Field applications of behind-pipe saturation evaluation in a miscible CO2 flood

Document Type

Conference Proceeding

Publication Date

1-1-2010

Abstract

To evaluate the amount of bypassed oil in a CO2 flood, it is necessary to obtain some estimate of the remaining oil saturation. Near wellbore oil saturation determination requires a tool or sequence of tools that is able to distinguish oil from other phases that may be present in situ especially when those phases are miscible with the oil. Cased hole logging in waterfloods, steam floods and CO2 sequestration cases has been presented and the techniques used are in the process of becoming reasonably reliable evaluation tools. Very little work has been presented on the case where an existing CO 2 flood needs to be evaluated, but has no baseline cased hole logs to tie to. This paper presents the results of field tests where carbon-oxygen and pulsed neutron logs were used in combination to evaluate in situ saturations in an area where oil, water and CO2 are present but where no previous (baseline) cased hole logs had been run. One of the wells had a nearby core characterization and modern open-hole logs to tie the cased hole logs to while another was in the same formation, but only had 1960's vintage open-hole logs. Techniques described in a previous publication were used to perform the evaluation. The theoretical result previously presented worked fairly closely to what was described. However, there are a number of variable parameters required that need to be evaluated and reasonable estimates (or methods to obtain reasonable estimates) of those values are not well documented. This paper will also document the methodologies that seemed to work to successfully estimate these parameters. Copyright 2010, Society of Petroleum Engineers.

Publication Source (Journal or Book title)

Proceedings - SPE Symposium on Improved Oil Recovery

First Page

1498

Last Page

1514

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