CN106772681A - The method of testing of caving zone and height of the water conductive fracture zone - Google Patents

Abstract

The invention discloses a method for testing the height of a caving zone and a water-conducting crack zone. The test method includes the following steps: firstly, the predicted results of the heights of the two zones are obtained by calculating the heights of the two zones; secondly, the range of the heights of the two zones in the study area is preliminarily determined by using the geophysical detection method; thirdly, the water injection pressure measurement system, drilling The borehole TV system or the borehole flushing fluid observation system further determine the height range of the fixed-point two zones; finally, the range of the two zone heights is verified by simulation. The test method for the height of the caving zone and water-conducting fracture zone belongs to an efficient detection combination scheme, which can determine the boundary line with a targeted detection method after determining the range of the caving zone and water-conducting fracture zone as a whole, and verify The precise position of the dividing line in a small area improves the prediction accuracy and avoids redundancy and waste of technical resources.

Description

Test method for the height of caving zone and water-conducting crack zone

technical field

The invention relates to the field of mine safety mining, in particular to a method for testing the height of a caving zone and a water-conducting crack zone.

Background technique

At present, most scholars use the "two-zone" development height estimation formula proposed in the "three-down" mining regulations of the former Ministry of Coal Industry when studying the overlying rock failure height, and through corresponding calculations, the maximum overlying rock damage height is obtained. The formula for calculating the height of the "two zones" (the caving zone and the water-conducting crack zone) is as follows:

1) Height of caving zone

Considering the difference in the physical and mechanical properties of the coal seam roof, different lithologies can be calculated according to different formulas (Table 1).

Table 1 Empirical formula for calculating the height of the caving zone

∑M in the formulas in the above table is the cumulative thickness, the single-layer mining thickness shall not exceed 1-3m, and the cumulative thickness shall not exceed 15m.

2) The height of water-conducting crack zone

If the roof of the coal seam is hard, moderately hard, soft and extremely soft rock formations or interbeds, the maximum height of the water-conducting fracture zone can be estimated according to the empirical formula in Statistical Table 2.

Table 2 Calculation formulas for the height of water-conducting fracture zones in horizontal, gently inclined and middle inclined coal seams

Also, according to the latest national statistics of the empirical values of the heights of the two zones, the medium-hard overburden can refer to the regression equation of the reciprocal height of the medium-hard overburden water-conducting fracture zone and the reciprocal mining thickness:

However, the existing calculation methods have certain shortcomings, because the geological conditions of the project site are complex, and the lithology varies greatly from place to place. The formula given by the former Ministry of Coal cannot generally and accurately obtain the height data of the two zones through simple classification. Moreover, only the formula calculation method is written into the regulations for the height prediction method of the two zones at the present stage, and other emerging methods such as geophysical prospecting, simulation and drilling are only used as auxiliary means, and there is no overall planning. Some of the various methods can achieve the same detection purpose, and the results of repeated use not only waste manpower and material resources, but also affect the prediction accuracy and bring hidden dangers to safe production.

The information disclosed in this Background section is only for enhancing the understanding of the general background of the present invention and should not be taken as an acknowledgment or any form of suggestion that the information constitutes the prior art that is already known to those skilled in the art.

Contents of the invention

The object of the present invention is to provide a method for testing the height of the caving zone and the water-conducting crack zone with a simple and reasonable structure. The method for testing the height of the caving zone and the water-conducting crack zone belongs to an efficient detection combination scheme, which can After determining the range of the caving zone and the water-conducting fracture zone, the demarcation line is determined by using targeted detection methods to verify the precise position of the demarcation line in a small area, improve the prediction accuracy, and avoid redundancy and waste of technical resources.

In order to achieve the above object, the present invention provides a method for testing the height of the caving zone and water-conducting fracture zone, comprising the following steps: first, calculate the predicted results of the height of the two zones through the formula of the height of the two zones; secondly, apply the geophysical The detection method preliminarily determines the height range of the two zones in the study area; thirdly, the water injection pressure measurement system, the borehole TV system or the borehole flushing fluid observation system are used to further determine the height range of the two zones at fixed points; finally, the simulation method is used to verify the height range of the two zones scope.

Preferably, in the above technical solution, the geophysical detection methods include: electromagnetic method, three-dimensional seismic method, microseismic monitoring method and seismic wave CT method.

Preferably, in the above technical solution, the electromagnetic method determines the height of the water-conducting fault zone by mining the change in the apparent resistivity of the overlying rock.

Preferably, in the above technical solution, the geophysical detection method needs to focus on observing changes in the critical area based on the calculation results of the two-zone height formula.

Preferably, in the above technical solution, the simulation method includes: physical similarity simulation and numerical simulation.

Compared with the prior art, the present invention has the following beneficial effects: the test method for the height of the caving zone and the water-conducting crack zone belongs to an efficient detection combination scheme, and can determine the range of the caving zone and the water-conducting crack zone as a whole Finally, a targeted detection method is applied to determine the demarcation line, verify the precise position of the demarcation line in a small area, improve the prediction accuracy, and avoid redundancy and waste of technical resources.

Description of drawings

Fig. 1 is the flow chart of the test method of the height of the caving zone and the water-conducting crack zone of the present invention.

detailed description

The specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations thereof such as "includes" or "includes" and the like will be understood to include the stated elements or constituents, and not Other elements or other components are not excluded.

As shown in Figure 1, the method for testing the height of the caving zone and the water-conducting crack zone according to the specific embodiment of the present invention specifically includes the following steps:

Firstly, the prediction results of the height of the two zones are obtained by calculating the height of the two zones;

Collect data, conduct qualitative analysis on the geological conditions of the project site, sort and classify the obtained results, and substitute the corresponding parameters into the calculation formula of the height of the two zones according to different conditions, and obtain the prediction results of the height of the two zones.

Secondly, the application of geophysical detection method to preliminarily determine the range of the height of the two zones in the study area;

Among them, geophysical detection methods include: electromagnetic method, three-dimensional seismic method, microseismic monitoring method and seismic wave CT method, and focus on observing changes in the critical area based on formula calculation results. The electromagnetic method mainly determines the height of the water-conducting fault zone through the change of the apparent resistivity of the mining overlying rock, mainly including: high-density resistivity method, EH4 magnetotelluric method and transient electromagnetic method. When using geophysical detection methods: electromagnetic detection has a large volume effect, so it is difficult to accurately determine the critical apex of the water-conducting fault zone. Seismic wave CT method does not have volume effect. As long as the geophone distance is arranged reasonably and the vertical resolution is improved, The detection result is more accurate than the electromagnetic method. However, this method is difficult to infer the height of the caving zone and the development of fractures as a whole. The transient electromagnetic method is sensitive, and the exploration equipment has high requirements for the working environment, and it reacts strongly to small disturbance sources, so it cannot be widely used in downhole geophysical exploration on a large scale, but it has a good effect on the prediction of the height of the two zones. The various methods proposed above have their own advantages and disadvantages. They have different adaptability to different environmental conditions and can be used interchangeably according to different situations. The most widely used method is the transient electromagnetic method.

Thirdly, apply water injection pressure measurement system, borehole TV system or borehole flushing fluid observation system to further determine the height range of the fixed-point two zones;

Among them, the borehole flushing fluid observation system observes the loss of borehole fluid and pressure changes with time, and some characteristic pressure points in the process of hydraulic fracturing stress measurement, such as burst pressure Pb, retension pressure Pr, shut-off pressure Ps, etc. related to rock stress. In the two zones (the caving zone and the water-conducting fracture zone), the drilling loss fluid must be different, and the fracturing pressure will also change, so as to judge the approximate range of the height of the two zones. This method is highly targeted, but sometimes the selected parameters of the borehole are not representative, so the conclusion of the area cannot be drawn as a whole. This is the disadvantage of this method.

The borehole TV system puts a waterproof camera probe with light source into the underground borehole, which can observe, monitor and record various characteristics and subtle changes of geological bodies in the borehole in real time. Application Through ground drilling, by observing the integrity of the coal seam roof overlying strata in the borehole, the development characteristics of primary cracks, the crack development width and connectivity of the strata in the fracture zone of the mined rock mass, the fracture status of the rock mass and the caving The condition of the rock block can provide the most direct basis for the failure zoning of the overlying rock, and this method is the most intuitive observation method. Analyze the authenticity of the approximate data of the distribution range of overburden failure height. This method can be used as a method to improve detection accuracy in a small area. Also, this method is highly targeted, but sometimes the parameters selected for drilling are not representative, so conclusions about the region cannot be drawn as a whole. This is the disadvantage of this method.

Finally, the range of the heights of the two belts is verified by physical similarity simulation or numerical simulation.

Physical similarity simulation refers to the supplementary research through indoor physical similarity simulation. This method is difficult to simulate the groundwater environment, so it is used as a supplementary method to discuss the law of lithology migration to verify the results. The change characteristics of the height of the two zones under different conditions can be determined from the overall observation of the change law of the overlying rock after mining. It is intuitive and meaningful for the extraction of laws.

Numerical simulation refers to selecting a numerical software to simulate by setting parameters, such as FLAC, UDEC, PFC, RFPA, etc., to simulate the law of overlying rock under mining conditions. The advantage is that the method is easy to operate, and it is easy to simulate the laws under different conditions. The disadvantage is that there are too many factors considered, and it is difficult to guide production with definite conclusions.

When predicting the two zones in the production mining area, researchers can often use their own regional experience to judge the overlying rock damage height, compare the calculation results of the formula, know the approximate range of the parameters, narrow the scope of geophysical prospecting and drilling, and improve detection. precision. Among all the existing methods for predicting the maximum height of overburden failure, under the guidance of the method based on the calculation formula of the regulations, the latest drilling, geophysical prospecting and simulation methods are used to optimize the combination to obtain a set of more accurate detection methods. It is very meaningful and necessary to form a forecasting system.

In summary, the test method for the height of the caving zone and water-conducting fracture zone belongs to an efficient detection combination scheme, which can determine the range of the caving zone and water-conducting fracture zone as a whole, and then apply a targeted detection method to determine To verify the precise position of the dividing line in a small area, improve the prediction accuracy, and avoid the redundancy and waste of technical resources.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling others skilled in the art to make and use various exemplary embodiments of the invention, as well as various Choose and change. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims (5)

1. a method for testing the height of a caving zone and a water-conducting crack zone, is characterized in that, comprises the following steps: Firstly, the prediction results of the height of the two zones are obtained by calculating the height of the two zones; Secondly, the application of geophysical detection method to preliminarily determine the range of the height of the two zones in the study area; Thirdly, apply water injection pressure measurement system, borehole TV system or borehole flushing fluid observation system to further determine the height range of the fixed-point two zones; Finally, the range of the height of the two belts is verified by the simulation method. 2. The method for testing the height of the caving zone and water-conducting fracture zone according to claim 1, wherein the geophysical detection method comprises: electromagnetic method, three-dimensional seismic method, microseismic monitoring method and seismic wave CT method. 3. The method for testing the height of the caving zone and the water-conducting fracture zone according to claim 2, wherein the electromagnetic method determines the height of the water-conducting fracture zone by mining changes in the apparent resistivity of the overlying rock. 4. The method for testing the height of the caving zone and water-conducting fracture zone according to claim 2, wherein the geophysical detection method needs to focus on observing the change of the critical zone based on the calculation results of the two zone height formulas. 5. The method for testing the height of the caving zone and the water-conducting crack zone according to claim 1, wherein the simulation method comprises: physical similarity simulation and numerical simulation.