Applications of cavitating jets to radioactive scale cleaning in pipes

Abstract

Deposition of scale inside wellbores is causing millions of dollars in damage every year. Any water production or injection in the gas or oil well is creating a possibility of scale formation. It can reduce formation porosity and permeability, it can block flow in the pipes, and it can damage downhole completion equipment. Some mineral scales such as calcium carbonate (CaCO3) can be dissolved with acids but common hard scales such as barium sulfate (BaSO4) are extremely resistant to both chemical and mechanical removal.Another scale problem is natural radionuclides which are contained in rocks and are carried out on the surface during oil production. The cleaning of radioactive scale, is a very complicated and expensive process. In some cases, it is even easier to replace the pipes than to clean depositions of radioactive barium sulfate which generates accumulation of radioactive materials in storage fields.In the current study cavitating jets were used to remove barium sulfate scale from pipes and detailed experimental procedures for cavitating nozzles design and testing were shown. Optimal combination of hydrodynamic nozzles was defined and tested in the field. It was shown that designed combination of hydrodynamic nozzles significantly improved scale removal process.