The Coefficient of Isothermal Compressibility of Black Oils at Pressures Below the Bubblepoint

Summary Values of oil compressibility are required in all solutions of transient fluid-flow problems. Oil compressibility can be calculated directly if reservoir-fluid studies are available. In this paper, empirical equations are presented to provide accurate estimates of the compressibility of black oil at pressures below the bubblepoint when laboratory measurements are not available. The equations were developed with data from reservoir-fluid studies of 260 oil fields worldwide. The data encompassed a wide range of oil compressibilities, surface-gas specific gravities, stock-tank oil gravities, solution GOR's, reservoir pressures, reservoir temperatures, and bubblepoint pressures