Rapid Assessment of Khuff Reservoir Potential in Saudi Arabian Exploration Wells

Robert F. Lindsay
Saudi Aramco
[email protected]

Porosity breaks are routinely cored in Khuff exploration (wildcat) wells. These cores are rapidly described to assess reservoir potential prior to logging the well. This procedure ensures that timely and well-informed decisions can be made for further evaluation and testing of the well. Assessing reservoir potential while drilling an exploration well requires rapid acquisition of the following data: (1) percent visual porosity in each bed/cycle; (2) relative abundance of carbonate pore types to assess potential permeability; (3) rock types; (4) lithology (dolostone versus limestone); (4) carbonate and evaporite cement; (5) sedimentary structures; and (6) high-resolution sequence stratigraphy, identifying laminae/bed, cycle (parasequence), cycle set (parasequence set), high-frequency sequence, and composite sequence packages of strata. Thin-section petrography, scanning-electron microscopy (SEM), and biostratigraphy follow rapid core description and add information on chronostratigraphy, lithostratigraphy, depositional environment, and aspects of reservoir properties that are not evident macroscopically. Standard SEM images characterize the rock and porosity very well, but SEM images of relief pore casts characterize the pore system better by imaging the pore system three-dimensionally. Combining all of this information provides a comprehensive assessment of the cored section and also improves the understanding of open-hole log signatures and potential log-calibration problems.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain