Jones, Peter J.¹, Henry I. Halpern¹, Matthew W. Dahan², Gerhan Aktas², Isaac B. Ishak², Salman M. Al-Qathami¹, Khalid R. Al-Malki¹
(1) Saudi Aramco, Dhahran, Saudi Arabia

ABSTRACT: Applications of Pyrolysis to Optimize Oil Field Development in Saudi Arabia: Part 2 - "Real-Time" Application on Horizontal Wells

Pyrolytic assessment of historical core samples for the Arab-C Reservoir at Qatif Field revealed a variety of complex issues that would ultimately affect field development. Foremost of these issues is the existence of a substantial tar mat on the flanks of the field that greatly limits the options for placement of horizontal power water injectors (HPWIs) at the periphery of the field. However, variations in reservoir facies can be equally important and often complicate well placement issues further in tar mat regions. These issues often result in a very narrow tolerance for positioning HPWI wells below oil productive reservoir and away from tar occluded reservoir, where little or no water injection can be accomplished. 
The Pyrolytic Oil-Productivity Index (POPI), Apparent Water Saturation (ASW) Method, and Compositional Modeling Method (CoMod) were applied in “real-time” (at the wellsite) to assist with geosteering horizontal oilfield development wells. These methods were effective in: 1) confirming well placement within O/W transition zones; 2) identifying, characterizing, and quantifying tar intervals that were encountered; 3) assessing successful geosteering out of tar mats once encountered; and 4) identifying reservoir intervals that are favorable for water injection. Real-time pyrolysis has been a valuable tool for reservoir development at Qatif Field by both confirming additional movable hydrocarbons that were identified during planning and by enhancing well placement to recover additional reserves.

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