Paper: A New Self-Decentralizing Hydra-Jet Tool

The use of a fluid containing an abrasive for perforating casing and cleaning open hole has been an established technique for many years. Generally, the jetting tool is installed on tubing along with a collar locator, tubing hold-down, centralizer, and in some instances an anchor swivel. The tool is then lowered to the desired perforating or jetting depth to be cleaned. Perforating or jetting operations are initiated by pumping the abrasive fluid into the tubing conductor, then to the jet body, and out the jet nozzles at relatively high differential pressure on to the surface or surfaces to be cut or penetrated. Conversion of the pressure into kinetic energy imparts high velocity to the abrasive particles, which upon impact with the formation face or casing wall will erode the material in an organized pattern. A prime deterrent to effective hydraulic perforating an openhole section in an old well is the extended stand-off distance at which the perforating or jetting operation must be performed. This condition is particularly aggravated and critical in "shot" holes and openhole sections which have been previously acidized or fractured and have since become scaled or plugged. The purpose of this paper is to present a self-decentralizing hydraulic perforating tool which produces unbalanced forces and which, when coupled with a flexible fluid conductor, will provide a novel combination resulting in near zero stand-off hydraulic perforating conditions for improved effectiveness in perforating or penetrating a formation face in open hole. A sketch and general operating procedure plus some equations involved in development and several pertinent to its effectiveness for penetrating rock or scale are set forth. In general, this discussion is presented along operational lines and is substantiated by test target results, pictures, and after treatment responses. These results present concrete evidence, confirmed by representatives of various oil companies in West Texas and Southeast New Mexico that the successful development of the tool for perforating or penetrating formations in open hole or "shot" hole is an accomplished fact, and that this process can be relied on to penetrate rock or scale.