Traditional methods of monitoring the integrity of wellbore tubulars have been able to inspect the first few concentric strings of pipe, but not the outer strings.

“All the strings should be important because we are concerned as much for the outside integrity as we are concerned about the inside integrity,” says Freeman Hill, product manager for well and reservoir surveillance at Halliburton. “Corrosion feeds on itself. Corrosion issues can decimate a well.”

But locating the outer corrosion before leaks occur used to be “fairly impossible,” Hill says. “No one was able to take a look at the outmost pipes because the technology wasn’t there.”

While government regulations dictate minimum inspection intervals in some areas, routinely monitoring the tubulars for integrity can help operators reduce non-productive time and save money by making it easier to plan repairs before a small issue spirals into a major leak.

In October, Halliburton launched the Electromagnetic Pipe Xaminer V (EPX V) service, which the company says can pinpoint casing defects and metal corrosion in up to five tubular strings throughout the well.

Thorough and frequent inspection can help determine if corrosion is taking place at an acceptable rate for the design life of the well or if intervention is called for, Hill says.

“Is it meeting the corrosion rate the customer needs for the well so it can last the required life? Or is it corroding too fast? If it’s too fast, what measures can we put in place to correct it? We can monitor it more often, intervene,” he says. “We can help the customer beat the leak before it gets there.”

INSPECTION: The EPX V with high resolution array and full array sections. Photo: Halliburton

Hill says one of the first questions he hears from prospective clients is whether EPX V service can measure the collars in all the tubulars.

“We see the collars in all the strings. When we show them the fourth and fifth string collars, they know we can measure the metal on them. That tells them this really works,” he says.

Rated to 15,000 psi and 350 degrees Fahrenheit, with an outside diameter of 1-11/16 inches, the tool diagnoses each tubing string using high-definition frequency technology. The technology can run on mono-conductor wireline, Halliburton’s RELAY digital slickline, or on memory using standard slickline or coiled tubing.

Development on what became the EPX V started in 2015. The first deployment was onshore in the US in 2016.

“We had to find new technologies that would work together,” Hill says. “We truly had to innovate.”

The breakthrough came with high-definition frequency technology, Hill says.

“The EPX V uses an array and transmitters that continuously send out the electromagnetic wave in multiple frequencies at the same time. Because it is continuous and we can put power down there on it, we are able to put out the electromagnetic field further out than we were able to do before, so we get signals back from each pipe. It’s a very sophisticated process,” Hill says.

The omnidirectional tool provides more than 100 channels of information about the condition of the tubulars. The EPX V has two sections: a high-resolution shallow section that uses two receivers and one transmitter, and a full-resolution array section with six receivers and one transmitter.

The frequency phase shifts and magnitude of the signal indicate the integrity of the pipe.

“We have so much information on metals. We understand how the frequencies behave in different metal environments, so being able to control the frequencies and have this array is powerful,” Hill says.

The tool can also function in wellbores where the pipes aren’t perfectly aligned.

The 17.5-foot tool can provide details in real-time or run in memory mode. It can be used to monitor the condition of the well or diagnose existing problems. Halliburton can pair its Acoustic Conformation Xaminer (ACX) service, which identifies wellbore leaks, with the EPX V tool.

“If I have a leak on a well and it’s something I think is caused from corrosion, I’d want to run the EPX V so I could see the amount of corrosion,” Hill says. The ACX tool triangulates noise logs to identify the location of leaks.

The tool generates an analysis that summarises the well’s integrity, joint by joint for each tubular, and includes recommendations for remediation.

In one recent deployment, Halliburton ran the EPX V tool for a client and located a five-foot corrosion problem, along with a pair of similar corrosion problems further down the wellbore that might not have been identified using traditional inspection methods. The operator had the option to repair all three problems at once, saving a second intervention.

“Some operators want to know what’s coming and how long they have before it becomes a problem,” Hill says.

In at least one run, EPX V has allowed the operator to correct an existing schematic of the wellbore, Hill says.

“They can see everything now. They’ve been handicapped for a while. Things have changed,” Hill says.