Research On In-depth Profile Modification Mechanism Of Weak Gel

Weak gel has been widely applied to enhance oil recovery in deep reservoir in recentyears. But mechanism of in-depth profile modification has been seldom researched.So the work on in-depth profile modification mechanism is necessary. In this paperphysical simulation has been used to research on weak gel migration conditions andperformance of injectivity, shear, sealing characteristics along with injection time,mobile space, injection media, injection parameters separately. The objective of theresearch is to solve practicability problem of weak gel, to provide the rationale for theoptimized design, to establish the theory and the application foundation of weak gelin-depth profile modification system in reservoir with high water-cut.According to experimental study and theoretical analysis, the main achievements inthis paper are as follows:1. The model of physical simulation and experimental method have been established.The tubes filled with sands have been used to simulate high permeability zones. Inorder to research weak gel on way characteristic and resistance change rule, multi-spots measured presses system has been used to monitor the change of weak gelin-depth profile modification agent and injection pressure.2. Weak gel can be injected in fitting porous media. Resistance factor increases at thebeginning of injection, with injection time increasing resistance factor levels off.Both resistance factor and gel strength decrease in the inlet, with injection depthincreasing resistance factor and gel strength level off.3. Weak gel is fit for high permeability zones. In low permeability core tubes weakgel has been sheared seriously. But the injectivity of weak gel incompletely showsdirect ratio with permeability. There is an optimal permeability range for injectionof weak gel.4. The gel with high strength leads to high values of gel strength retention rate,resistance factor and residual resistance factor through core tubes. But weak gel isseriously sheared and injected difficultly with high resistance factor.5. The weak gel with fast injected leads to low values of resistance factor and gelstrength. Particularly in slow injection rate weak gel detention shows very large,which makes resistance factor increase.6. Though coarse media favors detention of weak gel, it sharpens shear of weak gel.7. Weak gel prefers to entering in water communication. Water communication ismore remarkably sealed than oil communication, which can reduce damage ofsubject reservoir.