Rotary drilling rigs often experience slippage when drilling into mudstone or silt layers, meaning the rig's pressure application becomes ineffective, making drilling impossible or difficult, thus affecting construction progress and production efficiency.#driller for sale#
I. Overview of Mudstone
Sedimentary rocks such as mudstone, sandy mudstone, argillaceous sandstone, sandstone, and shale are red, dark red, or brown due to their rich oxide content; these rocks are collectively called red sandstone. Red sandstone mainly exhibits two typical structural forms: granular clastic structure and muddy cemented structure. Most red sandstone can disintegrate and break down under atmospheric influences, even becoming muddy; therefore, the size and particle size distribution of its rock blocks will change with the time of wet-dry cycles. Mudstone is a sedimentary rock formed from solidified mud and clay; its composition and structure are similar to shale but it is less easily broken. It is a clay rock with indistinct bedding or foliation. Mudstone has water absorption and bonding properties.#driller for sale#
II. Causes of Slippage
During construction, when drilling dry holes into mudstone, using a spiral drill bit is more efficient. A double-bottom sand-scooping bucket can also be used, but with a higher load. Slippage occurs immediately upon encountering water in the hole. Therefore, slippage is directly related to water or mud. The main causes of mudstone slippage are: 1. Hardness of the mudstone; 2. Lubricating effect of water or mud; 3. Softening of the mudstone by absorbing water.
III. Drilling with Different Drilling Tools
1. When drilling water-bearing mudstone holes with a spiral drill bit, the mudstone softens upon contact with water, filling the cone tip of the spiral drill bit with mudstone debris, forming a solid mass. The drill bit then loses its drilling ability and cannot continue drilling. Water or mud then enters between the drill bit and the mudstone for lubrication, resulting in slippage.
2. When drilling into mudstone water holes using a double-bottomed cutting bit drill bit, the cutting bit drilling method utilizes the alloy head at the front end. The alloy head easily penetrates the mudstone, but because the alloy head is very short, the cutting bit body, which holds the alloy head in place, must follow suit. Since the cutting bit body is too blunt, it creates resistance, causing the cutting bit to penetrate the mudstone too shallowly. Mudstone is cemented, thus failing to achieve a breaking effect. Furthermore, a large amount of silt adheres to the outer wall of the drill bit during drilling, causing "floating drill." Therefore, continuous drilling is impossible, resulting in slippage.
3. Based on the above analysis, mudstone is highly cemented and difficult to break. Sharp cutting tools are needed to drill deep with low cutting resistance to achieve a cutting and breaking effect.#driller for sale#
