Different from conventional reservoirs, fluid percolation in tight reservoirs does not conform to the classic Darcy's law, but has both dynamic starting pressure gradient and stress sensitive effect. The JBN method don't take these two factors into account when calculating relative permeability, which is bound to cause calculation errors. The seepage mechanism of tight gas reservoir was analyze, then a two phase seepage calculation method was built and verified considering the dynamic threshold pressure gradient and stress effect. The results show that when consider the dynamic threshold pressure gradient and stress effect, the seepage ability of gas and water phase both decrease obviously, and the decrease degree of water is bigger than the gas phase. The isotonic point of relative permeability decreases and the residue water saturation increases in rock sample. With the decline of pore pressure, the effect of dynamic threshold pressure gradient and stress becomes more and more significant. The new relative permeability curves calculated by the new method is more different with the curves calculated by the JBN method. The new method can describe the seepage of fluid in tight formation more accuracy.

The northern transitional zone of Area S has the characteristics of high water cut, low oil recovery rate, rapid production decline, rapid rise of comprehensive water cut and poor development effect in oilfield development. In order to improve the development effect of the transition zone, the test of steam flooding infill adjustment was carried out in three or four zones in the northern transition zone. In this paper, a fine structure model and a fine reservoir model were established for the test area, historical fitting and precision analysis were made for the geological reserves and production, and set adjustment was made for the test area. Therefore, the change rule of the index before and after well pattern infilling and the effect evaluation can also effectively solve the problem of low reserve utilization caused by poor reservoir development and poor physical property of crude oil in the transitional zone. The research in this paper can also effectively guide the adjustment of measures and the preparation of comprehensive schemes.