Firstly, when selecting an oil drilling rig, for rotary drilling rigs, it is important to determine the model based on the geological conditions of the construction site. If the site primarily consists of hard rock formations, a high-torque model should be purchased. If the formation is softer, a smaller torque model may suffice. Torque is one of the key parameters of a drilling rig. The size of the torque determines the rig's ability to form a borehole. Generally, the larger the torque, the larger the diameter of the borehole that can be formed.

It’s important to avoid overly concentrating on a single model, as competition within the same circle can be fierce. Procurement plans should be based on the actual needs of your projects. For individual users, the number of rotary drilling rigs purchased should be based on ensuring the long-term normal operation of all equipment. Plans should not be made based on ideal workloads, as this can lead to significant waste of resources, occupying cash flow, and limiting future growth. Larger companies, while meeting project requirements, may consider purchasing one or two additional rotary drilling rigs as backups, ready for deployment at any time.

Once the model is determined, the next step is choosing the manufacturer. According to incomplete statistics, there are currently around 15,000 rotary drilling rigs in China, with foreign brands accounting for 18%. This data suggests that domestic manufacturers’ production capabilities have been widely recognized by most domestic users. Based on past experience, compared to equipment of the same specification, imported rigs are typically much more expensive than domestic ones, and their maintenance, upkeep, and spare part costs are also higher. If imported rotary drilling rigs are chosen, the high procurement cost and expensive subsequent use costs will pose a significant challenge to the user's financial strength.

In terms of price, it’s difficult to know the base price of a company, so it is necessary to contact multiple companies for comparison. Because manufacturers provide different supporting parts, price differences are usually significant.

As a type of borehole machinery that has been gradually accepted in recent years, rotary drilling rigs have gained widespread recognition in underground foundation construction. It has become a new type of pile construction method that has developed rapidly in recent years. Rotary drilling pile technology is known as a “green construction technology” due to its high efficiency, good construction quality, and minimal dust and slurry pollution. However, there are still some issues to consider. Compared to commonly used rotary drilling rigs, impact drilling rigs, and rotary drilling machines, we offer some suggestions on how to choose a drilling machine for pile foundation construction.

Below is a comparison of the three common types of drilling rigs: impact drilling rigs, rotary drilling rigs, and rotary excavation rigs.

1. Impact Drilling Rig Analysis

Impact drilling rigs are versatile machines, suitable for almost all geological conditions. They can handle dry soil, sandy soil, gravel layers, cobblestones, floating rocks, soft rock, and hard rock. Impact drills are particularly suitable for drilling pile holes in mountainous areas with embedded rocks. When the surface layer consists of weak soil, it can be replaced to stabilize the rig.

Impact drilling rigs can also be assembled according to the actual construction site situation, offering easy operation. In terms of structural complexity and operation procedures, impact drills are superior to both rotary and rotary excavation rigs. If geological conditions are the sole consideration, and engineering schedule and economic benefits are not a factor, an impact drilling rig can be used. However, in terms of drilling speed, impact drilling rigs are slower than rotary and rotary excavation rigs. In terms of cost per meter drilled, impact drilling rigs tend to be more expensive, with rotary drilling rigs being less expensive and rotary excavation rigs falling in between.

2. Rotary Drilling Rig Analysis

Rotary drilling rigs are suitable for dry soils, sandy layers with fewer gravel, cobblestones, and soft rock, whether using a direct circulation or a reverse circulation system. They are not suitable for large gravel layers or hard rock formations. Direct circulation rigs are suitable for silt, fine sand, medium sand, and coarse sand layers. If a reverse circulation rig is used in sandy layers, insufficient mud conditions or excessively fast drilling speeds may cause on-site drilling accidents.

Rotary drilling rigs are particularly suitable for drilling in inland alluvial layers in plains and coastal tidal areas. When considering drilling speed, rotary drilling rigs are faster than impact drills but slower than rotary excavation rigs. In terms of construction cost, rotary drilling rigs offer the best cost-performance ratio among the three types of rigs.