Offline Production Tree Installation: Key Decisions, Value Drivers and Lessons Learnt

Abstract After successfully drilling and completing 40 wells with 5000 psi rated production trees in the swamp operation within a 5-year campaign the diverter deck on the Swamp Rig barge never posed a challenge until 6650 psi production tree had to be installed on two non-associated gas wells. The Field Development Plan (FDP) was approved in 2013 and it contained a 2-well (NAG-1A and NAG-2A) development plan for the target reservoirs with estimated recovery of 213 BCF of rich gas and 4.6 MMSTB of pool condensate at initial production rates of 35 MMSCFD and 1,380 BCPD each for both wells. Gas production from these wells will bulk flow to the NAG separator located at the Production Flow Station where the pool condensate will be separated from it. The rich gas will subsequently be transported to the gas plant onshore bypass for supply to the domestic market through the ELPS. NAG-1A and NAG-2A wells are part of the Non-Associated Gas (NAG) development and were completed as single string deviated gas producers with HRWP completions to meet target production rates and reserve recovery. After successfully drilling and completing the NAG-1A well, it was later discovered that the diverter deck of the rig was going to impact the 6650 psi production tree while moving the rig onto the NAG-2A well slot on the same jacket. This paper sets out to give an overview of the planning, risks assessment and execution for using a crane barge to successfully install two 6650 psi production trees on two NAG wells incidents free, after the drilling rig departed location due to the diverter deck limitation. Lessons learned and best practices were captured as well as the resultant cost savings from using the crane barge instead of the rig to install the production trees on the two NAG wells. The total number of days to complete the offline XMT installation using a crane barge was 5 days for both wells while working daylight hours only. This resulted in a cost savings of 154,200 USD per well.