Research On Proppant Embedment Mechanism And The Experimental Study Of Fracture Conductivity

Low permeability oilfield is a major resource of China’s oil industry to increase reserves and production for a considerable long period in the future and the hydraulic fracturing is the primary means of low permeability oilfield development. Under the action of closure pressure, the proppant which is injected into fracture will occur the phenomenon of embedded crack surface embedding into the crack surface. On the one hand, the embedment will result in the reduce of porosity in the proppant pack. On the other hand, propped fracture width will be reduced which leads to reducing the ability to support the fracture conductivity. At the same time, proppant embedment will make the strata broken into fragments which causing the plug of the pores and reduce of permeability, thereby reducing the production of oil and gas. The quantitative research on proppant embedment is necessary to be carried out to ensure the fracturing results.Taking into account the influence of the deformation on fracture proppant slit width, the stress of the proppant in the fracture is analyzed to establish the calculation model of the depth、compression deformation、width variation and fracture conductivity. On the basis of the mathematical model, the influence of particle size of proppant, proppant elastic modulus, closure pressure on the crack width and the fracture conductivity are analyzed. At the same time, multi-row laid are considered. The method of theoretical research combined with indoor experiment is used in this paper completed the experiments of proppant flow.A comprehensive analysis of the experimental results, the trends of fracture conductivity is consistent with the calculation model. One factor of the elastic modulus, the proppant grain size, sand concentration, proppant and the elastic modulus of reservoir increase will lead to the increase of fracture flow capacity; With the closure pressure increase, fracture conductivity decreases; And the Poisson’s ratio of proppant and reservoir has little effect on the fracture conductivity.The research result of the paper, provides the theoretical foundation to the reasonable matching proppant for fracturing construction site and control cost of proppant, ensure that has guiding significance for optimizing the hydraulic fracturing.