Research And Application Of Oscillation Impacter

Along with the proportion of complex well in oil-gas field exploration and development has become larger and larger, such as horizontal well and extended reach well, followed by a series of problems:low ROP, poor tool face control, heavy BHA hang, irregular well, etc. Oscillation impacter is a kind of down hole equipment working with Water hammer, which can solve these problems well, and has great prospects for development. At present, only a few abroad companies mastered the key technology of oscillation impacter, in the domestic, the research is still in its infancy. This paper carried out a series of studies, from structure design to working principle to working characteristic and rock breaking mechanism, also includes drag reduction mechanism, Tool manufacture, the ground test and the field text, it is very helpful to the tool's development and field application.(1) This paper designs the structure of oscillation impacter, which comprises three main components:power section, valve system and oscillating system. With controlling the flow path size, generating the required pressure pulses inside the drill string, the hydraulic energy created by the pressure pulses inside the coiled tubing is transformed into mechanical energy as the string is being pulsed, to reduce friction; builds a physical-mathematical model of water-hammering process and longitudinal vibration about AG-itator tool, and studies its performance by using Visual Basic 6.0.to program the water-hammering process. The calculations show that an additional dynamic load acts on the rock which is in the form of sinusoid or cosinusoid. The peak of dynamic load is related to the difference between the maximum and minimum flow area, the frequency of dynamic load is related to the displacement of drilling fluid and the rate of power section.(2) On the basis of its performance research, dynamic-and-static-load rock breaking has been proved to be the primary rock-breaking mechanism supplemented by under-balanced rock breaking. By using ABAQUS to simulate the rock-breaking process, this paper studies the rock-breaking efficiency under different formations, operation frequency and peak value of load, shows that the efficiency of rock-breaking is in highlight at 16Hz, efficiency of rock-breaking increase as the peak of dynamic load increasing, when the peak load is above 10kN,the rock-breaking efficiency stabilized. This thesis also conducts a comparative analysis of AG-itator tool with the conventional rotary drilling and rotary percussion drilling, which provide a theoretical basis for the optimizing the structure of AG-itator tool and establishing relevant drilling process.(3) Based on studying the friction of horizontal well under the action of oscillation impacter, this paper established a vibration-friction mechanical model, elaborated the drag reduction mechanism, analyzed influence factors of friction and studied the location of oscillation impacter. We can conclude that the reduce of effective coefficient of friction is the key reason of smaller vibration friction than the maximal static friction, the ultimate principle of drag reduction is that the static friction was converted into vibration friction; the influence factors of friction include friction coefficient, drilling parameter, BHA and so on. The basic principle of where locate the tool is that the force of vibration must be larger than the maximal static friction from tool to the bit, in addition, locate multiple oscillation impacters in the same drill string assembly comply with the principle of confirmation from bottom up in turns.(4) Based on checking the tensile strength and torsional strength and completing the tool manufacture, the BHA has been recommended. For example, in straight wells, the oscillation impacter should be set as near as possible to the bit; in horizontal wells, the oscillation impacter can be located below the MWD or above the MWD; it is feasible to use multiple oscillation impacters in the same drill string assembly, only when the design of hydraulic parameters fit field requirements.(5) We carried out one time laboratory testing and three times field testing, the tests show that the tool's reliability and performance are very well, and its working frequency is proportional to the PDM's rotation speed, working pressure drop is about 3-4MPa, its amplitude is about 2-3mm, Water hammer force is larger than 100kN@27L/s; point contact TC bearing and tungsten carbide valve group are helpful to prolong the longevity of the tool, In the tool's working process, it is very friendly to the MWD signal, it also doesn't do any harm to the other downhole tools. In the last time field experiments, the ROP increased by 38.4% working with the oscillation impacter tool relative to without the tool.