The ability to determine oil saturation changes through time in the Kern River field is critical to heat management and optimization of reserves depletion. The Kern River reservoir is a complex multi-layered fresh water braided river deposit undergoing varying stages of thermal recovery. In the past, the practice had been to selectively core when new well locations were identified. An alternative to open hole core saturation measurements is the Carbon Oxygen Ratio (COR) log, which yields accurate and repeatable data that can be used to identify and monitor reserves depletion. In this field, time-lapse 4D oil saturation images are being generated from a grid of several hundred observation wells. Over 360,000 feet of COR data have been acquired. The project is realizing accuracies comparable to core data — bore out from a database containing 36,000 feet of core. In 1993, nine observation wells were drilled and cored. After casing was cemented in place, the wells were logged immediately to reduce uncertainties associated with subsequent production. Full field monitor logging was implemented in 1996 and again in 1997. Small changes in the COR oil saturation measurement over time are being monitored with a measurement precision of +/- 3.2 saturation units (su) with a confidence level of 95%. The highly accurate and precise data were made possible in part by reservoir conditions, well bore conditions, and a process improvement program incorporating all major steps from acquisition to data processing. A shared database tracked progress and monitored quality throughout the project. The project deliverables were in digital form only. Log-to-core data comparisons, steps to determine precision and accuracy, as well as time-lapse 4D images showing reservoir dynamics, will be discussed.

This paper was selected for preaentatim by sin SPE Progrsm Ccmmittae following review of information contained in an ebstract submiiad by the author(s) Contents of the p=spw, .ss presented, have not bean reviewed by the Society of Petroleum Engmaers and are subii to mrreclion by the author(a), Tha materisl, es presented, dew not necessarily raflact any position of the society of Petroleum Engineers, its officers, or members. Papara praeanted at SPE mwtings are subject to pubficetion review by Editorial Committees of the Wciety of Petroleum Engineers Electromc reprcducticm, distribution, or atoraga of any part of this paper for commercial purposes without the written cement of the Society of Petroleum Engimaers is prohibited. Permission to repreduca in print is restricted to an abstract of not more than 300 wmrd.s illustrations may not be copied. The abstract must contain conspicuous acknowkdgmant of tiare and by vdmm the patwr was prasented. Writa Librarian, SPE, P.O. Sox 833336, Richardson, TX 750S3-383S, U. S. A., fax 01-972.952-9435 AbstractThe ability to determine oil saturation changes through time in the Kern River field is critical to heat management and optimization of reserves depletion. The Kern River reservoir is a complex multi-layered fresh water braided river deposit undergoing varying stages of thermal recovery. In the past, the practice had been to selectively core when new well locations were identified. An alternative to open hole core saturation measurements is the Carbon Oxygen Ratio (COR) log, which yields accurate and repeatable data that can be used to identify and monitor reserves depletion.In this field, time-lapse 4D oil saturation images are being generated from a grid of several hundred observation wells. Over 360,000 feet of COR data have been acquired. The project is realizing accuracies comparable to core data --bore out from a database containing 36,000 feet of core. In 1993, nine observation wells were drilled and cored. Atler casing was cemented in place, the wells were logged immediately to reduce uncertainties associated with subsequent production. Full field monitor logging was implemented in 1996 and again in 1997.Small changes in the COR oil saturation measurement over time are being monitored with a measurement precision of +/-3.2 saturation units (SU) with a confidence level of 9570. The highly accurate and precise data were made possible in part by reservoir conditions, well bore conditions, and a process improvement program incorporating all major steps from acquisition to data processing. A shared database tracked progress and monitored quality throughout the project. The project deliverables were in digital form only.Log-to-core data comparisons, steps to determine precision and accuracy, as well as time-lapse 4D images showing reservoir dynamics, will be discussed. HARNESS, SHOTTS, HEMINGWAY, ROSE, VAN DER SLUIS SPE 46245 8processes used to collect COR data from a grid of several hundred observation wells over a period of five years. Recent ImprovementsOver the course...