Progress in enhanced oil recovery technologies through chemical flooding in high-temperature and high-salinity reservoirs in Shengli Oilfield
Shengli Oilfield has abundant chemical flooding resources.However,the implementation of chemical flooding technolo-gies is difficult due to strong reservoir heterogeneity,high reservoir temperature,high formation water mineralization,high cal-cium and magnesium ion content,and high crude oil viscosity.After years of research and development,the theory of chemical flooding for high-temperature and high-salinity reservoirs has been established,forming a series of chemical flooding technologies such as polymer flooding,alkali-free binary compound flooding,heterogeneous compound flooding,and viscosity-reducing com-pound flooding.These technologies have significantly enhanced oil recovery in reservoirs with a formation temperature of 85 ℃,a formation water mineralization of 30 000 mg/L,a calcium and magnesium ion concentration of 1 500 mg/L,and a crude oil viscos-ity of 1 000 mPa·s.In terms of basic theory,the mechanism of heterogeneous compound flooding was elucidated with"deforma-tion passage,fluid flow diversion,balanced displacement,and coordinated transfer and washing"to enhance oil recovery,and an essential understanding of"simultaneously increasing viscosity and elasticity"and"significantly reducing adhesion work"was ob-tained during chemical flooding in high-viscosity reservoirs.In terms of technical application,in response to the technical difficul-ties of significantly enhancing oil recovery in offshore oilfields,an efficient binary compound oil displacement system was con-structed,and a fully enclosed injection process was designed,forming a binary compound flooding technology for offshore oil-fields.For reservoirs after polymer flooding and high-temperature and high-salinity reservoirs,a viscoelastic particle oil displace-ment agents were invented,and a heterogeneous compound flooding system was constructed.In addition,heterogeneous compound flooding technology was developed.For high-viscosity reservoirs,highly viscoelastic polymers and efficient surfactants were devel-oped,and a viscosity-reducing compound flooding system was constructed,forming an alkali-free binary compound flooding tech-nology.As of October 2023,the chemical flooding technologies have achieved the produced geological petroleum reserve of 6.3×108 t,an accumulated oil production of 7 701×104 t,and an accumulated oil increase of 3 604×104 t for high-temperature and high-salinity reservoirs in Shengli Oilfield,providing significant support for the sustained and high-quality development.
chemical floodingbinary compound flooding for offshore oilfieldsheterogeneous compound floodingchemical flood-ing in high-viscosity reservoirsShengli Oilfield
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