Study On The Technology Of Keeping Straight And Preventing Deviation In Coal Mine Gas Extraction Drilling

Coal mine gas drainage along the common bias of drilling,in particular,gas drainage borehole bedding more serious skew conditions.Due to uneven distribution of boreholes and even too large spacing to form a blank area in the drainage area,the effect of gas drainage is affected,and gas accident safety accidents are easy to happen.In order to solve the above problems,this article planning to use the way that a combination of theoretical analysis and field test.The following studies have been carried out:(1)Through theoretical analysis,there are three main factors that cause drilled migration: geological factors,technical factors and technological factors;The force analysis of the hole bottom drill rod.The basic parameters of inclinometer borehole trajectory are tested and analyzed.The calculation results show that the borehole inclination appears generally large,somewhat less in the near the final hole near;azimuth angle variation is the overall trend of increase is the right angle and azimuth angle;the maximum change value of average variation were 9.8 degrees and 8.1 degrees;to every 20 m for a study interval,the dip angle of the maximum rate of area was 40-60m;in the end of the hole position,the overall average offset drilling is 9.9m.(2)By using the method of theoretical analysis and direct techniques of drilling,borehole deviation analysis combined with,take full hole drilling technology;comparative analysis of the three kinds of common pipe deslagging principle,adopt the groove drill pipe is connected with the short circuit discharge Sanleng technology;for the back drilling problems,put forward a new idea of reverse bit the.(3)Through the research of three key technologies,such as direct technology,slag removal technology and drilling technology,a set of borehole straight protection and anti slanting device is designed.The diameter of the device is the same as the diameter of the bit,the design of three spiral grooves and vertical grooves is adopted,and then the short row connection is used to achieve the slag discharge smoothly.After welding the three alloy sheets at the rear end of the device,it acts as a reverse drill bit to achieve the smooth drilling.(4)The field test was carried out by using the processing straight and anti tilt device.The test showed that the drilling distance reached the design depth of drilling hole,and there was no sticking phenomenon in the drilling process.Through the comparative analysis,the maximum change value of the inclination angle and azimuth angle is reduced by 51% and 44% respectively,and the interval change rate of borehole inclination is reduced,which inhibits the upward trend of borehole,and the overall offset decreases by 71%,which improves the quality of drilling.In order to achieve straight drilling,a kind of straight-retaining and anti-slanting device was designed.