Selection plan for geological exploration core drilling rigs, reference models suitable for soft and hard rock strata

In mineral exploration, engineering geological investigation and hydro-geological drilling projects, the rock strata conditions vary greatly, with soft soil layers, weathered rock strata and intact hard bedrock coexisting. Many exploration practitioners often wonder: Which core drilling rig should be selected for different rock strata?

How to avoid choosing the wrong model, which may lead to broken core sampling, slow drilling and insufficient core recovery rate? Xinhao drilling rigs will, in light of the characteristics of the stratum, provide a set of selection ideas for core drilling rigs that can be directly applied to the ground.

When choosing an exploration core drilling rig, one cannot merely consider the drilling depth parameter. A suitable drilling rig needs to match the hardness and integrity of the rock strata, while also taking into account the core recovery rate, relocation conditions and project budget. Soft strata prone to collapse hole sand core loss; Complete hard rock has extremely high requirements for the torque of the drilling rig and the wear resistance of the drilling tools.

When breaking inter-layer rock strata, it is necessary to cooperate with the wall process. Blindly purchasing machines without considering the stratum conditions can easily lead to delays in the construction period and a sharp increase in drilling costs.

Which type of core drilling rig is suitable for soft rock strata and loose strata? Soft formation mainly include weathered rock, mud-stone, shale, sandy soil, crush weathered layer. This type of stratum structure is loose, and the most difficult is not drilling, but preventing the collapse of the hole wall and ensuring the complete removal of the core.

Recommended: Vertical shaft core drilling rig, portable hydraulic exploration drilling rig

This type of drilling rig has adjustable rotational speed, a wide speed range, and can drill steadily at low speeds, reducing the disturbance to the soil layer. When used in conjunction with PVC protective wall tubs and single-tube/double-tube core drilling tools, it effectively increses the core recovery rate in loose strata. 

Advantage: the fuselage lightweight, tear open outfit is convenient, the mountains, road transport limited site flexible; It is easy to operate and suitable for medium and shallow hole exploration operations.

Shortage:The drilling speed in high-hardness intact bedrock is relatively weak, making it unsuitable for drilling in ultra-deep hard rock holes.

Complete hard rocks such as Granite, basalt, and dense limestone have high compressive strength and strong abrasiveness. The drilling rig requires sufficient rotational torque and stable drilling pressure to reduce drill bit wear.

Recommended: Fully hydraulic rope core drilling rig.

The rope core taking process does not require frequent lifting of the entire set of drill pipes,significantly saving auxiliary operation time. The full hydraulic power output is continuous and stable,capable of constantly applying drilling pressure. The diamond drill bit, in combination with the wire line coring drill tool, has a significant advantage in coring efficiency for hard rock.

Advantage: High core integrity and high drilling efficiency,suitable for medium and deep hole geological exploration projects; It has strong stability during long-term continuous operation.

Shortage: Equipment purchase cost is higher, the weight is big, and remote mountain short-distance transport there is a certain pressure.

Many field exploration sites do not have a single stratum. It often occurs that soft weathered layer alternates with the hard bedrock in a soft and hard inter-bedded condition. It is not recommended to fix a single drilling mode for this kind of case.

Preferable modular full hydraulic core drill, flexible switch single pipe core, double tube core, rope coring technology. For shallow soft layers, low-speed drilling and wall protection measures are adopted. Enter the deep hard rock layer switching rope core sampling system. One set of equipment is compatible with multiple strata, avoiding the repeated investment of multiple drilling rigs.

The core logic of selecting a core drilling for geological exploration always revolves around three key elements: rock layer conditions, drilling depth, and site transportation conditions. Priority lightweight vertical shaft drilling rig for soft rock loose strata; The fully hydraulic rope core drilling rig is the preferred choice for complete deep exploration of hard rock; For complex strata with interlaced hard and soft layers, it is recommended to use models with flexible replacement of drilling tool process. 

Before the project starts, it is recommended to conduct a surface geological survey first to understand the distribution of rock strata, and then determine the model of the drilling rig, the type of the drill bit and the corresponding core sampling tools. Reasonable selection not only improves the quality of core sampling but also effectively controls the loss of consumables, maximizing the reduction of overall drilling construction costs.