| The development of the research on the nonlinear flow in low permeability sandstones has been reviewed including all the papers published in the past 20 years in the world. Then, the environment of flow in the low permeability cores gotten from XiFeng oil field of ChangQing Shaanxi province North West China, had been studied by following method: mobile oil saturation in different pressure, the structure of the core by intrusive mercury cure, SEM and thin section technique Based on the research of the environment of flow, a lot of flow experiment in the cores from several different low permeability oil filed had been done to find the nonlinear porous flow phenomenon.The flow pressure from fracture media to the core had been found basing on the porous flow mechanics and experiments in our lab. The huge damage for the fracturing fluid to the face of fracture during fracturing stimulation to the oil layer has been found in this part of the paper. The more damaging is, higher of the pressure is. The damaging of the fracturing fluid would be reduced by chemical method.The rule of the nonlinear porous flow in low permeability cores can be divided three type flow by the flow numbers changing from 1 to 2 as the different flow rate. The flow formula using in the nonlinear porous flow in XiFeng oil filed is: Tl= Ge+1 including two non-dimensional number called Golbeen^ as the ratio of cohesive force to adhesive force and Tulri [TL]number as ratio of driving pressure .to the adhesive force.According to the relationship, we compared and estimated the productivity changes of different well locations, which of the vertical wells, vertically fractured wells and horizontal wells in Dongzhi Area of Xifeng Oil field. The results show that the lower the permeability of the formation is, the lower of mobile oil saturation is, around 0.3X 10-3?m2, under the natural conditions the mobile pore rate accounts for 5 per cent oftotal pore, even lower. The lower the mobile pore is, the lower the development potential is. Under the pressure gradients about 5MPa/m, increment of the ratio for moveable pore in different permeability was considered as the potential of development stimulation. The increment of the ratio of moveable pore increased by the permeabilityof 0.3X 10" u m , was from 10 per cent to 16 percent, while the other cores with different permeability can be increased about 30 per cent. During the development of oil field with ultra-low permeability, the higher pressure gradient could be produced by making use of the energy at the bottom of wells, the more could be achieved only productive well drilled at the higher permeability.area.Finally, the productivity estimation results including following wells: fracturing, vertical wells, horizontal wells, multi-branched wells in Dongzhi Area of Xifeng Oilfield. The results show that in the low velocity porous flow phase, the productivity of fracturing wells, multi-branched wells, horizontal wells were average 7.5 times, 6.5 times, 2.96 times than that of vertical wells. The effect of horizontal wells is worse than that of multi-branched wells. The productivity of fracture wells is strongly affected by the length of the fracture, the productivity averagely decreased 2.29 times with the fracture's decreasing 3 times (as the fracture length changing from 150m to 50m). Therefore, the quality of fracturing must be assured, the fracture with enough length and big enough fracture conductivity. From the relationship between the productivity and the permeability, the productivity of different kind of wells was not linear increased with the increase of permeability, but exponential increased.
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