Estimating Permeability Using a Reservoir Quality Data-set Derived from Drill Cuttings: an Example from Pakistan

The studied Cretaceous gas field is located in Pakistan. As part of a greater integrated proof-of-concept and reservoir quality prediction project, part of this project’s scope was to demonstrate the validity of optically-derived permeability estimates from drill cuttings.

The integration and interpretation of core, routine core analysis, petrology and drill cuttings data-sets has identified a set of ‘rules’ to constrain permeability estimates going forward and these are as follows:

≥80% total quartz + coarse clay + grain coating clay + mean GS ≥ 0.3mm = ≥100 mD

≥ 80% total quartz + coarse and/or fine clay ≥ 0.3mm mean GS = 10–100 mD

70–80% total quartz + coarse and/or fine clay + < 0.3mm mean GS = 1–10 mD

70–80% total quartz + fine clay + argillaceous matrix + < 0.3mm mean GS = 0.5–1 mD

<70% total quartz + fine clay + argillaceous matrix < 0.3 mm mean GS = ≤ 0.5 mD

Presence of bioclasts = ≤ 1 mD

Presence of detrital glauconite >8% = ≤ 1 mD

Once constrained by either core-based testing and/or operator experience (microscopic analysis of core and cuttings (MACC) data provides a robust, rock-based data-set that can be used to accurately estimate permeability.