Is the rocky shale aquifer an Ortonian karst water?

The definition is: all rocks with good permeability and large voids, as well as pebbles, coarse sand, loose sediments, rocks rich in fractures, and rocks developed in karst can be aquifers.

Geologically, an aquifer often refers to a saturated layer below the soil aeration layer, where the pores of the medium are completely filled with water. There are many types of aquifers, such as the aquifer is directly covered by impervious strata above and below, and the groundwater is filled with two layers of impervious aquifers, which are referred to as restricted aquifers. If there is no impervious layer above the groundwater surface, the water surface is the groundwater level, which is called the non-confined aquifer.

Groundwater is the water stored in the voids of the strata below the gas-bearing zone, including rock pores, fissures and karst caves.

Groundwater is further divided into pore water, fissure water and karst water. Pore water is groundwater that exists in the pores of rock and soil, such as loose sand, gravel, and sandstone layers. Fissure water is water that is present in cracks in hard rocks and certain clay layers.

Karst water, also known as karst water, refers to groundwater that exists in the cavities of soluble rocks (such as limestone, dolomite, etc.).

Therefore, groundwater is generally abundant in loose sand layers, gravel layers, sandstones, sandstones, and soluble rocks (limestone, dolomite, etc.), so these are prone to become aquifers.

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In general, the water richness of karst aquifers is relatively strong, but the water content is extremely uneven. Because karst water is not evenly distributed throughout the entire distribution range of soluble rocks, but is buried in the dissolution fissures and karst caves of soluble rocks, the same karst aquifer is often in the same elevation range, or in the same section, or even a few meters apart, and the water richness can differ dozens to hundreds of times. For example, during hydrogeological exploration near Baliang, Guangxi, the method of manual excavation was used in the distribution area of limestone and dolomite, and abundant groundwater gushing was found at both points.

A point where the water level drops by 8m is a water output of 15600m3 d; At another point, the water level has dropped, and the water output is still 2600 m3 d. The two points are about 1000m apart. In the seven boreholes drilled between the two points, the water output is less than 40 m3 d when the depth is greater than 5 m, and the difference in water richness is 60 360 times.

The development of karst has the law of gradual weakening to the depth, so that the water-richness of the aquifer also has strong and weak zonal characteristics. The drilling results near Kunming show that the limestone distribution in this area is rich in groundwater within a depth of no more than 100m.

Karst water also has obvious anisotropy in terms of hydraulic connection. When a mine in Guangxi drains the karst water of the coal seam floor, the dredging funnel formed is elliptical, and the difference between the long and short axes is more than 3 times; The most special is a borehole very close to the center of the water level drop, and the water level is not affected by dredging, becoming an "island" with no hydraulic connection. It can be seen that the water richness and hydraulic connection of karst water in the horizontal and vertical directions vary greatly.