mud pump valve seat failure free sample

The positive displacement mud pump is a key component of the drilling process and its lifespan and reliability are critical to a successful operation.

The fluid end is the most easily damaged part of the mud pump. The pumping process occurs within the fluid end with valves, pistons, and liners. Because these components are high-wear items, many pumps are designed to allow quick replacement of these parts.

Due to the nature of its operation, pistons, liners, and valve assemblies will wear and are considered expendable components. There will be some corrosion and metallurgy imperfections, but the majority of pump failures can be traced back to poor maintenance, errors during the repair process, and pumping drilling fluid with excessive solids content.

A few signs include cut piston rubber, discoloration, pistons that are hard to remove, scored liners, valve and seat pitting or cracks, valve inserts severely worn, cracked, or completely missing, and even drilling fluids making their way to the power end of the pump.

The fluid end of a positive displacement triplex pump presents many opportunities for issues. The results of these issues in such a high-pressure system can mean expensive downtime on the pump itself and, possibly, the entire rig — not to mention the costly repair or replacement of the pump. To reduce severe vibration caused by the pumping process, many pumps incorporate both a suction and discharge pulsation dampener; these are connected to the suction and discharge manifolds of the fluid end. These dampeners reduce the cavitation effect on the entire pump which increases the life of everything within the pump.

Poor maintenance — such as improper valve and seat installation — is another factor. Improper cleaning when replacing a valve seat can leave sand or debris in the valve seat area; preventing the new seat from properly forming a seal with the fluid cylinder, causing a pathway for a washout to occur. It is important to pull up on a seat firmly by hand and make sure it doesn’t pop out and is properly seated. The seats must be seated well, before resuming repairs. You should never reuse a valve seat if at all possible.

The fluid end is the most easily damaged part of the mud pump. The pumping process occurs within the fluid end with valves, pistons, and liners. Because these components are high-wear items, many pumps are designed to allow quick replacement of these parts.

A washout occurs when fluid and solids enter the area behind or underneath a valve seat and erode the sealing surface. Washouts are usually caused by one of three issues: a worn or cracked valve seat, improper cleaning of the valve seat and deck which creates a poor seat seal, and excessive sand content in your drilling fluid. Worn or cracked valve seats can allow fluid to enter the area around the valve seat and seat deck, creating a wash point on the valve seat and causing it to cut into the fluid cylinder and seat deck.

Additionally, the throat (inside diameter) can begin to wash out from extended usage hours or rather quickly when the fluid solids content is excessive. When this happens it can cut all the way through the seat and into the fluid end module/seat deck. This causes excessive expense not only from a parts standpoint but also extended downtime for parts delivery and labor hours to remove and replace the fluid module. With that said, a properly operated and maintained mud recycling system is vital to not only the pump but everything the drilling fluid comes in contact with downstream.

abstractNote = {Failure of a liner seal is one of the more critical failures on a mud pump because this seal interfaces with the pump body. Therefore, failures, usually damage the pump body, leading to repair or replacement of the fluid end itself. One of the more common liner seal problems involves counter-bore-type seals. This type of seal is easily affected by two aspects of the problem that are found in the mud pump fluid end-wear and foreign matter in the seal groove. Factors relative to difficult liner removal are discussed. Piston damage, careless seal installation and corrosion damage are also examined.},

My first days as an MWD field tech I heard horror stories surrounding what is commonly referred to as “pump noise”. I quickly identified the importance of learning to properly identify this “noise”. From the way it was explained to me, this skill might prevent the company you work from losing a job with an exploration company, satisfy your supervisor or even allow you to become regarded as hero within your organization if you’ve proven yourself handy at this skill.

“Pump noise” is a reference to an instability in surface pressure created by the mud pumps on a modern drilling rig, often conflated with any pressure fluctuation at a similar frequency to pulses generated by a mud pulser, but caused by a source external to the mud pulser. This change in pressure is what stands in the way of the decoder properly understanding what the MWD tool is trying to communicate. For the better part of the first year of learning my role I wrongly assumed that all “noise” would be something audible to the human ear, but this is rarely the case.

In an ideal drilling environment surface pressure will remain steady and all pressure increases, and decreases will be gradual. This way, when the pulser valve closes(pulses), it’s easily detectable on surface by computers. Unfortunately drilling environments are rarely perfect and there are many things that can emulate a pulse thus causing poor or inaccurate data delivery to surface. The unfortunate circumstance of this means drilling operations must come to halt until data can once again be decoded on surface. This pause in the drilling process is commonly referred to at NPT or non-productive time. For those of you unfamiliar these concepts, I’ll explain some of the basics.

A mud pulser is a valve that briefly inhibits flow of drilling fluid traveling through the drill string, creating a sharp rise and fall of pressure seen on surface, also known as a “pulse”.

Depending on if the drilling fluid is being circulated in closed or open loop, it will be drawn from a tank or a plastic lined reservoir by a series(or one) mud pumps and channeled into the stand pipe, which runs up the derrick to the Kelly-hose, through the saver sub and down the drill-pipe(drill-string). Through the filter screen past an agitator or exciter, around the MWD tool, through a mud motor and out of the nozzles in the bit. At this point the fluid begins it’s journey back to the drilling rig through the annulus, past the BOP then out of the flow line and either over the shale shakers and/or back in the fluid reservoir.

Developing a firm grasp on these fundamentals were instrumental in my success as a field technician and an effective troubleshooter. As you can tell, there are a lot of components involved in this conduit which a mud pulser telemeters through. The way in which many of these components interact with the drilling fluid can suddenly change in ways that slightly create sharp changes in pressure, often referred to as “noise”. This “noise” creates difficulty for the decoder by suddenly reducing or increasing pressure in a manner that the decoder interprets a pulse. To isolate these issues, you must first acknowledge potential of their existence. I will give few examples of some of these instances below:

Suction screens on intake hoses will occasionally be too large, fail or become unfastened thus allowing large debris in the mud system. Depending on the size of debris and a little bit of luck it can end up in an area that will inhibit flow, circumstantially resulting in a sudden fluctuation of pressure.

Any solid form of drilling fluid additive, if improperly or inconsistently mixed, can restrict the flow path of the fluid resulting in pressure increase. Most notably this can happen at the pulser valve itself, but it is not the only possible outcome. Several other parts of this system can be affected as well. LCM or loss of circulation material is by far the most common additive, but the least overlooked. It’s important for an MWD technician to be aware of what’s being added into the drilling fluid regardless if LCM isn’t present. Through the years I have seen serval other improperly mixed additives cause a litany of pressure related issues.

This specifically is a term used to refer to the mud motor stator rubber deterioration, tearing into small pieces and passing through the nozzles of the bit. Brief spikes in pressure as chunks of rubber pass through one or more nozzles of the bit can often be wrongly interpreted as pulses.

Sometimes when mud is displaced or a pump suction isn’t completely submerged, tiny air bubbles are introduced into the drilling fluid. Being that air compresses and fluid does not, pulses can be significantly diminished and sometimes non-existent.

As many of you know the downhole mud motor is what enables most drilling rigs to steer a well to a targeted location. The motor generates bit RPM by converting fluid velocity to rotor/bit RPM, otherwise known as hydraulic horsepower. Anything downhole that interacts with the bit will inevitably affect surface pressure. One of the most common is bit weight. As bit weight is increased, so does surface pressure. It’s important to note that consistent weight tends to be helpful to the decoder by increasing the amplitude of pulses, but inconsistent bit weight, depending on frequency of change, can negatively affect decoding. Bit bounce, bit bite and inconsistent weight transfer can all cause pressure oscillation resulting in poor decoding. Improper bit speed or bit type relative to a given formation are other examples of possible culprits as well.

Over time mud pump components wear to the point failure. Pump pistons(swabs), liners, valves and valve seats are all necessary components for generating stable pressure. These are the moving parts on the fluid side of the pump and the most frequent point of failure. Another possible culprit but less common is an inadequately charged pulsation dampener. Deteriorating rubber hoses anywhere in the fluid path, from the mud pump to the saver sub, such as a kelly-hose, can cause an occasional pressure oscillation.

If I could change one thing about today’s directional drilling industry, it would be eliminating the term “pump noise”. The misleading term alone has caused confusion for countless people working on a drilling rig. On the other hand, I’m happy to have learned these lessons the hard way because they seem engrained into my memory. As technology improves, so does the opportunities for MWD technology companies to provide useful solutions. Solutions to aid MWD service providers to properly isolate or overcome the challenges that lead to decoding issues. As an industry we have come a lot further from when I had started, but there is much left to be desired. I’m happy I can use my experiences by contributing to an organization capable of acknowledging and overcoming these obstacles through the development of new technology.

Not only can these failures be extremely costly to repair, but these catastrophic failures can be dangerous, especially when they occur on the road or at high speeds.

At this point, detrimental engine failure could be just a matter of time, turning a couple hundred dollar repair into one that could quickly cost thousands.

With frequent fuel filter clogging, fuel pump failure is often to follow. Because of the restriction caused by the clogged filters, the fuel pump could be working harder than designed to deliver fuel from the tank to the engine.

While a fuel pump is failing, the fuel pump will not be able to deliver a steady flow of fuel, interrupting the mechanical stroke and function of the engine. This can be especially noticeable under acceleration, where fuel demand is increased however the fuel pump is unable to deliver the fuel at the requested rate.

When a fuel pump is exerted to the point of failure, it is past the point of simple maintenance to get the engine running again. When a fuel pump fails, fuel line pressure is lost thus not being able to deliver any fuel for the engine to fire up. Downtime of equipment for major repair is expected at this point to get the fuel flowing properly again.

A major reason for engine inefficiency stems from the partial failure of an engine’s fuel injection system, something not well understood by a majority of people.

Partial functional injector failure isn’t a failure point that is well-documented in many industries, leaving a lapse in the understanding of the symptoms that come with this kind of failure.

Although the equipment is still operable, partial functional failure of a fuel injection system is generally one that reduces engine efficiency or performance. The symptoms of such failures within an injection system may include the following:

Any number of these factors can alter the engineered functionality of a fuel injector, leading to a snowball effect of internal engine damage that could eventually progress into full functional engine failure.

When catastrophic engine injector failures are experienced, the engine fails to continue operation due to these sudden occurrences. Typically, these experienced events can only be restored through costly repairs that often result in prolonged equipment downtime.

Operations and equipment managers rely on proper equipment functionality to maintain revenue margins and business profitability. It is for these reasons that attention should be directed at managing, predicting, and preventing these failures from occurring through proper equipment maintenance and operation.

Equipment specialists and OEMs typically operate their equipment around recommended maintenance procedures that are designed to limit component failure and prolong equipment life.

With the use of contaminated fuel, erosion of the injector valve seat is likely, resulting in a partial functional failure that will eventually lead to a full functional failure of the fuel injector valve.

Fuel injector nozzles are designed to spray a mist of fuel into the cylinder for piston compression and fuel combustion. These fuel nozzles primarily come in two designs: the SAC (area around pintel tip) nozzle and the VCO (valve-covered orifice) nozzle.

The VCO injection needle valves are known for having particularly fine tolerances and are extremely sensitive to partial failure during the rise and fall actions.

The rise and fall injection actions can occur dozens of times every second in a diesel engine. That is why injector tolerances are critically important in maintaining reliable operation and avoiding partial failures in the fuel injection function.

Typically, fuel injector nozzle holes are susceptible to two circumstances that can lead to injector failure. These two circumstances are blockages and erosions.

When injector tolerances have been compromised, fuel droplets from the injector nozzle may not be able to achieve complete combustion, often resulting in smoke and soot emissions. If the issue is not addressed, soot will build on the injector tips and eventually cause blockages. These blockages can also occur within the engine valves, cylinder walls, and exhaust system.

When these partial functional failures within the injector occur, it is perceived as best practice to use diesel fuel additives that are chemically designed to clean soot build-up from the fuel injectors.

There are two commonly used fuel injectors in modern engines, electronically controlled unit injectors (EUI) and high-pressure common rail injectors (HPCR). The needle valve in both of these fuel injection types is engineered to stop the fuel from running through the injector tip after the fuel injection action.

When a needle valve fails to properly seal, fuel will drip down into the engine cylinder and onto the piston(s). This dripping fuel can be the catalyst for severe engine problems and catastrophic failures.

In HPCR injection systems, the fuel injectors are continuously under sustained pressure while the engine is running. This leads to a higher likelihood of harm if a fuel injector’s needle valve fails.

The control valves in EUI injectors are controlled by an electronic solenoid. HPCR injectors are controlled with a Piezoelectric actuated valve. These Piezoelectric valves are often seen as the most critical injector component because they enable the injection system to have more control of the distance of valve movement and valve speed.

The Piezoelectric valves are especially sensitive to fuel contamination because it wears and damages the components and compromises the designed injection tolerances.

With prolonged exposure to contaminated fuel, contaminants can build up within the injector and result in lethargic movement of the needle valve. This causes wear on the valve, and eventually leads to partial, if not full, functional failure of the needle component within the fuel injector.

Fluid sampling pumps are often used to obtain fluid samples from hard-to-reach spots using flexible tubing. This allows for fluids to be drawn without the worry of cross-contamination, as the fluid never comes into contact with the pump.

Corrosion inhibitors in certain fuel additives prevent corrosion on metal surfaces, which prolong engine life and equipment operability. This reduces the amount of “surprise” equipment maintenance that is needed due to the failure of certain parts within an engine’s mechanical system.