polymer mixing

Oil sludge treatment, oil base mud and drill cuttings treatment is the major product made by GN Solids Control. Some clients do not know the difference of Oil sludge treatment system and oil base cuttings treatment system. They want to know the difference and know how to choose the right separation equipment.

Normally for OBM cuttings treatment, clients will separate cuttings and recover usable drilling fluids, and sell the drilling fluids. It is 2-phase separation. While for oil sludge treatment, clients will separate oil, water and solids. They do 3-phase separation.

Below are some general information to let clients know more about the different and about the equipment choosing.

1) As 3-phase centrifuge can only allow slurry with max. 10% solids content and particle size less than 2mm, 2-phase decanter centrifuge is must to be used before 3-phase separation to reduce the mud weight and solids percentage. After 2-phase centrifuge separation, the oil, water and soil mixture slurry flow into 3-phase decanter centrifuge to get oil, water and soil.

2) In order to remove as more ultra fine solids as possible, chemical dosing unit will be used together with decanter centrifuges for dewantering flocculation treatment. We quote you the 3-tank antomatic chemical dosing unit. It is used for powder chemicals. If you will use liquid chemical, pls tell me to revise the quotation.

3) Per our communication on Whatsapp. The pre-separation equipment for OBM cuttings and oil sludge is different. For pure OBM cuttings from shale shaker and mud cleaner, Vertical cuttings dryer is better. It can reduce the oil on the cuttings to 3% ~ 5%. It can remove more usable liquid. And the solids discharge is very dry.

But vertical cuttings dryer cannot be used to treat the soil sludge discharged from centrifuge. As its screen basket opening is 0.5mm, 0.35mm and min. 0.25mm. The soil cake from centrifuge is very fine and will all pass the screen opening.

4) Oil sludge is normally the mixture from different application, like drilling mud, drilling cuttings, soil cake from centrifuge separation, tank bottom slurry, slope oil, refinery waste oil slurry, industry waste oil, etc… The solids size and solids content is more complex. In this case, high G drying shaker is used for pre-seperation. And as the oil slurry is more complex, sometime, need to dilute and heating the sludge before separation. The solids waste discharge from High G drying shaker is with higher oil on the cuttings after separation. For example, before treatment the sludge with 15~20% oil content. After high G drying shaker, maybe around 10~15%, or even higher if the sludge with high viscosity and density.

Drilling cuttings would be produced when drilling. In order to recover and reuse the drilling fluids, the operator need remove the drilling cutting from the drilling fluids. The well known equipment to remove the cutting from drilling fluids is the solids control equipment. So, what is the cuttings dewatering system? And how it works to remove the cuttings in the drilling fluids?

The drilling fluids with cuttings coming from the well hole is fed to the shale shaker unit via the elevated pipeline, this the method used in oil rig package. For some other drilling project, like the no-dig horizontal directional drilling, the used drilling fluids would be collected into a pit on the ground, and then the fluids would be transferred by a slurry pump to the shale shaker unit.


Mud Dewatering

Shale shaker unit is the first stage for removing the coarse size cuttings in the drilling fluids. And then the de-sander and de-silter cyclone could remove out the cuttings with size down to around 20 microns. The used drilling fluids treated by the de-silter cyclone are already clean enough to be reused. However, the cuttings with size less than 20 microns would build up to make a heavy mud which is not suitable for normal drilling application.
The dewatering system is especially equipped to remove the ultra fine solids that even cannot be separated by the decanter centrifuge unit. A decanter centrifuge like GN’s 22 inch model GNLW553 can remove the cutting with size down to 5 microns. For the even finer cuttings, we need a flocculation process to gather the ultra fine solids so that the decanter centrifuge could remove out. The polymer mixing system is a critical part of the dewatering system, GN’s polymer mixing system is designed with powder hose conveyer, automatic dosing system, mixing tank and diaphragm pump for transferring the polymer to the drilling fluids. For better flocculation process, always one acid tank and one alkali tank is equip to make the suitable PH value.
Sometimes, the drilling fluids are mixture of water and oil, GN is also able to provide the oil water separator system for recovering the water and oil.
GN now has already have the design of the complete system for drilling cutting dewatering system, for more
information, please feel free to contact with us.