Sometimes size does matter.
Introducing The GEOP 150 Slim
Our GEOP 127 Slim downhole gauge is the world’s smallest real-time downhole pressure and temperature monitoring tool.
With an industry-leading 0.5” OD and 8.375” length there is simply no competition for accurate real-time downhole measurement in tight spaces.
Miniaturization Without Compromise
The GEOP 127 Slim features a 0.5” OD and 8.375” length including the tubular encapsulated cable (TEC) connection.
Our talented engineering team successfully tackled the challenge of reducing the size of the printed circuit board without compromising any of the smart technologies found in other GEO PSI real-time downhole gauges. This means that in spite of its incredibly small package users can still enjoy the industry leading reliability they have come to expect from GEO PSI downhole gauges, and the live transmitting of:
- Device Configuration
- Device health
- Downhole head Voltage
- Current
- Calibration Files
- Downhole Serial Number Identity
Mechanically, the gauge is constructed with either Stainless Steel 316L or Inconel 718 for corrosive applications, and there are no elastomer seals which greatly extends operational life of the gauge.
The transducer is welded to the gauge body, and the TEC seals with our patented Easy-ConnectTM Cablehead system which features highly reliable metal-to-metal compression fittings.
The GEOP 127 Slim has a pressure rating of 6,000 psi, a full scale accuracy of +/-0.05%, a sample rate of up to 10 times per second, and a temperature rating of 150°C. This versatility and accuracy makes the gauge a suitable option for a wide variety of different applications and depths.
In spite of its compact package it has easily passed our rigorous vibration tests. This includes random vibrations @ 10 G’s up to 2,000 Hz, 80G shock tests on X, Y,Z axis’s, and 500G impact tests.
To summarize, we here at GEO PSI have achieved full scale performance in an incredibly small package.

Figure 1: GEOP 127 Slim Downhole Gauge
Applications
The most obvious application for a specialty tool like the GEOP 127 Slim is slim hole calculations such as 2.875” tubing inside 4.5” casing.
Other applications where the GEOP 127 Slim makes sense include:
- Coiled Tubing Pump Down
- Intelligent Coil Strings
- Casing Liners
- Cemented In Operations Where Drill Bit Size & Casing OD Do Not Accommodate Larger Sized Gauges
- Wellbore Or PVC Suspended Applications
Wellbore Suspended ½” FNPT Wellhead Opening

Figure 2: Wellbore Suspended 1/2″ FNPT Wellhead Opening Demo
The example shown is a water well with no surface pressure. The GEOP 127 Slim is installed through a ½” opening on the wellhead.
Coiled Tubing Inteligent String

Figure 3: 3/4″ Coiled Tubing Intelligent String
The GEOP 150 Slim can be deployed in 3/4″ or other sized coiled tubing intelligent string completions. The 0.5″ OD gauge and downhole instrumentation cable are pumped down through the coil.
Cemented In Casing Systems

Figure 4: Cemented In Casing System Graphic
Reducing the drill bit size on cemented in casing systems to accommodate casing and downhole measurement related equipment can save time and money.
Summary
The GEOP 127 Slim is a specialty gauge and an important piece of our comprehensive arsenal of downhole monitoring solutions.
It’s engineered for tight spaces without compromising data accuracy and resolution or impeding mechanical performance.
If you have a slim hole completion or unique application where a 0.5″ OD gauge could be of use we encourage you to contact us and we would be happy to share more about this specialty solution.