Studies On Indoor Chemical Oil Displacement System Of Changqing Low Permeability Reservoir

With the deepening of the oil and gas field development, low permeability reservoir has become the main reserve replacement and capacity development, further improving the oil displacement effect of low permeability reservoir is particularly important. And how to ensure that the drive system is under the condition of a certain intensity, and maintain good injection is the focus of attention. This article in view of the low permeability reservoir, low permeability, high water injection pressure, serious water lock, the characteristics of the energy transfer is slow and so on, will combine oil displacement and profile control, research and development of the low density, low viscosity, highly active, can improve injection profile, increase sweep efficiency and improve the efficiency of washing oil compound system.Developed for this experiment through optimization, changqing sickle bay under the condition of low permeability reservoir, oil displacement system and optimized formula: authigenic foam weak gel system 800 mg/AOS LHPAM + 0.20% + 0.20% organic chromium cross linking agent + 0.50 mol/LNaNO2 / NH4 Cl + 0.04% catalyst; Non-alkali surfactant system APG + 0.20% thiourea 0.15%. And then determines the formation of the two systems are suitable temperature range, pH range, salinity range. Oil displacement experiment results show that the authigenic bubble weak gel displacement system under the condition of low permeability, good injection after gel plugging rate reached more than 90%. For its oil displacement performance, with the increase of injection system volume, improve the recovery efficiency is also increased, thus, 0.30 PV is an optimal number of injection volume; Double tube surface parallel experiment, authigenic foam weak gel system selectively on low permeability tube plugging displacement, increase the recovery rate of 16.9%, increased by 10.8% hypertonic tube, from the point of diversion discharge curve, shunt amount is the same as the two tube after the displacement, the displacement effect is good. For no alkali surfactant system, sand pack oil displacement experiment research proves that the injection timing delay, ultimate recovery has a tendency to decrease, but fell very slowly, injection timing of water cut of 90% and 95%, the ultimate recovery of both. Therefore, this system is suitable for the low permeability oil displacement high water-cut stage. Through the slug combination optimization experiment, we concluded that the optimal slug combination for the system: 0.15 PV authigenic bubble weak gel displacement system + 0.15 PV non-alkali surfactant system. Microscopic oil displacement experiment to verify the effectiveness of the system of two oil displacement mechanism for extrusion effect to carry, the selective plugging big channel, reduce the interfacial tension, emulsifying carry etc.