3-D Fracture System Characterization Using Borehole Image Logs

Mitch Pavlovic
Baker Atlas, Houston, TX

The key to successful exploration in fractured reservoirs is to predict where natural fracturing is abundant. Therefore, the use of borehole imaging technology to locate fractures and determine the geometry of the existing fractures, lateral and vertical distribution of productive fractures, fracture quality and hydrocarbon potential prior setting casing is an essential element in evaluating the economics of any given well.

Naturally fractured reservoirs have always been difficult to describe and evaluate. The complex interaction of fractures, fault zones, matrix, and fluids is sufficiently variable to render each naturally fractured reservoir unique. There are many complex questions that have to be answered for a satisfactory evaluation. Where are the fractured zones? What is the density of the fractures in the system, their distribution and orientation, and what is the anisotropy of the fracture system? Does the system contain open or closed fractures? And above all, is the fracture system capable of flowing hydrocarbons or not?

This paper aims to present results of several detailed 3-D fracture system characterization studies demonstrating how the information obtained from the borehole imaging devices provides for better understanding of the complex fractured reservoirs. Examples include data acquired in a range of geological environments and borehole conditions, including horizontal wells. Furthermore, field data presented here include borehole imagining examples from wells drilled with both conductive and non-conductive (i.e. oil-based) muds.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005