Artificial Lift Techbook 2019

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Page 32 of 59 | April 2019 | 31 ARTIFICIAL LIFT: TECHNOLOGY Reducing high ESP intervention costs and reduc- ing production downtime is a major driving force for operators utilizing ESPs. David Malone, CEO and president of AccessESP, said that his company is in the rig-elimination and reducing production downtime business. "Everything we do is offshore or in remote locations. It is in places where rig access is difficult and expensive, and there is a lot of lost production with ESP downtime. It is offshore and in West Africa, the Middle East and Alaska." As an example, operators in offshore West Africa have small platforms and have to bring in a jackup rig or hydraulic workover unit for replacing ESPs. Many operators wait for two or three ESPs to fail before they can economically justify a workover program. "We just did a program where the first ESP that went down was offline for almost 24 months. They lost 24 months of production waiting for two more ESPs to die. Total workover costs to bring a rig on site to swap these ESPs was over $10 million," Malone explained. "By changing the ESP thru-tubing and on slickline, AccessESP can mobilize its equipment on the platform—without the need for a jackup or workover unit—and do a live-well swap using only slickline. The typical intervention savings and value of added production we see when we put in our systems is on the order of $2 to $5 per barrel." It is not just old technology that is new again; there is a lot of new technology coming into the artificial lift market as well. John Morgan, vice president and general manager of production oil and gas Internet of Things (IoT) for WellAware, noted that one of the company's challenges has been "helping customers to understand the benefits of implementing the Indus- trial Internet of Things [IIoT], not only for improving their operational efficiency but also for opening other business models for the companies internally." The applications that WellAware has mapped are known as micro-verticals and are different applica- tions on the wellpads and pipelines. The company looks at the ecosystem to understand applications for monitoring and controlling IIoT devices, accord- ing to Morgan. More detailed explanations of the challenges and solutions for artificial lift systems follow. Dealing with gas slugging "For the majority of horizontal wells, we're dealing with very high quantities of liquid—oil and water— and very, very high quantities of gas. Some of these wells have produced several million cubic feet of gas per day while we're pumping oil and water out of the well," Halliburton's de Long said. "We have to have an ESP system that will handle the significant vol- ume of gas along with the high volumes of liquids." The undulations in the horizontal laterals cause a significant amount of slugging. Gas caps build up in the high points of the casing, which effectively block the fluid or liquid flow until there is enough pressure behind the cap to push the gas slug. In turn that causes a very high velocity fluid surge that carries solids with it. The gas slug itself actually stops any kind of pumping system, disrupting the pumping mechanism, with the exception of plunger lift, he explained. "We've developed numerous pump stages that are specifically designed in quasi-axial flow arrangement to allow us to pump high volumes of gas without gas slugging. Gas gets in there and shuts off operation of the pump. We can get into a well that has 70% to 90% free gas at the pump intake and still manage to produce that well. We do that through various mechanisms of self-orienting intakes that allow gas to pass by the equipment," de Long said. "One of the biggest problems that ESP systems have in unconventional wells is because of intermit- tent flow due to slugging. The ESP system, partic- ularly the pump, will get extremely hot very, very quickly when it gets into a gas-slug situation. The hardened bearings will come loose, shatter or fall out, which is pretty disastrous for the pump," de Long said. "We have developed a mechanism for locking the bearing assemblies inside the pump to allow the pump to go through extreme excursions without having a bearing failure." It is a simple idea using a mechanical and an elas- tomeric locking mechanism in the bearing itself to keep them in place, he added. The company has gas separators, gas-handling pumps and fluid conditioners to get the multiphase fluid stream into the ESP, compress it, put it through the pump and up to the surface. The length of the lateral doesn't make much dif- ference but the crookedness of it and the tendency for larger and longer duration slug flow coming through that causes problems. "There are mechanisms that are being developed and deployed in some areas of the world that will actually equalize the flow across that horizontal section and stabilize some of the flow that turns to slugging. That is being employed to take care of the long, crooked sections," he noted. As de Long pointed out, Halliburton's focus is primarily on ESPs at this point. "From our perspec- tive we are dealing with high-volume production systems. Production rates can be anywhere from 200 to 300 barrels per day up to several thousand

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