In the vast journey of geological exploration, every technological leap is a brave exploration and deep insight into the unknown world. With the rapid development of science and technology, hydrogeological drilling has also ushered in a technological innovation-the birth of DTH hammer drilling with casing technology. It is like a strong east wind, blowing away the fog of traditional drilling technology and opening up a new channel for the industry that is efficient, safe, and environmentally friendly. This technology not only enhances drilling efficiency and operational safety but also, with its unique advantages, becomes a golden key to solving drilling problems under complex geological conditions, opening a new chapter in hydrogeological drilling.
Background Overview
Hydrogeological drilling is a pivotal means of obtaining groundwater resource information and assessing the stability of geological structures and has long been an indispensable part of geological work. However, traditional drilling technology often faces challenges such as low efficiency, high cost, and high safety risks when facing complex strata, solid rocks, or special geological conditions. It is in this context that DTH hammer drilling with casing technology came into being, bringing revolutionary changes to hydrogeological drilling with its high efficiency, safety, and economy.
Technical Principle
DTH hammer drilling with casing technology is a drilling method that combines the speed advantage of air DTH hammer drilling and the advantage of casing wall protection that is beneficial to the stability of the borehole wall. When drilling, the eccentric drill bit is thrown out when the eccentric block rotates forward. The diameter of the thrown eccentric drilling tool is larger than the diameter of the center drill bit. While drilling, the casing is driven to follow up synchronously through the casing shoe. Seamless steel pipes are crucial to protecting the stability of the borehole wall of the exploration and production well and preventing the hole wall from falling off and collapsing. When the eccentric drill bit drills into the complete formation, after drilling 0.5~1m, the eccentric block is retracted by reversing, and then the eccentric drilling tool is retrieved from the wall protection casing so that the Quaternary overburden and the broken and complex stratum can be traversed more smoothly.
Technical Features
1. DTH hammer drilling with casing technology fully utilizes the advantages of the pneumatic DTH hammer in rapidly crushing rocks, which is conducive to the development and implementation of exploration and production combined well work in hydrogeological surveys.
2. The casing drilling technology follows the casing while drilling and does not require water and drilling mud. Especially in dry and water-scarce areas, it can achieve twice the result with half the effort, avoiding the difficulty of buying water for drilling, which is very beneficial to improving work efficiency.
3. This drilling technology uses synchronous follow-up casing to protect the wall during drilling, using the full advantage of the air DTH hammer in rapidly crushing rocks while keeping the wall of the Quaternary weak covering layer above the borehole stable. The crushed rock cuttings are taken out of the hole by high-speed airflow, and the suction effect is conducive to the opening of the water outlet channel. The continuous flushing of the hole wall by high-speed air will also shorten the washing time, which is conducive to improving the efficiency of hydrogeological drilling and well completion.
4. The DTH hammer drilling with casing technology is applicable to hard rock drilling. For clay formations or similar soft formations, it is easy to block the airway, and the discharged drill cuttings are easy to hang on the hole wall to form mud plugs, so it is impossible to realize the ideal drilling efficiency.
5. After completing the wall protection task, the casing of the DTH hammer drilling with casing can be pulled out by special equipment and can be recycled within a certain period to reduce construction costs.
Casing drilling process
The key to the casing drilling technology of the DTH hammer is to follow the casing synchronously during drilling to protect the stability of the borehole wall.
1. Carefully check whether the connection between the eccentric drill bit and the hammer is reasonable and reliable before drilling.
2. Check whether the hammer can work properly.
3. Try to pass on the matching between the eccentric drill bit and the casing shoe.
4. During the drilling process, the drilling tool should be kept slightly away from the bottom of the hole, so that the high-pressure airflow can continuously bring the broken rock chips out of the borehole to avoid repeated crushing and increase drilling costs.
5. After completing the drilling operation, carefully perform the drill bit reversal operation to recover the eccentric block that was thrown out. During this process, we need to precisely control the magnitude and speed of reversal to ensure smooth operation, effectively prevent the risk of accidental fall-off of the drill bit due to excessive reversal or improper operation, and ensure operation safety and efficiency.
6. When the drilling reaches the preset depth, the operator should not immediately stop drilling and lift the rock drilling tool. Instead, the operator should adopt a continuous operation: the drilling tool should be slightly lifted and put back into the hole repeatedly. During this process, high-pressure airflow is used to forcefully remove the accumulated rock debris in the hole to ensure that the hole is clean and free of residue. At the same time, this operation also helps to flush and remove the rock debris that may adhere to the hole wall, thereby keeping the drilling hole unobstructed and laying a good foundation for subsequent operations.
Anti-deflection technology
In the high-efficiency drilling of the DTH hammer, although the speed advantage is significant, it is accompanied by the problem that the drilling hole is easy to tilt. Once the hole inclination of the exploration and production well exceeds the established standard, it violates the strict specifications of hydrogeological drilling but also directly hinders the smooth running of the water filter well pipe, thus affecting subsequent operations and overall project efficiency. Therefore, during the drilling construction process, strictly controlling and effectively preventing the inclination of the exploration wellbore has become an indispensable and crucial part of the work.
In the drilling construction of exploration and production combined wells:
1. The drill jumbo must be perpendicular to the ground plane.
2. After opening the hole 2~3m, the drilling tool is lifted out, and the center position of the bottom of the hole will be defined by inverted pendant law, and the position of the drill jumbo is adjusted to make it better.
3. A centralizer must be added between the drill rod and the hammer to reduce the hole deflection. The centralizer can also be added between the drill rods as needed.
4. It is also crucial to adjust the appropriate feed pressure and control the drilling speed during drilling. The drilling speed is fast in the steep stratum, and it is easy to tilt along the layer, making the hole skewed. In the homogeneous stratum, the drilling speed is determined by the smoothness or otherwise of the slag discharge.
Conclusion
With its excellent performance and broad application prospects, the DTH hammer and casing technology has undoubtedly become a revolution in hydrogeological drilling. It solves many problems encountered by traditional drilling technology under complex geological conditions and injects new vitality and motivation into geological exploration with its high efficiency, safety, and environmental protection. Looking to the future, with the continuous maturity of technology and the continuous deepening of application, the DTH hammer and casing drilling technology will show its unique value in more fields and make more positive contributions to the development and utilization of geological resources, the prediction and prevention of natural disasters, and the sustainable development of human society. In this exploration ocean full of challenges and opportunities, the DTH hammer and casing drilling technology is leading us to write the splendor of the new era.
