Optimizing Fracture Data Acquisition from Archived Core

John C. Lorenz¹ and Scott P. Cooper^2
1Geoflight LLC
²Cooper Geological Consulting

The maximum amount and highest quality of fracture data are acquired from freshly cut core. However, when times are tough and fewer cores are being cut, archived core is an alternate and viable source of significant fracture data even if that core has been slabbed an/or is now in discontinuous pieces. Acquisition of decent fracture data from archived core requires careful observation and analysis, starting with a thorough washing of the core. Slabs and butts should be examined together where possible. Slabbing may in fact expose the smaller fractures that are not obvious on the core surface. Fracture analyses of archived core will of necessity be less quantitative than analyses done on fresh core, and the largest fractures may have been removed as samples and souvenirs long ago. However, fractures are common enough in many reservoirs that even archived core remnants often contain fracture samples which will allow a qualitative assessment of parameters such as fracture distributions with respect to lithology and gross fracture characteristics (i.e., dips, planarity, mineralization, aperture). These fracture samples may also contain clues on the mode of fracture formation which can be used to make qualitative estimates of interwell fracture distributions and intensities. Estimates can also be made of natural fracture strikes if they can be related to the strikes of the induced fractures that are common in many cores.

AAPG Search and Discovery Article #90089©2009 AAPG Southwest Section Meeting, Midland, Texas, April 26-29, 2009