Benefits Evaluation of Deepwater Intelligent Completion on Three Isolated Productive Zones Offshore Nigeria
- Michele Arena (Schlumberger) | Stefano Di Vincenzo | Massimo Rossi (NAE)
- Document ID
- Society of Petroleum Engineers
- SPE Annual Technical Conference and Exhibition, 19-22 September, Florence, Italy
- Publication Date
- Document Type
- Conference Paper
- 2010. Society of Petroleum Engineers
- 4.5.3 Floating Production Systems, 2.2.2 Perforating, 3.2.5 Produced Sand / Solids Management and Control, 4.5.7 Controls and Umbilicals, 4.6 Natural Gas, 2.4.4 Screen Selection, 5.1.2 Faults and Fracture Characterisation, 3.2.2 Downhole intervention and remediation (including wireline and coiled tubing), 2.4.5 Gravel pack design & evaluation, 1.6 Drilling Operations, 4.1.5 Processing Equipment, 5.7.2 Recovery Factors, 2.4.3 Sand/Solids Control, 7.2.1 Risk, Uncertainty and Risk Assessment, 3 Production and Well Operations, 4.2 Pipelines, Flowlines and Risers, 1.1.2 Authority for expenditures (AFE), 1.7.5 Well Control, 2.4.6 Frac and Pack, 2 Well Completion, 4.5 Offshore Facilities and Subsea Systems, 4.1.2 Separation and Treating
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This paper describes the experience and advantages of both the operator and service company in using Intelligent Completion (IC) technology in deepwater challenging environment. Following a feasibility and risk analysis study performed by the operator, a single well with a triple zone the IC was selected as the best completion solution compared to a dual zone or single wells cluster solutions. The increased cost of this technology was justified by the overall CAPEX project reduction, increment of expected cumulative production and anticipated reservoir's lower layers production.
While two zones IC can be completed with the flow control valves run above the gravel packed zones, the same cannot be done in triple zone IC; in this case, to allow fully independent zonal monitoring and control, two out of three of flow control valves and gauges needs to be run inside the lower zone gravel pack assemblies, bringing a complete new set of interface challenges between the upper and lower completion equipment.
Equipment and procedure's risks were addressed and mitigated through Failure Mode and Effects Criticality Analysis (FMECA) reviews and completion System Integration Test (SIT).
Flow control valve's choke design were also checked, based on the expected production profiles and downhole PVT, to cover the entire production rate and achieve the best draw down applicable.
The well was completed across November and December 2008 with no incident and lost time and the completion solution adopted proved not only to solve all the initial reservoir challenges but also to reduce the number of well interventions, workover costs and risk. The well was successfully started up in February 2009 with a NPV increment of 15% and a reservoir recovery factor increase of 6%.
Eight wells were drilled in this field prior triple zone IC. Well 1, the discovery well, Well 2, Well 3, Well 5 and Well 6, located in Northern lobe, Well 4 and Well 7, located in the Southern lobe; all these wells were drilled in the main level A. Well 8 was drilled in 2005 to further investigate a multi-layer interval within the main field. The well found 3 main levels: A, B and C, all subdivided in many sand lobes.
Following this discovery the well engineers start looking in completion solutions to selectively isolate and monitor, as per Nigerian policy, the three productive zones and, at the same time, to prevent sand production and crossflow from these three layers with different oil and reservoirs properties.
The following objectives and challenges were identified during the field development's feasibility study:
• Well control: Three IC zones fully separated and monitored to be deployed in a single completion run.
• Equipment clearance: Interface and size between the upper and lower completion equipment.
• Zonal allocation: Downhole zonal production allocation as requested by Nigerian law.
• Zonal isolation: For selective zonal monitoring and control.
• Well position: Water depth of 679 m using a Dynamic Position (DP) rig.
The operator internal assessment selected a single deviated well with triple IC and frac pack, producing commingled from all levels, as the best solution suitable for the field development; this completion solution was compared and preferred versus other two solutions: 1) three single wells, each producing from a different level, 2) One single well, producing from level B, plus a dual zones with IC, producing from level A and C.
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