A Study And Application Of The Weak Gel Profile Modification Agent

Weak gel control technology is a new technology between near-wellbore profile control and polymer flooding. Unique performance weak gel as a fliud transferred agent of deeper layers can improve the anisotropism of the reservoir and the effect of water flooding during the high water-cut period. In recent years, the technology has obtained successful application in oilfield, attracting increasing attention.We can make use of the viscosity law to identify the weak gel density because of lower viscosity of phenolic resins crosslinked polyacrylamide weak gel system. Synthesizing a water-soluble phenoic resin with phenol and formaldehyde, we do experimental reseach on phenolic resin/polyacrylamide weak gel system. Then we choose the best gel fomula:Polyacrylamide 0.3%, phenol 1.1%, Crosslinking agent 1.2%, accommodating agent,0.4%. For the formula, the gel strength and gelling time were relatively larger. Along with increasing crosslinking agent content and the phenol content, gel strength increased but gelling time decreased. With the increase of the accommodating agent, gelling time decreased but the gel strength did not change much.We do the test about the impact factors of weak gel systerm,aging the gel in different pH and salinity medium. It has good stability if it did not break. The gel viscosity has been greatly reduced under shear action. But it could crosslinking again and the viscosity is about 40 times more than the gel without crosslinking action. This is key difference between crosslinking polymer and ordinary polymer.The effect of profile modification is that the oillayers absorbent sections have been revised after profile control. The thickness of absorbent layers has been increased and the absorbent rate of high-permeability layers has been limited. Absorbent capacity of low-permeability layers have been strengthened. Moreover, due to starting pressure increasing, all wells absorbent layers become thick. Plane unformity has been adjusted. The oil wells increase oil production but decease water production. Recovery rate has been enhanced by 3.72%. The ratio between input and output is 1:10.6～1:6.6.