There are a number of global initiatives to understand and mitigate the impacts of extreme space weather on critical infrastructure and modern society. This paper provides the results of an analysis to estimate extreme geoelectric field values for the Australian region to facilitate evaluation of Australia's power system response to extreme geomagnetic storms. Geoelectric fields are calculated using a grid of modeled magnetotelluric impedance tensors obtained from a 3-D conductivity model of the Australian region. Statistical metrics derived from grids of geoelectric field time series are analyzed as a function of Dst index for different storm days to extrapolate geoelectric fields to extreme storm levels over a range of ground conductivity conditions. For Carrington event storm levels, geoelectric field values of 5.3 ± 3.8 V/km in the north-south direction and 9.6 ± 4.3 V/km in the east-west direction are expected for areas of electrically resistive rocks near coastlines that are adjacent to deep highly conductive oceans, and inland, where there are large contrasts between the electrical conductivities of different rock types across Australia. Further, geoelectric field values may change by at least an order of magnitude over the grid spacing interval of 50 km in these areas. The results of the analysis also suggest that upscaling grids of geoelectric field time series derived from an observed storm by the ratio of extreme storm Dst to the observed storm Dst are a valid approach for the Australian region that provides extreme storm scenarios for different storm morphologies.
Over 400 wells have been very successfully hydraulically fractured on the Kuparuk Sand for the Kuparuk River Unit Field (KRU)1. Comparatively smaller petroleum deposits of the Kuparuk Sand have recently been developed in the adjacent Prudhoe Bay Field. These satellite pools, namely the Aurora and Borealis, similarly benefit from fracturing. Significant productivity increases from aggressive Tip Screen-out (TSO) fracture designs have delivered over 40, 000 bopd from 11 wells. This paper describes the rationale, events and lessons learned leading up to the final very aggressive TSO designs for these satellite wells. In many cases, fracturing fluid efficiencies measured during datafracs for the satellite wells were approximately two times higher than the Kuparuk Sand analog in the KRU area. Pad volumes during fracturing were as little as 3% of the total treatment volume with modeled proppant concentrations of 5 lbs/ft2 placed. The majority of wells were S-shaped to minimize fracture complexity. Directional drilling costs, NWPL's and production results are shown. Bottom hole pressure gauge data is presented allowing refinement of the designs via net pressure analysis and times to start TSO. Production and pressure transient analysis results are also presented. Introduction Both Aurora &Borealis Pools are located on Alaska's North Slope and produce from the Kuparuk River Formation. (See figure 1). Although the structures were penetrated and proven to bear hydrocarbons in 1969, development did not commence upon until 1999. Reservoir Description The Kuparuk River Formation is stratigraphically complex and is characterized by multiple unconformities, changes in thickness, sedimentary facies, and local digenetic cementation. The Kuparuk Formation is divided into three intervals, the A, B, and C intervals, (from oldest to youngest) with the A and C intervals divided into a number of sub-intervals. See, figure 2 V-200 type log in appendix. An overlying unit, called the Kuparuk D Shale, is locally present in some areas of the Borealis Pool. The uppermost unit, the Kuparuk C sand is the primary reservoir sand. Although both the Aurora and Borealis Pools produce from the same formation and are in close proximity, structurally they are quite different. Kuparuk Aurora. Top Kuparuk structure in the Aurora area is broken up by north-south striking faults with up to 200 feet of down-to-the-west displacement. The faults effectively bisect the Aurora Pool and at least 7 different compartments have been identified based on pressure and fluid data. The Kuparuk thickness at Aurora is highly variable and ranges from 0 feet at the eastern truncation, to 210 feet at the Beechey Point wells in the northwestern portion. Kuparuk Borealis. The Borealis structure is shaped by basement-involved northwest-southeast trending faults that are intersected by a younger set of north-south striking faults. The trending faults were active during deposition of the lower Kuparuk C (C-1), but do not appear to have been contemporaneous with Upper Kuparuk C (C-2 to C-4) deposition. The compartmentalization within the Borealis field, it is not as severe as Aurora due to a relatively higher net and a significantly higher gross reservoir thickness. Kuparuk Aurora. Top Kuparuk structure in the Aurora area is broken up by north-south striking faults with up to 200 feet of down-to-the-west displacement. The faults effectively bisect the Aurora Pool and at least 7 different compartments have been identified based on pressure and fluid data. The Kuparuk thickness at Aurora is highly variable and ranges from 0 feet at the eastern truncation, to 210 feet at the Beechey Point wells in the northwestern portion. Kuparuk Borealis. The Borealis structure is shaped by basement-involved northwest-southeast trending faults that are intersected by a younger set of north-south striking faults. The trending faults were active during deposition of the lower Kuparuk C (C-1), but do not appear to have been contemporaneous with Upper Kuparuk C (C-2 to C-4) deposition. The compartmentalization within the Borealis field, it is not as severe as Aurora due to a relatively higher net and a significantly higher gross reservoir thickness.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractAlthough three 1969 exploration wells discovered hydrocarbons in the Aurora structure, development was not possible until a scope change to the V-200 exploration well demonstrated commerciality 30-years later. Commencing in June 2000, an aggressive 6-well horizontal and vertical development/appraisal program yielded over 1.75 million barrels of oil in the first year and provided a better understanding of a reservoir previously thought marginally commercial. Investment in reservoir description and proactive surveillance led to accurate decision-making, and with innovations, yielded significant return from a "marginal" field.
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