Research On Mechanism Of Foam Percolation Based On Percolation Network Model

Lots of facts indicate that foam is used in porous media for many primary purposes,such as gas diversion to improve oil recovery, acid diversion for matrix acid treatments. and Foam is also used to direct the flow of remediation fluids in subsurface aquifer-remediation processes. Especially Foam greatly reduces gas mobility, to an extent that increases with increasing permeability, thereby reducing the effects of reservoir heterogeneity. However, many aspects of foam flow are still unclear, which restricts the application of foam in oil industry. So it is of great importance to study the percolation mechanism of foam for the recent development of oil exploitation and production.In the thesis, the percolation mechanism of foam in porous media is researched using the percolation network model. And the achievements are obtained as following: (1) Invasion percolation algorithm is improved in two aspects: searching methods and loopless path. Thus a better performance is acquired when the network has lots of sites. (2) Considering the special features of foam, a new algorithm named Dynamic Invasion Percolation, which assigns resistance at the pore throat by probability, is put forward. At the same time a computer program is written with C++. (3) The procedure of immiscible displacement of water by gas is simulated with MIP algorithm in percolation network model; the pressure difference and minimum resistance path of gas front are calculated; and the trapping of gas and water in porous media is researched. (4) Based on percolation network model and DIP algorithm, the invasion of gas into porous media saturated by surfactant is simulated; the pressure gradient and minimum resistance path of gas front are calculated; and the influence of foam on gas mobility and sweep efficiency is also studied. (5) On the basis of percolation network model, the displacement of surfactant solution by gas in heterogeneous porous media is simulated and the way to improve recovery ratio in layered heterogeneous porous media is studied.