Deep Fluid Diversion for Profile Control and Oil Displacement Technologies

Abstract

Abstract Through 50 years of water injection production, Daqing Oilfield has developed matched chemical and mechanical zonal injection and production technologies. However, due to residue oil scattering here and there, and serious low effective and non-effective circulations happening in high watercut period, the existing profile modification system can hardly meet reservoir requirements. Currently, water injection well averagely serves 3 to 4 intervals, and oil wells mostly produce commingled. It's urgent to realize multi-zone fine zonal water injection, oil well fine production and injection-production well integrity. In later high watercut stage, to enhance water flooding recovery rate is our new challenge. Based on profile control technology, we've developed low cost, long efficiency deep fluid conversion profile control and oil displacement technologies, and high efficiency fine control water injection technologies, which contribute to the accuracy of water injection, and recovery rate rise of 2–3% in reservoirs with watercut above 90%. Introduction Most fields in Daqing Oilfield are continentally sedimented with high heterogeneity. With decades of water injection development, the heterogeneity is worsened, and large pores are developed in deep reservoir and near wellbore formations. Along the large pores is the water flow strengthened, and less or no water passes through low permeability zones. What is worse, in deep reservoir formations, the large pores and high permeability zones are enlarged, even water channels are formed, proved by core analysis. As a result, the deep reservoir heterogeneity is getting worse. More and more water passes through the high permeability zones, while the low permeability zones are weakly flooded by water and little oil is moved. High water production from the high permeability zones affects well productivity a lot, as it usually leads to high bottom-hole pressure, which inhibits oil being produced from low permeability zones. Since the high permeability zones have already been flooded largely, the injected water takes little or no effect on moving the remaining oil. To solve the problem, conformance improvement technique gets in our mind. However, near wellbore profile correction treatment can only improve the heterogeneity in the vicinity of the injector. For high heterogeneity in deep reservoir areas, the technique needs improving. A type of high strength swelling delayed particle and a type of zwitterionic polymer gel are developed in the work and used in the field.