Weak Gel Tone Drive Inject Curve Characteristics, And

According to research about rheology and flow characteristic of the weak gel in porous media, its flow phase around the injection well was divided into three different flow regions. Meanwhile, typical characteristic of weak gel's permeability adjusting/oil displacing injection curve was confirmed by studying the unstable radial flow law of non-Newtonian fluids. And then we can judge whether the construction parameter, formula composition etc. are fit for the reservoir condition or not by analyzing lots of weak gel's permeability adjusting/oil displacing injection curves characteristic. Construction parameter, formula etc. can be adjusted in time during injection process so as to have better effect. Work and conclusions in detail as follows:(1) Area around the injection well was divided into different flow regions by studying the rheology and flow characteristic of weal gel. It shows that weak gel's rheology and flow characteristic have four properties other than power-law fluid property, creep property, shear stress hysteresis property and so on. First, viscosity of the cross-linking polymer can also recover to some degree after viscosity decrease by shearing. This is the obvious distinction between cross-linking polymer and common polymer. Second, weak gel's rheology property depends on aperture size. Third, intermolecular cross-linking degree is much higher, so the nonlinear of the system is much stronger. Thus, the viscoelastic property is more obvious. Finally, weak gel has the function of selective permeability adjusting/oil displacing. Therefore, the author divided the flow regions of the weak gel around the permeability adjusting/oil displacing well into three different regions as follows: high velocity shearing region near the wellbore, transitional regions and viscosity recovery region which is far from the wellbore.(2) The author checked the characteristic of the weak gel's permeability adjusting/oil displacing curve by studying the characteristic of unstable radial flow of the non-Newtonian fluids. According to the nonlinear partial differential equation and linearized approximate analytic solution of power-law non-Newtonian flowing through the porous media which was deduced by Odeh and Yang, it shows that high flow velocity shearing region belongs to pipe flow, power-law flow. But the viscosity recovery region which is far away from the wellbore belongs to low velocity, high viscosity, Darcy flow or power-law flow. It also shows that, near the wellbore and far from the wellbore, it displays two rectilinear with different slopes in ΔΔp-t log-log graph. The slope are (1-n₁)/(3-n₁) and (1-n₂)/(3-n₂) respectively.(3) Plenty of example analysis show: weak gel's permeability adjusting/oil displacing effect matching well with the weak gel injection curve is better than that matching not very well with the weak gel injection curve. The starting of the second power-law flow corresponds to the radial flow phase. At the beginning and middle term of this phase, it can achieve fairy good area plugging effect. Plugging agent volume used is determined in light of in light of high permeable layer's thickness, water flooding orientation and so on. When it achieve large area of radial flow, weak gel's viscosity recovery even increase is the main purpose of formula and construction parameter. It is the key to succeed in permeability adjusting/oil displacing. We can assure permeability adjusting/oil displacing effect by...