Large-Scale Pipe Flow Experiments for the Evaluation of Nonchemical Solutions for Calcium Carbonate Scaling Inhibition and Control

Abstract

Summary Inorganic scaling is a phenomenon of common occurrence both in nature and in industrial operations. In general, its effects can be highly detrimental for the oil industry, as fouling can take place in different stages of the production, from the wellbore and downhole production control valves to upstream primary oil processing and separation equipment. The deposition of precipitated crystals on pipe walls and valves can result in severe production decline. Despite the high costs involved in the design and operation of separate lines for additive injection, chemical inhibition is typically the solution adopted by the oil companies to mitigate scaling. The purpose of the present work is to show the results of large-scale laboratory pipe flow experiments to evaluate the performance of nonchemical solutions to mitigate and control calcium carbonate scaling. Magnetic, electromagnetic, and ultrasound devices have been tested in a setup that simulates the mixing of two incompatible brine solutions that cause precipitation and deposition of calcium carbonate for a high Reynolds number pipe flow. The performance of the devices is evaluated from pressure drop measurements along the pipe, carbonate deposited mass on the pipe wall, and pipe diameter reduction. Additional results include evaluation of particle-size distribution of precipitated crystals, scanning electron microscopy, X-ray diffraction analysis for identification of the crystalline structure, and pH and conductivity. Results show that the magnetic field furnishes a beneficial effect, as it delays the time observed for the onset of flow restriction in both pipe and valve. The use of a magnetic field slows down scaling, thus delaying the increase in pressure drop. The time scale associated with this delay is of two to four times the required time in tests carried out without a magnetic field. Ultrasound devices are also shown to provide a beneficial impact on the delay of the appearance of scaling effects. An ultrasound field influences the precipitation phenomena, inducing particle sizes to be kept at very small values, an effect that prevents crystal deposition. The main contribution of the present work is to provide an evaluation method of antiscaling devices based on large-scale experiments that are representative of real field applications.