阅读说明：本技术 一种煤矿冲击煤层高效水压致裂弱化防冲的判定方法 (Method for judging coal mine impacted coal seam efficient hydraulic fracturing weakening scour prevention ) 是由 王永 王维斌 赵忠显 吴广彬 徐晓利 于 2019-08-29 设计创作，主要内容包括：本发明公开了煤矿技术领域的一种一种煤矿冲击煤层高效水压致裂弱化防冲的判定方法,该方法包括以下步骤：步骤一：测定煤层注水可注性指标：分别测试3煤层煤样的参数,根据判定规则判别3煤层的可注性；步骤二：测定冲击倾向性指标：分别测试3煤层煤样的动态破坏时间、冲击能量指数、弹性能量指数及单轴抗压强度；步骤三：测定不同浸水时间的冲击倾向性指标：对煤样试件分别浸水,并对应测试出其不同浸水时间时的动态破坏时间、弹性能量指数、冲击地压能量指数、单轴抗压强度,分析不同浸水时间下煤样冲击倾向性的变化,本方法通过实验室浸水实验测定煤层物理力学参数变化情况,避免直接决定采用水力压裂和煤层注水等措施的卸压操作。(The invention discloses a method for judging high-efficiency hydraulic fracturing weakening scour prevention of a coal mine impacted coal bed in the technical field of coal mines, which comprises the following steps: the method comprises the following steps: measuring the coal seam water injection injectibility index: respectively testing the parameters of the coal samples of the 3 coal seams, and judging the injectibility of the 3 coal seams according to a judgment rule; step two: determination of impact tendency index: respectively testing the dynamic failure time, the impact energy index, the elastic energy index and the uniaxial compressive strength of the coal sample of the 3 coal beds; step three: determining impact tendency indexes of different soaking times: the method comprises the steps of soaking a coal sample test piece respectively, testing dynamic destruction time, elastic energy index, rock burst energy index and uniaxial compressive strength of the test piece in different soaking times correspondingly, and analyzing change of impact tendentiousness of the coal sample in different soaking times.)

1. A method for judging coal mine impact coal seam efficient hydraulic fracturing weakening scour prevention is characterized by comprising the following steps: the method comprises the following steps:

the method comprises the following steps: measuring the coal seam water injection injectibility index: respectively testing original moisture (W), porosity (n), water absorption (delta) and firmness coefficient (f) of the coal sample of the 3 coal beds, and judging the injectibility of the 3 coal beds according to a judgment rule;

step two: determination of impact tendency index: respectively testing the dynamic failure time, the impact energy index, the elastic energy index and the uniaxial compressive strength of the coal bed coal sample of 3 coal beds, and comprehensively judging the impact tendency of the coal;

step three: determining impact tendency indexes of different soaking times: and (3) soaking the coal sample test piece respectively, correspondingly testing the dynamic failure time, the elastic energy index, the rock burst energy index and the uniaxial compressive strength of the coal sample test piece at different soaking times, and analyzing the change of the impact tendency of the coal sample at different soaking times.

Technical Field

The invention discloses a method for judging high-efficiency hydrofracturing weakening scour prevention of a coal mine impacted coal bed, and particularly relates to the technical field of coal mines.

Background

At present, coal mines all over the country actively carry out the pressure relief work of rock burst prevention and control, and the pressure relief work mainly takes large-aperture drilling for pressure relief and is assisted by deep hole blasting of a coal seam. However, different defects exist due to the influence of conditions such as a pressure relief mode, a construction method and the like, wherein the large-aperture drilling pressure relief method has the problems of large construction engineering quantity, high labor intensity of workers, influence on pedestrian and material transportation in a roadway and the like; the coal seam deep hole blasting method not only influences the normal production of a working face, but also brings potential safety hazards due to the fact that a roadway is possibly damaged due to untight hole sealing and the problem of explosion rejection. The coal seam high-pressure water injection method is widely applied to other mines as a control means of rock burst, compared with other methods, the coal seam high-pressure water injection method has the characteristics of simplicity, practicability, low construction cost and wide applicability, and the adopted coal seam high-pressure water injection not only can change the stress state of a coal body through pressure relief, but also can change the physical and mechanical properties of the coal body through wetting the coal body, so that the impact property of the coal body is reduced. In addition, coal seam water injection can also play a role in dust fall, temperature reduction, fire prevention and outburst prevention, and the control of other disasters is considered while the rock burst is controlled, so that the method has a great effect, and the method is taken as a first-choice measure for the rock burst control of coal mines in China.

The high-pressure water injection pressure of the coal bed is generally more than 10MPa, even more than 25MPa, and the weakening principle is that the stress state of the coal rock mass at the hole edge is changed by utilizing the action of high-pressure water in a drilling hole, so that the hole edge cracks and cracks are expanded, and then the expansion of the water pressure cracks is controlled by utilizing the water pressure of the cracks, so that the overall mechanical property of the coal rock mass is weakened; meanwhile, the permeability of the coal rock mass is changed, so that the coal rock mass is fully water-absorbing and moist, and the coal rock mass is further softened.

The change condition of physical and mechanical parameters of the coal seam after being soaked in water directly determines the pressure relief effect of measures such as hydraulic fracturing and coal seam water injection. In order to find the applicability of hydraulic fracturing to various coal mines, laboratory water immersion experiment determination needs to be carried out on a main mining coal layer.

Disclosure of Invention

The invention aims to provide a method for judging high-efficiency hydraulic fracturing weakening scour prevention of a coal mine impacted coal bed, and the method is used for solving the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: a method for judging coal mine impact coal seam efficient hydraulic fracturing weakening scour prevention comprises the following steps:

the method comprises the following steps: measuring the coal seam water injection injectibility index: respectively testing original moisture (W), porosity (n), water absorption (delta) and firmness coefficient (f) of the coal sample of the 3 coal beds, and judging the injectibility of the 3 coal beds according to a judgment rule;

step two: determination of impact tendency index: respectively testing the dynamic failure time, the impact energy index, the elastic energy index and the uniaxial compressive strength of the coal bed coal sample of 3 coal beds, and comprehensively judging the impact tendency of the coal;

step three: determining impact tendency indexes of different soaking times: and (3) soaking the coal sample test piece respectively, correspondingly testing the dynamic failure time, the elastic energy index, the rock burst energy index and the uniaxial compressive strength of the coal sample test piece at different soaking times, and analyzing the change of the impact tendency of the coal sample at different soaking times.

Compared with the prior art, the invention has the beneficial effects that: according to the method, the change condition of the physical and mechanical parameters of the coal bed is measured through a laboratory water immersion experiment, the pressure relief operation of directly determining measures such as hydraulic fracturing and coal bed water injection is avoided, and the waste of resources is effectively avoided.

Drawings

FIG. 1 is a graph showing impact propensity class, name and index measurements of coals according to the present invention;

FIG. 2 is a schematic diagram of the dynamic destruction time of a coal sample according to the present invention as a function of the soaking time;

FIG. 3 is a schematic diagram of the change of the impact energy index of a coal sample with soaking time according to the invention;

FIG. 4 is a schematic diagram of the change of the elastic energy index of the coal sample with the soaking time according to the invention;

FIG. 5 is a schematic diagram showing the change of uniaxial compressive strength of a coal sample according to the invention with soaking time.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.