Study On The Percolation Properties Of Branched-Preformed Particle Gel(B-PPG) In Porous Media

Aiming at the reservoir with high temperature and high salinity and the heavy heterogeneous in Shengli Oilfield,this paper studied the Percolation Properties of B-PPG in Porous Media and its oil displacement characteristics,the flow characteristic of B-PPG and its compatibility with pore size were investigated emphatically.Static experiments were used to study the swelling property,tackifying property and suspension property of B-PPG.Results show that B-PPG have strong swelling ability,temperature-resistance and salt-resistance.The expansion rate of B-PPG increase with decreasing particle diameter.B-PPG system have a certain viscosity under the shear,because the particle collide with each other in the system,increased the fluid flow resistance.Compared with PPG,B-PPG have better suspension property and tackifying property because of its partial long chain branch.Percolation experiments in porous media were used to study the flow characteristic of BPPG and its compatibility with pore size.Results show that the transport behavior of B-PPG through a porous media have five types,directly passing through throats,deformable passing through throats,snap-off and passing through throats,trapped by throats and absorbed onto rock face.B-PPG have favorable viscoelasticity.When the ratio of size of B-PPG to width of porous is between 10 and 14,the particle can pass through throats by repeating the piling up-plugpressure rising-extending and deforming to pass proceeding at porous throats.While when the ratio is less than 8,the particle directly pass through throats.While when the ratio is more than 17,the particle can be trapped by throats.The width of porous which B-PPG can compatible with also increase with the decrease of velocity,as the velocity changes within certain range.The width of porous which B-PPG can compatible with increase with the increase of velocity,as the concentration changes within certain range.Through the experimental research on enhanced oil recovery in the homogeneous and heterogeneous model,studied the displacement characteristics and results of B-PPG.Results show that B-PPG has higher recovery efficiency than HPAM in the homogeneous and heterogeneous model under certain conditions,because it has higher sweep efficiency by its migration and plugging in porous media.The microscopic flooding mechanism of B-PPG can be summarized in three patterns: deep profile control,oil displacement of viscoelastic B-PPG and oil displacement and forming oil block.B-PPG has better effects in displacing cluster,flake rod-shaped filmed and isolated-island residual oil.The effect in displacing corners residual oil is not good with the B-PPG solution.