Pressure sensitivity of low permeability sandstones

摘要: Abstract Detailed core analysis has been carried out on 32 tight sandstones with permeabilities ranging over four orders of magnitude (0.0002 to 4.8 mD at 5000 psi confining pressure). Relationships between gas permeability and net pressure were measured for cycles loading unloading. For some samples, both along across bedding planes. Large variations in stress sensitivity observed from one sample another. The ratio a nominal 500 that was used define ratio. given sample, vs followed linear log-log relationship, the slope which provided an index sensitivity. This index, as obtained first unloading data, testing relationships other rock properties. Pressure tended increase carbonate content depth, decrease porosity, sodium feldspar. However, scatter these increased decreased. Tests correlations various combinations variables are reported. Details pore structure related diagenetic changes appears be much greater significance than mineral composition.