Multilateral Wells Reduce CAPEX of Offshore, subsea Development in Australia’s Northwest Shelf

Abstract Multilateral technology reduces the number of production well slots required to effectively drain a reservoir, resulting in time and cost savings. Having fewer discrete subsea wellheads translates into a major reduction of investment capital in offshore environments. Reducing the cost of the subsea infrastructure is the primary benefit of multilateral well architecture, but additional benefits include reduced top-hole drilling costs, reduced project execution time, accelerated production, increased productivity index and fewer rig moves. To take advantage of the benefits, the appropriate multilateral technology must be selected to avoid introducing additional risk and non-productive time (NPT) to the project. The multilateral junction system that meets the requirements of the wells on the Northwest Shelf of Australia has a proven track record in subsea installations. For this application, a TAML Level 5 system is required to provide hydraulic and mechanical isolation of the connected wellbores. Over the past 10 years, TAML Level 5 multilateral technology has been used extensively in the North Sea, whereas the Northwest Shelf of western Australia saw its inauguration in the southern hemisphere. This paper discusses the lessons learned from nine horizontal TAML Level 5 dual-lateral wells drilled offshore in the Van Gogh field. The Van Gogh field provides an excellent example of a field that was developed from start to finish with multilateral technology as the enabler. The project was successfully completed in the second quarter of 2009 with a significantly lower capital investment than would have been required to develop the field with single horizontal wells.