The majority of carbonate reservoir is oil-wet, which is an unfavorable
condition for oil production. Generally, the total oil recovery after both primary and
secondary recovery in an oil-wet reservoir is low. The amount of producible oil by
enhanced oil recovery techniques is still large. Alkali substances are proven to be able
to reverse rock wettability from oil-wet to water-wet, which is a favorable condition
for oil production. However, the wettability reversal mechanism would require a noneconomical
aging period to reach the maximum reversal condition. An intermittent
flow with the optimum pausing period is then combined with alkali flooding
(combination technique) to increase the wettability reversal mechanism and as a
consequence, oil recovery is improved.
The aims of this study are to evaluate the efficiency of the combination
technique and to study the parameters that affect this method. In order to implement
alkali flooding, reservoir rock and fluid properties were gathered, e.g. interfacial
tension of fluids, rock wettability, etc. The flooding efficiency curves are obtained
from core flooding and used as a major criterion for evaluation the performance of
technique.
The combination technique improves oil recovery when the alkali
concentration is lower than 1% wt. (where the wettability reversal mechanism is
dominant). The soap plug (that appears when high alkali concentration is used) is
absent in this combination as seen from no drop of production rate. Moreover, the use
of low alkali concentration limits alkali loss. This combination probably improves oil
recovery also in the fractured carbonate reservoirs in which oil is uneconomically
produced.
The results from the current study indicate that the combination technique is
an option that can improve the production of carbonate reservoirs. And a less quantity
of alkali is consumed in the process.
| Identifer | oai:union.ndltd.org:unibo.it/oai:amsdottorato.cib.unibo.it:857 |
| Date | 16 April 2008 |
| Creators | Srisuriyachai, Falan <1980> |
| Contributors | Gottardi, Guido |
| Publisher | Alma Mater Studiorum - Università di Bologna |
| Source Sets | Università di Bologna |
| Language | Italian |
| Detected Language | English |
| Type | Doctoral Thesis, PeerReviewed |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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