ... -
Acoustic Wave Propagation In A Fluid-Filled Borehole With A Horizontal Fracture
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1990)The propagation of guided waves in a fluid-filled borehole with an open horizontal fracture is investigated both theoretically and experimentally. The fracture is modeled as a fluid layer that separates the domain of ... -
Acoustic Wave Propagation In And Around A Fluid-Filled Borehole Of Irregular Cross-Section
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1994)Boreholes with 10% or more ellipticity are not uncommon. In this paper, we consider the coupling of an incident elastic wave into a borehole of irregular cross-section and investigate the cross-mode coupling phenomenon ... -
Acoustic Waveform Logging - Advances In Theory And Application
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1992-02)Full-waveform acoustic logging has made significant advances in both theory and application in recent years, and these advances have greatly increased the capability of log analysts to measure the physical properties of ... -
Application Of Rayleigh's Principle To Guided Waves In A Borehole
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1988)The Lagrangian for guided waves in a completely general borehole model is presented. Rayleigh's principle is used to derive the first order perturbations in wavenumber and frequency due to slight perturbations in the ... -
Applications Of Perturbation Theory To Acoustic Logging
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1989)For guided wave propagation in boreholes, perturbation theory is used to calculate (1) the partial derivative of the wavenumber or frequency with respect to an elastic modulus or density, (2) group velocity, and (3) the ... -
Approximate Effects of Off-Center Acoustic Sondes and Elliptic Boreholes Upon Full Waveform Logs
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)Full waveform acoustic well logging has become instrumental to hydrocarbon exploration because of its ability to determine in situ velocity information for P and S waves as well as the attenuation (or absorption) of seismic ... -
Asymmetric Modes of Elastic Wave Propagation in a Fluid-Filled Borehole
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1985)A numerical investigation of asymmetric modes of elastic wave propagation in a fluid-filled borehole is treated in this paper. The dispersion curves of guided waves (called flexural waves) and synthetic microseismograms ... -
Borehole Effects On Downhole Seismic Measurements
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1992)An exact formulation for borehole coupling, which is valid for all frequencies and all azimuthally symmetric and nonsymrnetric components, is given in this paper. The borehole effects on downhole measurements are studied ... -
Borehole Stoneley Wave Propagation Across Heterogeneous And Permeable Structures
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1991)This study investigates the propagation of borehole Stoneley waves across heterogeneous and permeable structures. By modeling the structure as a zone intersecting the borehole, a simple one-dimensional theory is formulated ... -
Borehole Stoneley Wave Propagation Across Permeable Structures: Comparison Between Theory And Experiment
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1992)The attenuation of borehole Stoneley waves across a permeable structure (e.g., fractures or fracture zone) is correlated with the permeability of the structure. Using a simplified Biot theory, the structure can be modelled ... -
Borehole Wave Propagation In Isotropic And Anisotropic Media I: Finite Difference Method
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1994)In this paper we developed a 3-D finite difference method to simulate wave propagations in an isotropic medium. The wave equation is formulated into the first-order hyperbolic equations by using velocity and stress and ... -
Borehole Wave Propagation In Isotropic And Anisotropic Media II: Isotropic Formation
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1994)In this paper we apply the 3-D finite difference method to simulate borehole wave propagations in an isotropic formation. The scheme is tested in a fluid-filled borehole surrounded by the homogeneous elastic formation. ... -
Borehole Wave Propagation In Isotropic And Anisotropic Media III: Anisotropic Formation
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1994)In this paper we extend the 3-D finite difference method to simulate wave propagations in an anisotropic medium. The scheme is tested in the homogeneous medium. The finite difference results agree excellently with the ... -
Cased Borehole Effect On Downhole Seismic Measurements
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1993)Approximate and exact formulations are presented for the interaction of an incident wave with a cased borehole. In the approximate method, the borehole coupling theory is used to compute pressure in the fluid at a low ... -
Crack Models For A Transversely Anisotropic Medium
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1992)A commonly used model for a transversely anisotropic crack rock is that by Hudson (1980, 1981). This model is based on a simplified analysis of a thin circular crack, with displacement and stress conditions specified on ... -
Decomposition And Particle Motion Of The Acoustic Dipole Log In Anisotropic Formation
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1995)For linear wave propagation in anisotropic media, the principle of superposition still holds. The decomposition of the acoustic dipole log is based on this principle. In the forward decomposition inline and crossline ... -
Detection of Open Fractures with Vertical Seismic Profiling
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1984-01-01)In Vertical Seismic Profiling surveys tube waves are generated by compressional waves impinging on subsurface fractures or permeable zones. The problem of generation of these waves by a non-normal incident P wave for an ... -
Detection Of Subsurface Fractures And Permeable Zones By The Analysis Of Tube Waves
(Massachusetts Institute of Technology. Earth Resources Laboratory, 1983)In Vertical Seismic Profiling tube waves are generated by compressional waves impinging on subsurface fractures or permeable zones. The amplitude of tube waves is dependent upon the formation permeability, the length of ...
