One of the Eocene age fields in Cambay Basin of India, having about 1000 MMbbls of initial oil implace, has got nine reservoirs of thickness varying from 14 ft to 66 ft. Two main multilayered reservoirs are being produced under peripheral water flood from early stage of exploitation. The estimated oil implace of these two reservoirs is 560 MMbbls and 170 MMbbls and expected ultimate recovery is 55 percent and 61 percent respectively. while about 82 percent of recoverable oil from these two reservoirs has been already recovered their present rate of production is 5200 BOPD with 72 percent of water.

Drilling of a few new wells for EOR, in the area that was expected to be flooded by encroaching injected water in the said two reservoirs has shown virgin oil saturation. On this basis, study of movement of advancing flood front in past - dynamic model, mapping of heterogeneity distribution pattern static model and, calculation of natural water influx and voidage have been taken up. Integration of these studies along with recovery analysis and cased hole carbon oxygen logging have been used in identifying areas of bypassed oil. The waterflood management by shift of injection row, regulation of injection rate and selective injection in low permeable layers in different flow regimes has been found to be effective in exploiting bypassed oil and improving sweep efficiency, in turn enhancing recovery and increasing oil production. Implementation of study in field has resulted in an increase in oil production form 1400 BOPD to 2000 BOPD from one sand.

The field has already produced 46.7 percent of total inplace oil in the last 35 years. The economic life the field will get extended by exploitation of bypassed oil and improvement in sweep efficiency through effective surveillance of water flood. P. 727

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