Behavior of hydrocarbon reservoir sands and sandstones

Most new oil and gas reservoirs are discovered in sands and weak sandstones, and the petroleum industry has therefore generated an extensive amount of data from laboratory tests on these materials. Some of these data are reexamined in this paper within the context of recent soil mechanics research. Of key importance to petroleum engineers is the compressibility of the sands, and this is shown to be related both to the current density and stress level of the soil and to the location of its normal compression line. When present, the cement bonds between the particles appear to be weaker than the particles themselves, so that the major yield point during compression is still associated with breakage of the particles rather than of the cement bonds. The paper also examines the behavior of the sands and sandstones in shearing, allowing a more general understanding of the mechanics of the materials to be developed. CE Database subject headings: Sand; Sandstone; Triaxial tests; Oil recovery; Stiffness; Strength; Compressibility.