Recovery of Bypassed Reserves Above Top Packer Using Innovative Cement Packer and Through-Tubing Perforation
West Lutong is a mature field with 8 rounds of field development campaigns and close to 40 years of production. Currently, only 50% of total strings are flowing. However, the idle wells could possibly access undeveloped marginal reserves in shallow reservoirs. These shallow reserves are located above top production packer as they were not previously included in initial completion due to historical sand problem
Following West Lutong Full Field Review in 2006, presence of by passed potential reserves above top production packer were confirmed. Conventional workover rig to re-complete these potentials is not economically viable due to significant cost and complexity. An innovative, rigless "cement packer?? approach, had been chosen for the pilot job in Well # A, while retaining necessary level of completion integrity .The proper placement of cement packer approach involves usage of hydrostatic sequence valve as choke manifold to prevent U tube effect. Numerous down hole problems such as wax, scale, sand and fish from insert string had been rectified using appropriate coiled tubing solutions. Conventional E-line perforation using high density shot gun and deep penetrating charges were then used.
Well # A had been producing, under controlled condition, average 930 bopd without sand problem for 10 months since July 2008 with 1.10 MMstb reserves monetized.The total cost was only 10% of a conventional workover.
This paper shares a detailed case study of Well # A in term of candidate's selection, reserves estimation, cement packer execution, lessons learnt, and future recommendations. It is evident that cement packer technology is feasible and economic for accessing by passed reserves above existing production packer.