Controlled high pressure slurry injection in water jetting applications-a new approach

Abstract

The ability of an abrasive assisted water jet to cut through rocks and metals has potential applications in the oilfield. However, the size of cutting nozzle has not allowed water jet to be used on commercial scale for drilling reservoir rocks down-hole. Inefficient momentum transfer to abrasive particles from pressurized water and lack of abrasive feed rate control in commercially available units has further discouraged the use of water jet in oil industry. Despite various technical difficulties, immense power of water jet cannot be neglected. Studies have shown that momentum transfer can be improved significantly, if abrasive particles are introduced upstream of the nozzle. Limited techniques are available where abrasives are first suspended in a fluid stream and are then introduced in high-pressure water stream upstream of the nozzle. However, control over abrasive feed rate was lacking in past studies. In this investigation, an experimental apparatus was assembled a polymer solution was injected upstream of the nozzle. Injection rate was controlled, by varying the rpm of the plunger pump. The apparatus was used to study the effect of Xanthan and Polyacrylamide on water jet coherency. It is shown that addition of polymer leads to a focused water jet for a longer distance before it starts disintegrating into a mist. Furthermore, there is an optimum concentration of polymer at which the jet stays focused for the longest distance.