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Frenkel, Michael A.1, Michael Walker2
(1) Baker Hughes Inc, Houston, TX (2) Baker Hughes, East Perth, WA, Australia

ABSTRACT: Improved Characterization of Fractured Formations Using Array Lateral Log Technology

Fractured granite basement is an important play in many petroleum basins around the world. Prolific production from the fracture networks in the Cuu Long basin offshore Vietnam has been a driver for exploration over the past ten years. Now exploration and development efforts are being focused on the fracture basement as the primary target.
Fracture detection techniques using conventional wireline devices, image logs or acoustic waveform logs are generally limited to the surface of the well bore. Attempts have been made to estimate fracture apertures using pad resistivity devices or by direct measurement with the acoustic devices. However, the aperture at the well bore may or may not relate to how deep the fracture may extend away from the borehole.
The array lateral data can be processed to reveal fractures that extend a significant distance away from the well bore. The same data can be used to expose the drilling induced fractures and breakout, which do not extend any substantial distance away from the well bore. In order to test this concept, some synthetic examples were modeled. A suggested three-step interpretation process is as follows:
1. Detect fractured sections and rank fractures according to how far they may extend away from the well bore using the shallowest lateral measurements processed by an inversion technique. 2. Incorporate the fractures into an interpretation model. 3. Fix the fracture parameters and determine the remaining formation parameters using the deep lateral measurements processed by an inversion technique.
Examples from the fractured granite basement reservoirs of offshore Vietnam are shown, where image logs and acoustic waveform data are also available. Combining data from the array lateral log with borehole images and acoustic waveform data provide improved fracture characterization.


AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.