Dual / Multi Diameter
Electronic Gauging and Caliper Pig
The multi-diameter electronic gauging and caliper pig is primarily intended for gauging multi-diameter subsea pipelines, which cannot be gauged using standard gauge plates or smart gauge tools. For instance, it provides a unique solution to the challenge posed in gauging a pipeline section that is only accessible through a thick-walled, smaller internal diameter section. It will gauge all the sections of a multi-bore installation in one pass. Virtual gauge plate dimensions are stored in the memory of the data logging system and these are compared to the calibrated responses from the calliper sensors. A ‘hit’ on any of the virtual gauge plates triggers an acoustic pinger response, which remotely indicates which of the 'plates' has been ‘hit’. At the end of the run, the pinger can be interrogated to determine the status of the pipeline and, if required, the pig can be retrieved for access to the data logged during the run. The multi-channel caliper data can then be offloaded and analysed to determine the location and profile of any restrictions in the line.
As well as having the unique functionality described above, the tool is highly appropriate for general caliper work.
Key Design Features:
- Up to 4 pipe nominal bores can be gauged in one pass.
- During set-up, the user enters the pipe diameters to be gauged and pre-sets the gauge plate diameters for each pipe diameter.
- During the run, the tool carries out real time measurement of the pipe bore, in standard units, and determines the local pipe diameter to allow selection of the appropriate pre-set gauge parameter for the current pipe section.
- If any of the diameters measured by the caliper arms fall below the notional Gauge Plate diameter then a ‘hit’ on the virtual gauge plate is recorded, triggering an acoustic pinger response.
- Each size of virtual gauge plate encodes a different pattern in the pinger transmission sequence and, at the end of the run, this sequence can be decoded to determine in which of the sections, if any, a 'hit' occurred.
Typically the Remote Indicating Caliper will be run into the subsea receiver where it will transmit the pinger code appropriate to the virtual gauge plates which have been hit. A hydrophone placed on the outside of the receiver can be used to pick up the pinger information and transmit it to the surface. If no hits have occurred, the operator can decide to leave the caliper tool in the receiver for recovery at a later time (date), when a suitable vessel is available. If the pinger indicates that hits have occurred, then the caliper can be recovered to the surface for data offload and analysis.
For more information on Dual / multi-diameter electronic gauging and caliper pig applications see the Case History section.