He Shunli

The Characteristics of Lognormal Distribution of Pore and Throat Size of a Low Permeability Core

The pore-throat size distributions (PTSDs) of low-permeability cores can be characterized by constant-rate mercury injection capillary pressure test (CMICPT), which can distinguish the pore and throat. The data from CMICPT of cores in X reservoir were analyzed. The result shows that the PTSDs are abided by lognormal distribution. The relationship between parameters α, σ of lognormal distribution of throat size in different cores and permeability is logarithmic, while those of pore size are unified. Finally, the reason why the distribution of throat size and pore size are lognormal distribution is discussed. The result will help deepen the understanding the relationship between pore structure and permeability of low-permeability reservoir.

Ultra-low Permeability Rocks: Laboratory Measurement and Low Pressure Gradient Analysis

The flow curve of standard brine (salinity: 80 g/L), kerosene, and light crude oil in the ultra-low permeability core plugs with full diameter drilled from the Erdos basin have been measured through fully automatic flooding system-AFS300 provided by Core Lab of America (Houston, TX) under low pressure gradient (0.005–0.3 MPa/m) with the steady-state approach. The experiments indicated that the flow rate of the downstream of the core plug increases linearly as the increase of the pressure gradient and nonlinearity was not observed. In a way, the experiments indicated that the Darcy law holds in the ultra-low permeability in the experiment and the interaction force between the porous surface of the cores and the brine, kerosene, and light crude oil cannot cause nonlinearity.