Study On Deep Profile Modification Cross-linking System

More than 80% of China's oil fields by waterflooding, due to differences in water layer and strong absorbing ability of high-permeability zone, forming a water channel and ineffective water cycle, while the low-permeability zone is not injected by water, in order to improve the swept volume of water and the oil/water displacement efficiency, using profile control agent to block high permeability zone and ultimately achieving a balancing injection profile of purposes. Delayed crosslinked time of traditional high strength profile control agent is short, small radius of profile control has resulted in sequent injection grout bypass the block area is still channeling back to high permeability zone after profile controlling in a serious interlayer crossflow reservoir, leading to inefficient cycle of injected water. The purpose of this topic is to prepare a deep profile control crosslinked system for the large difference in permeability formation whose gel time of a controllable and adjustable gel strength.Choose Cr3 + as crosslinking center ion, sodium acetate and Seignette salt as complexing ligand to form a complex ligand Cr (â…¢) crosslinking agent. As an inhibitor, seignette salt could play a significant role indelayed crosslinking. This cross linking agent and HPAM that composed of deep profile crosslinking system performance is studied. By examining the amount of the delayed crosslinked raw material, the concentration of delayed crosslinking agent, polymer concentration, pH, degree of mineralization and other factors to determine the organic chromium deep profile crosslinked system, the basic formula: The amount of delay crosslinked raw material ratio of 1:3:0.4 ~ 1:3:0.8, the concentration of 100~150mg/L(in Cr3+), polymer concentration of 1500 ~ 3000mg / L, pH value of 5 ~ 7. under this formula prepared the deep profile crosslinking system has a high intensity and a good stability .The aldehydes, phenol, resorcinol according to certain proportion preparation phenol aldehyde class crosslinking agent, prepare the accent under certain pH value and the temperature to split the medicinal preparation.Split the crossing linking system to this depth portion accent the performance to conduct the research.The factors which may affect the properties of the phenol-based cross linking agents were determined, including the HPAM concentration, the phenol-based cross linking agents concentration, the amount of the stabilizer and control agents. Through the investigation the optimum of the phenol-based cross linking system formulation were being determined, HPAM concentration is 1500 mg/L, organic chromium cross-linking agent concentration is 2500~4000mg/L, the stabilizer concentration is 1500mg/L, the control agents concentration is 5~50mg/L, pH value is 5.0~6.0, under this formulation the cross-linking system have much higher strength and better stabilities.The selective blocking experiments of the two kinds of cross-linking system in the core were made respectively, single-tube core simulation results showed that both the organic chromium cross-linking system and phenol cross-linking system had much higher blocking ratios; the paralleled core simulation experiments results showed that the high permeability core sub-flows declined, medium and low permeability core sub-flow increased, this indicate that both cross-linking system have much higher blocking ratio on the high permeability core and much stronger profile control capabilities.