Study On Fine Division Of Coal Seam Gas Extraction Unit And Design Method And Application Of Borehole

Gas extration is the fundamental measure of gas control.As one of the key parameters in the design of drilling holes,the design method of hole spacing corresponding to one working face is often adopted at present.This design method may cause problems such as substandard extraction or increased production cost,so it is urgent to conduct further research on hole spacing.For this reason,the paper puts forward the method of line division of coal seam gas extraction unit and drilling design,and applies the method in the field.The main research contents and results are as follows:(1)Fully considering the impact of key factors of the coal seam and in-depth analysis,constructed with mining plan,the gas occurrence and typical tectonic level according to the index system of gas extraction unit,will be fine gas extraction area is divided into different extraction unit,the main basis of division:according to the mining plan to calculate the subsequent planning area of the largest drainage period,provide the basis for arrangement of borehole spacing.According to the conditiong of gas occurrence,the demand for preventing sudden,reducing air and waiting to be determined on the working face was divided,and the adjacent area with similar gas content and type was divided into the same extraction unit,and the range was divided at about 100m.In typical areas such as faults,it is divided and designed separately according to the coal seam.(2)By dividing the gas extraction units and combining the time-efficiency of effective radius and pre-extraction time,the relationship between borehole spacing of each extraction unit is determined,and the fine dividing of the gas extraction unit is obtained.(3)Face to make use of the above methods,under the ideal state of the gas extraction unit division,in the region of the stripe and working face in coal roadway wear layer drilling design and drilling design respectively,according to the effective radius of the timeliness of determine the hole spacing of each extraction unit drilling parameters calculation,the drilling design method of fine division of gas extraction unit is obtained.(4)Taking the lower auxiliary roadway of 25011 of the Gaocheng coal mine as the test area,it is divided into 9 extraction units by using the drilling design method of fine division of gas extraction units.The representative Unit ?(hole spacing of 8m×8m),Unit ?(hole spacing of 10m× 10m),and Unit ?(hole spacing of 6m×6m)are selected to carry out detailed drilling design.Through the analysis 'of various indicators of gas extraction in each unit,all of them meet the requirements of gas extraction standards,and comprehensively determine that within 300 days of the pre-extraction period,gas extraction standards meet the design requirements.By comparing and analyzing the design method in this paper with the previous design method with the spacing of drilling holes being 6m×6m,it is concluded that the design method in this paper reduces the amount of engineering of about 688 drilling holes and greatly saves the production cost on the premise of reaching the standard of pumping and production.Figure[45]table[15]reference[83]...