Aiming at W block in J Oilfield, combining screening criteria, theoretical calculation and numerical simulation method, while evaluating reservoir properties, remaining reserves and development status, a feasibility evaluation method of steam ensuing steam stimulation was established. Then the steam feasibility of target block was evaluated: It turns out that the geological characteristics of this block agreed well with the screening standard of steam flooding. Furthermore, the steam flooding generates a higher recoverable reserve than steam stimulation, the effective heat communication was formed between wells, and he degree of reservoir heated during stimulation stage can meet the needs of steam flooding. The project of converting to steam flooding after steam stimulation was optimized. It was determined that conducting the intermittent steam injection performed a better flooding effect when the recovery factor of steam stimulation reached 15.20%, in which steam injection time, interval time, steam injection rate, steam quality and production⁃injection ratio were 3 months, 1 month, 133.33 t/d, 0.60 and 1.3 respectively. The recovery factor was 42.3% when the oil⁃steam ratio reached 0.12, 29.6% higher than that of steam stimulation. This study contributed an evaluation method for steam flooding ensuing stimulation, and provided a good reference to similar reservoirs.

A new method was proposed to measure the thickness of the boundary layer, and the thickness of the boundary layer under different viscosity and different pressure gradient was measured. The research results show that under the same pore throat radius and pressure gradient, the relation between the viscosity of the fluid and the proportion of the boundary layer is linear. The greater the viscosity, the greater the proportion of the boundary layer. Under the same viscosity and pressure gradient, with the increase of pore throat radius, the proportion of the boundary layer decreases rapidly. Under the same viscosity and pore throat radius, with the increase of the pressure gradient, boundary layer ratio decreases and tends to be stable. In addition by drawing the boundary layer thickness ratio chart, the influence of viscosity and displacement pressure gradient on nonlinear seepage is analyzed, and the results further confirme that the boundary layer is the fundamental reason for the nonlinear flow characteristics in tight oil cores.