Abstract:

The salt lake area of the Qaidam basin has abundant reserves of underground brine resources, the regional brine reservoirs have the characteristics of lower porosity, strong heterogeneity and anisotropy, and large differences in regional brine-rich properties. In order to accurately detect the underground brine enrichment area and determine variation range of salt rock distribution density difference of the Mahai Salt Lake, it is aimed at the unique salt rock medium, the high salinity of intercrystalline brine, and the coexistence of various brine storage modes such as pore brine storage and structural brine control in the salt lake area of the Qaidam basin. The multi-scale and multi-geophysical exploration method including pumping test, high-precision gravity method, audio magnetotelluric method and high-resolution seismic method were used to detect the distribution density difference variation range of salt rock layer, the electrical change of crystalline salt layer and brine-rich stratum. The pumping test shows that the brine enrichment area composed of Wells K12, K13, K14 etc. has a water yield of 37 297 m3/d in brine rich area Ⅰ. The brine enrichment area composed of T1, K1, K4 etc. has a water yield of 35 736 m3/d in brine rich area Ⅱ. Based on pumping test and integration technology of various geophysical exploration information, two underground brine enrichment areas that can be sustainably and stably exploitated were determined, stratigraphic structure and geological structure in the Mahai Salt Lake were delineated and established.

Key words: geophysical exploration, information integration, underground brine, brine enrichment area, Mahai Salt Lake, Qaidam basin