Abstract
In this age of multi-zone and multilateral wells, existing technologies are always challenged to achieve desired results. In the case of Statoil Skinfaks/Rimfaks (SRI) wells, capabilities of intelligent completion systems were stretched to the limit. Some of the challenges included depth, system optimization, feedback monitoring, subsea logic, placement of downhole hydraulic logic switches, hydraulic timing, cross flow design due to limited control lines, development of an auxiliary logic switch, etc. Operational requirements also pushed downhole tools like the flow control valves and logic switches in a novel and previously untried configuration. System operation logic mandated the design of a very complex hydraulic circuit.
Cross flow design with limited control lines proved to be a significant challenge. Each of the wells had three zones to be controlled. The existing subsea trees allowed only three hydraulic control lines. Three balanced piston flow control valves normally require at least four control lines to be operated. A new system was to be developed to be able to control all three balanced piston valves with only three hydraulic control lines.
This paper will present how a combination of analytical modeling, simulation and laboratory testing was used to overcome these and other design challenges during the system development phase. This novel methodology will aid the optimization and reduction in design cycle time of future intelligent completion systems. Four wells in the Statoil Skinfaks/Rimfaks Improved Oil Recovery Project were completed with intelligent systems in 2007. Thorough planning and execution yielded higher operational efficiency which resulted in job completion ahead of schedule. The installation phase will be discussed in the paper with special emphasis on pre-job planning, operational procedures, post-job results and lessons learned.