Abstract: To address the lack of a suitable calculation model for productivity prediction of thermal soaking recovery in horizontal wells in conventional heavy oil reservoirs, by establishing composite geological model including heating zone and unheated zone and considering the difference of crude oil viscosity between the heating and unheated zones, an analytical model describing the production capacity of thermal soaking recovery in a single horizontal well was determined. Further, an equation for calculating the productivity increase of thermal soaking recovery with respect to cold recovery was proposed. The results show that the productivity multiple is mainly affected by factors such as the heating radius, oil layer thickness, and horizontal section length. Based on typical thermal recovery data in horizontal wells in the Bohai N oilfield, a mechanistic model was established. The heating radius of different soaking cycles was obtained by numerical simulation. On this basis, the increase of production capacity in different soaking cycles was calculated by the new model. It is predicted that the productivity increase of the first soaking cycle was 1.6 times, which was in good agreement with the evaluation results of the first thermal soaking cycle in the ten thermal soaking recovery horizontal wells at the Bohai N Oilfield.

Key words: heavy oil reservoir, horizontal well, steam soaking, heating radius, productivity prediction