Artificial Lift Techbook 2019

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32 | April 2019 | ARTIFICIAL LIFT: TECHNOLOGY barrels per day. We have to have an ESP system that will handle a significant volume of gas along with the high volumes of liquids." Halliburton has stages designed specifically to handle a very wide operating range. "We sacrifice a little bit of the absolute, highest efficiency point to expand the operating range. We do that because these wells start out at 2,000 barrels per day and six months to a year later the wells are 200 barrels per day. We want to be able to handle those extreme ranges with a single pump so we don't have to have a rig come in, pull the unit and replace it with a different size," he explained. The company focuses on putting a pump in the hole that can be left there for long periods of time. "It is not uncommon to have an ESP system run 10 to 15 years. We put a lot of engineering into making sure that we are able to get those extremely long run times. The way we do that is match the hydraulic performance of the pump, the mechanical compo- nents, the bearing systems, corrosion resistance, sand resistance and gas-handling capabilities. We make sure the equipment is matched for the conditions in that well," he said. "What I've done over the past 10 years was spend a considerable amount of time with guys doing well layout and profile that will actually suit their long- term artificial lift needs. It is probably one of the single biggest factors relating to the success of a long-term artificial lift program. It is not the pump you put in the hole; it is the well plan you're forced to live with," de Long emphasized. Mitigating power brownouts With regard to ESPs as well as other types of pump- ing systems, one of the biggest problems in regions across the globe is electrical brownouts, or a situa- tion where the grid's voltage output momentarily drops. As residential and commercial demand for electricity continues to stress the grid's transmission capacity, an electricity bottleneck is creating signif- icant challenges for oil and gas operators in places like Texas and Colorado. "What I am referring to is that we expect to see the voltage coming into a drive at 480 volts. In a place where operators have equipment hooked into the grid, such as variable speed drives, it draws from the transmission capacity on location and that 480 volts drops to 450 volts. The incoming voltage may only drop for three seconds or so below the voltage threshold, but the ESP shuts down," he said. When that happens, the operator has to time it out and restart. Usually that takes one to two hours, although it could be a 24-hour shutdown in cases where a pumper has to go out and manually restart. Most of the time, Valiant ESPs are programmed to automatically attempt to restart in the case of a shutdown. "Flowback through the production tubing puts all that sand back in the pump. Without a sand barrier device, the ESP could twist a shaft on startup. Ultimately, you would have a failure with the ESP that really had nothing to do with the equipment—it was caused by the incoming power," Martensen explained. Halliburton engineers at Summit ESP Research and Technology Center can validate theory by creating harsh environments to aggressively test every component of an ESP system before ever going out into the field. (Photo courtesy of Halliburton)

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