Issue link: http://yearbook.epmag.com/i/671218
ARTIFICIAL LIFT TECHBOOK: TECHNOLOGY EPmag.com | May 2016 | 23 "These wells are, for the most part, hard on artifcial lift, because they've got a lot of gas. You immediately say, 'well, we need to put them on gas lift, we've already got a lot of gas' but you have to have an injection gas supply from somewhere," said Berry. "Compression can be expensive if a high-pressure gas well is not available to supply the gas for gas lift. Maybe you want to forget about the gas lift and maybe even the ESPs and just pump what you can with the rod pump? You lose a lit- tle triangle of potential production, but you don't have to run this huge power system for an ESP or gas lines for a gas lift system. You need to run the economics to see if it will pay out." For jet pumps, ESPs and rod lift systems, advancements in technology and materials are helping each to be more robust in design and in applications. "Unconventional production has caused us to rethink which tools were used for initial pro- duction," said Weatherford's Lane. "For example, the frst fuids that must be removed are the frack fowback fuids. Typically they're full of particulate matter, frack sand and produced sand. Jet pumps are very effective at removing these materials, and so jet pumps have become a leading technology for cleaning up wells. They can then be used for initial high production rates before transitioning to other types of artifcial lift." In addition to cleaning up wells during fowback, jet pumps have been used to get production fowing again. A South Texas operator contacted Dover Arti- fcial Lift to get a well back online that was damaged due to a "frack hit" from an adjacent well workover without a large opex cost, according to a compa- ny-issued press release. The solution used a 1.25 in. jet pump installed inside the existing 2.875-in. pro- duction tubing just above the lateral. Power fuid was pumped down the integral joint tubing to the jet pump, where it combined with the formation fuid to exit the jet and travel back to the surface through the created annulus. The revived well gen- erates $250,000 worth of production per month, according to the company. Costs were reduced over- all to the operator, with produced natural gas being used to power the power fuid pumping unit with no additional costs. For Charlie Fowler, vice president of technology for Dover Artifcial Lift, there are three ways to deal with sand, and recent advances in new products demonstrate that approach. "One is to eliminate as much as possible through separation before it enters the pump. Another is to use materials in the pump that are harder than the sand. The third is to optimize the geometry of the pump so that the sand passes right through it with minimal effect," Fowler said. For wells on rod pumps, the accumulation of sand can cause signifcant abrasion to the barrel/plunger. "Producing sandy fuids has been a problem in both conventional and unconventional production. Weath- erford now offers a sand tolerant pump [STP], which is the frst rod pump to dramatically improve pump run life in very sandy environments. The STP represents a paradigm shift in pumping technology," said Lane. The company released its STP onto the market in 2015 although it had been in feld tests since 2012. The STP prevents abrasion caused by sand accumulation in the barrel/plunger sealing areas by fltering the fuid flm between the barrel and plunger. The flter screen is designed to prevent sand buildup on the screen, and the pumping action washes the screen clean on each downstroke. A pressure-balanced wiper assembly and flter cou- pling creates a barrier to prevent sand from falling back into the pump-sealing areas. For wells equipped with an ESP, frack sand and other solids can lead to severe erosion and wear. In addition, sand accumulation, plugging or contam- ination can also wreck havoc on a well. "Though it could reasonably be argued that the majority of failures are unnecessary, the failure modes of artifcial lift systems, and particularly of pumps and ESPs, are varied. Consequently, there are numerous initiatives to increase system run life," Griffths said. "The Schlumberger MaxFORTE high-reliability ESP system is aimed to increase run life tenfold by paying meticulous attention to detail at every stage of the system life cycle from design through manufacturing, QA/QC, and installation to surveillance and optimization." The approach to understanding wear and tear on pumps is built on collaboration, analysis and material science.