طريقة لعلاج الانزلاق عند الحفر في الصخر الزيتي أو التربة الغرينية مثقب

Spiral drilling rigs often slip when drilling into mudstone or mud layers, meaning that the pressure exerted by the rig is ineffective, making it impossible or difficult to drill, thereby affecting construction progress and production efficiency. The following is an effective method for drilling shale with a rotary drilling rig.

1、 Introduction to Mudstone

Mudstone, sandy mudstone, argillaceous sandstone, sandstone, shale and other sedimentary rocks contain abundant oxides, which are red, dark red or brown in color, hence they are collectively referred to as red sandstone. Red sandstone is mainly composed of granular debris structures and argillaceous gel structures. Most red sandstones undergo fragmentation, fragmentation, and even mudification under atmospheric conditions. Therefore, the particle size and particle size distribution of red sandstone will vary with the time course of wet dry cycles. Mudstone is a sedimentary rock formed by solidification of mud and clay. Its composition is similar to structure and shale, but it is not fragile. Unclear bedding or shale clay rock. Mudstone has water absorption and adhesion properties. The following figure shows a typical mudstone formation.

2、 Reason for slippage

During the construction process, if dry drilling is used to drill into mudstone, the drilling efficiency is higher; If a double-layer bottom bucket is used, the drilling efficiency is higher, but the load is larger; Once water enters the hole, immediate slippage occurs, so slippage is directly related to water or mud. Therefore, the main reasons for mudstone slippage are as follows: 1. Mudstone. Hardness; 2. Lubrication with water or mud; 3. Mudstone absorbs water and softens.

3、 Using different drilling tools for drilling

When drilling water holes in mudstone with a screw drill bucket, due to the softening of mudstone by water, the front cone of the screw drill bucket will be filled with mudstone slag soil to form a whole, causing the drilling tool to lose its drilling function. After unsustainable drilling, water or mud enters between the drilling bucket and mudstone, providing lubrication and forming slippage.

When using a double bottom bucket to drill into mudstone water holes, the tail cutting drilling method is to use a front alloy drill bit for drilling. The alloy head is prone to breaking into mudstone, but due to the short length of the front alloy head, the truncated body with a fixed alloy head must move accordingly. Due to the bluntness of the blade, resistance will be formed, causing the blade to break into shallow mudstone, which has a cementing effect and cannot achieve the crushing effect. In addition, during the drilling process, a large amount of mud will adhere to the outer wall of the drilling bucket, causing "floating drilling". Therefore, if drilling cannot continue, slippage will occur.

Based on the above analysis, the cementation of mudstone is not easily broken. We need sharper tools, deeper drilling depths, and lower cutting resistance to achieve the effect of cutting and crushing.

4、 Handling of slippage during mudstone drilling:

Therefore, choosing a double bottom salvage bucket and cutting the borehole conforms to the above analysis. But actual sand buckets can also slip, but there are many factors involved.

1. Defects on the drill bucket, such as difficulty in locating the center too long, too wide, too dull, the angle of the tooth tip and the position of the gap between the teeth, the diameter of the teeth at the edges, the type of bucket teeth or the penetration of the tooth tip, it is best to increase the length of the tooth tip to reduce the contact area. The drill bit bucket shown in the following figure is specially improved for shale drilling, including bucket tooth reverse installation, bucket tooth extension, etc.

The larger the diameter of the bucket, the larger the contact area, and the more difficult it is to overcome slippage. Therefore, the larger the diameter of the pile, the smaller the diameter of the bucket can be used first.

The main reason for overcoming slip is slip caused by water or slurry lubrication. Therefore, as long as the influence of softened mudstone and surface water or mud is overcome, the slip of mudstone can be overcome. After overcoming this problem, continuous drilling should be carried out to minimize the idling of the power head in the hole, so that water or mud cannot enter the cutting surface, and the tooth tip should always be in contact with dry geological conditions, allowing for normal drilling.

4. Operational control is very important. Due to its hardness and good cementation, mudstone is not easy to cut under water lubrication conditions. Firstly, the power head must be raised to the highest level. Afterwards, the power head must be controlled to rotate slowly and continuously. The speed and pressure of the power head must be well matched. If the pressure stroke is completed, there is no insertion. Mudstone, then lift the power head to continue drilling until the geological load enters and rises, and then continue drilling. When the load is too large, the power head needs to be lifted to reduce the load and protect the drilling rig components. When the load decreases, the friction coefficient should continue to be reduced by waterproofing or mud entering the cutting surface.

Due to the softening of mudstone, there are two types of slip phenomena in slip graded drilling. One is support slippage, namely mudstone slippage; Another type is mudstone slippage, as mudstone is difficult to drill and cut, and may slip underwater or under mud lubrication. Therefore, in order to effectively handle slip, it is necessary to identify the type of slip.

The difference between these two types of slippage is very important, and the handling methods are also different. If the mudstone softens, the basement slip is overcome by reverse positive pressure. If the rigidity of mudstone is strong and the friction coefficient decreases with the decrease of water, it can be overcome through the series of integration methods mentioned above. Due to the different bonding materials and weathering degrees, the strength of mudstone varies greatly, and not all mudstones can be drilled using cutting methods.