Computerized Simulation Research On The DTH Hammer

With the increase of horizontal well and development of drilling large diameter and deep holes, drilling problems of hard formation and pressure increasingly prominent, which include short bit life, low drilling efficiency, high cost, long drilling cycle etc. Drilling technology of the DTH hammer has the following characteristics in addition to the characteristics of the air drilling. For example, low drilling pressure, improve the quality of well depth in the easily-inclined formation, fast drilling speed of hard formation, clean effectively the cuttings of bottom hole, reduce wear of drilling tool, wide application range etc. The technology can solve the above problems perfectly. The DTH hammer is one of its core components. The evaluation of its design and its performance’s disadvantages and advantages can be realized by simulation zooming.Through analyzing the DTH hammer structure and understanding the characteristics, the suitable formations, application fields and trend of the DTH hammer, the article establishes a mathematical model, which is based on the relevant theories of solid kinematics, dynamics and gas dynamics. The main theoretical equations comprise gas state equation, energy equation, gasses energy balance differential equation, effective heat efficiency equation and dynamic differential equation of the piston motion and so on. Through analyzing gas distribution process and motion mechanism of the DTH hammer, supposing the simulation conditions, the computerized simulation software of the DTH hammer is developed based on the definite differential principle. It can do simulation calculation for the motion process of the DTH hammer. The calculated results of gas state parameters and motion parameters in every short bursts are obtained in the form of data table. And for-and-aft gas cell pressure curve, velocity curve, displacement curve, volumetric flow rate curve and acceleration curve can be drawn. They indicate internal dynamic process of the DTH hammer. Moreover, the computer repeats calculating several cycles, then it outputs the calculated results of the whole working performance parameters of the DTH hammer, which includes piston’s journey, simple impact energy, impact frequency, gas-consuming, air pressure, impact power and available thermal power etc. According to calculation result, the article finds that structure parameters of the DTH hammer have influence on working performance, such as, air source pressure, distribution journey, structure journey, gravity of the DTH hammer, diameter of piston’s centre hole, diameter of piston’s rough end, diameter of piston’s thin end.The developed computerized simulation software of the DTH hammer.guides the DTH hammer to carry on design. The DTH hammer designed is well applied in the actual production and creates a certain economic value for the society.