In this paper we describe a case history of a raging battle against scale deposition in the production system of Tinggi oil field in offshore Terengganu, Malaysia. This field experienced a sharp production decline from 1995 to 1997 at a rate of 26% per year. Scale deposition in various parts of the production system together with sand and emulsion caused widespread equipment/instruments failure, valves/chokes malfunction and most importantly severe piping restrictions at various points of the entire production system, surface and subsurface. A facilities capacity review study was conducted in order to differentiate between real facilities bottlenecks and scaled up restrictions. Pin pointing all the scaled up bottlenecks was quite a challenge. Diagnosis methods included visual inspection, pressure drop comparison, temperature sensing and gamma ray scanning. All scaled up points were successfully detected and cleaned up. As a result of this work together with sand, emulsion control and other production optimization efforts, oil production started to pick up by mid 1998. Production increased by 64% within a year with a total gain of 3.7 MSTB/d.
A comprehensive scale management plan was put together, both short term and long term. Routine scale cleanup, identification of scale-prone source reservoir and its management, scale inhibitor chemical injection program, routine stroking of control valves, scale buildup monitoring program of surface flowlines are some of the short term measures taken. Amongst long term measures, a study of effectiveness of Magnetic Fluid Conditioners (MFC) has been initiated. One commercial magnetic tool has been tried so far, with no benefit observed. While long term study continues, short term measures have brought the situation completely under control.