EOR technology by heterogeneous on-line profile control and flooding for offshore heavy oil field - take Well Group E of Bohai B Oilfield as an example

In view of limited offshore platform life, small space of platform and difficulty in treating the polymer flooding produced fluids, this paper introduces the idea of EOR using heterogeneous profile control and flooding technology. Using longitudinally 3-layer heterogeneous physical model, the oil displacement effects by different heterogeneous systems were investigated after water flooding,polymer flooding and SP flooding; in combination with remaining oil distribution in cores after displacement, the difference of heterogeneous profile control and flooding and conventional polymer flooding was analyzed in oil displacement mechanism. Research results show that, the heterogeneous profile control and flooding can greatly enhance oil recovery after water flooding, polymer flooding and SP flooding, which enhance values are over 6.95%, 9.57% and 11.46% respectively. Under the heterogeneous system of the same concentration,two injection methods –injection after swelling and swelling after injection – are almost the same in oil displacement effect,indicating that the system can achieve the same effect in cores as in indoor static evaluation swelling and that the particle size of dispersion phase has a very critical effect on oil displacement, where large particles are more meant to “profile control” while the small particles to “flooding”. Reservoir remaining oil distribution after polymer flooding is more scattered, so the potential for further EOP lies mainly in low permeability layer; simply depending on increasing the displacement efficiency of oil displacement systems is not sufficient to improve its production degree, so it is necessary to further expand the swept volume of oil displacement systems.