METHODS AND SYSTEMS FOR DETERMINING BULK DENSITY, POROSITY, AND PORE SIZE DISTRIBUTION OF SUBSURFACE FORMATIONS

摘要

Herein methods and systems for determining matrix or grain density of a subsurface formation are described. This includes measuring in-air mass of a fluid-saturated sample of the subsurface formation, wherein the in-air mass comprises mass of matrix or grains of the sample, mass of a fluid surrounding the sample, and mass of the fluid inside the sample. The volume of the fluid inside the sample, V_ϕ, and volume of the fluid surrounding the sample, V_sur, are determined using nuclear magnetic resonance (NMR). The fluid-saturated sample can then be submerged in a predetermined volume of a weighing fluid and mass of the fluid-saturated sample without the surrounding fluid in the weighing fluid, m_f is measured. Using the measured and determined values one can determine the volume of the sample without the surrounding fluid, V_c, the bulk density of the fluid-saturated sample without the surrounding fluid, ρ_b, the volume of the matrix, V_m, and the matrix or grain density of the subsurface formation, ρ_m.