Showing papers by "Jack Dvorkin published in 2002"

On the universality of diagenetic trends

Abstract: For decades, the main use of seismic data has been to delineate sedimentary bodies and tectonic features in the subsurface. The mission of seeing inside the geologic body has been added recently. Mapping porosity, lithology, and other reservoir bulk properties inside the geologic body has become possible due to the recent dramatic improvement in seismic acquisition, imaging, and inversion quality as well as the accompanying progress of rock physics.

Stratigraphy-guided rock physics

Abstract: Porosity and permeability heterogeneity prevents efficient drainage and sweep of hydrocarbons and results in low recovery efficiency. This heterogeneity is often linked to the facies architecture inherited from the original depositional system as well as to subsequent rock diagenesis. Undrained zones can be precisely targeted if a detailed description of reservoir bulk properties in 3-D is available. It is natural to derive such description from 3-D reflection seismology because of its superior ability to illuminate the subsurface.

Shear Velocity Prediction in the Norwegian Sea

Abstract: Well-bore derived measurements provide a link through rock physics, to the seismic domain. Shear wave velocity log data is important for many aspects of seismic modeling, including offset synthetic seismogram generation, and half space modeling for AVO analysis. Due to the relatively recent advent of shear wave velocity logs (VS), VS data is in many instances missing or unreliable. However, as compressional velocity logs (VP) are widely available a local empirical transform relating VP to VS would be useful. Several authors have published methods for predicting shear wave velocities in the absence of measured data, including Greenberg and Castagna (1992) and Krief (1990). These published models require, P-wave velocity information, but also accurate porosity, mineralogical content, fluid content, and associated elastic parameters. Han (1986) related VP to VS using empirical regressions of ultrasonic velocities, of 80 well-consolidated Gulf Coast sandstones. Here in, we present a simple method for determining an empirical relationship between VP and VS, and apply that relationship to a regional study in the Norwegian Sea. Discussion Our overall objective is to improve the reliability and accuracy of seismic to well ties in the Norwegian Sea, as well as to evaluate the response of synthetic seismograms to the effect of varying potential reservoir fluids. A main component is a rational rock physics model that allows for the robust prediction of shear velocity. Proper preconditioning of the well log data through rigorous log analysis is necessary to build a log suite that can be used in rock physics modeling (i.e. fluid substitution or porosity modeling) and synthetic seismogram generation. Shear wave information is vital for both. If shear velocity information is missing, VS must first be predicted.