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The AAPG/Datapages Combined Publications Database

Houston Geological Society Bulletin

Abstract


Houston Geological Society Bulletin, Volume 47, No. 2, October 2004. Pages 27 and 29.

Abstract: Use of Well Logs in Previous HitSeismicNext Hit Reservoir Characterization

By

Joel Walls
Rock Solid Images, Houston, Texas

Previous HitSeismicNext Hit reservoir characterization, also known as reservoir geophysics, has evolved over the past several years into a multi-disciplinary, business-critical function in most ED&P organizations. Sheriff defines reservoir geophysics as “The use of geophysical methods to assist in delineating or describing a reservoir or monitoring the changes in a reservoir as it is produced.” Reservoir geophysics is applied across a wide spectrum of the oilfield life cycle from discovery and early development to tertiary recovery. One critical part of this process is careful analysis and understanding of petrophysical properties from well logs and core data (Previous HitseismicNext Hit petrophysics).

This presentation will illustrate why Previous HitseismicNext Hit petrophysics is so important and will show how carefully constructed synthetic models can help the geoscientist interpret acoustic and elastic impedance inversion from Previous HitseismicNext Hit data.

Previous HitSeismicNext Hit petrophysics can be performed on single or multiple wells and consists of the following basic steps.

Geophysical Well Log Analysis (GWLA)

  • Collect and organize input data, reservoir conditions, and fluid properties
  • Perform geophysical log interpretation for volume minerals, porosity, and fluids over entire well
  • Edit logs and perform mud filtrate invasion correction (as needed)
  • Generate missing curves (for example shear wave velocity).

Rock Physics Modeling and Perturbations

Perturb reservoir properties using rock physics effective medium models and compute new Vp, Vs and density curves.

  • Fluid Saturation
  • Porosity
  • Lithology
  • Net/gross

Synthetics

Compute synthetic Previous HitseismicNext Hit traces for in-situ and modeled conditions. May also include:

  • AVO response
  • Acoustic impedance (AI) and elastic impedance (EI)
  • Other Previous HitseismicNext Hit attributes as needed

Examples show the effects of mud filtrate invasion effects, wellbore washouts and a bad Vshear log on Previous HitseismicNext Hit well tie. An example is also shown of how Previous HitseismicNext Hit

Figure 1.

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petrophysics can be used to interpret acoustic and elastic impedance inversions for oil saturation and porosity in an on-shore United States oil sand. The pricipal benefits of Previous HitseismicNext Hit petrophysics are improved well-to-Previous HitseismicNext Hit ties, improved calibration of Previous HitseismicNext Hit attributes to reservoir properties, and more reliable models of Previous HitseismicNext Hit response due to reservoir changes (vertically, laterally and temporally). These models can improve interpretation of 3D Previous HitseismicTop data, especially acoustic and elastic impedance inversion. This improved interpretation can reduce drilling risk, enhance field productivity and ultimately increase asset value.

Note: This presentation is based on OTC paper 16921, May 2004.

Figure 2.

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