Your engineering team tells you the new deep-water product is ready for field trials because it has passed an API validation test in the lab. But as the OEM engineering manager overseeing product development, how do you know that passing just the validation test is sufficient? [Read more…]
Equipment Risk and Reliability in Downhole Applications
The equipment used in oil and gas wells is designed to operate for long periods of time at very high absolute pressures and temperatures, frequently in highly corrosive environments, and with little opportunity for visual surveillance of equipment condition. The reliability of these products directly affects the economics of operating these wells, the environment, and the safety of the communities in which the wells are located. This series of five articles explores the risk and reliability associated with the downhole tools used in oil and gas well applications and provides recommendations for engineers on how to include reliability thought and practice in design.
Factors of Safety and Load Factors
The new deepwater expansion joint design meets company requirements for factors of safety but cannot comply with ASME Section VIII load factors. How does the OEM engineering manager proceed?
Design for Reliability (DfR)
You are an engineering manager overseeing product development. For the new offshore product developed by your team, you want to know:
- If the final design margins comply with company standards
- If the thin-wall components are susceptible to Bauschinger Effect
- Which load factors were used for the ASME section 8 analysis.
High temperature stress analysis of metallic components must account for an inevitable decrease in room temperature minimum yield strength (Sy). Linear-elastic stress analysis is the norm for nearly all downhole metallic components and accurate results depend upon the use of reliable temperature deration factors. [Read more…]
Materials and Design Risk
The materials used in new equipment can pose a design risk. But what makes a material a design risk? And how is de-risking achieved for metallic and nonmetallic materials?
To satisfy design requirements for loading, corrosion resistance, and manufacturability, materials properties must be controlled. Design risk is high when material properties are not controlled and materials are not selected using best practices. And as stated in Equipment Risk, material stability is also necessary for long service life, meaning that mechanical and physical property response to elevated temperature and corrosive media is predictable or reasonably estimated. Thus, controls for material properties and selection are the basis of de-risking. [Read more…]
Technology Readiness Level (TRL)
Your staff has a concept for a deepwater completion product. They say it is the solution offshore operators need. The concept contains many new components and seems risky. How mature is the technology?
Conducting a Technology Readiness Assessment (TRA) answers these questions. A TRA assesses the maturity of the technology in a product and assigns it a Technology Readiness Level, or TRL. The higher the TRL, the more mature the technology, and the lower the risk. [Read more…]
Critical Equipment Fundamentals
Critical is defined as “a situation or problem having the potential to become disastrous”. A system of physical well barriers is used in offshore wells to mitigate against a disastrous event. The United States Bureau of Safety and Environmental Enforcement (BSEE) refers to Category 1 and 2 well barriers. A failure of a barrier can lead to a blowout or fluids spill into the ocean, either of which is high severity. Thus, it is customary in the upstream energy industry to refer to well barriers as “critical equipment”. [Read more…]
Tortuosity is defined as “something winding or twisted” or “full of twists and turns”.
Well tortuosity is typical of today’s unconventional wells (see Figure 1) and is now acknowledged to result in casing deformation such as collapsed inner diameters (“ovalized casing”). There is also growing awareness among shale operators that excessive tortuosity can predispose the casing to rupture which results in fracturing fluids going into the wrong stages. Rupture occurs in sections which are deformed and therefore more vulnerable to cyclic fracturing pressures, pressure-induced bending, and earth loads. [Read more…]
The Pump-in Process
As stated in The Plug and Perf Process, electric line and frac pump crews coordinate the pump-in process to convey each FP-setting tool-perforating gun “assembly” along the lateral section of the well – perhaps 70 times per well. High mechanical reliability is expected, so the pump-in process must also be reliable. But to achieve this, many process risks must be mitigated. How are some of these risks mitigated? [Read more…]
Ballistic Setting Tools
Ballistic setting tools (wireline setting tools) have been used for over sixty years to convey downhole packer devices, including frac plugs, into oil and gas wells. The principle of operation is simple: at setting depth, current sent down the electric line ignites the on-board power charge, which burns and liberates high-pressure gas, which displaces a piston over a fixed distance. This creates the mechanical force used for “setting” the frac plug in casing. [Read more…]
Frac Plug Reliability
Frac plugs create a seal with the inner diameter of the casing. With the frac ball on seat in the frac plug, a check valve is formed in the casing which resists fracturing pressures up to 15,000 psi. Composite frac plugs use substantially composite components and rubber seals. Degradable frac plugs use components manufactured from magnesium (Mg) alloys. [Read more…]
The Plug and Perf Process
Multi-stage horizontal wells have been drilled and completed in shale formations in North America for two decades, and now account for nearly 90% of new wells drilled in the U.S. The Plug and Perf process (PnP) is used for completing most of these wells. [Read more…]
The Importance of Post-delivery Feedback
In the article Reliability in Equipment Design it was stated that a project team can set reliability target(s) for new equipment using historical reliability data. One option OEMs have for capturing historical reliability data is a Failure Reporting And Corrective Action System, or FRACAS. The data captured can provide a comprehensive view of how the equipment is performing. This data can be used to improve legacy equipment and drive decision-making on new equipment. [Read more…]
Reliability in Equipment Design
Changes are a part of the evolution of a new design. But managing the timing of changes is important. Figure 1 shows that the cost of making design changes increases rapidly beginning late in development. In well-run projects, design changes are mostly complete by early development. But project teams that ignore reliability often discover the need for changes during lab testing (late development) or commercialization. This is very costly, creates schedule delays, and can lead to brand damage. In Maximizing Oilfield Equipment Reliability, it is stated that Design for Reliability (DfR) programs are used by OEMs to elevate reliability. But DfR activities can also reduce the cost of changes. How is this achieved? [Read more…]
Maximizing Oilfield Equipment Reliability
High reliability is expected of mature products with track records (low hazard rate). But new products with little or no track record (hazard rate = ?) are commercialized every day in the upstream industry. The technical objectives for new equipment always consist of performance targets, but should also include designing to maximize reliability. So, how does an OEM achieve this? The answer involves culture, capabilities, and best practices. [Read more…]