Experimental Research On Flow In The Efflux Element Of The Hydro-efflux Hammer With PIV

With the depth of oil and gas well increasing, the difficultyof hard rockdrillingisaddedtoo.Atpresent,thetraditionalrotarydrillingmethodswithconebitorPDCbitismoreoftenused.Whendrillingahardformation,thepenetration rate is low, the service lifetime of bit is short and the cost ishigh. According to the rock-breaking theories, the percussion-rotarydrilling technique is one of the most effective ways to drill hard rock.Hydro-efflux percussive-rotary drilling is deployed to exploratory drillingof gas-oil field, the anticipative average drilling efficiency of hard rockwouldbeadvanced30%to50%,andthecostfell15%to20%.Fluid Efflux Hammer has a good name in the field of drilling for itsparticular style and specific performance, from its burning. An experimenton one type of this drill has been done successfully under the simulateddeepholeconditionsinInstituteofClausthalUniversityinGermany.Whenthe surrounding pressure is 400 bars, it can still work normally. However,in the application process, with the changing of working condition andspecific operating requirement, its advantages was not made full use, andsome interior structure members accumulated some questions whenapplicated. Wheneffluxcompactorwasapplicatedindeepholedrilling,forexample, petroleum drilling and CCSD etc, the working life of effluxelement is very low. For expediting the steps of the theoretical research ofHydro-efflux Hammer, therefore, some aspects would be studied asfollows:1. Disengages the efflux and the piston housing, and measures thefrequency of the piston when efflux hammer being in normal operatingconditions.2. In order to improve the performance of efflux element, we must testthe internal flow of efflux element .Qualitative and quantitative analysis isused on flow field of efflux element by using the particle imaging velocimetry(PIV). So that we can understand the internal flow, holdconstruction and distributing of internal field, and confirm the correctnessofdesigntheory.3. Proceeds analogsimulation analyses, combined with experiment data,for being affluent intheoretical investigations, perfecting parameter designof efflux element. It should be used for supervising the design philosophyandtheoreticalanalysisofeffluxhammer.There is one important conclusion: SC-89 efflux hammer is still able tonormally work when the element is departed from piston housing to threemeter long. In the previous design experience, the element was connectedwith piston housing as short as possible, making the pressure signaltransfer as soon as possible. But the large output in petroleum drillingcomes into being high pressure in the working housing of efflux element.The velocity of evacuation passage is very high. It is adverse to the life ofefflux hammer. Therefore, according to this experiment, we can length theoutputpassageoftheeffluxelementinordertoaggrandizementevacuationpassage, decreasingerodibilityofflushingfluidattheevacuationpassage.Particle image velocimetry technology (PIV) is adopted to measure theflowfieldofeffluxelementforthefirsttime.Fromthisexperiment,wegetmore truly distribution of velocity in the flow field. It supplies reliableexperiment data for design and improvement of the efflux element.At last,we proceed simulation the flow field of the efflux element. The results ofnumerical simulation and PIV are analyzed and compared in this paper.The difference of two methods is relatively small.The results of PIVmeasurement are applied to pave good basement for setting model ofnumericalsimulationandofferreliabledatafornumericalsimulation.