Tilden: Improved Oil Recovery Strategies in Microfractured Silurian Reef Using Nitrogen Gas

R. Stewart¹ and T. Maness^2
1Stewart Producers, Inc., Mt. Vernon, IL 62864, [email protected]
²Maness Petroleum Corporation, Mt. pleasant, MI 48804, [email protected]

Tilden Oil field, located in Randolph County, Illinois, is a Silurian reef reservoir that was discovered in 1953. The field has produced 6 million barrels of oil to date from carbonate fossil buildups that have been intensely altered by diagenesis and micro-fracturing. The field has undergone several phases of drilling, development step-outs, and deeper drilling to produce from over 350 feet of reef reservoir in places. Log and core evaluation can offer only small glimpses of the reservoir and subsurface correlation is not possible with any degree of certainty. Heterogeneous, complexly-compartmentalized and interconnected compartments in reef reservoirs traditionally do not respond well to water flooding. Therefore, alternative methods for improved oil recovery were evaluated. Factors important in the selection of improved recovery methods include economic factors and accessibility to sources of injection materials. A plan to re-pressure the reservoir by gas cap injection has been chosen and will be put into operation later this year. The coordinated geological and engineering assessment of the reservoir, and the strategies used to develop the project will be presented.

AAPG Search and Discovery Article #90095©2009 AAPG Eastern Section Meeting, Evansville, Indiana, September 20-22, 2009