A Petrographic Study of the Three Forks Formation (Upper Devonian), Williston Basin, North Dakota: Based on Thin Section Analysis, XRD and SEM

Table 4

Reservoir quality and porosity controlling factors of the Three Forks Formation.

Sample ID	Location	Pore types	Tin section porosity (%)	Main 𝜙 Controls	Minor 𝜙 Controls	Reservoir quality
1	Top	Ix1, mV, mP	3	Comp, Dol, Hem	Cal, Clasts, Py	P-M
3	Middle	Ix1, mP	2	Comp, Dol, Hem	Cal, Clasts, Py	P-M
4	Lower	Ix1, mP	Trace	Hem, Comp, Dol	Clasts, Py	P

Pore types: Ix1: intercrystalline; mP: microporosity; mV: microvuggy.
Reservoir quality: P: poor; M: moderate; G: good.
Main 𝜙 Controls: Dol: dolomitization; Py: pyrite; Cal: calcite; Hem: hematite.
Clast: clay or dolomicrites rich clast.
Comp: mechanical compaction.