In this tough economic climate, efficient mature field rejuvenation has become a major challenge for operators looking to balance the books.
The most successful mature field rejuvenation projects are ultimately driven by a solid understanding of the existing infrastructure, reservoir geometry, and remaining hydrocarbons in place. Most large mature fields were initially developed long before many of the technologies we use today were available, such as permanent reservoir monitoring1 and distributed optical sensing (DAS/DTS).2 In fact, even the first commercial 4D seismic projects only happened as recently as the late 1990s. Because of this lack of subsurface information, mature fields simply were not understood well enough in the past to boost production in the most effective manner possible.
One of the most effective ways to start a long-term mature field rejuvenation project is to acquire an updated 3D survey. By making comparisons to previous seismic volumes, this establishes an understanding of the hydrocarbons remaining in situ, and identifies any geomechanical alteration of the reservoir geometry that has occurred through the initial phases of depletion. This new subsurface insight enables productive infill drilling campaigns to be planned, or for enhanced oil recovery (EOR) flood programs to be modified in order to improve sweep efficiency.
Infill campaigns targeting undeveloped fault blocks via extended reach drilling (ERD) or trapped attic oil pay using horizontal geosteering techniques have proven to enhance ultimate recovery. To get the most out of these wells, though, placement optimization is crucial. Well placement optimization should take into account fluid properties, reservoir heterogeneity, well costs, and long-term production forecasting. For high-permeability attic oil pay scenarios, it may prove to be as simple as maximizing operational efficiency and establishing sufficient reservoir contact; however, for entirely bypassed fault blocks and complex heterogeneous reservoirs, optimization algorithms should be used to model and maximize recovery over the entire planned life of the wells.3 Having a collaborative well planning and geoscience platform where the reservoir engineer, geologist, and well engineer can work together to evaluate the overall net present value (NPV) is key to this process.
Making the most of mature fields with intelligent infill drilling campaigns is not just about the geology – aging platforms and wells represent significant technical and economic engineering challenges. Well integrity problems place significant limits on what can be practically achieved in terms of slot recovery, re-drills and workovers. These well engineering problems all too often result in unanticipated costs. Therefore, it is even more critical that the operations that can be planned and controlled are lean by design and focused on efficiency in order to maximize value.
|Understand the existing subsurface, well, and topside infrastructure.|
|Build a balanced scope of opportunities for the mature asset – including low-cost, low-impact intervention – in order to maximize productivity of existing wells and intelligently place new infill wells to rejuvenate field productivity.|
|Focus on technical efficiency and lean organizational structure – i.e., results-focused operations.|
|Fast-track high-NPV and high-impact operations.|
1 Fouda, Wilson, Donderici, and Samson, Halliburton. New Resistivity Models for Reservoir Monitoring Applications. SPWLA 56th Annual Logging Symposium, 2015.
2 Nath, Finley, Kaura, Halliburton; Krismartopo and Yudhiarto, Chevron. Real-time Fiber Optic Distributed Temperature Sensing (DTS) – New Applications in the Oilfield. SPE 103069, Annual Technical Conference, 2006.
3 Costa, Halliburton; and Bampi, Petrobras. Marlim Field: An Optimization Study on a Mature Field. SPE 139376, Latin American & Caribbean Petroleum Engineering Conference, 2010.