JUMPER

A jumper for insuring electrical or fluid communication between the liner and the casing of an oil field downhole. The jumper has a first tubing adapted to be inserted in the liner, a second tubing adapted to be inserted in the casing and an anchor adapted to be rigidly mounted in the casing. The first and second tubings are composed of an electrically conductive material and are supported by the anchor with an insulated joint. Each of the first and second tubings has a plurality of centering devices, each consisting of a pair of rings surrounding the tubing and an array of bowed springs bridging between the rings and biased to bow outwardly from the tubing into engagement with the inner circumference liner or the casing, as the case may be. One of the two rings is electrically connected to the tubing, for example by welding, whereas the other ring is free to be displaced longitudinally of the tubing so that the outer diameter of the array of bowed springs may expand or contract, as needed. Each bowed spring in the array is provided with a series of electrical contacts which insure electrical conductivity between the welded ring and the surrounding liner or casing through the bowed spring.