Abnormal production decline causes concerns like high operating cost, premature field abandonment resulting in reserves loss and staff demoralisation, all of which have an adverse effect on an E&P company. Operational problems like high sand & emulsion, high scale deposition in the production system adds to the normal challenges of an aging field, making decline analysis more complicated where actual reservoir production decline gets masked by non-reservoir factors. Overcoming all these operational challenges as well as natural production decline calls for innovative thinking and a holistic approach, especially because all the interrelated problems need to be addressed simultaneously and that too sometimes with insufficient data. Reservoir productivity, tubing and surface facilities performances must be optimised as an integrated system. Otherwise, isolated efforts at various parts of the production system are bound to give poor results.

In this paper we describe a case history of an integrated production optimisation effort undertaken on Tinggi field in offshore Terengganu, Malaysia. The field suffers from operational problems like sand, emulsion and scale resulting in widespread equipment malfunction, measurement problems, erosion of valves, chokes, orifices etc. Production declined sharply at a rate of about 26% per year over 1994 to 1997. In early 1998 it was producing 5.8 MSTB/d of oil with a water cut of about 90%. A multidisciplinary team was then formed in order to mitigate this sharp decline which threatened the viability of the field's operations. The team took an innovative approach in coming up with practical and cost effective solutions by studying all the problems and their correlation. All the key operations personnel were interviewed in order to gather information vital to diagnose all the problems systematically. Despite lack of sufficient good quality data (caused by operational problems) the team came up with solutions, implementation of which were gradual and phased, in order to minimize risk in the face of many uncertainties. Production started picking up immediately and the field's current production is 9.5 MSTB/d (in June 1999) with further production gain yet to be realized through additional perforations campaign targeted in October 1999. Most of the earlier solutions were implemented at minimal additional cost. The company plans to extend the result of this study to other fields in a more proactive manner.

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