Desanding improves unconventional reservoir production
PHOTO: 2019 Gen 1 Automated Desander Pilot at Rice University Pad in Eagle Ford
PHOTO: 2019 Gen 1 Automated Desander Pilot at Rice University Pad in Eagle Ford
As oil and gas companies drill longer laterals to increase production and reduce costs, well completions have changed. Longer wells require finer-grained sand for hydraulic fracturing, and more sand is returned to the surface during flowback, the phase that removes fluids that were introduced to the well and any debris that accumulated in the wellbore.
Sand is erosive. It can damage equipment and increase the potential for incidents. It fills production equipment, causing inefficiency and product losses. The increase in sand impacts ConocoPhillips’ operations in the Bakken, the Permian, the Montney and the Eagle Ford.
Staff Process Engineer Ramesh Sharma works with Lower 48 and Canada business units to minimize sand’s impact. “The finer-grain sand gives us significant uplift in production and improved completion efficiency but results in increased sand production.” He has engaged the Unconventional Reservoirs Excellence (URE) team to support improved sand management by facilitating continuous knowledge sharing across unconventional assets and functions. This sand management community focuses on issues such as sand separation technologies, erosion, sand detection and measurement, and costs associated with sand production. “Knowledge shared allows the team to leverage learnings and accelerate adoption of new ideas and technologies."
Starting with the Eagle Ford in southwest Texas in 2017, the company’s Lower 48 business units tested semi-cyclonic and cyclonic desanders to manage sand removal. High efficiency desanding equipment is now implemented in the Permian of West Texas and eastern New Mexico, the Bakken in North Dakota, and Montney in Northern Canada. The Eagle Ford continues to work with suppliers to design a desander that meets its specific needs.
Cyclonic desanders create centrifugal force, spinning solids and fluids into separate streams. Solids spiral down to the underflow outlet, while fluids are forced in the opposite direction to the overflow. Solids are removed from the accumulator while the unit remains online. Cyclonic and semi-cyclonic wellhead desanders treat full wellstream flow, including gas, oil and water.
“The desanders’ value is significant,” said Sharma. “We can flow back safely, minimize HSE incidents, and reduce wear and tear on equipment. Ramp-up is faster, flowback time is reduced by an average of 50%, and we can clean up wells faster. Fifty-plus deployments mean we’ve matured and perfected a new tool for large scale deployment.”
The Bakken business unit started testing cyclonic technology in 2016 and decided to go wholly cyclonic by 2017.
"The efficiency is in the 95-98% range,” said First Delivery Supervisor Rory Ketterling. “Since going to cyclonic, we have less frequent need to clean out the facilities. The system allows us to have less equipment on hand, shortening the time it takes to move from well to well. It also allows us to clean up wells faster and more efficiently.”
Cyclonic desanding improved the safety and efficiency of sand removal, but operating costs increased when sand cans were left on for extended periods of time. The Bakken began piloting high rate flowback at the end of 2019.
“The conventional approaches to flowback can require more than 100 days of operation for well cleanup, which incurs significant cost,” said Sr. Facilities Engineer Alison Mariano. “The new flowback method increases production for a single well up to 6,000 barrels a day, accelerating clean-up by lifting two to three times more sand mass out of the wellbore during the first two weeks of operation.”
At the heart of this method is an innovative skid design that combines a high-efficiency cyclonic desander with an automated well test unit, using data analytics to predict valve washouts and automating operation to reduce flaring and manpower for flowback. The program has been deployed fieldwide and is projected to save millions of dollars per year while improving the safety and reliability of operations.
When Permian First Delivery Supervisor Jeff Anaya started at the company in 2017, there were issues with sand plugging up the facilities.
He reached out to Sharma, who provided info about a true cyclonic desander. After working through some issues, they started their original pilot in March 2019.
“The sand problem limited us, from erosion on flow lines and piping to plugging up facilities. The sand is so fine that it gets into both the water and oil stream and even passes through the exchangers at central facilities. We felt like we were spinning our wheels.”
Sharma explained to him the difference between the true cyclonic and semi-cyclonic desanders. “I was reaching out for any lifeline because we were having so much trouble,” Anaya said. “We did the pilot and made a concerted effort to collect data. With the semi-cyclonic we were collecting 50-60% of the sand; with the cyclonic it was 85-95%.”
The true cyclonic has decreased downtime. “Since our quad pads go to one bulk separator, with the semi-cyclonic we had to take four wells offline to clean out the vessel,” Anaya said. “With the true cyclonic, we were able to go 90-120 days without a separator cleanout. This new, aggressive approach also allowed us to optimize our flowback strategy, cutting costs by over 40%.”
The Permian team will conduct a pilot program with the same automated high-pressure sand separator prototype that was tested in the Eagle Ford in 2019. This collaborative approach to innovation and data gathering will lay the foundation for how the Permian team develops its flowback program, with an overall goal of protecting personnel and reducing greenhouse gases.
“We trialed the first semi-cyclonic on a single well pad in 2017,” said Senior Production Engineer Shaun Ninan. “Later we brought on a six-well pad with conventional sand separators, and we couldn’t handle the sand. We rigged up a semi-cyclonic and didn’t see sand issues on our equipment. With many wells expected to come online, semi-cyclonics were most available, so we went forward with that option.”
Eagle Ford Field Supervisor Juan Benavides saw that being unable to exactly quantify produced sand made it difficult to efficiently manage flowback. “We cannot improve if we cannot measure,” he said. “We developed a tool to precisely measure how much sand is produced by the well and how much is carried over from the desander to production equipment.”
“We drill a lot of wells in the Eagle Ford,” said Francisco Gamarra, staff well intervention engineer. “As we see it now, this equipment will be for special cases where we think we’ll produce a lot of sand.”
In the last quarter of 2019, a prototype automated high-pressure sand separator was tested successfully in two new wells in Eagle Ford. The produced sand was dumped directly to an open top tank without human intervention and at minimum pressure. The automated sand separator proved to be safer, has the potential to reduce costs, and minimizes greenhouse emissions. The equipment is ready to continue testing in other assets.
The improved operational practices, sand measurement and interaction with suppliers, have reduced costs and decreased production losses. Going forward, the business unit will continue to focus on managing asset integrity, cost and production through best practices, technology, and collaboration.
ConocoPhillips’ Montney wells, located in northeast British Columbia, are currently in the late appraisal phase, so the team is working to better understand flow assurance and well performance issue that could affect initial predictions, including early life sand production.
A major component of operating costs and risks during early well life is sand and solids management. A key strategy in developing Montney’s sand management plan is leveraging knowledge from the Lower 48 business units, industry peers, vendors and ConocoPhillips subject matter experts.
“We are using learnings and experience from others, along with field trials, to help us optimize sand removal technology selection and sand erosion prediction and minimization,” said Montney Infrastructure Specialist, Andy Daley. “We are evaluating a number of different sand removal technologies, including dual horizontal filter elements, semi-cyclonics and various cyclonic designs. We are completing trials of the equipment utilizing ultrasonic sand detectors and continuous pipe wall loss monitoring probes to assist with performance evaluations.”
An initial cyclonic trial on a legacy well in the first quarter of 2020 proved successful and, while further trials and reviews are ongoing, the team will transition to a cyclonic design for future wells.