Abstract
Monobore completions are an efficient way to exploit multilayer reservoirs. During the life of a field, targeted layers can be either opened or closed in order to optimize hydrocarbon production and avoid undesirable fluid entry. For these cases, nippleless retrievable bridge plugs are often required to isolate or to patch a specific reservoir. However, currently available tools fail due to their traditional rubber sealing element that swells under the effect of temperature and gas, and then hardens, which prevents them from being easily retrieved – and sometimes even set.
To solve these problems, a tool has been developed based on a segmented sealing ring that expands by the mechanical displacement of blocks, rather than by stressing the sealing element. Based on materials other than rubber, this sealing technology is free from the burning issue of elastomers. This design also eliminates traditional extrusion gaps and so performs well in HP/HT wells.
This revolutionary kinematic seal, associated with a breakthrough fail-safe mandrel mechanism has been successfully qualified in a very harsh environment (condensates and sour gases) where conventional technology has always been unsuccessful. A case history is presented where the rubber of a traditional plug swelled when running into the hole, which led to premature setting. The innovative bridge plug, on the other hand, was set and retrieved easily using a light slickline unit.
The total cost of the intervention was greatly reduced by using an interactive slickline conveyance system that provides real-time depth correlation, and then using a standard slickline unit for retrieval.
Due to its unique design, flowing applications such as electromagnetic controlled WR-SC/SSSV, choke, SSCSV, straddle packers (patch or screen) … will soon be available down to 2⅞" tubing size. Consequently, a new scope of operations is now accessible in monobore completions, such as temporary setting of the lock with a downhole shut-in device and gauges for accurate reservoir evaluation, or multiple settings in a single run in order to test, plug, and detect tubing leaks.
