Overcoming Challenging Production Environments with Multiphase Boosting

The increasing use of downhole pumps has become necessary, often right from the start of producing a reservoir as operators push to accelerate recovery from shale and tight formations with faster decline rates. In North America, more than 85% of all producing wells are on some form of artificial lift. In addition, multi-well drill centers and pad production are used to maximize operating efficiencies, centralize surface processing and minimize facility footprints.?

For all its benefits, pad-based unconventional reservoir development also can lead to complex well architectures with long horizontal legs. The added complexity makes lifting with conventional downhole pumps difficult and can present the operator with a whole new set of problems, including unpredictable production flows with declining revenue streams because of interruptions and unplanned costs for well service, work-overs and well interventions.?

To overcome this challenging production environment, operators are adding multiphase boosting with twin-screw pumps to existing artificial lift systems. Installing a multiphase pump on a multiwell gathering system offers many advantages for optimizing artificial lift. Reducing the flowing surface pressure reduces backpressure on flowlines, production headers, well-heads, and further upstream, downhole pumps. The lower surface pressure results in lower bottom-hole pressure for improved IPR, better well inflow and increased liquid levels in the wellbore.?

Higher liquid levels are important for artificial lift. The deeper submergence of ESPs and sucker rod pumps enhances hydraulic performance by improving net positive suction head. At low wellbore liquid levels, downhole pumps operate in or close to the bubble point region. Gas will come out of solution and rest1ict the inlet flow, resulting in poor hydraulic performance with an instant production drop and possible damage to the equipment.?

By reducing flowing wellhead backpressure with a multiphase pump, the resulting higher liquid level will keep the gas in solution and allow the downhole pump to operate above the bubble point. A downhole pump running at its optimal efficiency point on the curve will improve its gas handling ability and substantially reduce the risk of vapor locking and head loss caused by entrained or free gas.?

As shown in Table 1, after a multiphase pump was installed in one field application, the higher liquid level associated with the lower bottom-hole pressure added significant submergence of both ESPs and sucker rod pumps. The reduced hydraulic work improves service life, reduces electric loads on ESPs, and lessens wear and tear on beam pump rods, couplings and connectors.?

An additional advantage manifested itself in a situation where there were problems maintaining constant production flow and pressure in test lines from wells during testing. Placing a multiphase pump down stream of the test separator facilitates well testing by managing test line flow using the pump's speed control. The flow is directly proportional to speed and largely independent of backpressure from the production separator.?

Wells on gas lift also can improve production and total recovery substantially when multiphase pumps are used to reduce backpressure. Gas-lifted wells, which have a tendency to liquid load and can experience very unstable flow because of lift gas supply or underperforming gas lift valves, will be supported by the reduced backpressure created by a multiphase pump. In wet-gas wells, the reduced wellhead backpressure will assist in unclogging the liquids trapped in the wellbore much faster than is possible with conventional plungers, quickly bringing wells back to production.?