"Several new oilfields have been developed in northeastern Wyoming during the past 10 years. Production is obtained from discontinuous, permeable sands enclosed within impermeable shales. The energy to drive the oil to producing wells is supplied by gas in solution in the oil. Most of the wells had high-initial potentials, but rates of oil production have steadily declined, indicating a dissipation of the driving energy and the possibility that large volumes of oil will remain unrecovered in the reservoirs. The studies reported in this paper were undertaken to develop laboratory data of the type most likely to be needed by persons studying the susceptibility of the Newcastle sand reservoir to secondary-recovery methods."