What is the difference in operation between positive displacement pump and centrifugal pump?

Positive Displacement Pumpswill not p roduce the same flow at a given speed (RPM) no matter the discharge pressure.

positive displacement pump

Positive Displacement Pump must not be operated against a closed valve on the discharge side of the pump because it has no shut-off head like Centrifugal Pumps. A Positive Displacement Pump operating against a closed discharge valve, will continue to produce flow until the pressure in the discharge line are increased until the line bursts or the pump is severely damaged – or both.

The positive displacement pump can be applied as

• rotary lobe pump
• progressing cavity pump
• rotary gear pump
• piston pump
• diaphragm pump
• screw pump

When positive displacement pumps serve as a screw pump for feeding drilling fluids decanter centrifuge, when you change the frequency of the main motor through the VFD control panel, the treating capacity of decanter centrifuge will change, so the flow rate need to be lessed.

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Closed loop drilling fluids system (sometimes referred to as closed mud or pitless system)are system which do not need mud pits, which can greatly reduce or eliminate the discharge of toxic drilling wastes on site.

What mud systems need mud pits?

closed loop drilling fluids system

1 HDD  mud system need mud pits, the drilling mud flow to mud pit, and the slurry pump installed into the mud pit transfer the mud to HDD mud cleaning system, and the processed mud is pumped to the rig again.

2 At a typical oil & gas drilling site, drilling fluids are circulated through the wellbore, then the fluids and drill cuttings are deposited in a reserve pit dug near well. This pit is used to hold used drilling fluids and wastes. There are many potential problems from pits — leaky liners and overflows can lead to soil and water contamination, pits can produce odors and toxic air contaminants, and pits can be a hazard for birds and wildlife.

What is closed loop drilling fluids system?

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Liquid mud plant(LMP) is a big project which is built for mixing, treating and storing expensive invert oil emulsion mud. The Liquid Mud Plants are able to store and supply liquid chemicals such as Oil Base Mud, Base Oil and Water Mud to meet the demands for deep and ultra-deep offshore drilling activities.

liquid mud plant in China

GN can provide rectangular mud storage tank for the liquid mud plant, also with the mud agitator, mud gun and centrifugal pump/transfer pump, mud mixing hopper installed on the mud tank. We can make customized pipelines to connect the tanks with further equipments. Some liquid mud plants may include some solids control equipments like below:

1 shale shaker with feeding pump

2 decanter centrifuge with feeding pump

3 transfer pump/mixing pump

4 mixing/shearing hopper

5 mud agitator

6 mud gun

7 water pump (for water storage tank)

8 cutting collection box

Plus, the electric motor and control panel can be comply with ATEX explosion proof or IEC Ex explosion proof or US standard, and we can make it mobile liquid mud plant. Welcome to contact GN sales for customized solution.

Big Bowl, large Extruder rate, PLC control is the development trend of centrifuge production, especially for oil & gas drilling fluids decanter centrifuge. VFD and Hydraulic are 2 kinds of drive method, both of them have their own advantages, but VFD control decanter centrifuge is much more popular and easy maintenance at present. Here I will introduce and compare some world famous VFD big bowl decanter centrifuge.

BIG BOWL VFD CENTRIFUGE

According to the chart above, their bowl size, bowl length is similar to each other, but the G-force, motor power, differential speed etc specification has big difference. Also the treating capacity varies by different model, different brand centrifuge. Continue reading →

GN solids control mud system can be used for both oil & gas drilling and water well drilling. Water wellis an excavation or structure created in the ground by drilling to access groundwater in underground aquifers. Most shallow well drilling machines are mounted on large trucks, trailers, or tracked vehicle carriages. Water wells typically range from 3 to 18 m deep, but in some areas can go deeper than 900 m.

GN200gpm trailer mounted mud system for water well drilling

Most of the water well drilling rig is trailer mounted or truck mounted, for convenient transportation from one place to another. Some contractors do not process the used mud from water well drilling, but recently there are more strict laws for environment protection, they have to search for small mud recycling system to complete the job. They prefer trailer mounted mud system, GN 200gpm trailer mounted mud recycling system is widely used for water well drilling. Total transportation dimension is 5500x2300x4000mm( including the trailer height), it meets the transportation limit in most of the countries in the world( you do not need to remove anything when transport in domestic). You only need to remove the mud cleaner and shale shaker from the tank, then I can fit for 40feet standard container.

GN200gpm trailer mounted mud system including:

GNZS752 shale shaker 1set

GNZJ752 mud cleaner 1 set

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Mainly there are 3 types of drilling fluids, water-based mud, oil based mud & synthetic based mud.

Synthetic-based fluid is a mud where the base fluid is a synthetic oil. This is most often used on offshore rigs because it has the properties of an oil-based mud, but the toxicity of the fluid fumes are much less than an oil-based fluid. This is important when men work with the fluid in an enclosed space such as an offshore drilling rig.

There is a technical limit to what can be achieved with water-based fluids, especially in the short and medium terms. For this reason, I believe advances in the environmental performance of synthetic-based fluids can be expected to occur faster, in combination with improved treatment and new drilling techniques. But synthetic based mud’s cost is much higher than water-based mud.

The mud recycling system for the 3 types of mud is basically similar but has little difference.

synthetic based mud recycling system

Synthetic based mud is mostly used for offshore drilling, people sometimes do not process and recycle the used mud at jobsite, they have the used drilling fluids in mud pits and transport them to a drilling fluids plant or factory for recycling and treatment, then ship back to the rig. In some other situations, they have the solids control system at jobsite, but no drilling waste management equipments at jobsite.

Water based mud is with cheaper cost and also environment friendly, it is mainly used for land drilling, in most oilfield in China or some developing countries, water based mud is widely used, and it works well with solids control system produced in China.

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Centrifugal pumpsare used widely in drilling fluids system, as feeding pump, transfer pump, trip pump, charging pump, mixing pump, weighting pump. Mechanical seal became a popular type centrifugal pump at present.

mechanical seal in centrifugal pump

What is mechanical seal?

Mechanical seal is a device which to prevent liquid under pressure from leaking out of the pump, or from drawing air into the pump when under vacuum conditions.

Mechanical seal centrifugal pump is a type of Single-stage & single-suction mud pump, Material of pump housing, stuffing box, impeller, bracket mount is Grey iron casting HT250, and pump shaft is made of 42CrMo, Mechanical seal material including :

Rubber material is viton

Skid, spring is made of SS316

Surface of seal is made of tungsten carbide

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The landfills are low-cost and low-technology, so until now, it is the most popular method for drilling waste disposalin developing companies, who do not have much concern about environment.

drilling waste management equipments

1 Landfill

After drilling waste are maximum recovered and the certain level for oil, salt, metals or industrial chemicals can reach the disposal standard set up by environment Department, it can be landfill disposal. Even with low-concentration levels, pits must be structurally sound and isolated from groundwater sources, so that it can not be thread of groundwater supplies.

Waste with slightly higher concentrations can be blended with clean soil to meet acceptable levels. Pits can be located within plant rooting zones, but cannot intersect with ground water tables. If waste exhibits toxic concentrations, disposal can only occur in specially engineered and legally permitted landfills (on-site or off-site)

2 Drilling waste management

Only when the drilling waste is maximum recycled and treatment and reach the certain level, it can be landfill. GN solids control worked together with drilling waste management service companies, we provide equipments to support the service company to do the drilling waste disposal service.GN Vertical cutting dryer can make the drill cutting dryer and oil content in the cuttings is lower than 5%, then the water can be chemical treatment and the cuttings can be landfill or others.

Although there are a lot of methods for drilling waste disposal, the core solution is to reduce the drilling waste and maximum recycling them. A proper solids control system can minimize the drill cuttings and recycle more useful drilling fluids, a good drilling waste management system can recycle more cleaning drilling fluids from the cuttings, both of them can less the drilling waste disposal. GN provide both solids control & waste management solution, you need further process for the drilling waste disposal.

GN designed and produced customized screw conveyorfor drill cuttings. We can design screw conveyor system according to client’s requirement.

Screw Conveyor for drill cuttings

GN has standard 14 inch and 18 inch diameter screw conveyor for option, also you can choose 2 section, 3 section, or 4 section ( maximum). Each Screw with electric motor and control panel, we also provide motor and control panel with IEC certification for option. The painting and material can also be choose, we have carbon steel, stainless steel and another much harder material than stainless steel for option. The installation tilt Angle of the Auger has 2 options, ≤5°or ≤40°. You can choose fixed speed or variable speed drive for the screw propeller.

The screw conveyor is a simple way to transport drilled solids. Screw conveyors are typically used to transport drilled cuttings from the shale shaker area to a discharge port, skip or to secondary processing equipment ( like drilling waste management system). The inside scroll( screw) also called auger, which is drived by a electric motor, drill cutting is fed into the Screw Conveyor and transported along by the rotating scroll.

Screw conveyor size and horsepower requirements will vary, dependent upon the length of the run, bit size, rate of penetration and flow rate. Additional sizes are available upon request. For detailed chart, pls contact GN solids control.

Simply speaking, mud cleaner is shale shaker, desander, desilter assy, it is also called 3 in 1. GNZJ703 & GNZJ853 is the best choice for large treating capacity, large screen area mud cleaner, most of our clients use GN made mud cleaner before GN decanter centrifuge, this action can improve the performance of GN decanting centrifuge.

mud cleaner

Mud cleaner maintenance including

1 vibration motor maintenance

(1)Clean dust on shell regularly

(2)Before operating, must check the bolts to confirm whether there is loose or not. Otherwise, we must screw bolts tight before running shaker

(3)Inspect the cable, whether there is wear, hold down, crushing, etc.

(4)the vibration motor should be under good lubrication during operation:

Motors before fixed on shaker, the bearing is filled with SKF specific lubricate grease, the temperature range is -40 ~ 200℃

2 shaker screen maintenance

(1)Before every shut off, the shaker should run without any load for 5-10 minutes, at the same time, use clean water to flush screen clean

(2)Every time finish operation, the shaker frame and screen should be flushed by water. Pls replace new screen or repair the damaged screen once it is found damage, otherwise large cutting may dropped into the clean mud and influence the following process.

3 Electric cabinet maintenance

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