The Optimization Study Of Well Space For Low Permeability Reservoir In Binnan Oil Field

Due to low permeability reservoir's poor property,it's difficult to establish effective displacement system.The main reason is that limit flow radius calculate by formula is larger than the actual situation,when we determine injection-production well space.So it's necessary to find more accurate calculating formula.And it's helpful to optimize the well space of low permeability reservoir,increase production speed and geologic reserve producing level.In this paper,based on the study of well pattern and space and low permeability reservoir developing characteristics,for the example of Binnan typical low permeability reservoir,we have carried out stress-sensitivity and threshold gradient experiment firstly and summarized their mathematical description form.Secondly,by using experiment data and non-linear flow theory,we have founded the new limit flow radius calculating formula which can consider the reservoir permeability,stress-sensitivity,threshold gradient,injection-production pressure,and fluid viscosity.Lastly,we have lunched well space and array optimization study for Binnan typical low permeability reservoir(Li853,Bin 660,Bin 685),we come to the conclusion that Li853,Bin 660,Bin 685's limit flow radius is respectively 48 m,50m and 70 m.When the injection-production pressure is 20 MPa and half fracture length is 70 m,Li853,Bin 660,Bin 685's reasonable well space is respectively 260 m,240m and 320m;Li853,Bin 660,Bin 685's reasonable well array is respectively 120 m,120m,160 m.For the target of equilibrium displacement and water breakthrough at the same time,we have proposed well pattern adjustment suggestion: reducing the well space and array along the direction of permeability decrease.Comparing the effect of reservoir reconstruction: volume fracturing>multi-stage fracturing>usual fracturing.