Su6Well Gas Reservoir Area And Reduce The Harm Factor Analysis Method Of Water Block Damage

The gas reservoir of Su-6well block is late in development, due to inappropriate development, serious reservoir damage, natural gas recovery decreased. Therefore, this article in large amounts of data and field research, based on the combination of geological characteristics of the Soviet Union six wells, from both qualitative and quantitative research, a detailed analysis of the potential harm to the block mechanism of reservoir formation damage caused by the factors and size. Damage factor based on the size of the blocks proposed method of reducing water lock.Studies have shown:the main reservoir of way for water damage to the lock damage.injury experimental core level of the water lock on average between61～98%,is strong-strong water lock, the other order of the sensitivity of the damage for the stress-sensitive, acid sensitivity, water sensitivity, speed-sensitive, alkaline sensitivity injury. Therefore, we should work to lift the water lock the first place, proved by experiments, of the study area water block damages factors:interfacial tension, core self-absorption time, operating pressure:water saturation, pore structure and permeability of the size and so on. According to the water damage the lock mechanism to change the locks damage caused by external conditions of the water as a breakthrough, we propose two ways to reduce water block damage:(1) the use of alcohols or surfactants, reduce the surface tension between gas and liquid, thereby reducing the core of the capillary pressure and water saturation method;(2) dry nitrogen gas displacement method, using dry nitrogen, good flexibility, as well as gas-lift effect, by increasing the driving pressure and displacement time to the maximum to overcome the capillary force, reducing core water saturation, so that the liquid cores smooth back row, reducing the water block damage. The results show that:methanol, ethanol, FS208-CAO solution to the reservoir water has a significant effect of lifting the lock. The obvious effect of the order:methanol the best, followed by ethanol, FS208-CAO solution of the worst (permeability recovery rate was27.7%,12.8%,5.2%).The concentration of methanol effect on the impact of water lock is removed, but the concentration is not the higher the better. Therefore, the process of practice in the field, the reservoir must be based on the actual alcohol concentration to choose reasonable. Dry nitrogen method unlocks the effect of water is also obvious. Limited to2hours, the driving pressure is0.5MPa, the core permeability measurements, the average gas recovery rate from2.7%to43.7%; driving pressure is1.OMPa, the core permeability measurements, the average gas recovery rate from5.7%increase to50.5%. This shows that core of relatively low permeability, dry nitrogen gas displacement method unlocks the effect of the water higher than the core permeability is better than that.However, water damage and can not lift the lock can only be slowed or reduced. Therefore, the gas reservoir development and said the injury focus on prevention, lifting supplement. Injury prevention, and water block should be considered in stages.