Message in a Bottle: Tracing Production from Zone to Wellhead

Although operators always want more data about their production, getting inflow production information isn’t easy. Historically, it has required shutting in a well or using intervention equipment.

Both methods are problematic in their own ways. Operators don’t want to shut down production if they can avoid it and using intervention equipment affects the flow.

“When you convey intervention technology with a tool in hole and you try to measure flow, it's actually creating a huge choke back in your well, so that your inflow measurement from a mechanical system is not actually giving you a true flow indication from the bottom of your well,” RESMAN Energy Technology CEO Bonnie Powell told Hart Energy.

In a bid to provide on-demand production data while a well is still online, Olaf Huseby, RESMAN’s chief physicist and vice president of production, developed a new way to use information generated by production tracers capable of tracking oil, gas and water.

“It’s like measurement while producing [MWP],” Powell said. “You no longer have to shut in the well to get inflow production data.”

Existing RESMAN tracers were previously aggregated near installation points and flowed with the well fluids.

“We needed to be able to look at time differences of the arrival of these tracers,” Huseby said. “You can measure the time it takes to move to the surface, and then the time difference and the volume of the well gives you the flow rate. And that's still a valid method, and that method works for all wells.”

But, he said, by looking at the phase of concentrations in each tracer collection bottle, it’s possible to compare concentrations directly. 

“It's really a combination of new operational procedures and interpretation insights combined with the previous systems,” Huseby said, noting some of those insights were built on the back of capabilities brought by RESMAN’s 2018 acquisition of Restrack.

Collection bottles are first filled with production fluid at the wellhead. Sensitive and sophisticated machines then measure and analyze the bottle’s contents, seeking the presence of the unique tracer for each zone down to parts per trillion.

Repeating the analysis at intervals creates time-lapse production data for the field.

“If you do that in every production well in the field, you have a complete understanding of the inflow of oil and water along every section of the well throughout the field,” Huseby said. “And you have that every time you take a sample. So that really gives a four dimensional view of the reservoir.”

The tracer chemistry, Powell noted, is installed into the completions equipment before it’s deployed downhole.

“No electronics, no connectivity, no batteries, just chemistry,” she said. “A tracer is simple, right? It follows the water; it follows the gas … so it moves with the reservoir. So essentially what it's doing is, it is using the natural energy of your reservoir to carry the data about your production to the surface into a bottle. And then from this bottle we can count the unique fingerprint from each zone and then therefore quantify your production without any intervention.”

The new MWP method has been deployed on more than 20 wells, including, in 2020, a ConocoPhillips’ well in the Eldfisk Field in the North Sea.

Powell said RESMAN deployed the polymer chemistry-based technology on a ConocoPhillips well monthly and obtained inflow production data without disturbing production and at minimum cost. The footprint? A bottle, which collects the tracer at the wellhead. And at a monthly interval, it provides data for tracking the well over time.

“It’s on-demand PLT 4D with a simple bottle, and it also gives you a true undisturbed measurement in understanding of your production by zone,” she said.

Powell said the method allows for diagnostic actions to ensure intervention can optimize production.

“If you want to know what's wrong with your heart today in oil and gas, you have to have an open heart surgery, mechanically push something in hole to figure out where the water's coming from and manage your production. Imagine now you can get a scan without any risks and get it on demand and then when you have a surgery, you're just actually fixing things,” Powell said.

In addition, she said, the technology can validate if an intelligent completion is functioning correctly.

Typically, the solution is installed on new wells because the tracer is initially installed when the completion is run, but RESMAN is working on a retrofit version, Huseby said.

He said RESMAN is also expanding the capabilities of the tech and offering it to more customers. 

“Improvements on the technology side, hotter, higher pressure, more types of wells, et cetera. And also really expanding beyond oil and gas,” he said.

And because tracer methods in general are generic as long as there is a phase of interest, such as CO₂, it’s possible to track that phase using the same methodology, he said.