| Popis: |
Statfjord Field is one of the largest and oldest fields on NCS (North Sea Continental Shelf) and operates with three platforms Stafjord A, B and C. In recent years, slot recovery to drill more wells has posed big challenges to deliver wells with Gas Lift design due to extensive and cost/time consuming P&A and casing cut and pull operations. In addition to these technical challenges, improving operational excellence has driven the concept of innovative casing design with 11 ¾-in liner. This design eliminates the time spent on extensive casing retrieval operations. This reduces time and risks associated with drilling 17 ½-in section that requires changing from 13 5/8-in to 21 ¼-in BOP, higher flow rates for hole cleaning, larger volume of cutting injection, and waiting 13 3/8-in casing hangers that are crucial long lead items. Installation of 11 ¾-in liner at required depth and cementing, potential collapse of Hordaland formation due to extended time exposure, high flow rates for hole cleaning and minimizing well collision risks with producers in 8 ½-in were identified as high priority design goals in the early planning phase. To address aforementioned challenges and meet design goal in time and cost efficient way, innovative ideas were fundamental necessity. This paper discusses the integration of novel drilling approaches used in accomplishing a new gas lift well design that has opened redundant well slotson Statfjord field for drilling. Operational highlights leading to successful well delivery are: First use of dual reamer RSS BHA in 12 ¼ x 13 ½-in to minimize the rat hole and exposure time across “creeping” Hordaland formation in one run and helped 11 ¾-in liner to reach gas lift formation strength depth. Use of new generation RSS technology to drill ~930m 8 ½-in section to widen the operational flow range for hole cleaning and steering in high stick slip and collision environment. Use of modern surveying technique and magnetic ranging technology to drill 8 ½ -in section in potential collision environment. This was first ever use of dual reamer point the bit RSS BHA in North Sea and New generation RSS and special surveying technique on Statfjord. |
