CA7 — Centering Adjustable Taxi for 7in

The CA7 is a slip over Roller with a 3-5/8” bore designed to centre wireline tools across the range of 7” casings.

A ground-up analysis of centralization mechanics and current logging applications led to the revolutionary architecture of the CA7.

Despite the compact design (9.7” /13lbs) the device has the capability to centralise 260lbf in a horizontal well. In deviated wells this high load capacity is very important. Note that at only 50deg deviation a centraliser must support 77% of toolstring weight. The CA7 can be placed between the Transmitter and Receiver on Sonic Logging tools, exactly where centralization is required.

The maximum diameter of the device can be easily pre-set by the user to suit casing weight. Once set, the rollers will keep this maximum OD. This feature prevents toolstring hold-up at casing joints or the BOP stack. It also ensures that the load carried by the wheels, and thus bearing friction, is only that required to support the toolstring with no additional loads due to centraliser spring force

In addition, the CA7 can collapse to its minimum designed diameter to enable the toolstring to pass through restrictions such as a cement sheath.

The CA7 incorporates Petromac’s unique bearing technology which has enabled our family of devices to descend by gravity to world-record deviations.

Petromac’s recommends setting the device OD to “Casing Drift”, within 0.07in of casing centreline. Casing weights are annotated on the device for ease of adjustment (Paper# 21206, International Petroleum Technology Conference 2021)

Device diameter is set to the nominal Drift ID of the 7” casing by rotating the adjustment bolt until the slider is set the middle of the corresponding casing weight mark.

By setting the device diameter to “Casing drift”, drag is reduced as centraliser spring force is not converted into friction. This setup is possible as the CA7 can carry its full load capacity in two of the six roller arms.