GEO PSI Downhole Cable History

A look at our first 12 years of innovation, achievement, and excellence in downhole TEC manufacturing

Follow along as we highlight some of the products and manufacturing milestones of our companies downhole cable history.

What is TEC?

TEC is an abbreviation for Tubing Encapsulated Cable.

TEC cables are predominantly used in the oil and gas sector for providing power to downhole instrumentation and returning signal to the surface. TEC is a metal armored and welded signal cable that is designed to withstand harsh downhole environments. It’s typically offered in Stainless Steel 316L and Incoloy 825 metallurgies.

Here at GEO PSI we manufacture our own TEC in-house and have brought innovations that have set new industry standards for downhole cable performance and reliability. Take a look at this timeline of our cable history below.


Figure 1: GEO PSI Downhole Cable History Timeline



4mm (0.160”) Single Conductor TEC, Bare and optional 11mm Square Encapsulated 125°C Polyethylene Insulation

The first introduction of our industry-leading 4mm cable. Primary applications include Downhole Monitoring and Wellbore Suspended SRO’s.



4mm (0.160”) Single Conductor TEC, Bare and optional 11mm Square Encapsulated 150°C Polypropylene Insulation

With the introduction of our new higher-temp insulation users could achieve greater reliability at elevated temperatures. Primary applications include Downhole Monitoring and Wellbore Suspended SRO’s.



4mm (0.160”) PFA Insulated Type K Duplex Thermocouples 300°C

With the introduction of our industry-first PFA insulated Type K Thermocouples, we achieved greater reliability and ease of installation in the field compared to traditional MICA insulated cables. Primary applications are distributed wellbore temperature measurement for geothermal and SAGD and downhole heater process control.


4mm (0.160”) PFA Insulated Type K Redundant Single Point Thermocouple 300°C

The redundant measurement of these Type K Thermocouples ensures reliability and accuracy for end users. Primary applications are distributed wellbore temperature measurement for geothermal and SAGD and downhole heater process control.



4mm (0.160”) Torch Line 600°C TEC with MICA Insulation

This specialty TEC cable is designed specifically to withstand extreme heat. Primary applications are for instrumentation installed in extreme temperature applications such as downhole combustion or industrial furnaces.


4mm (0.160”) Quad Conductor PTFE TEC 260°C

Our first high-temp TEC product with 4 conductors. Primary applications are for high-temperature downhole pressure temperature sensors such as Piezometers.

4mm (0.160”) Quad Conductor PFA TEC 300°C

Increased temperature rating of our four-conductor cable to 300°C for higher temperature downhole wellbores.


4mm (0.160”) Single Conductor TEC, Bare and optional 11mm Round Encapsulated 200°C TEFCEL Insulation

The first introduction of our far superior round encapsulation offering greater strength, easier spooling, all in a lighter package. Primary applications include Downhole Monitoring and Wellbore Suspended SRO’s.



4mm (0.160”) Kevlar / Aramid-Reinforced TEC. The genesis of GEO PSI’s eSlickline™

This .160” slickline cable with a conductor inside of it is compatible with all major eline tools and telemetry systems. Primary applications include Downhole Production Logging, Camera’s, Light  Duty mechanical slickline, and Perforating.



4mm (0.160”) Quad Conductor 300°C Optimized for new High-Temp GEOTRU Pressure and Temperature Gauges

With the launch of our ground-breaking GEOTRU gauges, we further optimized our quadline cable for reliability at extreme temperatures. Designed exclusively for our ultra-high temperature GEOTRU 300 downhole pressure and temperature gauge which is installed in SAGD and Geothermal wells around the world.


0.250” 6 Point Type K 300°C Thermocouple Bundle

Our new bundling capability enabled us to manufacture a dedicated thermocouple line designed to measure 6 different temperature points in a wellbore. The primary applications are SAGD and Geothermal wells.



0.375” 18 Point, 19 Conductor Type K 300°C Thermocouple Bundle

We expanded our bundling capability even further enabling us to manufacture a dedicated thermocouple line designed to measure 18 different temperature points in a wellbore. The primary applications are SAGD and Geothermal wells.


4mm (0.160”) 3 Point Type K 300°C Thermocouple Bundle

A multi-point thermocouple bundle designed to maintain a slim 4mm OD. The primary applications are SAGD and Geothermal wells.


4mm (0.160”) Single-Mode, Multi-Mode, and Combo Fiber Optic Cables

Our first dedicated Fiber Optic cables designed for permanent install. The primary applications include wireline, and coiled tubing wellbore interventions.


0.250” and 0.375” Capillary Tube in Duplex 2205, Stainless Steel 316L, and Incoloy 825

Our first 0.25″ and 0.375″ Capillary Tube. Utilizing our expertise from nearly a decade of manufacturing the industry’s best 4mm TEC these products are made in-house adhering to our strict quality control measures. They mare ideal for chemical injection and fiber optic pump down applications.



Flat Pack Downhole Cable Manufacturing

We expanded the capability of our manufacturing facility to produce Flat Packs. These encapsulated bundles can include any or all of the following: TEC, Capillary Cable, and Strength Membranes. These are ideal for offshore or cemented in downhole monitoring systems.



0.375” ESP Cable TEC, 5000V #4 Conductor

We designed a revolutionary ESP cable that eliminates EPDM insulation that breaks down over time. Our ESP TEC is designed to improve run time and simplify motor lead and wellhead penetrator connections.

The Challenges With 0.25" TEC

Before GEO PSI was created our founders had their doubts as to if 0.25” TEC is really the best format for downhole monitoring. Due to a number of handling issues they wondered why 0.25” became the industry standard for TEC in the first place.

Our senior management team had previously installed hundreds of wells with 1/4” TEC. One of the problems that we encountered with 0.25” TEC is differential tension from the inside to the outside of the cable. We used to receive ¼” TEC and the conductor that had recessed inside the outer steel tube. Furthermore, when the TEC is unwound and installed into a warm well – we lost connection several times for the same reason.

In the early 2000s, customers were looking for ways to install TEC inside the tubing as a suspended hang-off system. Due to its stiffness ¼” TEC is difficult to work with for this type of service. We needed huge shives and even contemplated purchasing a capillary injection system.

4mm (0.160”) OD – The New Standard For TEC

Our senior management team began to wonder… Is there a better alternative?

They experimented with different sizes of metal tubes until they came across the perfect solution. 4mm (0.160”) with an 0.030” wall thickness.

Not only did we match the tensile strength of ¼” TEC, but we exceeded the crush force rating by a considerable margin. Our 4mm (0.160”) TEC with 0.030” wall thickness has >40% more crush tolerance than ¼” TEC with 0.049” wall thickness.

Other problems went away too. By removing the unnecessary plastic filler and proprietary manufacturing techniques, we eliminated problems caused by differential tension from the inside to the outside of the cable. No more conductor shrinkage!!

Reducing the diameter to 0.160” was well received by the market due in large part to its flexibility. It became easy to install permanent downhole gauges in wellbores that didn’t have ported tubing hangers. We can easily exit our TEC out of the casing bowl through the 2” flow line.

Even better, we help energy companies by providing extra wraps of cable underneath the tubing hanger so that pull and re-runs of completions do not require a splice.

Most importantly the reduced diameter opened the market for hang-off / suspended gauges inside of tubing. Because 4mm (0.160”) is a common slickline size, our customers suddenly had access to a wide variety of BOP’s and Pack Offs that were commonly used in the marketplace. We opened the market and have hang off gauges inside of tubing up to 5,000 meters deep.

We were then able to find partners to help us launch our eSlickline™ platform. eSlickline™ is compatible with all the leading eline tools and telemetries. Applications include production logging, downhole cameras, pulse neutron, and light-duty slickline work. Anything is mechanically possible with eSlickline ™ that can be achieved with 0.108″ slickline cable.

Square vs. Round Encapsulation

As business progressed, we began to question other standard industry practices.

A good percentage of TEC is sold with an external protective plastic jacket to add extra bumper protection. We wondered why it was square?

We hired an FEA firm and studied if square was in fact the best shape for crush protection. Surprisingly, we found out that square is a poor choice for bumper protection.

Square shapes radiate force to the middle. Simply put, it causes more damage to TEC instead of protecting it. Round encapsulation, on the other hand, radiates impact force around the outside parameter, protecting the inside TEC. the same theory applies to why Romans used arches in their architecture and bridges.

To learn more about the specific benefits of round vs. square encapsulation we encourage you to read our blog article where we take an in depth look at the many advantages of a round profile.


Thermocouple Bundles

Canada is the largest market for downhole thermocouples installed in SAGD wells.  Previous to our innovations here at GEO PSI, downhole thermocouples were insulated with MICA insulation.

MICA is problematic for several different reasons which we will highlight below. Mainly it’s a poor insulator. As thermocouple cables bend and twist during the install it causes attenuation and negatively affects the accuracy of the reading. Our PFA thermocouples are well insulated and do not suffer from attenuation.

MICA thermocouples are drawn during the manufacturing process and have serious depth limitations. We are able to make 4,500-meter-long thermocouples that are splice free.

MICA cables require brazing for terminations, splices, and surface cable leads. Our PFA thermocouples do not require brazing and very easy to install and terminate.

MICA thermocouples have limited mechanical strength. Our thermocouples have 2,140 lb tensile strength and can withstand > 13,000 # pounds of crush.

To learn more about the benefits of our thermocouples visit the link below.


Our first 12+ years of cable manufacturing have been a fantastic voyage. We have innovated products that have set new standards in our industry, and have continued to expand our manufacturing capability.

Thanks to our customers, we’ve steadily grown our business and look forward to developing many new exciting downhole cables during the next 12 years!

If you would like to know more about any of our cable products we encourage you to contact us.

If youd like to be among the first to know about new innovations we encourage you to subscribe to our newsletter!

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And finally, if you’d like to take a behind the scenes look at our manufactuing facility where all of our TEC is made you can watch this facility walkthrough video!

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