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How to find the bedrock fracture water by physical ground water detector astrometric method?

Views: 34     Author: pqwt     Publish Time: 2022-12-27      Origin: PQWT

How can the low value layers with and without water be distinguished from each other. In our previous discussions, we concluded that "the magnitude of the value of the method in the same electromagnetic environment is determined by "water", whether it is useful fracture water, pore water, or useless crystalline water, structural water."

ground water detector

In [Theory Discussion] No. 5, we introduced that fracture water is a polar molecule, which generally shows low values in the astrograph. Some rocks in the formation contain mineral water (structural water, crystalline water, adsorbed water), which are also polar molecules and will also form low values. As a physical prospector can not be forewarned to analyze which low values are formed by rocks containing mineral water and which low values are formed by fracture water. It is necessary to summarize the law, from the low value form, value size, rock properties, known well conditions and other aspects of analysis and research.

Fracture water can cause low values, and rocks containing mineral water can also cause low values, and sometimes it is difficult to distinguish, which causes the Tiandian method "measuring the map is easy to read the map is difficult". Look at the map can not only look at the color of the map and anomaly form, but also look at the size of the background values outside the anomaly. To exclude false anomalies after "high school to find low, low to find high". In other words, if the background value is high, we should look for low value anomalies, and if the background value is low, we should look for high value anomalies, and it is dangerous to choose low value anomalies regardless of the background value.

According to our years of research on the use of PQWT series ground water detector, we found that the low value of fracture water is not exactly the same as the low value of mineral water law. The biggest difference between the two is that: the fracture water is mostly water in the tectonic fracture, and the distribution of the low value caused by it is mostly localized and limited in scope, which often shows the "abnormality" of sudden change in value. In contrast, the low value caused by mineral water is mostly in a wide range, the layer is more stable, and rarely appears a real local anomaly.

Specifically, the following eleven experiences can be provided for your reference (each refers to the hydrostatic level below).

1. To study the high and low value anomalies, we should read three maps together (original curve map, original profile map and processing profile map), and pay attention to the abrupt changes of the values in the lateral or vertical direction, as well as the detailed changes in the map. When there are many low values whether there are low values of anomalies, often processing graphs to see more clearly. If you only like to look at the graphs and will not look at the profiles, you will not analyze the causes of the anomalies. In particular, the most fearful thing to do anything is that the original information is not true. Found anomalies if you are not willing to do misalignment retesting verification, but only subjectively think it is real, the same is the chance.

2, lateral v-shaped low value anomaly, if the source of the low value in the shallowest part, whether it is a single-channel or multi-channel instrument measurement should be done again misalignment retesting, in order to exclude non-structural low value down transmission. As long as the exclusion of non-structural low-value transmission most of the water, the size of the water and lithology related.

3, in the v-shaped low value downward transmission of a certain depth again appear low value mass, to observe whether it is a longitudinal and horizontal low value superposition caused by, if not superposition, then it is certain that there is another low value body, containing fracture water may be very large.

4, in the same depth appears immediately after the high value of the low value block, or in the middle of the high value of the low value block, its cause is generally unrelated to the low value of the lower transmission, most of the water will be good. Can be verified with co-location re-testing, in case the signal time-varying problems due to poor electromagnetic environment.

5, if the measurement points are more, both sides are high value, the middle is low value, but the low value of the anomaly is not very narrow v-shaped, as long as you can exclude the high and low value of downward transmission causes, hit the high and low value contact zone generally have water, the size of water and lithology. In sedimentary rock areas, if the electromagnetic environment is normal, the maximum value of the original map is small, and the choice of low value drilling, you need to consider whether there is a risk of bad lithology. The size of the value is important for the analysis of the diagram, but when measuring the size of the value must pay attention to the impact of the electromagnetic environment on it.

6、If the graph has a high value at one end and a low value at the other end, and the value is asymptotic, it is important to consider whether there is a possibility of thickening of the soil layer or weathering layer on the low value side (if this is indeed the case, this is also caused by non-tectonic low value downward transmission, and there is a small possibility of water).

7, if the maximum value of the graph is small and not in the unused area, it means that the lithology is soft. The value of the low value layer or low value point in the graph will be smaller, and such low values are generally of no use. This is the case, for example, with muddy rocks. In addition, in basaltic areas, as columnar joints are very developed, the joints are often filled with very thin mud. Some basaltic rocks containing itingite, chemical formula has 4 crystalline water, the rock hardness, but the value of Tiandian is small, so the effect of choosing the low value in the low value is generally not good, it is appropriate to choose the high and low value contact zone.

There are strata containing muddy rocks to find brittle hard gravel, should choose high value anomaly. There is no muddy rock of brittle hard rock areas should choose low value anomaly, containing the possibility of fracture water.

In the value is not very large crystalline rocks (such as granite, gneiss, etc.) in the light-colored vein rock, the mineral composition is mainly quartz, feldspar, non-polar material, vein rock rarely contains mineral water, will generally show high value anomalies, but also good conditions, must not be indiscriminate selection of low value anomalies.

8, if the maximum value in the figure is very large, the electromagnetic environment is normal, indicating that the rock is hard, the value of the thinner low-value interlayer in the figure will not be small, indicating that it is not soft rock, there is a greater possibility of fracture water.

9, most of the shallow low-value layers in the graph are related to the weathering layer, if the maximum value of the graph is large, the possibility of water in the shallow low-value layer is large. If the maximum value of the diagram is not large, as long as there is no sand layer water, shallow low-value layer has a small possibility of water (the size of the value can be referred to the circle of friends 6.21 one of theoretical discussions).

10, to the horizontal laminar-based profile, if the high value layer and low value layer between, more layers, generally have water, which is the so-called "horizontal multi-layers have water quite a lot". If the layer is less, the value of the high value layer and the low value layer is more contrast, in the processing of the profile of the low value layer under the high value layer is easy to have water. If the low value layer in the upper high value layer in the lower, the contrast between the two is large, when the value of the low value layer is not very small, the low value layer is easy to have water. When the value of the low value layer is very small, it is easy to have water in the high value layer below (measure the size of the value also depends on how the nearby electromagnetic environment affects it).

11、If the low value layer is wider, thicker and more stable, there is a great possibility of mineral water in the rock, and it is easy to become "high resistance low value layer" or "low resistance low value layer with bad water.