By Patty Sullivan
Imagine a big sand box. Your mission is to move thick fluids through the loose sand into a pump turning at 3,000 revolutions a minute or higher.
“Things plug up, things wear out,” said Pete Fox, Staff Petroleum Engineer at ConocoPhillips Alaska. “The biggest challenge is the reservoir itself.”
Welcome to West Sak, a shallow reservoir in the Kuparuk River Unit on Alaska’s North Slope. The reservoir is 14 miles wide by 28 miles long and has been producing viscous oil since 1998.
“Viscous oil is not an easy flowing fluid,” Fox said. “It’s an emulsified goo. Pumping it effectively is a continuing challenge.”
The goo-and-sand problem isn’t new. In the late 1990s, John Patterson, then a Production Engineer at heritage company ARCO, was confronted with it.
“We found a lot of oil yet getting it out of the ground in West Sak was not easy,” said Principal Artificial Lift Coordinator Grant Dornan, of Patterson’s dilemma. “How do we do it affordably, profitably?”
Patterson and team championed a vision for a hybrid, electric submersible pump system (ESP). The motor and cable were conventionally deployed with the production tubing. The pump sections, which are subject to abrasive wear, were replaceable with just a wireline unit for quick servicing.
“In a perfect world, the well has enough pressure and energy to produce,” said Global Production ESP Subject Matter Expert Richard Delaloye. “You open the valve for more oil and close it for less, but as the well ages or if the reservoir doesn’t have enough initial energy, you need to boost it. This is one form of doing it.”
ESP Artificial Lift is one component of the overall strategy to capture the difficult but plentiful West Sak oil.
Today, ConocoPhillips and AccessESP have partnered to further develop the ESP system. The AccessESP system reduces costs by not requiring rigs; adds revenue by accessing difficult oil; and keeps ConocoPhillips on the cutting edge of innovation.
“The rigless ESP wells on the North Slope allow us to clean out sand in multi-lateral wells far below the set depth of the motor without performing a costly rig workover,” said Senior Production Engineer Marina Krysinski. “It’s truly a game changer.”
ESPs have been around for 90 years. Heritage company, Phillips Petroleum, provided venture capital to launch the global ESP industry. Reda Pump Company, based in Bartlesville, Okla., originated from the ESP.
New breakthroughs began in 2005 when ConocoPhillips Alaska funded a small business located in the United Kingdom called Artificial Lift Company, ALC. Selected for its expertise in electric motors, ALC developed the first prototype rigless ESP system. After multiple upgrades and variations, the rigless ESP technology became commercially available in 2014 with the original company rebranded as AccessESP.
West Sak sand will plug off a well bore below the pump and above it.
“Traditionally, to repair that would require a rig workover costing millions of dollars,” said Access ESP’s Matt Walker. “With a rigless ESP, a wireline unit and a coiled tubing unit can do it in days for 10 percent of the cost.”
When older wells become choked with sand today, maintenance can turn to much lighter gear than a six-million-pound rig. “The ESP is deployed using a pickup truck and a crane with a wireline,” said Walker.
“You run it in and out of the well with the equivalent of a big open-faced fishing reel,” said Delaloye. “It allows installation and well maintenance without the $200,000 to $300,000 a day cost of a drilling rig. You can do maintenance affordably in a matter of days, instead of waiting six to nine months for a drilling rig,” he said.
Development of the technology involved the expertise of AccessESP and the vision of ConocoPhillips. Multiple ConocoPhillips teams collaborated: the Emerging Technology Group, the Lower 48 Business Unit and the Alaska Business Unit. Those teams made innovations in partnership with contractors AccessESP, Baker Hughes and Halliburton.
“The development of this unique solution is a direct result of our inclusive company culture,” said Fiord West Subsurface Supervisor Mike Driscoll. “It fosters team-building across the global company with our contractors.”
The affordable and easier maintenance of wells also extends the scheduling of a workover. “On a given well, you’re changing your heavy workover interval on the order of 10 years or more instead of four,” Walker said.
Several major oil and gas producers in high-cost operating environments are now using the AccessESP system.
“Commitment from ConocoPhillips allowed AccessESP to develop an industry-changing technology,” said AccessESP President and CEO Dave Malone. “We have expanded our operations from Alaska to West Africa, Asia, Europe and the Middle East.”
Back in West Sak, eight ESPs are working in the ground, some have been running for up to six years. Given the success, multiple additional units are planned.
“We know these pumps will wear out,” said Delaloye. “The magic of rigless is that we can replace the pump affordably, in a matter of two to three days, and get back to producing oil.”