Generally speaking, the lower the filtration rate of drilling fluid, the stronger the colloid and viscosity. Sometimes, in order to reduce the filtrate loss of drilling fluid to a certain value, it is necessary to add a lot of materials to further increase the liquid viscosity of drilling fluid. For example, in the case of the same composition, the filtration rate of drilling fluid with a filtration rate of 5mL is reduced from 5mL to 4mL, even greater than that of drilling fluid with a filtration rate of 25mL, and the filtration rate is reduced from 25mL to 5mL. This shows that in the case of low filtration, even if the filtration is reduced by 1mL, a large amount of treatment agent is needed.
In addition to increasing the cost, the liquid viscosity of drilling fluid and energy consumption increase due to the increase of the dosage of treatment agent. It can be said that the reasonable determination of filtration rate is beneficial to reduce energy consumption. As long as the inhibition performance of drilling fluid meets the requirements and the comprehensive performance meets the needs of downhole safety, the relaxation of filtration rate is conducive to improving ROP and saving costs. Therefore, according to the formation characteristics in different areas, the index of filtration can be adjusted appropriately on the premise of ensuring the stability of the borehole wall.