科研之友
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摘要
The shallow brine reservoir of Qarhan Salt Lake contains considerable reserves of solid potash resources, and it is currently at the stage of liquefaction mining. The dissolution of solid potassium salt minerals in the brine reservoir and the structural changes of the brine reservoir are controlled by the solvent injection rate, however, the control mechanism is still unclear. In this paper, a typical borehole core in the shallow brine reservoir of Qarhan Salt Lake was investigated. Through the indoor core column seepage simulation experiment, the permeability coefficient of the brine reservoir and the dissolution of solid potash minerals under three flow rates are studied. The results show that: (1) With the increase of the solvent injection rate, the core permeability coefficient shows a gradually increasing trend, and the potassium ion concentration in the exudate shows a continuous decreasing trend, but at the time node when the flow velocity changes, the rock core both the core permeability coefficient and the potassium ion concentration in the corresponding dissolution liquid showed an abnormal increase. The dissolution of minerals causes the porosity of the reservoir to increase, and the change of the solvent flow rate causes the reorganization of loose salt mineral particles. (2) The dissolution of solid potash minerals in the brine core was significantly affected by the solvent injection rate. The increase in injection rate causes the reorganization of mineral particles and the release of high-concentration water from the retained pores, which were the main reasons for the temporary increase of K+ concentration in the exudate. This experimental study has certain theoretical guiding significance for the water-soluble mining of low-grade solid potassium salt in the study area.
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