Research On Medium Depth Profile Control Technology

At present,medium-deep gel blocking technical is the most effective measures to enhance the recover of the oil during the later stage of field development. It plays more and more important role in stabilizing the production of the oil and reducing the production of water.However,the shadow blocking measures presents the following problems:higher operating expenses, lower production and longer cost recovery cycle for tight formation, which cannot be applied in large scale.Therefore,according the formation character of the Da Qing peripheral oil field and the present problems,this paper combines the optimizing formulas and field application and provides a new experiment measure.The gel formulas as follows:HPAM as the main part,Na2Cr2O7 as crosslinker.During the experiments process,the concentrations of crosslinker,acidity modifier,reductant,antioxidant and other addictives were changed in order to observe the optimizing formulas of HPAM,Na2Cr2O7,thiocarbamide,sodium sulphite and sodium carbonate under different matching conditions. It also evaluates the gel strength and the viscosity under different temperatures.The optimizing formulas as follows:HPAM1000mg/L+crosslinker600 mg/L+modifier 400 mg/L+intensifier 500 mg/L+antioxidant 300 mg/L.The in-house performance index and physical model of the blocking agent were founded.Through the in-house core experiments,we can infer that the more saturation of water irreducible,the more water plugging rate.Most of the pore volume is covered by oil in lower water saturation formation,water dispering in the oil.Although less plugging agent was injected into the reservoir,the plugging agent can still block the flow of the water,the polymer can't extend in the oil-bearing core,which makes the polymer can't form net structure.The polymer would be sweepouted by the sequent oil,which would decrease the blocking rate of oil permeability.Finally,according to the principle of high water cut block,the whole construction program was designed. The preparation of blocking agent and field process has been innovated.Dynamic analysis was carried on the fracture before and after installation phase.Field experiments indicated that the blocking agent could meet the technical requirements.All kinds of experimental parameters could meet the performance index required by the field experiments.