mud pump flush procedure quotation

The “pond” is actually a man made dam which covers an area of about 40ha and has rockfill embankments of up to 53m high along the southern side that forms the impoundment.  It initially constructed in 1959 to act as a tailings pond to take the bauxite residue (red mud) from the Ewarton Plant situated about 5km away and 300m lower.  The red mud was pumped as a slurry comprising about 20% solids to the pond over a period of about 32 years up to 1991 when the pond was replaced by the Charlemount Mud Stacking and Drying Facility.  During this period the pond embankments (referred to as dams), were raised up to 7 times providing a final crest elevation of 472m.  The pond was however never filled to its final design capacity and the mud beach level remained at about 469m and the central area about 458m leaving a concave depression which held about 1.4mil m3 of water with elevated pH and some caustic content.

The remediation plan for the pond includes the removal of the ponded water and then the regrading of the mud surface to be free draining so that it can be stabilised and vegetated.  About 500,000 m3 of mud will need to be moved over a distance of up to 1km in order to create the required profile.  Due to the very soft nature of the surface muds (shear strength of less than 3kPa) its bearing capacity is less than 20kPa hence it is not accessible using even modified earthworks equipment.  In addition, the muds are thyrotrophic and under any vibration or shear loading, rapidly liquefy resulting in significant reduction in shear strength and loss of bearing capacity.  Using conventional earthmoving equipment would therefore require extensive “floating” haul roads with a high risk of machinery getting stuck or entire plant loss and risk to personnel.  It was therefore decided to investigate the possibility of pumping the in-situ red mud.

A mud pumping trial was undertaken to assess the feasibility of using this technique to do the bulk mud moving.  Pumping red mud is not unusual and the muds were initially pumped up to Mt Rosser Pond.  However, the muds are usually pumped at a solids content of 30% or less.  Once deposited, they can take years to reconsolidate and firm up sufficiently to allow access for light earthworks and agricultural plant.

In addition to the mud pumping, the trial included infilling three small scale geotubes to assess their performance as these may be needed as part of the regrading works.

The main aim of the pump trial was to determine if the muds could be pumped in their insitu state, and if not, what amount of water is required and how the variations in water content affect pump rates.

The mud pumping trial was undertaken using a 4” EDDY Pump.  This pump was recommended due to its ability to handle variable solids and robust operating mechanism.  The pump unit incorporated a hydraulic drive and cutter head.  The unit was mounted onto the boom of a JCB 220 excavator which also supplied the hydraulic feed to power the pump for the required range of 30-40 GPM at 3,500 to 4,000 psi (2428MPa).  The cutter head was powered by a standalone hydraulic power unit capable of providing the required 30gpm at 200psi (1.9 l/s at 13.8MPa).  If mounted on a 30-ton excavator with a System 14 hydraulic system and dual auxiliary feeds to the boom, all necessary hydraulic power for the pump and cutter head can be supplied by the excavator.  This equipment was however not available at the time in Jamaica.

In addition to the pump mounted on the excavator a Long Reach excavator (CAT 325) was used to move muds towards the cutter head but also to loosen up the muds and mix in additional water to facilitate pumping.  Water was added by pumping it directly from the pond using a 3” diesel water pump.

Prior to pumping the muds, the mud pump would operate in recirculation mode in order to prime the pump.  When in recirculation (re-circ) mode, the material pumped would be diverted to a short discharge pipe mounted on the pump directed back parallel to the cutter head. This action would help agitate and stir the muds.

A geotechnical soils investigation was undertaken on the muds within Mt Rosser pond in 2004.  It showed the material to be predominantly clayey silt with approximately 13% sand, 29% clay and 58% silt using conventional sieve analysis and hydrometer.  Atterberg limits indicate that the material is an intermediate to high plasticity clay.  The muds do however vary across the lake and also vertically. This is mainly as a consequence of the deposition process and discharge location.  Close to the discharge location the courser materials would settle out first and the finer materials would disperse furthest and to the opposite end of the pond.  The results are presented in figure 4.1.

Earlier this year, additional mud samples were tested as it was evident that standard soil mechanics tests did not provide an accurate assessment of this fine material.  This was particularly evident in tests done with dry sieving which shows the material as well-graded sand (see results for samples 5300, 5301, 5302 on figure 4.2).  When dispersed in water, even with an agent, the ‘yield-pseudo-plastic’ rheology of the muds appeared to affect the hydrometer results with large variations between tests (see results of samples PFT4&5 taken during mud pumping trials on figure 4.2).

The additional testing comprised of undertaking gradings using a Laser Particle Analyzer. The results indicated that the muds are predominantly Silt although the silt % varied from 30% to 80% with the material being either more sandy or more clayey (up to 15% clay). See results of samples ending in “L” on figure 4.2 below.

Moisture content tests on the muds taken from within the mud pond but below the ponded water ranged from 100% to 150% (50% to 40% solids).  The muds at the pump test location were 137% (42% solids).

Shear strength was generally very low ranging from 1kPa to 6kPa increasing with depth.  Dynamic probes previously undertaken indicated that the muds are “very soft” to 5m increasing in strength slightly to “soft” at a depth of 9m after which they increase to firm becoming stiff.

The pH of the muds ranged from 10.3 to 11.7, (ave 11.2).  Previous testing indicated that the surface muds have the lower pH although once through the crust, the pH tends to be higher. When doing the trials, the muds up to a depth of about 2.5m was intermixed, hence any stratification in pH could not be determined.

Initially, pumping was problematic mainly due to the excavator being underpowered. This was diagnosed as a hydraulic pump problem and the excavator was replaced.  The cutter head (which also acts to protect the intake) tended to blind with mud (Photo 5.1) and was also not providing enough agitation to liquefy the muds.  This was partly resolved by adding “stirrers” (2 steel loops welded either side) to the rotating cutter head and also a “comb” (Photo 5.2) to keep the gaps within the cutter head open.

Mud pumping rates varied from 21 l/s to 52 l/s (332 – 824gpm) and it was clearly visible that the more liquid the muds were the higher the pump rate was.  Samples were taken at different discharge rates and moisture content and percent solids determined by laboratory testing.  The results are plotted in Figure 5.1 and although scattered, do give an indication of the effects of solids content on flow rates.  The natural moisture content of the muds (insitu) at the test location was 137%, or 42% solids.  This is shown in Figure 5.1 as a vertical line.  Pumping muds close to the percent solids was achieved although flow rates were low.

As mentioned previously, the long reach excavator was used to loosen up the muds.  Water was pumped from the pond using a 3” pump into the excavation and the long reach would then work the muds to mix the water in.  The mud pump would then be used in recirculation mode to further mix the muds into a more consistent state.  Even with this mixing and agitation, the water tended to concentrate on the surface. This aided the initial process of priming the pump and once primed thicker muds at 1m to 2m below the surface could be pumped.  However, it was found that the deeper muds tended to be lumpy and this would significantly reduce or stop the flow requiring the pump to be lifted into thinner muds or having to go back into re-circ mode or having to fully re-prime.  The pump discharge was therefore very inconsistent as the suction intake position constantly needed adjustment in an attempt to get adequate discharge but also pump the thickest muds possible.

Discharge of the pumped muds was through 30m of flexible hose then 60m of 4” HDPE pipe which had an internal diameter of about 87mm (3.5”).    The muds were discharged onto the original mud beach which lies at a gradient of about 9%. On deposition the muds slowly flowed down gradient.  At times the flow would stop and the muds would build up then flow again in a wave motion.  The natural angle of repose would therefore be a few degrees less than this – probably 5% to 6%.

Although the muds have very low shear strength, and on agitation liquefy, the sides of the excavation had sufficient strength to stand about 2m near vertical.  Even overnight, there was limited slumping and the bank could be undermined by about 0.5m with the cutter head/agitator before collapsing.

On termination of pumping, in order to flush the pipeline, thin watery muds were pumped until the line was clear. A “T” valve system was then used to connect the 3” water pump line and this was then used to flush the pipe with water.

Three geotubes (1m x 6m) were filled with red muds pumped using the 4” Eddy pump. Fill rates were about 30 to 40l/s although it was difficult to assess as the flow and mud consistence was not visible.

Tube 1 was filled initially with more runny mud and then thicker muds as the pump operator got a better feel for conditions.  The tube was filled until firm.  The second tube was filled with thicker muds and filling continued until the tube was taut.  These two tubes were positioned on the sloping beach in order to form a small “U” impoundment area that would later be filled with pumped muds.  Although the area was prepared, the sloping ground caused the first tube to rotate through about 20 degrees. The tube was staked and the downslope side backfilled.  A more defined bed was created for the second tube and the same rotational issue was limited.  The two filled tubes with the ponded mud are shown in Photos 5.7 and 5.8.  Other than a small leak at the contact between the two geotubes, the ponding of the muds was successful.

The third tube was positioned on level ground. It was filled with medium runny (but consistent thickness) muds and was filled until the tube was taut.

In all three cases, there was very little mud loss or seepage from the tubes.  When stood on, some red water would squeeze out around the pressure area.  Once filled taut, the entire bag would have small red water droplets form on the outside (visible in Photo 5.11) , but the seepage was in general nominal.

The tubes have been monitored and the most recent photo’s taken on 10 October 2011 (6 weeks after filling) show how the tubes have reduced in volume due to the dewatering of the contained muds.  Volume loss is estimated to be around 30%.  The anticipated moisture content would therefore be about 90% and the solids around 53%.

The muds pumped into the trial pond behind the geotubes were medium thick to thick, probably in the order of 37 – 40% solids.  After 6 weeks the mud has not only firmed-up but had dried out significantly with wide and deep surface cracks as are evident in Photo 5.14 and 5.15.

The muds can be pumped at close to their insitu moisture content and most likely at their in-situ moisture content if they were agitated more and the pipeline system was designed to reduce friction losses.

Be able to access the mud surface and move around efficiently and safely. The suggestion is to have the pump mounted on a pontoon that is positioned using high strength rope (dynema) or steel cable.  The pump system should be remotely controlled as this would limit regular movement of personnel on the muds.

Have sufficient power and volume capacity to pump the muds at close to or at in-situ moisture content and discharge them about 1000m through a flexible pipeline.

It was also evident from the trials that the muds do not slump and flow readily.  It will therefore be necessary to have an amphibious excavator to loosen up the muds in the area around the pump head.  This weakened and more liquid mud would also aid the movement of the pump pontoon.  To also limit the amount of movement the pontoon will need to do, the amphibious excavator could also move muds towards the pump location.

Using the capacity of the 4” mud pump, mud moving would take about 1.5 to 2 years, the pump will however need to be more suited to the task.  A target period of 1 year however seems reasonable.  However, prior to this, equipment will need to be procured and imported into Jamaica. The 6 and 10 inch Excavator Dredge Pump Attachments are also being considered as an option for higher GMP and a more aggressive completion timeline.  A preliminary programme is as follows:

Pressure relief valves are generally positioned on your vacuum pump truck’s primary or secondary tank but can be retrofitted to go between the primary tank and the secondary scrubber. An adjustable pressure relief valve is often paired with a vacuum relief valve, and both can be monitored with a dual vacuum/pressure gauge as seen in Moro’s Pressure/Vacuum Relief Tree. A vacuum relief valve functions similarly to a pressure relief valve but is more concerned with keeping the vacuum pump safe and preventing tank implosion, rather than the larger issue of keeping personnel safe.

The RIV 1-1/2” Pressure Relief Valve also features a convenient hose shank connection to divert air and overflow liquids away from the vacuum pump to an appropriate vessel. This keeps your pump cleaner, reduces maintenance for you and your staff, and extends the overall life of the pump.

Under normal circumstances, your system – the pipes, fittings, tanks, pumps, and other equipment – operates at or around a certain PSI. At this point, the pressure relief valve is not engaged and remains closed. Inside the relief valve there is a large, adjustable spring that is set to a specific pressure higher than that of the fluids in the system. When the pressure in the system is greater than that of the spring, it will force a small poppet inside to lift, compressing the spring, and opening the valve. Excess pressure is discharged, and PSI is reduced. Once it has returned to the desired operating pressure, the spring’s force will again be greater than that of the process fluid and will release, pushing the poppet back down into its seat, closing the valve, and returning the system to the appropriate pressure.

Pumps are often designed to operate at a single point known as the Best Efficiency Point (BEP). As components begin to wear, a pumps performance begins to decline, with operation away from this point leading to issues such as accelerated bearing or seal wear, vibration, excess temperature rise or cavitation. Quite often declining performance can start gradually, before quickly accelerating until failure if performance issues are not addressed in a timely fashion.

Corrective Maintenance is undertaken when failure has occurred. The unit may be leaking, efficiency reduced, pump stopped or motor tripped, leading to loss of production resulting in an urgent situation where parts must be sourced and fitted quicky.

Preventative Maintenance is inspection and repair scheduled at specific intervals (daily, weekly, monthly, yearly) or based on the number of hours run. Visual inspections are made externally and internally by dismantling the unit, replacing seals such as gaskets and mechanical seals, with pump parts checked for wear.

Differential Pressure:Check the operating pressure by calculating the difference between the inlet and outlet pressure of the pump ensuring it is operating on curve.

Although Proactive Maintenance can seem to avoid the urgent costs and downtime associated with reactive maintenance, PM maintenance costs can be high due to the cost of labour in dismantling of complicated designs such as Progressing Cavity, or Triplex Plunger pumps which are often time consuming to maintain with more than one person required to undertake work.

On dismantling units, some seals require replacing regardless of condition, and excess spares can be required in case of gasket entrapment during assembly. Rental of specialist lifting equipment may be required and there can be situations where when inspected, pump parts do not require replacement.

This can be achieved through a monitoring device, where when the right data is collected, pump failure can be anticipated between 3 and 12 months in advance with an 80-95% accuracy.

With the average lead time on DN100 pumps, and units over 5 years old being 3 months or more, it is essential that spares are either on the shelf or failure is anticipated through advance ordering.

There are hazards during any maintenance activity. Always ensure the correct PPE is worn before attempting repair, that sufficient expertise is on hand and chemical data sheets of any fluid being pumped are checked prior to undertaking work. A full risk assessment should be completed in advance.

Hazardous FluidsIrritation, Chemical burns, ignitionEnsure when pump is opened the unit is cool, not pressurized, ignition sources are not present, and any fluids spilt are contained.

If inspection has been neglected for some time, then additional parts may require replacing than had the unit been inspected earlier, with some pump parts becoming beyond economical repair.

Enables planned work to be undertaken during lower activity levels and at lowest cost & risk.Pump has to be crucial within a process or above a certain size for monitoring to be cost effective

Thread Sealant –The use of semi-permanent thread sealant will ensure vitality important threaded fasteners such as bolts or screws on shafts, couplings or pump casings do not self-loosen due to vibration and become disengaged.

Interchangeable Spares –Our range of pumps are modular in design utilizing interchangeable spares, meaning on site stock holding of parts can be reduced by up to 80% further reducing slow moving stock.

Repair & Replace –Choosing to repair an existing pump within a process of vital importance, as well as replace, is a strategy we recommend for maximizing plant efficiencies and reducing downtime. Should unexpected pump failure occur, your process can be restored quickly.

indicates which areas should be checked, but note that a units maintenance routine is dependent on several factors such as hours of operation, duty, aggressiveness of pump medium, rpm of motor, temperature, inlet conditions and location of equipment.

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According to the customer’s working condition, we recommended the submersible mud pump model: NSQ500-15-45, which is a low-lift and large-flow submersible mud pump, very suitable for short-distance mud sand transportation.

Flow rate is 500 cubic meters per hour, lift 15 meters, power 45kw, pump outlet diameter 8 inches, maximum through particles 46mm, working voltage 380V, 50Hz.

When we got this feedback, the technical department quickly respond to a solution, suggested customer install an auxiliary flushing device. The auxiliary flushing device can disperse the sediment and increase the sediment concentration, and also can prevent the pump buried.

After the auxiliary flushing device is installed, the sediment concentration is significantly increased, and the sludge pumping effect is very good, meeting customer requirements.

The Walker Pump dredge is capable of passing large volumes of sediment, sludge, woody debris and other material in rivers, dams, reservoir without clogging.

In order to understand centrifugal pump leakage, it’s important to first understand the basic operation of a centrifugal pump. As the flow enters through the impeller eye of the pump and up the impeller vanes, the fluid is at a lower pressure and low velocity. When the flow passes through the volute, the pressure increases and the velocity increases. The flow then exits through the discharge, at which point the pressure is high but the velocity slows. The flow that goes into the pump has to go out of the pump. The pump imparts head (or pressure), which means it increases the energy of the pump fluid.

Certain component failures of a centrifugal pump, such as coupling, hydraulic, static joints, and bearings, will cause the whole system to fail, but approximately sixty-nine percent of all pump failures result from the sealing device malfunctioning.

Before mechanical seals were developed, engineers typically sealed a pump with mechanical packing. Mechanical packing, a fibrous material usually impregnated with a lubricant such as graphite, was cut into sections and stuffed down what was called a “stuffing box.” A packing gland was then added to the backside in order to pack everything down. Since the packing is in direct contact with the shaft, it requires lubrication, but will still rob horsepower.

Usually a “lantern ring” allows flush water to be applied to the packing. That water, necessary to lubricate and cool the shaft, will leak either into the process or into the atmosphere. Depending on your application, you may need to:

As with every pump, you’ll want to test your pump to discover the annual costs it requires to run. A packing pump may be affordable to install and maintain, but if you calculate how many gallons of water it consumes per minute or per year, you may be surprised by the cost. A mechanical seal pump could potentially save you a lot of annual costs.

If the centrifugal pump exhibits an uncontrolled leak, you must thoroughly check all potential causes to determine if you need repairs or a new installation.

Neglecting the Best Efficiency Point: Are you operating the pump at the Best Efficiency Point (BEP) on a performance curve? Each pump is designed with a specific Efficiency Point. When you operate the pump outside that region, you create problems with the flow that cause the system to fail.

Insufficient Net Positive Suction Head (NPSH): If you don’t have enough suction head to your pump, the rotating assembly can become unstable, cause cavitation, and result in a seal failure.

Operating Dead-Headed: If you set the control valve too low to throttle the pump, you can choke the flow. Choked flow causes recirculation within the pump, which generates heat and promotes a seal failure.

Dry Running & Improper Venting of Seal: A vertical pump is the most susceptible since the mechanical seal is positioned on top. If you have improper venting, air can get trapped around the seal and won’t be able to evacuate the stuffing box. The mechanical seal will soon fail if the pump continues to run in this condition.

Shaft misalignment, coupling imbalance, and impeller imbalance can all contribute to mechanical seal failures. In addition, after the pump is installed, if you have misaligned pipes bolted to it, you will impart a lot of strain on the pump. You also need to avoid a bad base: Is the base secure? Is it grouted properly? Do you have a soft foot? Is it bolted correctly? And last, check the bearings. If the tolerance of the bearings wears thin, the shafts will move and cause vibrations in the pump.

You need a proper seal flush arrangement, along with sufficient cooling. Dual systems have barrier fluids; the auxiliary seal pot needs to be in the right location, with the correct instrumentation and piping. You need to take the Length of Straight Pipe at Suction into account—some older pump systems that often came as a packaged skid include a 90º elbow at suction right before the flow enters the impeller eye. The elbow causes a turbulent flow that creates instabilities in the rotating assembly. All the suction/discharge and bypass piping needs to be engineered correctly as well, especially if some pipes have been repaired at some point over the years.

Frank Rotello is mechanical seal reliability engineer for Cummins-Wagner. Cummins-Wagner Co., Inc. is a distributor for industrial and mechanical equipment covering the mid-Atlantic states with leading brands of compressors, pumps, and heat transfer equipment, and offer support services such as system design, assembly, and aftermarket service and repair. For more information, visit www.cummins-wagner.com.

BW850-5 mud pumps horizontal, two-cylinder, double-acting, drive with built-in gear reducer and are designed to discharge washing liquid (water, mud) in the hole in exploration and stratigraphic drilling for oil and gas. Mud pumps are also widely used in the food, chemical and construction industries for pumping various non-aggressive liquids.

When drilling, use the pump BW850-5 for supplying washing liquid. To operate this pump may be at different temperatures (from-50 C to +40 C). The washing liquid may be water or various emulsion, a basic requirement for which is:Density,viscosity,the amount of sand,the number of cuttings.

Equipped with ball valves pump BW850-5 can be used for pumping a variety of complex solutions, which must have certain parameters:Density,viscosity,solid particles in the composition.

They are also the main equipment of the geological survey,the main role in the process of core drilling boreholes is to supply fluid(mud or water),making it circulate during drilling and carry rock waste back to the ground,in order to achieve and maintain the bottom hole clean and lubricate drill bits and drilling tools with cooling.

A Mud pump refers to a machine that transports flushing fluid such as mud or water into the borehole during drilling. Besides, it’s an important part of drilling equipment.

BW drilling mud pumps are used to pump the medium containing solid particles. According to the process conditions, the equipment should be suitable for handling abrasive or corrosive liquids.

In the common positive circulation drilling, a mud pump provides pressure to the surface flushing medium, such as clean water, mud, or polymer flushing fluid. Under this pressure, the surface flushing medium will go through the high-pressure hose, faucet, and the center hole of the drill pipe string, directly to the bottom of the drill bit. Then it can achieve the purpose of cooling the drill bit, removing the cutting debris, and transporting debris to the surface.

This is BW series triplex mud pump, a kind of horizontal type, 3-cylinder, single-acting reciprocating piston pump. The followings are about the parameters of different types.

YG Machinery offers a series of special high-pressure pumps for circulating drilling mud through a drill pipe that is specifically designed to handle mild and heavy mud. The BW series mud pump of YG Machinery is piston type. The crankshaft of the pump is driven by the power machine to rotate, and the crankshaft drives the piston to reciprocate in the pump cylinder through the crosshead. Under the alternate action of suction and discharge valves, the purpose of pressure feeding and flushing liquid circulating is realized.

BW series mud pumps adopt advanced anti-wear measures to increase the service life of vulnerable parts, reduce engineering investment and improve production efficiency. At the same time, Henan Yugong Machinery will provide replacement parts for clients. These wearing parts should be kept ready for timely replacement.

YG Machinery specializes in making drilling mud pumps and oil drilling rig components with over 20 years of experience. We have different types of pumps for sale, corresponding to different pressures and flow rates. You can choose the most suitable one according to your needs. If you want to get the machine price or learn more about pumps, feel free to contact us, you will get the latest quote and receive a reply asap.

Whether onshore or offshore, well drilling sites rely on a multitude of systems to successfully perform the drilling operation. The mud pump is a key component tasked with circulating drilling fluid under high pressure downhole. The mud pump can be divided into two key sections: the power end or crosshead and the fluid end. Proper alignment of the pump’s crosshead to the fluid end liner is necessary to maximizing piston and liner life. Misalignment contributes to

accelerated wear on both the piston and the liner, and replacing these components requires downtime of the pump. Traditional methods of inspecting alignment range from using uncalibrated wooden rods, Faro Arms and micrometers to check the vertical and horizontal alignment of the piston rod OD to the piston liner ID. These are time consuming and cumbersome techniques that are ultimately not well suited to troubleshoot and solve alignment issues.

A “Mud Pump Laser Alignment Kit” enables you to measure where the piston will run through the liner at various positions along the pump’s stroke. It will also project a laser centerline from the fluid end back towards the rear power end of the pump that can be used to determine how much shimming is required to correct any alignment issues. The kit can include either a 2-Axis receiver or a 4-Axis which accepts the laser beam and documents where it falls on the active surface of the receiver. The 4-Axis receiver can decrease alignment time by as much as 50% as it will measure angularity as well as X and Y while the 2-Axis does not and will need multiple measurement locations to get the same information. In addition, the alignment system is a non-intrusive service requiring the removal of only the piston rod which allows for much quicker service and less down time on the pump. As the mud pumps in question are located globally both on and offshore, having a small, portable system is another great advantage. Our recommendation would be Pinpoint laser System’s “Mud Pump Alignment Kit”. They are being used by many of the leading repair service companies and have been their main alignment tool for over 15 years. Manufacturers are also utilizing these for new pump set-up.

This invention relates to apparatus useful in connection with the drilling of wells, such as oil wells, wherein a mud pump is used to circulate drilling mud under pressure through a drill string, down to and around the drill bit and out the annulus of the bore hole of the well to a mud reservoir; the apparatus of the present invention being useful for simultaneously degassing drilling mud and supercharging the mud pump.

In the drilling of deep wells, such as oil wells, it is common practice to penetrate the earth with a drill bit supported on a drill string in the bore of the well being drilled. In order to lubricate the drill bit, protect the well against blowouts, etc., it is conventional practice to circulate mud under pressure through the drill string down to and around the drill bit and up the annulus between the drill string and the bore of the well. Mud flowing from the well is passed through a suitable device such as a shaker, etc., in order to remove drill cuttings, etc., and is then delivered to a mud reservoir, such as a mud tank, for recirculation to the mud pump for pressured injection into the well.

It is also conventional practice to use a mud pump, such as a duplex or triplex mud pump comprising reciprocating pistons mounted in cylinders for pressuring the incoming drilling mud and delivering it to the well bore under pressure. The operation and construction of mud pumps is well known to those of ordinary skill in the art, as illustrated, for example, by the textbook "Mud Pump Handbook" by Samuel L. Collier (Gulf Publishing Company, Houston, Tex., 1983).

It is known, as explained in the Collier handbook, that the efficiency of a mud pump can be significantly improved by supercharging the pump; that is, by delivering drilling mud under pressure to the mud pump inlet to the cylinders containing the reciprocating pumping pistons.

It is also known to remove occluded gasses such as air, methane, etc., from drilling mud before it is delivered to the mud pump as illustrated, for example, by Burgess U.S. Pat. No. 3,973,930, Burgess U.S. Pat. No. 3,999,965 and Burgess U.S. Pat. No. 4,084,946.

Other drilling mud degassing devices are known to the art, such as those disclosed in Phillips et al. U.S. Pat. No. 4,088,457, Brown et al. U.S. Pat. No. 4,113,452, Egbert U.S. Pat. No. 4,365,977, Gowan et al. U.S. Pat. No. 4,397,659, etc.

Mud pumps used for delivering drilling mud under pressure to the bore hole of a well are conventionally of the type wherein a reciprocating piston in a cylinder is used to pressure drilling mud delivered to the cylinder for delivery to the well bore. Normally, two or three such cylinders are used, such pumps being conventionally referred to as duplex and triplex pumps. During each stroke of the piston, the piston is initially accelerated by an appropriate drive means, such as a crank shaft, from a starting position to a midcylinder position, and then decelerated to a final position within the cylinder. This constantly changing rate of motion of a reciprocating piston can result in knocking, cavitation, etc., all of which impair the efficiency of the pump. It is known to use centrifugal pumps, commonly known as superchargers, in order to deliver drilling mud to the inlet of the cylinder under pressure in order to alleviate such problems and improve the efficiency of operation of the pump.

It is undesirable to recirculate drilling mud containing occluded gases to a well bore, and therefore it is common practice to remove a significant portion of occluded gas from the drilling mud before it is recirculated to the mud pump. Normally, separate pieces of equipment that operate independently of each other are used for supercharging the mud pump and for degassing the drilling mud.

It has been discovered in accordance with the present invention that a drilling mud degasser of the type disclosed in the Burgess patents can be modified to simultaneously degas drilling mud and to supercharge the mud pump to which the degassed mud is to be delivered.

This is accomplished in accordance with the present invention through the provision of a device for simultaneously supercharging a mud pump having pistons reciprocably mounted in cylinders while degassing drilling mud to be delivered to said pistons comprising:

vacuum chamber means for continuously accelerating and centrifuging drilling mud under vacuum to thereby substantially completely remove occluded gas from the drilling mud,

a first conduit interconnecting said vacuum chamber with a drilling mud reservoir for delivering drilling mud to be degassed to said vacuum chamber means,

a first valve controlled branch conduit interconnecting said second conduit with said drilling mud reservoir for delivering drilling mud to said drilling mud reservoir when the pressure in said second conduit exceeds a predetermined value, and

a second branch conduit containing normally closed flow control means interconnecting said second conduit with said first conduit and said drilling mud reservoir operable on loss of pressure in said second conduit to permit flow of drilling mud directly from said drilling mud reservoir to said second conduit.

Referring now to the drawing, there is shown a supercharging drilling mud degasser 10 of the present invention which comprises a degassing chamber designated generally by the number 12, a power source such as an electric powered motor or a hydraulically powered motor designated generally by the number 14, a vacuum blower such as a regenerative vacuum blower, designated generally by the number 16, a gear box designated generally by the number 18, an evacuation pump designated generally by the number 20 and a drilling mud chamber designated generally by the number 22.

In accordance with this construction, there is provided a drilling mud degasser of the type shown in Burgess U.S. Pat. No. 4,084,946, housed in a cylindrical pressure vessel 24. The motor 14 is supported on vacuum blower 16 which, in turn, is supported by vacuum motor support 26 and vacuum blower brackets 28. To facilitate movement of the degasser 10, motor handling brackets 30 may be provided on the top of the motor 14 to which the hook of a crane or other appropriate means (not shown) may be attached.

Drilling mud pump impeller 42 is fixed to the centrifuge tube 40 for rotation therewith within the housing 46 of drilling mud evacuation pump 20. Cross braces 48 mounted in the cylindrical vessel 24 support lower stops 50 and upper stops 52 for an annular float 56 that surrounds the slots of the centrifuge tube 40 and partially closes them, such that the free area of the slots will be determined by the relative position of the annular float 56.

A drilling mud inlet 60 is connected to the bottom of the housing 46 for the evacuation pump 20 for the delivery of degassed drilling mud thereto. Drilling mud is delivered to the slotted centrifuge tube 40 by an inlet conduit 62 which preferably terminates inside the housing 46 for the evacuation pump 20. The top of the inlet line 62 is spaced from the bottom of the slotted centrifuge tube 40 so that the rotating centrifuge tube 40 can rotate freely without bearing upon the top of the inlet line 62. The resultant "controlled seepage" of fluid from the inlet tube 62 into the evacuation pump 20 provides a low pressure area for high effeciency scanvenging of occluded gases. Also, there is no need for bearings and seals at the bottom of the slotted centrifuge tube 40.

With this construction there is also provided an outlet line or conduit 66 connected with the discharge side of the evacuation pump 20 and extending through the wall of the cylinder 24 for connection with a suitable first conduit 68 leading, for example, to a triplex pump 70 for injecting drilling mud under pressure into a well penetrating a subterranean formation in order to lubricate the drill bit, protect the well against blow outs, etc., it is conventional practice to circulate mud under pressure through the drill string down to and around the drill bit and up the annulus beteen the drill string and the bore of the well. Mud flowing from the well is passed through a suitable device such as a shaker, etc. (not shown) in order to remove drill cuttings, etc., and is then delivered to a mud reservoir, such as a mud tank 84, for recirculation to the mud pump 70 in the manner described herein for pressured injection into the well.

The first conduit 68 may comprise, for example, a connecting pipe 72 interconnecting the outlet line 66 with the flexible hose 74 which, in turn, is connected to a mud pump inlet line 76. The flexible hose 74, which is provided for ease in alignment, may be secured to the connecting pipe 72 by a clamp 78 of any suitable construction and to the mud pump inlet line 76 by a clamp 80 of any suitable construction.

A second conduit 82 interconnects a drilling mud reservoir such as a mud tank 84 with the inlet conduit 62 leading to the slotted centrifuge tube 40 for the degasser 10.

Preferably, the second conduit 82 is provided with valve means such as a butterfly valve 86 which may be used to close the second conduit 82 when both the drilling mud degasser 10 and the mud pump 70 are to be idled for any appreciable time.

A first branch conduit 88 interconnects the first conduit 68 with the mud tank 84 and contains pressure sensitive control means such as a spring biased relief valve 90 in order to permit drilling mud to recycle from the first conduit 68 to the mud tank 84 when the pressure in the first conduit 68 exceeds a predetermined value.

A second branch conduit 92 interconnects the first conduit 68 with the inlet conduit 62 and the second conduit 82. The second branch conduit 92 contains normally closed flow control means such as a check valve 94 to permit flow of drilling mud directly from the mud tank 84 to the mud pump 70 if the pressure in the first conduit 68 falls below a predetermined value.

During drilling operations, rotation of an appropriate vacuum blower such as a regenerative vacuum blower by the drive shaft 32 for the motor 14 will generate a vacuum in the degassing chamber 12 such that drilling mud sprayed from the slots in the centrifuge tube 40 will tend to impact upon the inner sides of the degassing chamber 12 thereby initiating degassing of the drilling mud fed through the inlet line 62. Rotation of the centrifuge tube 40 will impart upward accelerating rotary motion to partially degassed drilling mud delivered thereto through the line 62 and the resultant spraying of the thus centrifuged drilling mud through the slots in the centrifuge tube 40 will result in a sheet of drilling mud being sprayed onto and impacting on the inner walls of the degassing chamber 12 to thus substantially complete the removal of gas from the drilling mud. The thus degassed drilling mud will flow downwardly past cross braces 48 and into inlet 60 leading through the housing 46 of the evacuation pump 20 where the impeller 42 will repressure the now degassed drilling mud for discharge through the outlet line 66 which is interconnected with a triplex pump 70 by first conduit 68 for supercharging the pump 70, which further pressures the degassed drilling mud for injection into a well bore penetrating a subterranean formation.

In order to prevent the entrainment of drilling mud droplets in the gases withdrawn through the gas evacuation suction pipe 98, a splatter plate 100 is provided in the degassing chamber 12 and a combination of a foam separation impeller 36 with a splatter disk 102 is provided adjacent the top of the degassing chamber 12 so that gas liberated in the vacuum chamber must follow a sinuous path arriving at the upper chamber gas evacuation suction pipe 98.

In accordance with the present invention, the motor 14 is operated such that drilling mud delivered to the first conduit 68 will be at a predetermined appropriate supercharging pressure for the mud pump 70, (e.g. a pressure of about 20 to 30 psig).

The pressure sensitive control means, such as a spring biased relief valve 90, is set to open at a predetermined pressure about 5 to 10 psi higher than the desired pressure in the first conduit 68 so that, if the indicated pressure limit is exceeded, the pressure relief valve 90 will open in order to permit drilling mud to recycle to the mud tank 84.

This will happen if the mud pump 70 malfunctions and also when the mud pump 70 is turned off, as will happen from time to time. For example, it is necessary to turn off the mud pump 70 during drilling operations when a new stand of drill pipe is to be added to the drill string. It is also necessary to turn off the mud pump 70 when the drill string is being withdrawn from the well bore in order to replace the drill bit, while well logging operations are in progress, if it is necessary to "fish" for a piece of equipment lost down the hole, etc. However, if the drilling mud in the mud tank 84 is permitted to remain quiescent for more than a limited period of time, the drilling mud may start to gel and/or to stratify. This problem is conventionally avoided by providing a separate agitator (not shown) for the mud tank 84 in order to stir the drilling mud when the mud pump 70 is idle. However, through the provision of the present invention, there is no need for a separate agitator for the mud tank 84 because recirculation of drilling mud through the first branch conduit 88 will impart a "roiling" motion or agitation to the drilling mud in mud tank 84 to inhibit gelling and/or stratification of the drilling mud while the mud pump 70 is idle.

Loss of pressure in the first conduit 68 can occur in the event of malfunction of the degasser 10 or in the event it is desired to shut the degasser 10 down for a limited period of time. In this event, drilling mud flows directly from the mud tank 84 through the second conduit 82, the second branch conduit 92 and the flexible hose 74 to the mud pump 70 so that the mud pum 70 is not "starved" for drilling mud to be injected into the well.

Historically, centrifugal pumps have usually been designed with packing seals. Packing seals are packed with a lubricated fibrous material that came into direct contact with the shaft, so flush water is necessary to cool and lubricate the shaft. Flush water has to be directed away from the process to prevent contamination, and care has to be taken to protect the bearing box from flush water that contaminates the oil, as well as to prevent the safety problem of water pooling on the floor.

Mechanical seals may have a higher initial cost, but they often save a great deal of operational cost depending on how much flush water a packing seal pump consumes.

Many industrial processes still use a packing seal for positive displacement pump applications. Packing seals, which are designed to allow some controlled leakage, can be a reliable method of preventing excessive leaks. However, stricter standards in industries like food processing are reducing the amount of acceptable leakage.