Fracture Evaluation in Channel Deposits

GRACE, L. M., Schlumberger Well Services, Dallas, TX

Exploration and exploitation of subsurface channel deposits using electrical images of sedimentary structures are well documented from previous studies. More recently, it has been observed that near-vertical fractures and fracture sets occur in channel deposits in a predictable orientation. Our field studies have shown that fractures are oriented perpendicular to the channel axis. Additionally, this geometric relationship occurs in all depositional environments regardless of sinuosity, texture, composition, depth of burial, and age. The results of many worldwide cause studies will illustrate this observation.

Interpretations of these observations could include (1) regional structural setting controls channel orientation which may be overprinted locally by near-field stresses; and (2) differential compaction, most notably in channel sands encase in shale.

In the channel systems examined, fracture evaluation from electrical images also includes fracture orientation, hydraulic aperture, porosity, and density, all of which are required for maximum recovery efficiency and successful reservoir development.

AAPG Search and Discovery Article #91007© 1991 AAPG International Conference, London, England, September 29-October 2, 1991 (2009)