Field Pigging Modeling for Predicting Wax Breaking Force and Wax Removal Efficiency of Disk Pig

Abstract

Summary Pigging technology is the most common and cost-effective method for wax deposition remediation, but the inability to accurately predict the pigging parameters during the field pigging process causes pipe plugging incidents to occur from time to time. This study developed a theoretical model that incorporates the rheomalaxis elastoviscoplasticity (REVP) of the wax deposit. The concepts of dynamic and static yield stresses were introduced to determine the maximum shear stress in two shear states. The proposed model can accurately estimate the wax breaking force (WBF) and the wax removal efficiency (WRE) under various pigging conditions, according to the experimental results and published data. In addition, the indoor pigging experiments revealed for the first time that a higher pigging speed could increase the WBF while reducing the WRE of the disk pig. The model interpreted these experimental results as a consequence of the rheological behavior of the wax deposit (i.e., the increase in the ramp rate of the shear rate leads to higher dynamic yield stress).