This paper presents a case study of using the dynamic multiphase simulator in planning an offshore well. The drilling engineers expected to encounter some issues that would lead to installing a smaller production liner. The use of the five-inch liner would affect the gas lift valves' location and lead to a shallower operating point of injection, which would not have considerable tolerance for the operational parameter's changes and would reduce lifetime and reserves.

Many scenarios were simulated using a commercial dynamic simulator to support operational planning. The scenarios included keeping the well flowing naturally, installing a gas lift system, using a tail pipe string, and a combination of gas lift and tail pipe. The effect of each decision on the well's abandonment pressure was studied using sensitivity and uncertainty and with near wellbore modeling. In addition, the study simulated the restarting of the well after shut-in under several operating conditions. The restarting options included supporting the gas lift with coiled tubing nitrogen lifting considering different types of killing fluid.

Combining the five-inch liner with a tail-pipe string can be used to restore the original well's lifetime. The study saved the company the cost and time of drilling a new hole. The well’s operating envelope was developed at each operational change to ensure stable production while taking the operational constraints into consideration. Complementing the steady-state gas lift design with dynamic testing enhanced the design and improved the standard procedures of the unloading.

This study brings the significance of dynamic simulations in the overall production cycle: planning to operations. Further, dynamic simulations also help arrive at guidelines for the operators on how to avoid failed start-ups and ensure stable operation. The power of integration between different disciplines is shown through the incorporation of several subsurface and surface information in the uncertainty study.

You can access this article if you purchase or spend a download.