A secondary heavy oil thermal recovery technology of superheated steam huff and puff

With superheated steam there is no direct relationship between temperature and pressure, and at a particular pressure it may be possible for superheated steam to exist at a wide range of temperatures. Superheated steam exsists at the temperature higher than that of its saturated steam. The heat transfer coefficient is 1/150-1/250 as much as that of saturated steam during heat transferring, it takes a relatively long time to cool, during which time the steam is releasing very little energy and transmitted long distances. The mechanisms of superheated steam huff and puff are reflected on the performance of the crude oil viscosity reduction, flow environment improved, rock wettability changes, oil displacement efficiency improved. Physical and numerical simulation shows that oil displacement efficiency by superheated steam was 6-12% higher than that of saturated steam at the same temperature, and under the condition of carrying the same heat, superheated steam enlarged the heating radius by about 10m, oil production increment by 1463t, oil steam ratio increase by 0.7. Superheated steam huff and puff was put into Kazakstan's heavy oil reservoir after saturated steam huff and Puff. The average daily oil production was 2-4 times that of saturated steam huff and puff, which improved heavy oil production effectively. The secondary heavy oil thermal recovery by superheated steam huff and puff applicated in marginal heavy oil reservoirs achieved satisfactory effect.