| While the exploration and development level of oil and gas resource isever-increasing throughout the world, the development of drilling technology istowards to the directional drilling like horizontal wells, highly-deviated wells andextended reach wells. Simultaneously, the conventional and mature slide steeringdrilling can almost meet the requirements of exploration and development.However, abundant drilling issues would be encountered in the process ofdirectional drilling, such as large frictional torque, difficulties in transmitting thebit weight and low drilling efficiency or rate of penetration, etc. The technologyof anti-friction and reducing torque is always the focus of drillers and researchers,and researches are emphasized on the control of borehole trajectory, the lubricityof drilling mud, flushing method of the borehole, the research and developmentof specialized tools for reducing friction and torque, the development of drillingtools with high strength, etc.Various drilling tools for specially reducing friction and torque had beendeveloped throughout the world and domestic. After the relevant survey andinvestigation, several mechanical drilling tools for reducing friction and torquehave been introduced in previous research literature, such as Weatherford rollertools, friction-reduction pup joint, anti-friction device with coiled tubing andaxial oscillation absorber, etc. Some tools have been serially manufactured and successfully applied to many drilling operations, yet some tools have just been intheoretical research period or field test period. Different types of directional wellhave different specialized drilling tool, and the tool types are rich. However, theextensive applied products are all researched and developed by foreign company,such as Agitator axial oscillation absorber, and domestic drilling engineeringneed to purchase, rent or employ their technical services if we want to use thosetools. Nevertheless, this increase the drilling cost due to the extremely expensivefee. In hence, the drilling research institution in domestic are automaticallystudying and developing the tools for reducing friction and torque.Simultaneously, the liquid jet percussive rotary drilling technology are of specialtechnology that China has the proprietary intellectual property rights, and thisdissertation has conducted an entire survey on this technology about the workingperformance of liquid hammer, simulation technology, test method and fieldapplication, etc.In this dissertation, a specialized tool for reducing friction and torque hasbeen researched and developed according to the problem on reducing friction andtorque in directional well drilling with the combination of liquid jet percussiverotary drilling technology, and tools for reducing friction, which is termed asliquid jet oscillation tool. The structure of the oscillation tool consists of upperaxial oscillation joint and lower liquid jet with pressure pulse joint. The basictheory of the oscillation tool is that the pressure pulse could induce an axialdisplacement, and acting on the drilling assembly in the bottom of the borehole,this could improve the frictional condition between drilling string in the hole andwell wall or the bearing sleeve, which could reduce the friction and torque,improve the drilling efficiency or rate of penetration (ROP), enhance the abilityof transmitting the bit weight, promoting the extension of hole trajectory, enlargethe resource exploration ability of the borehole. The research emphasis of thisdissertation is enclosed by the theoretical analysis, numerical simulationcomputation and field test research of liquid jet oscillation tool, the detailedresearch contents and conclusions are as follows: 1. Current development status and application prospect of friction andtorque reduction technology and liquid jet percussive rotary technology has beensurveyed, meanwhile the key technology and the necessity of researching anddeveloping the liquid jet oscillation tool has been conducted. Furthermore, thedrawing design of Φ120mm liquid jet oscillation tool, analysis on workingmechanism, CFD numerical simulation computation, prototype manufacture andtwo ground tests have been completed.2. The working mechanism of the liquid jet oscillation tool was computed byCFD numerical simulation, especially the fluidic parameter analysis of thepressure pulse joint, and the computational procedure of the numerical simulationwas detailedly described, including the options of turbulence model andalgorithm, the establishment of the grid model in computational domain, thedefinition of initial boundary conditions, the dynamic grid technology, slidinggrid technology, the user defined function and the settings of time step, etc.According to the CFD numerical simulation computation results, the workingprocess of fluidic device with water jet switch was monitored. At the meantime,the reciprocating motion of the piston and the reciprocating motion of the pistonrod in the taper hole of the throttle plate are also monitored, and the variation ofworking parameter of the liquid jet oscillation tool in various pumped fluxconditions are obtained. In addition, the pressure variation of the liquid jetoscillation tool is eminently analyzed.3. The liquid jet oscillation tool could stably working with different pumpedflux in both two ground tests, and the pressure on4diverse gauging points at thepressure pulse joint, and the displacement on1gauging point at the axialoscillation joint are recorded and stored by the data acquisition system. Moreover,the working theory of the oscillation tool was proved to be feasible through twoground tests.4. The oscillating displacement and oscillating frequency of the liquid jetoscillation tool are qualified to meet the requirement of the previous design. However, the working pressure loss of this toll is slightly high.5. The existence of throttle plate can’t be the key influence factor on thenormal working of liquid jet oscillation tool, but it could have an influence on theworking parameter of the liquid jet oscillation tool, and the working pressure lossof the liquid jet oscillation tool with no throttle plate is relatively low.6. The working pressure loss and oscillating frequency have a linearrelationship with the pumped flux, and the variation relationship betweenoscillating displacement and pumped flux is not linear. While the pumped flux isless than14L/s, the oscillating displacement is small, which is less than3.2mm.Nevertheless, when the pumped flux is more than14L/s, the oscillatingdisplacement is big, which is more than5.5mm. However, while the pumped fluxis more than16L/s, the oscillating displacement of the tool is reversely smallerthan the displacement of14L/s. It can be concluded from comprehensive analysisthat the pumped flux with14L/s is the most optimal flux for the Φ120mm liquidjet oscillation tool. At the moment, the oscillating displacement is the maximumvalue, and the working pressure loss is reasonable.The innovations of this dissertation are as follows:1. A specialized drilling tool for reducing friction and torque while beingemployed in various directional drilling wells like horizontal wells,highly-deviated wells and extended reach wells was designed and developed,which is termed as liquid jet oscillation tool. In addition, the friction reductiontechnology with oscillation and liquid jet percussive rotary drilling technologyare integrated to improve the transfer of bit weight and drilling efficiency.2. The research emphasis of liquid jet oscillation tool is on working pressureloss, oscillating frequency and the pressure pulse value generated in the inlet ofthe fluidic device while the piston is working, this differs from the previousresearches of working parameters of liquid jet hammer on the impact velocity,energy, frequency and the parameter of fluidic device, etc. 3. The “Interface” settings of sliding grids technology in FLUENT softwarewas applied to the CFD numerical simulation, which could handle the interfaceexisted between the dynamic fluids domain and the static fluids domain, and thereciprocating motion process of the piston rod in the taper hole of the throttleplate could be simulated by this technology.4. The working pressure and oscillating displacement of the liquid jetoscillation tool could be obtained by the data acquisition system (DAS), and thevariation law of the working pressure loss, oscillating frequency anddisplacement of this tool on the pumped flux could be obtained through thissystem.At present the theoretical feasibility of liquid jet oscillation tool was justverified by the ground test, the extensive application of this tool need to bedeeply researched in various aspects, and the working parameter like pressureloss, oscillating frequency and displacement of this tool had an extendedimprovement and optimization scope, and it was deserved further comprehensiveresearches in the future. |
PDF Full Text Request