L&TD

DESCRIPTION

The Platinum Resistance Thermometer is used to give a high precision reading of wellbore temperature. It outputs temperature data as a digital word allowing for very high resolution. Because of the small size of the tip it also has a very rapid response time, which minimizes the effects of differing line speeds. It can be run alone, or as part of a string of Production Logging tools.

OPERATING PRINCIPLE

The change of resistance of a length of platinum wire with changing well temperature is used to drive a Voltage Controller Oscillator. The frequency output from the VCO is digitized and encoded on the line. The high thermal conductivity copper tip is isolated with a low thermal conductivity body, which allows for high-resolution measurement even with high differential temperatures between the well fluid and the tool body.

SPECIFICATIONS

Benefits:  

• Indicating productive and injected zones, fluid entry point, leaks.

• Location of fluid movement behind the pipe or casing

• Cement top determination

• Can be used in horizontal/ highly deviated wells.

• It is sensitive with a wide range of fluid flow rates.

When downhole pressure is lower than bubble point pressure, associated gas is released. This gas could result in a temperature anomaly due to Joule – Thomson effect as shown in the plot opposite.

This plot indicates flow behind casing at 240m3/d flow rates.

The temperature curve shows flow behind the casing from 3800m down to 4176-4180m, where it enter the casing.