| Popis: |
In response to the need to drain more of the reservoir within the Troll Field, especially from low permeability mica-sands where production levels are low, the current dual lateral technology was advanced to include two lateral legs in addition to the mainbore by creating a stacked or trilateral system. Based on a conventional multilateral ITBS™ (Isolated Tie-Back System), two 9 5/8-in. liner joints — incorporating pre-milled windows and pre-installed latch couplings — are installed a specific distance apart but aligned to the same orientation. After installation of the windows and subsequent installation of the mainbore screens, a whipstock is latched into the lower coupling and the lower window opened up to drill the first lateral leg. To complete this section of the well, the whipstock is retrieved, replaced by a deflector over which a flexible hanger with D-section legs is installed to create the junction. One leg is attached to the lateral screens whereas the other leg is connected to a seal stinger. The flexible hanger is oriented to enable the stinger to land in a seal stack in the deflector thereby creating the means of communication with the main bore. Drilling out and completion of the upper lateral is a duplication of the lower lateral with some exceptions. This paper will discuss the factors leading to the development of the trilateral ITBS™, its installation and the impact on Troll Olje Field drainage. |
