Two highly successful polymer pilot experiments were carried out between 1987 and 1993 on the Daqing oil field (People Republic of China) after favorable laboratory results and preliminary reservoir studies.

The Daqing oil field is a fluvio-deltaic formation with several sand beds and great heterogeneities. The oil is slightly viscous (9.5 cp), water is fresh and the temperature is 45°C, making the conditions favorable for polymer injection.

Each pilot consisted of 4 injectors and 9 producers. One pilot was devoted to one reservoir, whereas simultaneous injection into two reservoirs was performed in the second pilot.

Polymer injection was started in 1990 with a 915-ppm-solution of Polyacrylamide. Approximately 0.6 PV of solution was injected in each pilot, yielding a significant decrease in the water-cut and a respective oil production of 73 120 m3 and 1 1 8 950 m3 in April 1993.

The results of the pilots were matched with a numerical simulator and interpreted in terms of reservoir description. The injection parameters were optimized in terms of viscosity and slug size, in order to extend the process to the whole field.

The sensitivity of the process to the reservoir heterogeneity was also considered.

Keywords:
oil rate, producer, injector, upstream oil & gas, polymer, incremental recovery, heterogeneity, polymer injection, chemical flooding methods, viscosity
Subjects:
Improved and Enhanced Recovery, Chemical flooding methods
Copyright 1994, Society of Petroleum Engineers
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