The effect of oil extraction on porosity and methane adsorption for dry and moisture-equilibrated shales

The porosity and methane adsorption capacity of shale used to estimate gas in place (GIP) are affected both by moisture oil residing the pore structure, as well naturally present from maturation, which can include contaminant drilling mud fluids for drilling. To demonstrate impact extractable on dry moisture-equilibrated shales, two overmature shales China (SH1, SH2) lower mature UK (BS3, GH4) have been investigated. oils extracted (<0.5 wt% TOC) low yield arise oil-based mud, while much higher yields maturity (1.1–2.5 is mainly generated maturation. After extraction, minimal changes (<5%) total nanopore volume (<100 nm) were observed over but significant increases (95 176%) shales. More than 60% resides micro mesopores, removal could unblock micropore necks enlarge accessible meso macropore volume. Moisture contents with reductions 7–37% observed. Methane equilibrium capacities increased after extraction wet especially where 200% Henry’s Law was show that there not amounts dissolved Extracting prior determining lead GIP being over-estimated equilibrated particularly oil-window an overestimation 22% obtained investigated this study. These findings provide a better understanding combined impacts residual water avoid its overestimation.