drilling rig mud pump knocking sound free sample

Cavitation is an undesirable condition that reduces pump efficiency and leads to excessive wear and damage to pump components. Factors that can contribute to cavitation, such as fluid velocity and pressure, can sometimes be attributed to an inadequate mud system design and/or the diminishing performance of the mud pump’s feed system.

When a mud pump has entered full cavitation, rig crews and field service technicians will see the equipment shaking and hear the pump “knocking,” which typically sounds like marbles and stones being thrown around inside the equipment. However, the process of cavitation starts long before audible signs reveal themselves – hence the name “the silent killer.”

Mild cavitation begins to occur when the mud pump is starved for fluid. While the pump itself may not be making noise, damage is still being done to the internal components of the fluid end. In the early stages, cavitation can damage a pump’s module, piston and valve assembly.

The imperceptible but intense shock waves generated by cavitation travel directly from the fluid end to the pump’s power end, causing premature vibrational damage to the crosshead slides. The vibrations are then passed onto the shaft, bull gear and into the main bearings.

If not corrected, the vibrations caused by cavitation will work their way directly to critical power end components, which will result in the premature failure of the mud pump. A busted mud pump means expensive downtime and repair costs.

Washouts are one of the leading causes of module failure and take place when the high-pressure fluid cuts through the module’s surface and damages a sealing surface. These unexpected failures are expensive and can lead to a minimum of eight hours of rig downtime for module replacement.

To stop cavitation before it starts, install and tune high-speed pressure sensors on the mud suction line set to sound an alarm if the pressure falls below 30 psi.

Although the pump may not be knocking loudly when cavitation first presents, regular inspections by a properly trained field technician may be able to detect moderate vibrations and slight knocking sounds.

Gardner Denver offers Pump University, a mobile classroom that travels to facilities and/or drilling rigs and trains rig crews on best practices for pumping equipment maintenance.

Severe cavitation will drastically decrease module life and will eventually lead to catastrophic pump failure. Along with downtime and repair costs, the failure of the drilling pump can also cause damage to the suction and discharge piping.

When a mud pump has entered full cavitation, rig crews and field service technicians will see the equipment shaking and hear the pump ‘knocking’… However, the process of cavitation starts long before audible signs reveal themselves – hence the name ‘the silent killer.’In 2017, a leading North American drilling contractor was encountering chronic mud system issues on multiple rigs. The contractor engaged in more than 25 premature module washes in one year and suffered a major power-end failure.

Gardner Denver’s engineering team spent time on the contractor’s rigs, observing the pumps during operation and surveying the mud system’s design and configuration.

The engineering team discovered that the suction systems were undersized, feed lines were too small and there was no dampening on the suction side of the pump.

Following the implementation of these recommendations, the contractor saw significant performance improvements from the drilling pumps. Consumables life was extended significantly, and module washes were reduced by nearly 85%.

Although pump age does not affect its susceptibility to cavitation, the age of the rig can. An older rig’s mud systems may not be equipped for the way pumps are run today – at maximum horsepower.

It may be impractical to flush system piping during drilling operations. However, strainer screens should be checked daily to remove any debris or other flow restrictions.

Measurement While Drilling tool is used to get realtime downhole data while drilling and used to make correct decision as soon as possible. The key to get realtime data is to decode the transmitted MWD signal on surface. Unable to decode transmitted signal may lead to loss of money, or even safety issue.

This article will focus on understanding of MWD signal decoding which is transmitted via mud pulse telemetry since this method of transmission is the most widely used commercially in the world.

As a basic idea, one must know that transmitted MWD signal is a wave that travels through a medium. In this case, the medium is mud column inside the drill string to mud pumps. Decoding is about detecting the travelling wave and convert it into data stream to be presented as numerical or graphical display.

The signal is produced by downhole transmitter in the form of positive pulse or negative pulse. It travels up hole through mud channel and received on the surface by pressure sensor. From this sensor, electrical signal is passed to surface computer via electrical cable.

On the way the signal leaves the transmitter, it experiences lots of disturbances that make the original signal distorted to various level, from minor distortion to severe distortion which makes decoding impossible. These disturbances are called noises.

Noise sources are bit, drill string vibration, bottom hole assemblies, signal reflection and mud pumps. Other than the noises, the signal is also dampened by the mud which make the signal becomes weak at the time it reaches the pressure sensor. Depth also weaken the signal strength, the deeper the depth, the weaker the signal detected.

Rock bit may create tri-lobe pattern. This pattern is created by the cones of the bit on the bottom of the hole. While drilling, the bit’s cones ride along this tri-lobe pattern and makes the bit bounce or known as axial vibration. As the bit bounces, back pressure is produced at the bit nozzles and transmitted to surface. The frequency of the noise created by bit bounce correlates with bit RPM. The formula to calculate its frequency is 3*(bit RPM)/60. When the bit bounce frequency match with MWD signal frequency, decoding is affected.

BHA components that have moving mechanical parts such as positive mud motor and agitator create noise at certain frequency. The frequency produced by these assemblies depends on the flow rate and the lobe configuration. The higher the flow rate and the higher the lobe configuration creates higher noise frequency.

Thruster, normally made up above MWD tool, tends to dampen the MWD signal significantly. It has a nozzle to use mud hydraulic power to push its spline mandrel – and then push the BHA components beneath it including the bit – against bottom of the hole. When the MWD signal is passing through the nozzle, the signal loses some of its energy. Weaker signal will then be detected on surface.

When the wave hits a solid surface like a pipe bend or a closed valve the wave will be reflected backward against the direction of original MWD signal as described in figure 2 below.

The pressure sensor on the pipe manifold detects 2 identical signals, one from the original MWD transmitter and another one comes from signal reflection, which are separated in some milliseconds. The result seen by the surface computer is the sum of those two signals. Depending on the individual signal width and the timing when the reflected signal arrives at the pressure sensor, surface computer may see a wider signal width or two identical signals adjacent to each other.

The common sources of signal reflection are pipe bending, change in pipe inner diameter or closed valve. These are easily found in pipe manifold on the rig floor. To avoid the signal reflection problem, the pressure sensor must be mounted in a free reflection source area, for example close to mud pumps. The most effective way to solve this problem is using dual pressure sensors method.

Mud pump is positive displacement pump. It uses pistons in triplex or duplex configuration. As the piston pushes the mud out of pump, pressure spikes created. When the piston retracts, the pressure back to idle. The back and forth action of pistons produce pressure fluctuation at the pump outlet.

Pressure fluctuation is dampened by a dampener which is located at the pump outlet. It is a big rounded metal filled with nitrogen gas and separated by a membrane from the mud output. When the piston pushes the mud the nitrogen gas in the dampener will be compressed storing the pressure energy; and when the piston retracts the compressed nitrogen gas in the dampener release the stored energy. So that the output pressure will be stable – no pressure fluctuation.

The dampener needs to be charged by adding nitrogen gas to certain pressure. If the nitrogen pressure is not at the right pressure, either too high or too low, the pump output pressure fluctuation will not be stabilized. This pressure fluctuation may match the MWD frequency signal and hence it disturbs decoding, it is called pump noise.

When the pump noise occurs, one may simply change the flow rate (stroke rate) so that the pump noise frequency fall outside the MWD frequency band – and then apply band pass frequency to the decoder.

The formula to calculate pump noise frequency is 3*(pump stroke rate)/60 for triplex pump and 2*(pump stroke rate)/60 for duplex pump. The rule of thumb to set up dampener pressure charge is a third (1/3) of the working standpipe pressure.

Sometime the MWD signal is not detected at all when making surface test although the MWD tool is working perfectly. This happen whenever the stand pipe pressure is the same with the pump dampener pressure. Reducing or increasing test flow rate to reduce or increase stand pipe pressure helps to overcome the problem.

When the MWD signal wave travels through mud as the transmission medium, the wave loses its energy. In other words, the wave is giving some energy to the mud.

The mud properties that are affecting MWD signal transmission is viscosity and weight. The increasing mud weight means there is more solid material or heavier material in the mud. Sometimes the mud weight increment is directly affecting mud viscosity to become higher. The MWD signal wave interacts with those materials and thus its energy is reduced on its way to surface. The more viscous the mud and the heavier the mud, the weaker the signal detected on surface.

Aerated mud often used in underbalance drilling to keep mud influx into the formation as low as possible. The gas injected into the mud acts as signal dampener as gas bubble is compressible. MWD signal suffers severely in this type of mud.

Proper planning before setting the MWD pulser gap, flow rate and pump dampener pressure based on mud properties information is the key to overcome weak signal.

The further the signal travels, the weaker the signal detected on the surface. The amount of detected signal weakness ratio compare to the original signal strength when it is created at the pulser depends on many factors, for example, mud properties, BHA component, temperature and surface equipment settings.

Rigging up sensor cables especially on the offshore rig is challenging since the cables must not create safety hazard to other people and equipment’s. Most of the time the cables must be run alongside rig’s high voltage electrical cables. The high voltage may induce sensor cables which creates continuous or temporal spiky signal in the surface decoder.

Long-term exposure to hazardous noise can result in permanent hearing loss. Oil and gas workers are often exposed to harmful noise levels on the job. According to WorkSafeBC1, noise sources can include:Mud pumps and tanks

The first line of defense against excessive noise exposure is to reduce or eliminate the risks with engineering and administrative controls, such as: using low-noise tools and machinery as well as barriers such as sound walls or curtains; operating noisy equipment when fewer people are exposed; limiting time spent at a noise source; providing quiet areas; and restricting worker proximity to noise sources.

Confined spaces are common in the oil and gas industry. Workers are often required to enter confined spaces such as petroleum and other storage tanks, mud pits, reserve pits and other excavated areas, sand storage containers, and other confined spaces around a wellhead. Safety hazards associated with confined spaces include ignition of flammable vapors or gases. Health hazards include asphyxiation and exposure to hazardous chemicals. Confined spaces that contain or have the potential to contain a serious atmospheric hazard must be classified as permit-required confined spaces, tested prior to entry, and continuously monitored, OSHA says.

There are many respiratory threats in the oil and gas industry, including exposure to hydrogen sulfide, drilling fluids and mercury vapor. This section focuses specifically on silica.

Workers in the oil and gas industry might be required to access platforms and equipment located high above the ground. OSHA requires fall protection to prevent falls from the mast, drilling platform, and other elevated equipment. Other fall hazards include:Uneven working surfaces

Long-term exposure to hazardous noise can result in permanent hearing loss. Oil and gas workers are often exposed to harmful noise levels on the job. According to WorkSafeBC1, noise sources can include:Mud pumps and tanks

The first line of defense against excessive noise exposure is to reduce or eliminate the risks with engineering and administrative controls, such as: using low-noise tools and machinery as well as barriers such as sound walls or curtains; operating noisy equipment when fewer people are exposed; limiting time spent at a noise source; providing quiet areas; and restricting worker proximity to noise sources.

Confined spaces are common in the oil and gas industry. Workers are often required to enter confined spaces such as petroleum and other storage tanks, mud pits, reserve pits and other excavated areas, sand storage containers, and other confined spaces around a wellhead. Safety hazards associated with confined spaces include ignition of flammable vapors or gases. Health hazards include asphyxiation and exposure to hazardous chemicals. Confined spaces that contain or have the potential to contain a serious atmospheric hazard must be classified as permit-required confined spaces, tested prior to entry, and continuously monitored, OSHA says.

There are many respiratory threats in the oil and gas industry, including exposure to hydrogen sulfide, drilling fluids and mercury vapor. This section focuses specifically on silica.

Workers in the oil and gas industry might be required to access platforms and equipment located high above the ground. OSHA requires fall protection to prevent falls from the mast, drilling platform, and other elevated equipment. Other fall hazards include:Uneven working surfaces

Insufficient NPSH AvailableSuction pressure is incorrect meaning pump is cavitating. Ensure all valves are open, check liquid temperature. To correct increase fluid in tank, check for air ingress, remove unnecessary bends, increase pipe diameter, install feed pump.

Ensure all valves are open, check liquid temperature. To correct increase fluid in tank, check for air ingress, remove unnecessary bends, increase pipe diameter, reduce fluid temperature, install feed pump.

PulsationSuction pressure is incorrect meaning pump is cavitating. Ensure all valves are open, check liquid temperature. To correct increase fluid in tank, check for air ingress, remove unnecessary bends, increase pipe diameter, reduce fluid temperature, install feed pump.

Inlet pressure too HighMaximum inlet pressure for piston pumps is 40psi (2.75 bar) and plunger pumps is 60-70psi (4-4.8bar). K Style pumps can accept higher inlet pressures.

Pump Dry RunningCheck Fluid level and that NPSHR is being met. Check inlet pipework, and filters for blockage, long suction lines, and presence of air ingress

Water in CrankcaseSpraying / Air CondensationProtect pump from direct spray with ventilated enclosure if necessary. Contaminated oil will damage bearings and other components within the drive.

Worn AdaptorSplit manifold designs of pumps have adapters within the pumps. Check O rings when servicing seals and valves and replace as required.

Manifold Wear / DamageCheck chemical compatibility of fluid and any cleaning fluids used. Operation with worn seals and o rings can accelerate manifold wear. Erosion can be limited by freshwater flushing between pump use.

Manifolds can be damaged by over pressure which may be caused by high inlet pressure, relief valve or regulating valve failure or blockage within pump.

Owners praise their Geoprobe® 3230DT drill rig for their ability to compete for geotechnical projects while expanding their  environmental work. With numerous features and configurations for success, crews rely on the 3230DT combination drill rig for its power and precision.

TRANSITIONS: work the inside diameter of the rod without moving the drill mast thanks to head travel along center. Conveniently transition from driving casing via direct push to wet rotary drilling ... in less than five minutes. Hold or pull rods, casings, or augers while maintaining an open tool string using the patented hydraulic head clamp, which easily manages the 80,000 lb. of pullback.

TAILORED: customize site setup by positioning the telescoping winch mast as well as the height and angle of the adjustable swing-arm control panel, steering clear of spinning tool strings or positioning comfortably close to align rods. Precisely dial in speeds, feeds, and pumps with the intuitive electronic controls. Equip the rig for your region, requirements, and desired utilization rates with the many standard ‘in demand’ features and an ever-growing list of options.

Withdrill rig service shops in Pennsylvania, Florida, and Kansas, you’ll have industry-leading drill rig service support nearby for your routine maintenance or more in-depth drill rig remounting and refurbishment work. Our service technicians are backed by our team of engineers to ensure solutions not bandaids to issues. And our production processes mean your drill rig is constructed consistently and tested thoroughly to ensure easier service support.

Completing the CB Combo Head is our built-in patented hydraulic head clamp, allowing users to safely and quickly hold or pull rods, casings, or augers while maintaining an open tool string. It easily manages the 80,000 lb. of pullback from the drill mast. Additionally, the combo head has functionality for direct push / percussion, mud rotary, air rotary, and rock coring.

After running this rig for a short time, you’ll be impressed with how easy and conveniently the 3230DT transitions from driving casing via direct push to wet rotary drilling ... in less than five minutes. The patented CB Combo Head, designed and built exclusively by Geoprobe®, allows you to do direct push hammering for sampling and monitoring well installation.

The rotation function of the head allows for different drilling techniques, such as air rotary, wet rotary, overburden rotary systems, augering, and rock coring. The rotation function handles the full 80,000 lbf of pullback required for a machine of this magnitude. And with the integrated hydraulic head clamp, you can easily hold or pull rods, casings, or augers while maintaining an open top tool string.

The adjustable swing-arm control panel with intuitive layout allows the operator to perform multiple tasks effortlessly. Speeds, feeds, and pumps can be precisely dialed in with the electronic controls. The control panel’s ability to swing freely from the rig lets the operator be in the position needed to help align a rod or to be at a comfortable distance away from a spinning drill string. Even controls to side-shift the Combo Head and reposition the Automatic Drop Hammer are at the operator’s fingertips.

Integrated Electronic Diagnostic System: An integrated Systems Display on the control panel provides real-time systems analysis and a suite of built-in diagnostic tools.  Also included are system safeguards that protect the main engine and hydraulic components when important operational parameters are compromised.  It’s all there to assist the rig operator.

Integrated Head Feed Pressure Controls (optional): Adding the head feed pressure control option for rotary drilling takes the strain off the operator by eliminating the need to manually adjust head feed rate.  Head feed pressure control provides consistent bit weight control for better penetration rates and longer bit life.  It also permits effective hands-free operation with the addition of an interlocked rotation guard.

If you’re using the Direct Push Hammer, you need to be able to pull casing back out of the ground. For that reason, engineers incorporated our patented hydraulic head clamp within the combo head to safely and quickly pull rods ranging from 1.25 to 6.0 in. OD while maintaining an open ID to speed up well installation. The built-in Head Clamp can handle the 80,000 lb. of the rig’s pullback.

All of the machine’s functions are at your fingertips on the control panel, including the hydraulic controls for positioning the side-shift function of the CB Combo Head. The combo head travels up to 24 inches to the left and 2 inches to the right from center so you can work the inside diameter of the rod without moving the drill mast. When using the drop hammer, it hydraulically swings into place for operation over the hole.

Optional front outriggers help keep the drill mast steady while drilling. With a 26-inch stroke, the drill mast can be left up while lowering the outriggers to have room for a mud pan, for using a breakout above the casing, or just to have extra room while augering.

Separate mud pump circuit eliminates the battle between drilling functions and fluid circulation for hydraulic flow and pressure, creating stable mud flow.

Some testing applications require that the tooling is pushed into the ground instead of hammered. To do this, the power of the machine"s probe cylinder is used to advance the rod string instead of energy from the hammer. To achieve any sort of depth, a suitable reaction force must be used to balance the pushing capacity of the rig. This means that you either need a really heavy rig or you need to anchor your machine.

The Geoprobe® 2060CPT is a 20 ton rated static push Cone Penetration Testing platform. The hydraulic push clamp and press advance the cone with up to 20 tons of downforce. When retracting the tool string, the 2060CPT has 30 tons of pullback. A hydraulic bottom clamp keeps rods from slipping back down hole when the push clamp is released during retrieval of the tool string. An optional 6712DT mast can be mounted on the porch end of the 2060CPT. This allows for coring, conventional soil sampling, shallow drilling for soil verification, and pre-drilling.

The Geoprobe® 3230DT combo rig has the ability to efficiently sample the subsurface using both direct push and rotary drilling techniques and then quickly transition to pushing CPT tooling. Anchors are installed using the CB combo head and the CPT system is automatically pushed at a rate of 2 cm / second using the same head. With the 3230DT, drillers have multiple drilling methods at their fingertips.

The Geoprobe® 7822DT is designed to easily switch between multiple sampling and logging methods, including pushing CPT tooling.  Anchors are installed with the augerhead to provide the reaction force needed for the up to 15 tons of push typical for this platform. Using an optional head feed control kit, automatic rate control provides cone advancement at the standard 2 cm per second. Switching between drilling tasks and pushing CPT is quick on the 7822DT and only takes a few additional components.

The 3100GT geotechnical drill rig can be setup for CPT by using a few simple anchoring components: a rod guide, anchor, and anchor bridge. Switching from geotechnical drilling to pushing CPT is a quick and simple process. Automatic head feed rate control advances the cone at a steady 2 centimeters per second specified by ASTM Standard D5778. This provides hands-free operation during advancement of each rod.