In the process of drilling, drilling fluid is invaded by gas or air, density is lower, viscosity higher .Drilling fluid density lower, which leads to the hydrostatic column pressure decreases, and may cause blowout, borehole collapse, etc malignant accident.It is very dangerous that drilling fluid is invaded by gas, therefore, must take measures to deal with.
After drilling gas layer, It is possible that gas invade in drilling fluid, and shale shaker, desander, desilter and mud gun, mud agitator etc could be invaded in drilling fluid by air in the work process.
Drilling fluid density is decreased obviously after gas intrusion ,but the impact on the static fluid column pressure is much smaller than people imagine.Because gas of invasion is compressible, the density of drilling fluid is increase gradually as the well depth.
Just according to the density of drilling fluid is lower by gas of invasion, It is very dangerous that the compound method is applied to make up for the lower density decision-making and can lead to excessive drilling fluid density, pressure formation, pollution formation.
At the same time can reduce the rate of penetration, cause lost circulation, results in the decrease of borehole liquid level, and then occur blowout.For example due to the intrusion of gas, measuring the density (the actual) is /cm3.
According to the request of balance drilling, The formation pressure of well depth will be controlled by/cm3 drilling fluid , at this time if the density of recycling system is aggravated to/cm3, it can produce two kinds of consequences, one is due to increase of density, rate of penetration decline;The second is higher about 3 Mpa than the original static fluid column pressure ,there is the risk of lost circulation.
In order to restore the density of drilling fluid , the most effective means is using vacuum degasser.
More info about our vacuum degasser,pls feel free to contact us.