A small, scaled physical vacuum model was built to study a steamflood process that uses a horizontal well to form a communication between vertical injector/producer well pairs in a heavy-oil reservoir. Linedrive steamflood operation was simulated over 1.37- and 2.75-acre patterns at 427- and 650-bbl/D injection rates. These studies yielded 60% to 80% recoveries at steam/oil ratios between 4 and 6.