Nano-petrophysics study of Haynesville Shale, East Texas, USA
Abstract
As one of the most productive shale gas plays, the Haynesville Shale has a high geopressure
gradient and high temperature, but with a lack of petrophysical understanding. To analyze the pore
geometry and wettability related connectivity of this formation, multiple methods such as total
organic carbon content (TOC), X-ray diffraction (XRD), vacuum saturation, mercury intrusion
capillary pressure (MICP), contact angle, fluid imbibition, and helium pycnometry were used on
10 Haynesville Shale core samples from a single well over a vertical distance of 123 ft. The results
from those tests show that the Haynesville Shale is calcareous shale with 2.26~5.28% of TOC.
The porosities range from 3 to 8%, and the pore-throat sizes are concentrated at the nanoscale
(2.8~50 nm). Moreover, the permeability and effective tortuosity of the pore network controlled
by 2.8 to 50 nm pore-throat size are 3.7 to 23.4 nD and 1413 to 3433, respectively. All ten samples
show strong oil-wet characteristics and only three samples exhibit mixed wettability (both oil-wet
and water-wet). In general oil-wet samples show higher pore connectivity when they imbibe
hydrophobic (a mixture of n-decane:toluene at 2:1, as an oil analog) than hydrophilic (deionized
water) fluids.