Prevention of Downhole Scale Deposition in the Ninian Field

This paper reports on conventional adsorption scale-inhibitor squeezes and newer equilibrium squeezes that have successfully prevented downhole scale at the Ninian field. A mathematical model matched or underpredicted the lifetime of the adsorption squeezes. Underprediction probably resulted from the exclusion of real phenomena, such as fluid crossflow and inhibitor precipitation. Both the model and the field data suggest that the most important design factor that determines squeeze life is the total amount of scale inhibitor injected. Equilibrium squeezes use a unique product that yields a longer treatment lifetime when designed properly. This process is more difficult to implement; it requires careful planning and quality control to be successful.