Basic knowledge of desander and desilter
1. Overview: both the desander and the desilter are composed of a set of hydrocyclone and a small ultra-fine mesh vibrating screen to deal with the low flow of the cyclone and recover drilling fluid.The desander is used to remove 30-74m solid particles, and the desilter is used to remove 10-30m solid particles.The particle size D50 in the hydrocyclone is not only related to the structure size of the hydrocyclone, but also related to the drilling fluid concentration, density and fluid inlet pressure.To handle all the drilling fluid, the desander and desilter must consist of a number of swirling cones.In order to ensure the normal operation of the cyclone, the liquid inlet pressure must be maintained within the range of 0.2-0.4MPa.Due to the number of swirling cones and the length of pipelines, the inlet pressure of the desilter should be a larger value.Due to less swirling cones and short pipelines, the liquid inlet pressure of desander should be a smaller value.
The size of the liquid inlet pressure mainly depends on whether the sand pump match is reasonable, so the choice of the sand pump is crucial. The head of the sand pump is usually about 40m water column, and the displacement can be equal to the processing capacity marked by the desander and desilter, which can meet the requirements of use.
At the same time, the selection of desander and desilter must refer to the maximum displacement of drilling pump, in order to achieve a reasonable match.
There is no strict limit on the use time of these two kinds of equipment. Generally, when drilling shallow formation and soft formation, the content of large particles in drilling fluid is high, and the two must be used at the same time.
In drilling formation and hard formation, if the use of fine mesh shaker, can be directly used to remove mud to deal with drilling fluid, which is drilling fluid purification quality has little effect, and very economic.
The application of hydrocyclone in modern drilling fluid treatment system is decreasing day by day. The main reasons are as follows:
1, vibrating screen technology progress, the treatment range is expanded, the fine screen can remove fine particles, can completely replace the desander.
2. The separation performance of the cyclone is greatly affected by the density and viscosity of drilling fluid.
