Combined Quartz Pressure and Casing-Collar Locator


Measures pressure and detects changes in metal volume of casing and tubing


  • Controlling depth in casing and tubing
  • Locating severe casing or tubing damage
  • Confirming perforation depths or intervals
  • Measuring the downhole pressure gradient for productivity index, nodal analysis, and drawdown and buildup pressure transient analysis

Features and Benefits

  • The resonant frequency of the crystal and a calibration supplied with the quartz pressure gauge help to create an accurate, high-resolution pressure reading over the wide measurement range.
  • Bellows fitted to the gauge provide isolation from well fluids.
  • A single filtered port provides pressure access, and a second flushing port available during maintenance helps to avoid debris in the filtered port that could alter the measurements.
  • Reduces the total tool-string length for applications with limited rig space, such as offshore operations
  • Can be combined with other Ultrawire™ tools to enable simultaneous measurements and increased operational efficiency

Tool Description

The combined quartz pressure and casing-collar locator (QPC) tool minimizes tool-string length by incorporating two sensors on a single tool body. A quartz gauge measures pressure and temperature while a casing-collar locator detects casing collars and other variations in the casing and tubing.

The quartz pressure gauge uses shaped quartz crystals to obtain measurements. The resonant frequencies of the crystals vary with the applied pressure. The gauge compensates these frequencies for temperature changes in the crystals. Thus, the gauge outputs both pressure and temperature measurements.

The coaxial casing-collar locator uses a pair of rare earth magnets and a single coil to detect changes in the amount of magnetic material around the tool. These variations induce the coil with electromagnetic frequencies, which are processed to produce the log.