Question-Answer
? Question: 1) How the device operates in the abrasive rocks, I mean the blurring of the channels during the passage of the abrasive flow during the drilling process? 2) What features in the calculation of the hydraulics? Required differential needs to be calculated as the chisel, and on the ejector? Lithology of the section? In any species have been observed to better effect? Does the ejector work on the rate of rise of particles of cuttings in the pipe for space? The linearity of the liquid. What is the flow at the outlet of a sloping channel? 3) cross-channel? If the liquid does not reach the nozzles of the bit, we don't get enough exit speed of the jet from the nozzles and as a consequence may not complete clearing of the total slaughter. If we get the effect of bit balling in service of the bit when drilling young viscous clays? In our areas they are present. 4) is There a danger of overlap of the channels drilled rock? 5) How this device works in conjunction with the PDC bits?
✎ Answer: 1. The experience of drilling in abrasive rocks with the use of EGG channels does not significantly eroded, the wear of body AGG: over 300 hours of work diameter is reduced by 3-4mm, but it has no effect on the operation of EGG. Dramatically increases the penetration of the bit: when drilling without EGG there is an intensive wear-out of drill bits, using EGG of wear-out of drill bits are almost there.
2. When calculating the hydraulics all nozzles are reduced to a single nozzle (equivalent diameter) and further all calculations are standard. Note that the minimum differential pressure at the bit and EGG shall be not less than 3.0 MPa, with the increase of pressure drop - increase the mechanical drilling speed and penetration of the bit is almost linear.
Lithology of the section: increasing the speed of drilling occurs in almost all breeds with the correct selection bit.
The optimum effect is present in the abrasive rocks (sandstones), carbonates and argillites (siltstones) in soft clays more difficult to establish the effect of high speed drilling on the base of the wells, but drilling of EGG in soft clays no talnikovskoye and the wellbore are close to the nominal.
Work ASG does not affect the rise speed of the particles of cuttings in the annulus, thus, the slurry is very quickly removed from the working area of the bit ( not the secondary grinding sludge because of this, the bit wear and drilling speed is increased), after AIG, the speed of rise of the sludge usual.
From sloping channel comes out of the turbulent fluid flow with a velocity of 30-70 m/s.
3. The hydraulic calculation we take into account the necessary expenses of a liquid for work bits (technologically required flow rate of the flushing liquid) and EGG, so the bottom is cleaned well, if this were not so, we would not be increasing the speed of drilling.
4. Sometimes the overlap of one or two channels drilled out of the rock at the junction of the vertical and inclined channels. This happens usually when drilling in hard rocks when break off large chunks of sludge (quartz) in the form closest to parallelepiped aspect ratio 15х10х25 or is scrapping tooth drill bit approximately the same size, but the drilling speed changes slightly. If the drill pipe is not installed the filter, it can clog the nozzle on EGG and it's quite a strong effect on the increase of the drilling speed, so for example, if zanyatsa 1 nozzle, increase the rate of drilling will fall by 15-20%, if 2 nozzles - by 30-50%.
5. With the PDC bits of EGG works well, the average gain in drilling rate is 25-30%, but the penetration is much higher.