Reciprocating Pumps Condition Monitoring
Hydraulic fracturing, or "fracking" as it is more commonly known, is one of the methods used for unconventional extraction of oil and natural gas fields. Fracking is a proven production enhancement technology used for extracting oil, natural gas, geothermal energy, or water from deep underground.
It is the process of injecting frack fluid (mixture of water, proppant, and chemicals) at high pressure to create small fractures in the rock formations to stimulate the production and safely extract energy from an underground well after the drilling has ended and the rig and derrick are removed from the site.
The process is variable from a single frac stage in an exploratory well to 50+ frac stages in unconventional reservoir well takes. The number of frac stages, fracture design, flow rates, volumes and frac fleet size (HHP) are defined by a group of specialists and once the fracturing operation is finished, the well is considered "completed" and is now ready to safely produce. Entire set up runs in several intermittent cycles.
Fracking operation involves injecting frack fluid at high pressures which is established through pumps. These fracking pumps, often reciprocating pumps, are either mounted on a skid on-ground or on mobile trucks. They are driven by diesel engine through a transmission gearbox involving clutches. Piping arrangements direct the high pressure frack from individual pumps to the common header before it is injected into downhole.
These fracking pumps operate in harsh operating conditions and face many challenges for continued operation:
Health, Safety and Environment (HSE) exposure - These pumps operate at extremely high pressures typically ranging between 11000 - 13000 psi (up to 900 bar) without any online protection system. This creates a significant exposure to people, assets, and environment from a HSE aspect.
Maintenance philosophy - The high-pressure reciprocating pumps used in fracking operations typically have very limited instrumentation to support online data analysis. Major maintenance decisions are therefore driven by time rather than based on the asset's real condition. Breakdown severely affects fracking cycles, increases maintenance costs and adds up to massive inventory requirements.
Operation Excellence - Fracking pumps operate in different operation modes. Different wells mean different operations and associated challenges. Intermittent operation, not fixed allocation and limited automation in places creates many variables needed to achieve sustained productivity, efficiency, availability, and reliability.
Bently Nevada's smart fracking instrumentation and monitoring solution is designed to address a wide range of safety and operational factors and ultimately improve operating margins. A few salient features are:
- Capture and register detailed fracking data
- Minimize risk of catastrophic equipment failures and labor accidents
- Reduce unplanned maintenance events
- Increase planned and low-cost maintenance activities, anticipating failures on rolling element bearing, transmission, power end and fluid end of pump
- Move away from time-dependent maintenance in favor of a condition-based maintenance approach (a cost-effective maintenance approach for optimal operation with minimal downtime and maintenance costs)
- Improve execution of maintenance activities
- Improve data integration, correlation, and analysis, to provide better in-depth knowledge and actionable information about equipment health
- Increase equipment availability and maximize the number of operations per day
- Increase operating efficiency
The solution can be deployed on any OEM's machine and is easy to retrofit as most sensors are case-mounted and just require simple modification of drill, tap and spot-face for installation. Bently Nevada's Smart Fracking solution was first deployed in Latin America and this article will discuss in-depth the installation and results from that installation.
The pump is divided into three main subsystems to assess condition and avoid failures. The following are the systems and the related sensors installed on them. A triplex (3 cylinder) reciprocating pump is being considered here for explanation. Please note that based on the pump's criticality, size and intended machine health monitoring extent, the number of sensors may be optimized with most vibration-sensitive locations being monitored as a minimum.
- 6x Accelerometers on fluid end [pilot installation used 3 Accelerometers on fluid end]
- 3x Accelerometers on crosshead guide - power end (1 on each crosshead guide)
- 2x Accelerometers on input power shaft bearings
- 2x Accelerometer main bearing crankshaft [pilot installation used 4 sensors]
- 1x Keyphasor (crankshaft) [the speed sensor on diesel engine can be used for fault frequencies on transmission]
Transmission gearbox (as per API 670 recommendations)
- 1x Accelerometer across high-speed shaft
- 1x Accelerometer across low-speed shaft
1x Accelerometer on the fan bearings
1x Accelerometer on the water pump
1x Accelerometer on the power shaft main bearing
Note: Pilot installation did not monitor diesel engine
MDS Technical Leader for RECIPs and Analytics Bently Nevada, MEIA
Fayyaz Qureshi is Senior Technical Leader for Reciprocating Compressors, Analytics and Retrofits in Middle East, India and Africa region; responsible for successful commissioning of condition monitoring and advanced analytics solutions on reciprocating machines and diagnostics.
Vinicius Alves Silva
Application Solution Architect
Started Bently Nevada as a trainee of Services in 2010, and gained expertise in products with emphasis on technologies software System 1 and Reciprocating Compressors. He is the Lead Application Solution Architect (ASA) and supports Reciprocating Compressors for Latin America.
Industrial Sales Director
Guilherme has more than 20 years of experience in asset condition monitoring management, working with different industry segments. Guilherme earned a mechanical engineer degree by EFEI and an MBA in UFRJ COPPEAD.
Product Line Director
Zacarias Guimarães is mechanical engineer with MBA in business, has more than 20 years’ experience in Pressure Pumping working in all Americas from deepwater to unconventional reservoir and currently is the Product Line Director for Latin America.