mud pump condition monitoring in stock

We have done a lot of CM work on drilling rigs including Mud Pumps. Most drilling equipment tends to be rough and poorly mounted (when compared with production equipment).

We have had problems where CM engineers who are unfamiliar with Drilling rig conditions end up condemning every bit of equipment on the plant. I’m not saying they are wrong but we have to pragmatic as it’s not unusual to have mud pumps running in excess of 12mm/s (1 IPS).

The 2,200-hp mud pump for offshore applications is a single-acting reciprocating triplex mud pump designed for high fluid flow rates, even at low operating speeds, and with a long stroke design. These features reduce the number of load reversals in critical components and increase the life of fluid end parts.

The pump’s critical components are strategically placed to make maintenance and inspection far easier and safer. The two-piece, quick-release piston rod lets you remove the piston without disturbing the liner, minimizing downtime when you’re replacing fluid parts.

A comprehensive range of mud pumping, mixing, and processing equipment is designed to streamline many essential but time-consuming operational and maintenance procedures, improve operator safety and productivity, and reduce costly system downtime.

A mud pump is a reciprocating piston/plunger device designed to circulate drilling fluid under high pressure down the drill string and back up the annulus.

Mud pumps come in a variety of sizes and configurations, but for the typical petroleum drilling rig, the triplex (three piston/plunger) mud pump is the pump of choice. Duplex mud pumps (two piston/plungers) have generally been replaced by the triplex pump, but are still common in developing countries. A later development is the hex pump with six pistons/plungers.

The normal mud pump consists of two main sub-assemblies—the fluid end and the power end. The fluid end produces the pumping process with valves, pistons, and liners. Because these components are high-wear items, modern pumps are designed to allow for quick replacement.

To reduce severe vibration caused by the pumping process, mud pumps incorporate both suction and discharge pulsation dampeners. These are connected to the inlet and outlet of the fluid end.

The number of mud pumps varies per drilling rig depending on the size of the drilling rig. The larger the rig the more mud pumps that will be needed. The mud pumps are considered vital to the operation of the drilling rig. If the mud pumps fail it affects production and can be very costly to repair due to the downtime in production.

To avoid any failures of the pumps, an online monitoring system was selected to collect and transmit vibration data back to a software system for analysis. This online monitoring and diagnostic system can also be expanded by a series of program modules (MUXs) that are specific to the application:

Power and high pressure mud management system is a core function in any oil field operation. Consequential cost of any failure results in an exponential manner through out the chain of drilling activity. Under an open pay zone condition, the effect would compound leading to complications in oil recovery, where such far flung effects are involved in terms of cost of failure, the demand of availability and reliability is not the final requirement of a maintenance manager. Monitoring the trend of all the achievements and failure also becomes an important activity to device a means for all the time injection of dependability. In this trend analysis the diverse and concurrent behavior of different group of equipments are to be monitored in a manageable manner for setting up the hypothesis structures to derive fairly repeatable and accurate predictions.

Unexpected failure of mud pumps during drilling operations can result in non-productive time (NPT) and increase well construction cost. Several prior studies and implementations of condition-based maintenance (CBM) systems for mud pumps have failed to provide a generalized solution for the variety of pump types encountered in the field, in particular by failing to detect damage early enough to mitigate NPT. Our research is aimed at improving upon this situation by developing a practical, generally-applicable CBM system for mud pumps.

In the study reported here, a laboratory test bed with a triplex mud pump was used to collect data to test a new approach to mud pump CBM. Artificial damage was introduced to the two most frequently replaced parts of the pump, i.e., the valve and piston. An accelerometer and an acoustic emission (AE) sensor were used to collect experimental data. Based on this data, an anomaly detection algorithm was constructed using a one-class support vector machine (OC-SVM) to pin-point the early onset of mud pump failure. The CBM methodology thus developed does not require prior knowledge (data) of the mud pump itself or of the failures of its components. This is key to it being more widely deployable.

The trained machine-learning algorithm in the test setup provided an accuracy greater than 90% in detecting the damaged state of the valve and piston. Only the characterization of the normal (i.e., non-damaged) state data was required to train the model. This is a very important result, because it implies that the sensors can be deployed directly onto mud pumps in the field – and additionally, that the first few hours of operation are sufficient to benchmark normal operating conditions. Also, it was observed that a multi-sensor approach improved the accuracy of detection of both the valve and piston damage. The system is able to detect early-stage damage by combining the cumulative sum control chart (CUSUM) with the damage index developed in this project.

This work is the first attempt at applying semi-supervised learning for CBM of mud pumps. The approach is applicable for field use with very little or no prior damage data, and in various working conditions. Additionally, the system can be universally deployed on any triplex pump and efficiently uses the data collected in the first few hours of operation as a baseline. Consequently, the practicality and scalability of the system are high. It is expected to enable the timely maintenance of critical rig equipment before catastrophic damage, failure and associated downtime occurs. The system has been deemed promising enough to be field-trialed, and is currently being trialed on rigs in North America.

Many things go into getting the most life out of your mud pump and its components — all important to extend the usage of this vital piece of equipment on an HDD jobsite. Some of the most important key points are covered below.

The most important thing you can do is service your pump, per the manufacturer’s requirements. We get plenty of pumps in the shop for service work that look like they have been abused for years without having basic maintenance,  such as regular oil changes. You wouldn’t dream of treating your personal vehicle like that, so why would you treat your pump like that.

Check the oil daily and change the oil regularly. If you find water or drilling mud contamination in the oil, change the oil as soon as possible. Failure to do so will most likely leave you a substantial bill to rebuild the gear end, which could have been avoided if proper maintenance procedures would have been followed. Water in the oil does not allow the oil to perform correctly, which will burn up your gear end. Drilling mud in your gear end will act as a lapping compound and will wear out all of the bearing surfaces in your pump. Either way it will be costly. The main reasons for having water or drilling mud in the gear end of your pump is because your pony rod packing is failing and/or you have let your liners and pistons get severely worn. Indication of this is fluid that should be contained inside the fluid end of your pump is now moving past your piston and spraying into the cradle of the pump, which forces its way past the pony rod packing. Pony rod packing is meant to keep the oil in the gear end and the liner wash fluid out of the gear end. Even with brand new packing, you can have water or drilling fluid enter the gear end if it is sprayed with sufficient force, because a piston or liner is worn out.

Monitor your oil and keep your pistons, liners and pony rod packing in good condition. If a liner starts to leak, identify the problem and change it as soon as possible.

There is also usually a valve on the inlet of the spray bar. This valve should be closed enough so that liner wash fluid does not spray all over the top of the pump and other components.

Liner wash fluid can be comprised of different fluids, but we recommend just using clean water. In extremely cold conditions, you can use RV antifreeze. The liner wash or rod wash system is usually a closed loop type of system, consisting of a tank, a small pump and a spray bar. The pump will move fluid from the tank through the spray bar, and onto the inside of the liner to cool the liner, preventing scorching. The fluid will then collect in the bottom of the cradle of the pump and drain back down into the collection tank below the cradle and repeat the cycle. It is important to have clean fluid no matter what fluid you use. If your liners are leaking and the tank is full of drilling fluid, you will not cool the liners properly — which will just make the situation worse. There is also usually a valve on the inlet of the spray bar. This valve should be closed enough so that liner wash fluid does not spray all over the top of the pump and other components. Ensure that the water is spraying inside the liner and that any overspray is not traveling out of the pump onto the ground or onto the pony rod packing where it could be pulled into the gear end. If the fluid is spraying out of the cradle area and falling onto the ground, it won’t be long before your liner wash tank is empty. It only takes a minute without the cooling fluid being sprayed before the liners become scorched. You will then need to replace the pistons and liners, which is an avoidable costly repair. Make a point to check the liner wash fluid level several times a day.

Liner wash fluid can be comprised of different fluids, but it is recommended to just using clean water. In extremely cold conditions, you can use RV antifreeze.

Drilling fluid — whether pumping drilling mud, straight water or some combination of fluid — needs to be clean. Clean meaning free of solids. If you are recycling your fluid, make sure you are using a quality mud recycling system and check the solids content often throughout the day to make sure the system is doing its job. A quality mud system being run correctly should be able to keep your solids content down to one quarter of 1 percent or lower. When filling your mud recycling system, be sure to screen the fluid coming into the tanks. If it is a mud recycling system, simply make sure the fluid is going over the scalping shaker with screens in the shaker. If using some other type of tank, use an inline filter or some other method of filtering. Pumping out of creeks, rivers, lakes and ponds can introduce plenty of solids into your tanks if you are not filtering this fluid. When obtaining water out of a fire hydrant, there can be a lot of sand in the line, so don’t assume it’s clean and ensure it’s filtered before use.

Cavitation is a whole other detailed discussion, but all triplex pumps have a minimum amount of suction pressure that is required to run properly. Make sure this suction pressure is maintained at all times or your pump may cavitate. If you run a pump that is cavitating, it will shorten the life of all fluid end expendables and, in severe cases, can lead to gear end and fluid end destruction. If the pump is experiencing cavitation issues, the problem must be identified and corrected immediately.

The long and the short of it is to use clean drilling fluid and you will extend the life of your pumps expendables and downhole tooling, and keep up with your maintenance on the gear end of your pump. Avoid pump cavitation at all times. Taking a few minutes a day to inspect and maintain your pump can save you downtime and costly repair bills.

Any drilling operations site that wants to optimize its process and preserve its equipment is well aware of its mud. Drilling fluid (what the layperson calls mud) is a vital part of the drilling process. Drilling mud is important for downhole drilling; cooling and lubricating the bit, removing debris from the well, controlling formation pressures and maintaining wellbore stability.

If a project is going to succeed, the drilling fluid system must be monitored, maintained and maximized. Go to any drilling site and someone there is keeping an eye on the mud.

There is no shortage of equipment, instruments and technologies that are used to maintain the drilling fluid process. Depending on site needs, drilling professionals might opt for flow meters, shakers, additives, centrifuges, degassers and any number of other technologies to monitor mud movement. The process can be further maximized for efficiency by using process instrumentation in the different phases of the mud system.

Radiometric sensors are a popular choice for pipeline mud flow. Maintaining the correct density profile of the mud traveling through the pipeline and ending down hole is important in maintaining stability and controlling formation pressures. The fluid also needs to be the correct density to both travel back up the annulus and carry away drilling debris. As a well is drilled, underground land formations change. That is just one of many factors that may affect the internal well pressure.

Continuous monitoring of the conditions inside the wellbore and the characteristics of the drilling fluid must be maintained to ensure well integrity. For an accurate account of those characteristics, users often trust radiometric density detectors.

The chief advantage of radiometric systems is that they operate without contacting the measured product. In a pipeline application, a secure source holder is mounted on one side of the pipe, and a detector is mounted on the other. The detector measures radioactive energy; the more energy it reads, the lower the inferred mud density. This noncontact design prevents the wear suffered by contact instruments abused by pipeline fluid. Additionally, because the system measures energy and not mud, the instruments do not need recalibration or adjustment to measure changing product. Radiometric sensors also offer durability in extreme heat and other adverse conditions. These instruments are rugged.

Through-air radar is noncontact and free from damage inflicted by corrosive products. These instruments are durable in challenging conditions and many models are sensitive enough to measure products of any chemical composition. Dielectric constant does not matter anymore. These sensors can measure virtually anything. If users considered through-air radar for level measurement and passed, now is the time to reevaluate radar, since the technology has advanced significantly in the last two years.

Drilling mud has to go somewhere and the tank that collects the spent mud also needs accurate process instruments. Product density is important to monitor and maintain in the mud tank. It is imperative that users maintain the correct formula of the fluid for downhole drilling propulsion and wellbore integrity. The mixture of additives and other products complicates the measurement, but an accurate reading of mud tank density measurement is necessary to controlling operations.

Electronic differential pressure (EDP) is a popular choice for measuring mud tank density. An EDP system consists of two independent instruments that deliver a differential pressure measurement without capillaries or impulse lines. EDP systems can be configured to output a number of values including density. EDP instruments are invulnerable to temperature changes that distort traditional DP measurements and optional ceramic measuring cells are resistant to abrasion and drift. These instruments also offer overload resistance. Maintenance free and relatively easy to install, there is a lot to like about EDP. However, not all EDP systems are created equal. Some EDP systems do not tolerate extreme heat, and metallic measurement diaphragms are susceptible to damage.

Every drilling project has to account for mud. From the pipeline to the storage tank and beyond, mud measurements are vital to a project’s success. Accurate measurements can help users optimize operations and make the most of materials and equipment. Selecting the right process instruments for mud measurement comes down to the realities of the project at hand.

Not all process needs are the same, and not all mud is either. Users should seek the counsel of their process instrumentation providers to select the mud measurement instrument that best suits their operation.

Compounding this growth are aging plants with critical equipment at the end of its life—increasing demands for reliability—and an aging workforce reaching retirement in the next few years. All these factors exponentially increase the need for effective and automatic knowledge transfer, training and new approaches to the maintenance of power generation assets. Today, the process of condition monitoring is largely conducted manually, meaning technicians and operators monitor equipment on their walking rounds or tours within a plant (Figure 1). This includes capturing data logs, inspections and assessments, performance testing, maintenance, and capturing history and events. In addition, this provides limited access to equipment condition monitoring.

difference between generating a profit or a loss. However, increased inspection through online monitoring and data collection can mitigate these risks.

To optimize machine maintenance and, therefore, machine reliability and use, monitoring health indicators such as mechanical vibration, temperature and power factor is a widely accepted practice. However, the cost of cabling the sensor and data acquisition hardware to the control room has impeded the use of monitoring for reliability and usage improvements. Today, with the use of wireless vibration and power monitoring devices, reliability engineers can overcome historical cost barriers.

Power generation providers are taking advantage of the cost effectiveness of wireless devices to add low-cost sensors to equipment. Without the need to connect wires to transfer data, reliability engineers can expand instrumentation beyond critical assets and communicate condition monitoring data for many assets across systems.

Online machine monitoring monitors equipment as it runs. Data are acquired by an embedded device and are transmitted to a main server for data analysis and maintenance scheduling.

Most machine condition monitoring sensors require some form of signal conditioning to optimally function, such as excitation power to an accelerometer. Filtering on the signal to reduce line noise and unwanted frequency ranges is also common.

Implementing an asset monitoring system provides other advantages in addition to cost savings. For example, organizations can plan replacement parts inventory to meet maintenance demands by ensuring that the correct parts are available at the right location as needed, ensuring better fleet management. Also, with a longer maintenance cycle based on machine health, a longer equipment life span can be expected.

Another benefit is the production assurance that an asset monitoring system provides. The system can identify developing faults with enough lead time to properly schedule maintenance during planned downtimes, avoiding unnecessary and expensive site shutdowns.

Most important, by monitoring the machine and its performance parameters, the condition monitoring system can signal a system shutdown before serious injury or other harm occurs.

With the advent of advanced maintenance methods, industrial machinery and asset monitoring systems continue to become more sophisticated. As a result, the requirements for such systems are constantly evolving, which creates new challenges for selecting the appropriate instrumentation for asset monitoring.

In power plants, for example, plant operations personnel access the business network of the plant using mobile devices such as tablets and cell phone technologies. With an industrial wireless network available within the plant, personnel can access email, internal documents and drawings, and other resources that they may need while performing operations in the field. Incorporating Wi-Fi access points with process plants, including power generation and oil and gas plants, offers a clear business benefit beyond condition monitoring. However, transmission of vibration time waveforms may use all the available bandwidth even with an 802.11n implementation.

To mitigate bandwidth issues with Wi-Fi, or any other radio technologies, a report featuring exception or decision-based data recording with store and forward capabilities is most appropriate (see Figure 2). Decision-based data recording devices are often referred to as a Data Acquisition and Analysis Node (DAAN). When the DAAN can evaluate all sensor values for exception and log sensor values locally, two main benefits are achieved. First, when reporting by exception sensory, data are filtered for changes, exceptions or required periodic reports. Second, recording sensor data and condition indicators is possible even when the wireless communications network is not available or experiences bandwidth degradation.

By leveraging a DAAN to filter data and to store sensor data and condition indicators locally, engineers can use the Wi-Fi networks in both process and manufacturing facilities. This makes deploying condition monitoring DAANs possible without the need to deploy communications cabling. Even with these capabilities, plant motors and equipment can cause communication noise. Both Cisco and N-Tron recommend and offer wireless network surveys to help determine the best wireless networking topology for individual applications.

Part Two of this series, which will appear in the December 2013 issue, will address the importance of reducing human exposure to hazardous environments—such as manual maintenance inspections on industrial mud pumps—during onshore and offshore drilling. It will discuss the hardware and software tools used to deploy an embedded system to monitor and analyze mud pump vibrations.