Laboratory Research Of Nitrogen Foam Preventing Edge-water Coning In Huff-n-puff Wells Of Nanpu Oilfied

For the complex fault block reservoir with edge water,there were many problems.For instance,water free production period would be shortened,water cut would rise fast and keep a high level.Therefore,an effective stimulation was required.The foam was ideal candidate for sealing high permeability zone.However,the application of foam displacement to preventing edge-water coning in huff-n-puff wells still need studying.Firstly,based on the condition of target reservoir and the property of formation fluid,we have optimized the foam system and evaluated its compatibility,temperature tolerance and sealing performance.Then,using the physical simulation test,optimized its gas fluid ratio of injection,gas fluid cycling plug of injectio.Afterwards,a related experimental model has been developed to evaluate the effectiveness of nitrogen foam preventing edge water coning in huff-n-puff wells.The model also could be used to analyze the effect factor and optimize some injection parameters.The results showed that the elected nitrogen foam could be friendly with temperature,salinity and the fluid of reservoir.The resistance factor was 26¹03,corresponding to the target formation permeability of 500¹500×10^-3?m².The ability of nitrogen foam to inhibition edge water coning would gain an ideal result with heterogeneous reservoir and low viscosity oil.When the edge water was insufficient,conversed in pump's velocity as 0.5 mL/min,the application of nitrogen foam would be more successful in controlling edge water coning as edge water force weakening.When the edge water was more adequate,conversed in pump's velocity 2.5 mL/min,with the volume of injecting foam selected 0.1 PV,the option of soaking time chosen 24 h and the water-cut in range of 85%,the huff-n-puff wells'oil displacement efficiency would increase by 7.57%,and the water cut would decrease by 21.81%.According to above maintain date,when an oilfield is chosen nitrogen foam as a stimulation to prevent edge-water coning in huff-n-puff wells,the study can provide a scientific guidence for a project design.