| Chaoyanggou Oilfield belongs to fractured low-permeability reservoir . The fracture density of first type tracts of the oilfield host body is 0.13 strip/m. After 17 years of waterflood development , the present recovery percent of reserves attains 20%, comprehensive water content is 48.7%. Because of finger advance nonhomogeneity , the interlayer and plane incensistence increase, water content rises continuously, and there is little room for the injection. It interlayer and plane inconsistence increase, water content rises continuously ,and there is little room for the injection-production system to be adjusted after linear water injection . It is difficult to adjust and exavate with conventional technical methods .In order to improve the development result further and enhance the recovery ratio , We has carried out the deep profile control research. It can seal fractures and high-permeability zones effectively. Make succeeding water enter the matrix and expand the swept volume, alleviate interlayer and plane inconsistence and improve the development result .According to the reservoir condition , we consider mainly the pore structure and fracture feature of low-permeability reservoir ,we has carried out the formula optimum of the profile control agent,property evaluation ,core sealing and oil displacement test after sealing,nuclear magnetic resonable image formation research and the sealed environment of gel to fracture eectronic lens scan microscopic test research . We optimized the profile control agent formula which is compatible with the Chaoyanggou reservoir.The profile control agent is made up of main agent ,cross-linking agent and addition agent . The main agent is HPAM . The primary material of the cross-linking agent is chlorinated chromium. The addition agentg is mainly thiourea.The polymer used for deep profile control is partly hydrolytic PAM. Its molecular weight is 14 million. Its degree of hydrolysis is 25%. The lab simulation test shows, with the increase of the concentration of polymer, the solution initial viscosity and gelation viscosity increase. Considering gelation viscosity and praltical injection capability, we determin the proper polymer concentration is 800-1200mg/l.Through the test of different cross-linking ratio of the oraganic chromium system's effect on gelation property, we conclude: with the increase of the cross-linking ratio ,the gel viscosity increase. Considering gelation viscosity and economic benefit, we determine the proper cross-linking ratio is 15:1.The test shows NaCl and NaHCO3 can adjust the cross-linking velocity. With the increase of the concentration, the cross-linking reaction gets faster. After screening, 600-800mg/l NaCl and 500-750mg/l NaHCO3 are proper. We use thiourea as the stabilizer of the formula gel. Its optimal concentration is 1000mg/l.The lab test shows, the cross-linking system is well compatible with the formation water and the injected water. The profile control agent has been diluted by the formation water before gelation. It also has good stability and mobility control capability.The oil displacement test of the natrual core with fractures shows, when water flooding gets residual condition, the gel seals the cores, the succeeding water flooding core recovery ratio can be increased by 6.3 to 9.1 percent.The result of nuclear magnetic resonance and microscopic emulation model test shows: the polymer and cross-linking agent mixed solution migrates through fractures after entering the model, packs the fractures, forms sealing function on fractures after gelation, forces succeeding injected water change liquid stream direction. And it enters the matrix of the model. With the succeeding water flooding, the swept volume is expanded. And it makes stable crude oil before packing in matrix migrate. Crude oil is displaced at model outlet. Thus the recovery ratio of crude oil is enhanced.The scanning electronic lens result of the sealing environment of gel on core with fractures shows: gel has better sealing function o...
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