An investigation of the optimization of startup procedure for single-well steam-assisted gravity drainage (SW-SAGD) was made as the project economics are influenced significantly by the early production response. An experimental investigation of two early-time processes namely cyclic steam injection and steam circulation to improve reservoir heating is discussed and compared to continuous steam injection as well as other well configurations like vertical injector-horizontal producer and horizontal injector- horizontal producer. Crushed limestone saturated with heavy oil (12.8degrees API) and water was packed in a laboratory model for the experiments. The effectiveness of the methods is compared within themselves and to conventional steam-assisted gravity drainage (SAGD) by measuring the size of the steam chamber as a function of time, The steam chamber area for cyclic steam injection is slightly greater than that of steam circulation case. Furthermore, numerical simulation studies of different early-time processes were conducted and compared to the experimental data using a commercial simulator. It was observed that the numerical model results underestimated the cumulative oil recovery and the steam chamber size. Results from this study, including cumulative recoveries, temperature distributions, and production rates display the differences between the methods. (C) 2001 Elsevier Science B.V. All rights reserved.