LockJar^®
Mono-Conductor Cased Hole
Electric Wireline Jar

A mono-conductor electric wireline LockJar was introduced in 2000 for cased-hole logging and perforating applications. The mono-conductor LockJar solved most of the functional limitations of mechanical jars, including downhole reliability both as a jarring device and power transmitter.

The mono-conductor LockJar, which has proven extremely effective for through-tubing perforating and setting bridge plugs, is hydraulically actuated and is equipped with a mechanical lock that can be manually adjusted during shop assembly to trigger activation with a pull from surface of 500 lbs or more. A hydraulic time delay mechanism allows the operator to pull the logging string through a tight spot without activating the jar, as long as the wireline tension is released before the time delay is surpassed.

In a typical wireline logging string, the mono-conductor LockJar is placed immediately above the logging or perforating tools, can be activated multiple times on every run, and requires very little maintenance.

The mono-conductor LockJar is pressure balanced to prevent collapse in the well bore, and internal parts - including the jar mechanism and the conductive path - are completely sealed and segregated from the well bore, preventing exposure to down hole fluids, reducing wear and corrosion thus increasing reliability. The hydraulic time delay is not temperature or pressure-sensitive, and the single conductor unit is designed to function in reservoir temperatures of up to 400 degrees Fahrenheit and pressures as great as 25,000 psi.

The reliability of the mono-conductor LockJar has been excellent, with no down hole failures reported in more than four years of commercial availability.