Research on the Changes in Physical Properties during the Seepage-Dissolution Process of Potassium Salt-bearing Reservoir in Qarhan Salt Lake
Qarhan Salt Lake is endowed with abundant low-grade solid potassium salt resources,playing a crucial role in the sustainable development of the potash industry in China.A thorough understanding of the dissolution mechanism of potassium salt minerals in brine reservoirs is essential to optimize resource exploi-tation.In this study,three representative drill cores containing different types of potassium salts from the shallow brine reservoir of Qarhan Salt Lake were selected for investigation.Through a laboratory seepage dissolution experiment,the efficiency of solid minerals'dissolution,as well as changes in porosity and per-meability of the drill cores,was simulated.The results of the percolation-dissolution experiment revealed that the potassium salt minerals in the three drill cores were totally dissolved.Among the core samples,those containing carnallite exhibited the highest dissolution rate,followed by sylvite-rich core samples,while,polyhalite-rich core samples showed the lowest dissolution rate.Throughout the experiment,the skeleton of the brine reservoirs did not collapse after the dissolution reaction,indicating effective protection provided by NaCl-saturated brine.The porosities of the three core samples declined due to halite precipita-tion and the migration of insoluble minerals.Specifically,the porosity of the carnallite-rich core decreased by 26%,while that of the sylvite-rich and polyhalite-rich cores decreased by 20%and 32%,respectively.Controlled by the dissolution of salt minerals,precipitation of halite,and migration/blockage of insoluble minerals,the core permeabilities of brine reservoirs diminished by 40%-70%.This research highlighted the importance of considering complex factors for a comprehensive understanding of the changes in the reser-voir's physical properties during the seepage-dissolution process.
Brine reservoirPotassium saltsHydraulic conductivityPorositySaturation index
NETL
NSTL
万方数据
维普
