Abstract:In the middle and later stages of steam huff and puff development in heavy oil reservoirs, the conversion of development mode is one of the important methods to improve oil recovery. F oilfield has made comprehensive adjustment according to the existing well pattern conditions and learned from the successful experience of other oilfields. The development of vertical well and horizontal well combined flooding and drainage (VHSD) has become the main method to succeed the effective development in the later stages of steam huff and puff development. In this paper, numerical simulation technology is used to carry out research and tracking of the development law of steam chamber in VHSD development, fluid flow trajectory, and analysis of the change law of remaining oil. Research results show that the steam stimulation to establish injector-producer rounds between hydrodynamic connected, reservoir using situation determines the steam cavity of the initial shape, with continuous injecting steam, the steam chamber has experienced formation, lateral extension, scaling down three stages, each stage of steam cavity expansion in a different direction, corresponds to the different characteristics of remaining oil distribution and production change, lateral extension stage of steam chamber as the main oil producing period, and phase output level was 28.8%, and the ultimate recovery of the reservoir can be up to 58.3%.