Heterogeneous Reservoir Selective Plugging Technology Research

In the oil field with water flooding, because of the quality of water injected, formation fluid and the reservoir characteristics, it is easy that the oil formation is plugged, then necessarily, the formation blocked is broken down, for the reservoir with high basal water, if the pretreatment is not carried out before it broken down, most of the blocking remover would enter the basal water, formation, which couldn't reach the aim of removing the plugging in reservoir.Through many experiments indoors, the poly-copolymer temporary blocking agent and the new complex blocking remover are developed out, and these agents are evaluated by the static experiments and core displacements. The results as follows:1. The poly-copolymer gel temporary blocking agent has the high selectivity performance, that is, after entering the formation, it expands with water while shrinks with oil, which blocks water, not oil, and it plugs the basal water layer, not the media-low-permeable oil formation. The water blocked coefficient is bigger than 99%, while the oil blocked coefficient smaller than 14%, in the core displacements.2. The new complex blocking remover has the performance with acidizing, thermal blocking removing and foam gas lifting, which seldom reacts with the temporary blocking agent. This system releases much heat and gas in the course of reaction, whose heat can enhance the temperature in the vicinity of wellbore and degrade the viscosity of the high-viscosity organism, such as colloid and bitumen, so as to upgrade the tlowability while it spreads in radial and vertical direction, and at the same time, a large amount of high-temperature gas released enter the formation pores can rush apart the "bridge" substance, which breaks the flowing drag force with capillary pressure.3. By the core displacements with cylinder and 3-layer long heterogeneous cores, it identifies: the strength of the temporary blocking gel injected is high enough to block the high-permeable oil formation, whose breakthrough pressure is much larger than the starting pressure in the media-low-permeable formation. Following that, the new complex blocking remover injected can only flow into the media-low-permeable formation. Finally, the goal broken down with selectivity is realized.