Recovery of Heavy Oil Using Horizontal Wells and Gravity Drainage with Pressure Maintenance

ABSTRACT

A series of experiments were performed in physical models saturated with heavy oils of 0.6 to 12.7 Pa.s. The oil was displaced by gravity drainage at constant pressure and it was produced using horizontal wells. The pressure was maintained either using a vacuum pump or by injection of an inert gas at low injection pressures. Computer Assisted Tomography was used for the visualization of the displacement front. Additional gravity drainage tests were performed in long vertical columns and in two dimensional glass micromodels. In this paper a detailed description of the performed experiments is presented. Production characteristics are shown and images of the gravity drainage process are a/so included. The recoveries varied from 20 % to 50 % recovery of the original oil in place. The pressure difference was maintained between 10 and 30 kPa. In the cases where sand parting was not observed, a uniform displacement front was formed. In the cases where parting was observed the experiment was temporarily shut in. Substantial amounts of oil were produced following the shut in period. Temporary shut in was also implemented at gas breakthrough with considerable increase in the oil recovery.

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