After extensive tubing stress analysis using Schlumberger TDAS* tubular design and analysis system software, a new stinger with anchor mechanism was designed to maintain the inner tubing string seal even when the outer tubing string moves. Engineers also recommended a longer tailpipe seal assembly to locate into the lower completion and accommodate potential relative tubing movements. In addition, new flow crossover, pod, and cable penetrators were developed to accommodate the expected differential pressures.
Before running the system into the first KOC well, Schlumberger performed a system integration test (SIT) in a test well to verify equipment functionality and optimize the assembly procedure.
Simultaneous production and injection eliminate dedicated injector wells
The first system was installed in early 2017. Since then, several systems have been installed, some in wells with the injection zone above the production zone and some with the zones reversed.
Initially the systems were operated in ESP-only mode while the surface injection flowlines were installed. The ESPs were operational for 3 months with stable production of approximately 2,300 bbl/d before injection commenced. As injection started in the first two wells, the ESPs continued to operate at the same rate and zonal isolation was maintained.
The system has proved that ESP production with simultaneous injection into another zone in the same well is possible. Eliminating the need to drill two separate injection wells saved approximately USD 2 million to 2.5 million per well and freed up drilling equipment for more high-value work.