Hasdrive (Heated Annulus Steam Drive) is an in-situ thermal process for recovering bitumen from tar sands. This paper presents the results of a numerical simulation of the HASDrive process in repeated, elongated well patterns. Results show that the process can effectively recover bitumen from tar sands. In a basic configuration, the cumulative recovery in ten years is predicted to be high, but the rate of production is low during the early steam-injecting period. Several well configurations and operating procedures were investigated to accelerate the early year production. The recovery mechanisms and the sensitivity of the process to various parameters are also discussed in this paper.