- Published on Monday, 22 June 2015 12:38
- Written by Kate Kunkel
CFD is used in early field issue resolution where a small section of geometry is modeled in order to test a hypothesis such as low-pressure zones around corners, minimum temperatures, impingement angles for wear studies, etc. With the advancement in CFD mathematical models and the increase in speed and capacity of desktop workstations, it has become possible to use the full mathematical modeling capability of modern commercially available CFD codes, producing full three-dimensional flow regimes and flow results.
This presentation focused on seven areas in which CFD has been used in a non-traditional way.
- Published on Tuesday, 16 June 2015 10:33
- Written by Kate Kunkel
One of the biggest objections to hydraulic fracturing centers around the fact that huge amounts of water are needed for the process. In fact, each well requires 60,000 to 100,000 barrels of water; it is the base fluid and biggest component of hydraulic fracturing. The problem is that agricultural, industrial and domestic users are vying for the same fresh water that producers need. Additionally, the flow-back and produced water coming out of the wells is contaminated so it cannot be simply returned to lakes and streams or aquifers and must be sent to disposal wells unless it is properly treated.
While they are both produced as a result of hydraulic fracturing, flow-back and produced water are quite different. Flow-back is a water-based solution that flows back to the surface during and after the completion of hydraulic fracturing. This fluid can contain clays, chemical additives, dissolved metal ions and total dissolved solids (TDS) and has a murky appearance from high levels of suspended particles. Most of the flow-back occurs in the first seven to 10 days of fracturing, but it can continue to flow for weeks and can be up to 20 to 40% of the volume that is initially injected into the well. Contrast this with produced water, which is naturally occurring water found in shale formations. It flows to the surface throughout the entire lifespan of the well and has high levels of TDS. It also leaches out minerals from the shale and contains dissolved hydrocarbons such as methane, ethane and propane along with naturally occurring radioactive materials (NORM) such as radium isotopes.
- Published on Sunday, 07 June 2015 23:24
- Written by Chris Warnett
When automated valves are needed for a project, the selection and procurement process involves many players. For a major capital installation, influencing parties will include not just the end user and valve and actuator manufacturers— engineering designers, construction and installation contractors will also be involved.
While these parties have some common interests, each of them also has specific individual interests. It is worth looking at the selection and procurement process through the eyes of each of these parties to see how their perspectives can influence the offerings and support provided by the automated valve suppliers. In an intensely competitive global marketplace, every valve and actuator manufacturer strives to bring value to all parties in the hope of winning business.
- Published on Tuesday, 26 May 2015 16:16
- Written by Chris O'Brien
The performance of valves and other final elements have a significant impact on the operations and safety performance of a process plant. Establishing effective programs based on realistic performance expectations is necessary to balance both cost and risk. Cost drivers include equipment and maintenance costs while risk can come from health and safety concerns as well as equipment availability. Gathering trusted information that can help inform decisions related to these factors can prove challenging.
To create a holistic view of field failure information, several key things need to be examined. These include collecting failure data, the functional failure modes of the equipment in question, available field studies, and finally, application stress considerations. We begin by looking at the most common ways of collecting field data.
- Published on Sunday, 10 May 2015 11:53
- Written by Peter Cleaveland
From time to time, we will re-post particularly well-received articles that have previously run on VALVEMagazine.com so that those who might have missed them will be able to catch up on the best of the best. This article, on the 'True Meaning of Double Block and Bleed' initially ran on June 1, 2010.
It’s time to do maintenance on a section of process. You don't want to shut down the entire facility, so you decide to block off and depressurize just the section you're working on. Just upstream is a double block and bleed valve—a trunnion-mounted ball valve with self-relieving seals and a bleed valve to vent the cavity. You close the ball valve and open the bleeder. Now you can de-pressurize the line downstream and open it up to work on it.