Study And Practice On Oil Production Technology Of Complex Profile Control And Flooding

Since the tenth Five-Year-Plan, tertiary oil recovery has developed very fast in Huabei Oilfield. As a dominant item, mobile gel controlling-displacing technology has been established , due to which the annual output of Huabei Oilfield is now up to 6～8×10⁴t.However, because of its high temperature (average reservoir temperature 117℃), high salinity (original reservoir water salinity 84151mg/L, average content of Ca²⁺ and Mg²⁺ 1604mg/L), middle-low permeability and high-temperature degradation, simple controlling-displacing technology can not satisfy the development requirements of Jin-45 Fault Block oil reservoir in Huabei Oilfield. Therefore, it is necessary to establish a kind of chemical displacing technology suitable to Jin-45 Fault Block oil reservoir according to its poor geological setting, disperse distribution of remaining oil, large difference of water injection, thin oil and poor sweep of thin beds.It was found by field tests in Jin-45 Fault Block oil reservoir that composite mobile gel-surfactant technology showed better oil increasing and water decreasing effects. This technology not only synthesized oil displacing function of each chemical agent, but also gave play to surfactant for both reducing residual oil saturation and increasing swept volume of water injected. In this way, oil recovery ratio was finally increased and synergistic effects of different chemical agents were fully revealed by increasing viscosity of injected water, improving mobility ratio and controlling profile, all of which increased the oil recovery ratio to higher level.In order to determine suitable oil displacing system, optimization and evaluation were conducted in this paper on mobile gel (profile control agent) surfactant (oil displacing agent) technology according to reservoir and fluid characteristics of Jin-45 Fault Block oil reservoir. Formula system was studied as the basis of enhancing oil recovery, and physical simulation was also done as an important method not only to the research on oil displacing effect of formula system but also to the numerical simulation and project design. Technical guidelines of polymers, surfactants and cross linking agents involved in this article were obtained from Huabei oil field research academy, and this paper carried out screening and evaluation on five types of polymers, five types of surfactant and four types of cross linking agents, which obviously provided basis for further development and application of this kind of controlling-displacing technology.