The New Pathways of Multiphase Flow Modeling

Abstract

Multiphase Flow In the realm of enabling technologies, multiphase flow modeling has proven to be one of the most important to the oil and gas industry. Without it, nearly all subsea wells would be too costly or dangerous to develop. While working to fine-tune its offshore capabilities, developers are also busy expanding the technology’s application areas to include shale field development, hydrate remediation, and heavy oil extraction. In the 1960s, when the industry began studying how to model multiphase flow, which is the science of how liquid and gas interact inside wellbores and pipelines, little was known about the complex physics involved. Back then, an engineer’s ability to predict flow behavior was strictly limited to what could be observed at the wellhead. Over the years, the industry invented devices that could accurately calculate flow rates, velocities, and volume fractions, along with downhole temperatures and pressures. Armed with these tools, engineers and scientists had the measurements they needed to marry computational science and fluid dynamics. More than anything else, this advancement is what has allowed offshore operators to extend their reach beyond the shallow-water fields and into those thousands of feet deep. “What we have done is to make it possible for the industry to live with the complex multiphase flow problems that face them on a daily basis,” said James Brill, a multiphase flow expert who recently retired as a research professor of petroleum engineering at the University of Tulsa. “When the industry first moved offshore, they were afraid to go with multiphase flow pipelines because they did not know what was happening inside of them, or what kind of facilities they would have to have at the outlet end in order to handle the fluctuating rivals of gas and liquid.” In lieu of a complete understanding of multiphase flow, Mack Shippen, a product champion for one of Schlumberger’s top multiphase modeling programs, said early offshore explorers were forced to make conservative design decisions when building a production platform. That meant using larger than needed processing equipment and pipelines to compensate for what they did not know about the behavior of the multiphase flow. “So yes, you had a safe design but you did not have one that in today’s world would be economic,” he said, explaining that, “if it is overdesigned, then essentially money has been wasted on equipment that is more than what is necessary.” If an operator can reduce the diameter of a subsea pipeline by just 1 in. or 2 in., “the difference can be on the scale of millions of dollars in capital investment,” he said.