The Influence of Corrosion Inhibitor / Scale Inhibitor Interference on the Selection of Chemical Treatments Under Harsh (HP/HT/HS) Reservoir Conditions

Abstract

The challenges of scale and corrosion control in a number of new HT/HP fields in the North Sea, such as the Heron cluster wells in the ETAP (Eastern Trough Area Project) development, are substantially more severe than those normally encountered. The extreme reservoir conditions (T > 175 °C, P ~13,500 psi, TDS > 350,000 mg/L), depths (~ 5 km) and the need for long tiebacks (26 km) along the sea bed, give rise to very large temperature and pressure changes throughout the production system. The high temperature and extreme water chemistries lead to faster scale nucleation and growth kinetics, and to a very severe corrosion potential, which is further exacerbated by the high flow velocities (> 25 m/s) and high shear stress (>500 Pa) experienced in the flow lines. Engineering foresight during the project development stages of this reservoir have successfully reduced the potential scale and corrosion challenges, for example by: •use of de-sulphated wash-water (DSSW) to reduce sulphate scaling potential;▪use of high chrome steel production tubulars to reduce corrosion potentialSuch