Solution Mining of Nahcolite—Piceance Creek Basin, Colorado, USA
AAI personnel have provided technical support during the development of this pioneer solution mining project using cavity development from long horizontal boreholes. Specifically, AAI provided field and technical support in a pilot drilling program to characterize rock structure and hydrologic data. Rock structural data generated from drill core and laboratory tests were used in the stability assessment of dissolution cavities and overlying roof strata. Alternative configurations of long prismatic cavities and single-hole circular cavities were evaluated to assess overall resource recovery.
Inter-cavern pillars were designed to preserve overlying water-bearing strata and to minimize any adverse impacts on future mining of overlying oil shale resources. As production progressed, the shape of the cavity was monitored using in-cavity sonic surveys and was compared to the predicted cavity shape. Methods of monitoring and predicting cavity shape in these long cavities were evaluated.