Since The Raw Foam Washing System And Its Performance Evaluation Of The Well Fluid

Waterflooding is the main development ways in oil fields at present. Because of economic reason, the majority of flood water is the processed sewage of oil field. So, the corruption and scaling of downhole string are grave in the long-term waterflooding process. Due to the reservoir polluted and blocked up by the mechanical impurity, the waterflood pressure rised. It seriously affected the dosing success rate and separate injection qualification rate of separate injection wells and restricted the oil field development strongly. There are many problems in the production tail of oil field, such as reservoir conditions worsening, injection well overflowing, sanding seriously, measure and allocation touching resistance, excluder failure and so on. So, it is necessary for the injection well to routine maintenance washing. The big problem faced in the later period of waterflooding is how to implement the injection well washing correctly, reasonably and effectively.Autogenetic foam washing technology is proposed in this paper to resolve the problem of adverse flooding during washing with water because of the low formation pressure coefficient of the Bei 301 operational zone in Hailer oil field. It has some advantages of no special apparatus (air compressor and foam generator), lower cost and simpler craft. The research work has been carried out as follows, (1) Studies on autogenetic foam washing system. We have got two autogenetic foam washing systems, that are the single -liquid system(30%～40% blowing agent A+0.15%AOS+1800mg/L KYPAM) and the double-liquid system(5%active acid +10%～15% blowing agent B+0.1%OP-10+2000 mg/L4039s).(2) Property evaluation of autogenetic foam washing system. We have studied the influences of temperature, salinity and crude oil on the system, and pressure on the system using CWYF-I HTHP reaction apparatus, and also the suspension property and entrainment property of the system. The experimental result indicated that the single-liquid system is fit for injection well above 60'C and the double-liquid system is below 50℃; the best concentration of salinity is at 4000～5000mg/L; the crude oil does not affect the foam property of these two systems when it' s content is smaller than 15%; when pressure is less than 4MPa, the system' s foam quality is above 70% and half time is more than 30min; suspension property of foam is much better than water' s; U-tube experiment results indicated that the more the entrainment property is, the more the blowing agent concentration. (3) Physical simulation experiment. We have studied the broken down efficiency after foam washing using sand packed model, the results indicated that the larger the permeability is and the higher formation pressure is, the better the broken down efficiency is; the broken down efficiency of the double-liquid system is better than the single-liquid system' s at the same permeability and formation pressure.The researches in this paper have further enriched the theory of foam, have provided a new technology and method for injection well washing, and have expanded the range of application of autogenetic foam. So this research has practical application and reference values.