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.
Drilling fluid is used to aid the drilling of boreholes into the earth. Often used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are also used for much simpler boreholes, such as water wells. Liquid drilling fluid is often called drilling mud.
In drilling operations, solid weighting materials are commonly added to the drilling fluid to give sufficient density to the fluid to hinder inflow of oil or gas into the wellbore from the down-hole formation. Weighting material sag. i.e. sedimentation of weighting material from the drilling fluid, has been and is currently one of the biggest challenges within the drilling fluids industry as it can lead to well control problems, lost circulation, hindered running of casing/liner, insufficient displacement etc.
weighting material adding equipment
CALCIUM CARBONATE is Acid souble weight material.It is used to prevent fluid invasion of permeable zones, and to prevent loss of circulation during drilling, workover, and completion activities. CALCIUM CARBONATE is applicable in all drilling fluids, aqueous and non-aqueous. It can be used to prepare a pill for spotting purposes. is also used as an acid soluble weighting material for drill-in or workover fluids with a density of 14.0 ppg or less.
HEMATITE is for extremely high density mud.It is used to obtain mud weights in excess of 20.0 ppg in water based drilling fluids, 19.0 ppg in oil based drilling fluids, or any time that exceptional control is required of solids percentage for rheology control.
Barite is the most used weighting material, has a density of 4.1. It is used for increasing the density of fresh water, salt water, and oil based muds.
Barite is added through a hopper, GN designed Jet mud mixer is used for barite adding, it consist of venturi hopper and mixing pump. It can be used with the complete mud system, also it can be used separately.
Jet shearing unit is consist of venturi hopper and shearing pump, which can cut the big section into small pieces and add weighting material then mix them. It is commonly used in oil & gas drilling solids control system, usually it is installed on the weighting tank or mixing tank. Sometimes it is used together with decanter centrifuge.
Screw conveyors, sometimes called augers or auger conveyor, are used as an efficient way to move a wide variety of materials. The auger is used to move material along a path using a helical screw. The process of drilling with a helical bit involves aspects of both: the creation of the hole with the tip of the bit is drilling, while moving the waste material out of the hole along the helical path is augering. Not all drilling involves augering (oil field drilling uses a pump to move the material). Screw conveyors in oilfield are often used horizontally or at a slight incline as an efficient way to move drilling fluids with drill cuttings.
Auger screw for oilfiled
Main components of Auger screw:
Motor, control panel, Screw( including blade and shaft),Conveyor housing, Supporting feet and saddles, Feed and discharge spouts, Cover, Through end, etc.
Screw consists of a several of blades of helix shape welded to a pipe or shaft. It moves the material. The following specs should be calculated carefully for proper use: Flight outside diameter, type of blades, spacing between the blades, thickness of the external diameter and interior shaft and rotation direction.
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Simply speaking, mud cleaner is desander, desilter, shale shaker 3 in 1, sometimes people called it 3 in 1. For a four phase cleaning solids control system, mud cleaner can do the job for 2nd and 3rdphase cleaning of drilling fluids.
GN mud cleaner features:
1 standard design with various treating capacity, 500gpm, 1000gpm, 1500gpm
2 large shaker screen area to dry the solids and recycle more fluids
3 compact footprint, container shipping suitable
4 Easy maintenance, stainless steel valve on each hydrocyclone can make the replacement of cone easier, you do not need to stop whole machine.
MI-SWACO mud cleaner features:
Designed to handle the entire circulating volume to remove and dry solids while retaining premium base fluid. They are equally effective for both weighted and unweighted drilling-fluids.The hydrocyclones make the primary separation with underflow directed onto the shaker vibrating screen.
GN mud cleaner VS MI-SWACO mud cleaner
|SWACO 2-12/6T4 combo
|SWACO 2-12/8T4 combo
||4” x 12ea
||4” x 12ea
||4” x 16ea
||4” x 16ea
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What is Barite used for？
Barite is commonly used to add weight to drilling fluid. Barite is of significance to petrophysicists because excess barite can require a correction factor in some well log measurements.
barite recycling centrifuge
GNLW452S centrifuge is an ideal choice for barite recycling centrifuge, it has been used in oilfield in Russia and middle east for barite recycling. Its max rotary speed is 2200rpm and max separation factor is 1220.
Barite recycling centrifuge is also called low speed centrifuge. Its separating factor is 500~700. To low-density solids, its separating point is 5~10μm. To high-density solids, its separating point is 4~7μm.
High speed centrifuge’s separating factor is 1200~2100 or so, separating point is 2~5μm, it is usually connected with low speed centrifuge to make up a dual centrifuge system. In the system, barite recycling centrifuge is installed in the first phase, barite separated from it is discharged into mud tank to be recovered, liquid is drained into a surge drum first, and then be sent by a pump to high speed centrifuge; the solid separated from high speed centrifuge will be discharged out of the tank and the liquid is back to recirculation system. GNLW363VFD centrifuge can be also used for barite recycling, you can control the speed to 1500~1800rpm by variable frequency drive control panel, when you need to separate more fine solids, you can adjust the speed to 3200~3500rpm.
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The drilling fluids with the cuttings from the well are discharged to a rig shale shaker where the cuttings are separated from the drilling fluid. The separation step does not completely remove drilling fluid from the cuttings, some drilling fluid and additives remain on the drill cuttings.
drilling cutting treatment equipments
Then such drilling cuttings with drilling fluids will be dropped into a GN drilling waste system, through physical way to separate the usable drilling fluids with unusable drilling cuttings. For example, hi-G shale shaker to separate larger drilling cuttings, then verti-cutting dryer to separate drilling cuttings with oil less than 5%.The usable drilling fluids are treated by decanter centrifuge, then clean drilling fluids and water will back to rig again.
The cuttings separated by verti-cutting dryer with less than 5% oil can not be drain off directly, it may pollute the environment. We must use chemical way to continue the treatment.
Drilling cuttings treatment method:
Thermal desorption, re-injection, incineration and solidification.These methods have been applied in the site, they may have their own advantages and disadvantages.
use of the patented Porcupine Processor to remove all water and oil, leaving a residual total petroleum hydrocarbon on cuttings of less than 1%.
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Decanter centrifuge can be used as 2 functions: one is to used in drilling mud solids control system, to recycle drilling fluids and get barite. The other one is to used in drilling waste management system, to treat the drilling waste and recycle drilling fluids. GN decanter centrifuges are working in many sites in Brazil for such purpose.
Other related equipments with centrifuge:
decanter centrifuge rental in Brazil
In drilling fluids solids control system, centrifuge is used after desander and desilter, when they need to separate fine solids.
In drilling waste management system, centrifuge is used after cutting dryer, when they need to recycle the clean drilling fluids and drain off the cuttings. Sometimes it is used after hi-G shaker, it depends on the drilling mud type.
GN can provide both equipments related to the centrifuge.
People rent centrifuge because of the high cost of US centrifuge, also because of the maintenance cost, sometimes clients only want to use the centrifuge for a short while, so centrifuge rental is economic for them. But most of the clients rent centrifuge because they have Continue reading »
When to use a centrifugal or a Positive Displacement pump (“PD Pump”) is not always a clear choice. Usually we use a positive displacement pump to feed for decanter centrifuge, it is called single screw pump.
The major benefit to use a positive displacement pump other than centrifugal pumpis that, it will not break the fine solids to smaller, so the centrifuge can separate the solids easily. Centrifugal force of centrifugal pump will cut the solids to smaller, it is not good for centrifuge’s operation.
positive displacement pump for centrifuge
How to operate a screw pump when feeding to decanter centrifuge?
1 Full fill the pump chamber with drilling fluids , if the media is too viscosity, then inject into other liquids; Inject the mud from the pump inlet connection, and rotate the pump by hand along the running direction of the motor to make the mud full fill the suction chamber.
2 Open the screw pump inlet valve and outlet valve (the valve is fully opened to prevent overload or no load suction), start the motor.
3 The pump should be started under the condition of fully opening the Inhale row valve and bypass valve to minimize the start load. Gradually close the bypass valve after the motor reaching the rated revolution.
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The majority of Mud Motor use is in the drilling of Directional Holes. Many of our HDD contractor clients asked if we have mud motor for sale, they prefer a complete solution for triplex mud pump, mud motor, recycler, mixing unit, GN can provide mud recycler and mixing unit as a package.
HDD mud motor recycler
Mud motor also called Drilling Motor refers to a Progressive Cavity Positive Displacement Pump placed in the Drill string to provide additional power to the bit while drilling. The PCPD Pump uses Drilling Fluid to create eccentric motion in the power section of the motor which is transferred as concentric power to the drill bit. The Mud Motor uses different rotor and stator configurations to provide optimum performance for the desired drilling operation, typically increasing the number of lobes and length of power assembly for greater horsepower. In certain applications, compressed air, or other gas, can be used for Mud Motor input power. Normal rotation of the bit while using a Mud Motor can be from 60 rpm, to over 100 rpm.
GN mud recycler and mixing unit can match with Ditch Witch HDD rig and Vermeer rig according to their required mud flow capacity. The recycled drilling fluids by GN mud recycler and mixing unit are provided to mud motor for charging.
Mud motors are powered by drilling fluid ,the fluid consists of water mixed with bentonite or polymer additives designed to match various soil conditions. The fluid is pumped down through the drill string to the downhole motor, which converts the flow to rotary speed and torque.
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GN solids control is specialist of solids control equipments for rotary rig in China, we have various kinds of mud equipments in stock, welcome to inquiry us.
Rotary rigs drill the vast majority of wells today, including all medium and deep wells. The rotary rig consists of four major systems. These include the engines, and the hoisting, rotating, and mud systems.
rotary rig equipments
General of drilling mud(drilling fluids)
Common drilling mud is made of bentonite clay. A heavier drilling mud can be made by adding barite. Various chemicals are also used in different situations. The drilling mud liquid is usually water but is sometimes oil-based. Drilling mud are described by weight. Water weighs 8.3 pounds per gallon. Average bentonite drilling mud weighs from 9 to 10 ppg. Heavy drilling mud weighs from 15 to 20 pounds per gallon. The heavier the drilling mud, the greater the pressure it exerts on the bottom of the well.
Fluid is circulated while the drilling proceeds. Powerful pumps move the fluid down to the pipe, through the bit and back to the surface, carrying the cuttings and other debris with it. Thus, on a rotary rig , drilling can be continuous as stopping to bail the cuttings is no longer required. The drilling mud also stabilizes the walls of the hole.
Mud circulation system for rotary rig
Drilling mud is stored in steel mud pits beside the rig. The drilling mud then flows down through the hollow rotating drill string and jets out through holes in the drilling bit on the bottom of the well. The drilling mud picks cuttings from the bottom of the well. It flows up the well in the space between the rotating drill string and well walls.
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