Causes and treatment of slipping of the hottest ro

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Causes and treatment of slip of rotary drilling rig when drilling mudstone

causes and treatment of slip of rotary drilling rig when drilling mudstone:

when drilling mudstone or sandstone, rotary drilling rig often slips, that is, there is no resistance or pressure, unable to drill or difficult to drill, thus affecting the construction progress and production efficiency. After a long time of construction and experience accumulation, I have also participated in many mudstone geological foundation construction projects, and have some understanding and opinions on drilling mudstone Integration of drilling tools and operations Finally, the problem of mudstone drilling will be solved

I. overview of mudstone

mud 10 Force measurement range: 2% - 100% FS (4kn ~ 200kn rocks, sandy mudstone, argillaceous sandstone, sandstone, shale and other sedimentary rocks are collectively referred to as red sandstone because they contain rich oxides in red, crimson or brown. Red sandstone mainly presents two typical structural forms: granular clastic structure and argillaceous cementation structure. Most red sandstones can be disintegrated and broken, or even argillated, under the action of atmospheric environment, so the size and particle grading of their rock blocks will change with the drying and wetting cycle Change with time. Mudstone is a kind of sedimentary rock solidified by mud and clay. Its composition is similar to structure and shale, but it is not fragile. A kind of clay rock whose bedding or foliation is not obvious. Mudstone has the characteristics of water absorption and bonding

II. Causes of slippage

during construction, if dry hole drilling is used to drill mudstone, the drilling efficiency of spiral bucket is higher, and if double bottom sand bucket is selected, it can also be drilled, but the load is larger; Once there is water in the hole, there will be slippage immediately, so the slippage is directly related to water or mud. Therefore, the main reasons for mudstone slippage are as follows: 1. The hardness of mudstone, 2. The lubrication of water or mud, 3. The softening of mudstone by water absorption, etc

III. drilling with different drilling tools

1. When the auger bucket drills the mudstone in the water inlet hole, because the mudstone softens when it meets water, the cone at the front end of the auger bucket will be filled with mudstone muck to form a whole, and the drilling tool will lose its drilling function. After continuous drilling is impossible, water or mud will enter between the drill bucket and mudstone and lubricate, forming slip

2 when drilling mudstone water holes with a double bottom pick drill bucket, because the pick drilling method is to use the alloy head at the front end to drill in, the alloy head is easy to break into the mudstone, but because the alloy head at the front end is very short, the pick body fixing the alloy head must follow up and cut in, but the pick body is too blunt, forming resistance. Because the pick breaks into the mudstone too shallow, the mudstone is cemented, so it cannot achieve the crushing effect, so it cannot continue to drill, Slip occurs when water or mud enters between the pick and mudstone and lubricates

3 according to the above analysis, the cementation of mudstone is not easy to be broken, which requires sharp knives, deep drilling and low cutting resistance to achieve the effect of cutting and breaking

IV. treatment method for mud rock drilling slipping:

therefore, double bottom bailing bucket is selected, and cutting drilling meets the above analysis. However, the actual sand bucket will also slip, but there are many factors

1. Defects on the drilling bucket, such as the central positioning tip is not easy to be too long, too wide and too blunt, the angle of the tooth tip and the composite polyurethane adhesive between the tooth seats. The upstream of the industry is the gap of the basic petrochemical raw materials industry, the diameter of the side teeth, the development of the bucket teeth after 107 years, innovative models or the wear of the tooth tip. It is best to improve the length of the tooth tip, Reduce the contact area

2. The diameter of the bailing bucket. The larger the diameter of the drilling bucket, the larger the contact area is also one of the important source areas of sand and dust in the northwest. The larger the area, the more difficult it is to overcome slip. Therefore, the larger the pile diameter, the smaller the diameter of the drilling bucket can be selected first

3. The analysis of overcoming slippage has mentioned that the main reason is the slippage caused by water or mud lubrication, so as long as the softened mudstone and the water or mud on the surface are overcome, the mudstone slippage can be overcome! After being overcome, it is necessary to continue drilling, so that water or mud cannot enter the cutting surface, so that the tooth tip has been in contact with dry geology, and then it can be drilled normally

4. Operation control is very important. Because the mudstone is hard and has good cementation, it is not easy to cut in under the lubrication of water. First, raise the power head to the highest level, and then control the power head to rotate slowly. The pressurization speed is slow and continuous. The power head must match the pressurization speed well. If the pressurization stroke is completed and the mudstone is not cut in, re lift the power head and continue drilling until the geological load rises, After that, continue drilling. When the load is too heavy, lift the power head to reduce the load, so as to protect the drilling rig components. When the load is reduced, continue to pressurize to prevent water or mud from entering the cut surface and reduce the friction coefficient

5. There are two kinds of slippage phenomena when drilling by slippage classification, because the mudstone is softened. One is bottom slippage, which is the so-called phenomenon of soil falling and slipping in the drilling mud layer; The other is mudstone slipping. Because mudstone is hard, it is difficult to drill and cut, but it slips under the lubrication of water or mud. There is a difference between the two kinds of slipping. Therefore, it is necessary to distinguish the type of slipping in order to deal with it effectively

6. It is very important to distinguish the two kinds of slippage, and the treatment methods are also different. If it is mudstone softening and bottom slippage, reverse the forward pressure to overcome it. If it is mudstone that is hard and the friction coefficient is reduced due to water, the slippage can be overcome through a series of integration methods mentioned above. Due to the difference of cementation material and weathering degree, the strength of mudstone changes greatly, so not all mudstone can be drilled by cutting

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