Low-Cost Multilateral on Gullfaks (2005)

Lowcost Multilateral on Gullfaks Ole H. Lie; Ole H. Lie Statoil ASA Search for other works by this author on: This Site Google Scholar Scott Fraser Scott Fraser Weatherford Drilling & Intervent Search for other works by this author on: This Site Google Scholar Paper presented at the SPE/IADC Middle East Drilling Technology Conference and Exhibition, Dubai, United Arab Emirates, September 2005. Paper Number: SPE-95818-MS https://doi.org/10.2118/95818-MS Published: September 12 2005 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Lie, Ole H., and Scott Fraser. "Lowcost Multilateral on Gullfaks." Paper presented at the SPE/IADC Middle East Drilling Technology Conference and Exhibition, Dubai, United Arab Emirates, September 2005. doi: https://doi.org/10.2118/95818-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE/IADC Middle East Drilling Technology Conference and Exhibition Search Advanced Search AbstractGullfaks is a typical mature field where cost efficient solutions need to be in focus. There is also the challenge that old wells produce at low rates, but nevertheless at rates not drastically lower than those that an alternative use of the slot can deliver. One solution to this challenge is to maintain production from the old well while simultaneously gaining inexpensive access to new a drainage point(s).B-1A on the Gullfaks field was drilled and completed in January 2003 using hollow whipstock technology. The operation was a technical success which proved that Multilateral (MLT) solutions can be delivered at costs only marginally above those of a conventional sidetrack. To further enhance the value of the slot, a second through tubing MLT lateral was added in January 2005.The key considerations during the planning phase were proven solutions, cheap technology and low risk. This paper illustrates the decision process prior to choosing this particular technology, the installation process itself, the lessons learned and the strategy which may be applied in the future.IntroductionThe Gullfaks field is located offshore Norway and is one of the largest producing fields in the North Sea (see Fig 1.). The field is operated by Statoil and has produced since 1986. It has been developed with three concrete integrated production and drilling platforms; namely the Gullfaks A, B and C. The total production rate from the Gullfaks field is currently some 26 000 Sm3/d with estimated total recoverable reserves of 360 million Sm3.B-1 was the first well to be completed on the Bravo platform and since the well came on line in 1989 it has produced almost 10 million Sm3. The well is a typical mature Gullfaks well with a decline curve that is characterized by a long and drawn out tail as the water cut gradually increases.In January 2003 the well was producing some 250Sm3/d with 84% water cut. A new prospect had been identified in the same segment and it was desirable to use the B-1 slot for its exploitation.However the new prospect was not anticipated to produce at a rate of more than 500 Sm3/d and it was therefore clear that plugging back the old B-1 was not an economically viable option.The operator decided to investigate the possibility of maintaining the old B-1 production while simultaneously producing from the new branch B-1A. It was very important that the multilateral solution should be technically robust and not jeopardize the contribution already available in B-1. It was also desirable that the cost of the solution be compatible with the modest additional volumes available in the new lateral.Selection Process - CriteriaThe option of maintaining production from B-1 seemed very tempting to the reservoir engineers. They did however present a challenge that would have to be met during the planning phase in that the perforations in the motherbore could not be exposed to drilling fluids.Some type of isolation would therefore have to be in place while drilling the lateral.On the technical side it was considered most important that the installation process differ as little as possible from a conventional sidetrack procedure and that only equipment with a proven track record be used.It was known, from experience when sidetracking in old wells, that equipment tolerances would have to be liberal in order to accommodate corrosion, wear and tear on existing tubulars and the debris created in the sidetracking process itself. A robust system was therefore considered to be of great importance.A further reservoir prospect, not yet matured, was also identified in the region and it was important that it would be possible to reach this target from this same well at some later stage. It was considered preferable that this additional sidetrack be conducted with another MLT solution and, if at all possible, using Thru Tubing Rotary Drilling (TTRD) techniques. Keywords: directional drilling, liner, spe iadc 95818, whipstock, assembly, drilling operation, perforation, motherbore, completion, packer Subjects: Drilling Operations, Directional drilling This content is only available via PDF. 2005. Society of Petroleum Engineers You can access this article if you purchase or spend a download.