The Damage Evaluation And Recovery Countermeasure For The Reservoir Of Injection Well

By use of the date of the core and geology of oil well, the paper is focus on the use of the method of experiments to evaluate the reservoir damage.Some experiments had been done according to the aim area, there are as follows: evaluate the sensitivity of speed of injection well's absorbing layer, confirm the rational speed of water injection and daily quantities, evaluate the daily quantities of water injection, evaluate the sensitivity of water and salt, confirm the absorbing layer's character of the sensitivity and water's reasonable salinity; analyse and determine the structure, constitute, lithology of the rock's absorbing layer of the injection well; analyse the latency factors which cause the damage to the absorbing layer as well as the damage mechanism which is likely to occur; analyse the water quality of water injection, analyse and find out the damage mechanism which is caused by water injection, and the damage degree. Completely simulate the water injection of oil field and using it review the damage degree to the reservoir's rocks. Bases on the evaluation experiments above, put forward the damage mechanism and the damage degree of the reservoir damage in the break cake of Wang 27,bring forward what questions must be noticed in the cause of water injection and the measures and means to prevent from damaging. The results indicate that:1.The experiments of simulating drilling and oil recovery technology indicate that: the absorbing layer is really damaged by using well drilling filtrate muddy, well cementing filtrate, perforating filtrate ,The total rate of damage is ranged from 55% to 60% of the primary permeability of formation water, and it became large with the physical feature getting worse.2.the evaluation of sensitivity of speed indicate lhat: the critical velocity of flow of the reservoir in this section is from 0.5ml/min to 0.75ml/min, which is transformed to the daily qualities is from 18m3/d to 28 mVd.3. In this area the sensitivity of water is middling, the critical salinity is 16000mg/L4.The water quality of the injection sewage indicates that the suspend oil, solid particles, granularity median which contained in the sewage go beyond standard seriously, they even reach about 20 to 156 times of the standard, these are key factors which cause the damage of the absorbing layer.5.the reservoir of this area is sensitive to acid, general acid can be used to dispel the damage zone, and it's effective if the acid can be flow back completely and correctly. But it hadn't been done after acidization, it caused the second damage to the absorbing layer, it's one of the reasons why the water can't be injected.The damage which be caused during the well-drilling, oil recovery, water injection and the unsettled sewage return injection are clearly the ultimate reasons why the injection wells were not able to be injected normally. And at last, coming up with the methods to deal with the sewage water and the measures and means to prevent from damaging.