Geophysical Monitoring Steamflood Advance

A new analytical technique was developed to monitor the changes in oil water saturation during thermal recovery of tar sands. During fracture assisted steamflood recovery, the reservoir is heated and depleted of most of its oil by the injected fluids. Changes in temperature and oil water saturation produce a significant change in resistivity at both the microscopic scale (grain size, pore flushing), and at the macroscopic scale (reservoir size. production pattern). This geophysicial technique uses geothermal technology to detect the steamflood advance from the surface by using a large electromagnetic signal generator and a permanent network of receiving stations to detect and measure the curvature of the secondary electric: field induced in the alteration zone produced by the the steamflood injection. The analytical technique allows interpretation of the observed anomaly in terms of thickness and lateral extent of the invaded zone. In addition, the technique was designed so that the reciever grid network is reoccupied later, producing more resistivity "snapshots", allowing measurements of the changes in distribution of injected fluids, temperature and oil water saturation during various phases of steamflood recovery of heavy oil.