Research On Reservoir Protection Technology Of Dehui Fault Depression

According to the formation features of Dehui fault depression, we have carried out the research on reservoir damage mechanism and indoor evaluation of reservoir protection. There are many analysis methods, such as core flow experiment, dispersion experiment, swelling experiment, surface tension and interfacial tension test and so on. By these methods, we determine that the damage mechanism is water sensitivity, water block and solid particle invasion to the micro cracks. Finally, we proposed a reservoir protection technology. Through the indoor contrast experiment, we optimized the better block agent, water sensitive inhibitor and water block resistant agent. And improve the drilling fluid system technology. On this basis, we evaluated the reservoir protection effect of this drilling fluid system with formation cores and natural outcrop cores respectively. The indoor evaluation results indicate that optimized drilling fluid has better rheological property and building capacity. The filtration is very low. It also has good stability in high temperature. Due to the strong inhibitory, the inhibiting effect of hydration dispersion and hydration swelling is remarkable. For the cores with low permeability, the damage degree of filtration invasion damage is very high. But the invasion depth is only 20 millimeters; it can be removed by perforation. While for high permeable cores, this drilling fluid system has better reservoir protection effect. The invasion depth is less than 15 millimeters, and recovery permeability reaches as high as 92.23%. This drilling fluid system has been applied in D-17 well, the drilling operation goes well. The recovery permeability in the field reached 92.35%. With the use of this drilling fluid system, the 10 millimeters nozzle can produce gas of 5.6 X 104 m3 every day. The fact proved that this drilling fluid can protect reservoir well, and get good effect.