ABSTRACT
The control of multiphase flow corrosion in oil and gas industry is one of the biggest challenging tasks. Since the 1990s, several organizations have established and operated large-scale flow loops to simulate and reproduce the field service environment of oil and gas pipelines. Based on comparison and investigation of the above loops, a new and advanced system, including several four inches internal diameter loops for studying corrosion under multiphase flows, was successfully built by us. By using this system, multiphase flows with various combinations of gas, water, oil and sand can be realized at the highest temperature of 140 °C and the highest pressure of 10 Mpa. Moreover, some loops in this system can adjust pipeline at different angels from 0 to 90°, which allow horizontal/vertical/sloping conditions to be simulated in laboratory. Many advanced measuring and monitoring technologies, such as Particle Imaging Velocimetry (PIV), high speed video camera and LPR/ER probe, are employed for simultaneously recording flow events and corrosion rates. An inhouse plane three-electrode probe is employed for conducting in situ electrochemical measurements. Such technologies would allow deep researching of corrosion behaviors and mechanisms in multiphase flow environments. Moreover, a new software based on Fluent and the existing multiphase corrosion models was developed to realize the numerical simulation of multiphase flow in loop.
As an important technical means for oil and gas transportation, multiphase transportation can greatly reduce the investment of pipeline construction. On the other hand, multiphase pipelines have a stronger applicability in some special areas, such as desert, beach or deep sea, in which it is difficult to install oil/gas or oil/water separation equipment. Based on these advantages, oil/gas/water multiphase transportation has been widely promoted and applied in oil and gas industry. According to incomplete statistics, more than 70% of oil and gas gathering pipelines in China are in two-phase or three-phase flow operation. However, multiphase transportation can cause serious multiphase flow corrosion problems, thereby increasing the risk of pipeline failure. How to accurately predict and effectively control the corrosion induced by multiphase flow of oil, gas (CO2, H2S) and water has become one of the biggest challenges for scientists and engineers.
