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Ⅰ. Core Components of Drilling Rig: Drill Derrick and Substructure As the "framework" of a drilling rig, the drill derrick and substructure jointly undertake the core load-bearing and spatial support functions of drilling operations. They directly affect drilling efficiency and safety, and both need to be coordinated and adapted to meet the requirements of different working conditions. 1. Drill Derrick/Mast It is the core load-bearing and operation framework of the drilling rig, mainly used to support long rod components such as drill pipes and casings. It provides vertical operation space for drilling operations and bears the weight of the traveling system (e.g., crown block, traveling block). Key Functions and Characteristics Spatial Support: The height is usually 30-60 meters (adjusted according to the rig model), providing sufficient stroke for the vertical movement of drilling tools. Load-Bearing Support: It needs to bear the weight of the drill string and casings, as well as the dynamic loads generated during drilling (e.g., impact loads during tripping operations). The structural material is mostly high-strength low-alloy steel to ensure fatigue resistance and corrosion resistance. Safety Protection: It is equipped with anti-fall guardrails, ladders, and lightning rods (for onshore derricks). Some offshore derricks also need additional wind-wave resistance and salt spray corrosion prevention designs. Types of Drill Derricks/Mast Derrick: It has a quadrangular pyramid tower shape and adopts a segmented welded structure. The height is usually 30-60 meters, with strong load-bearing capacity (up to thousands of tons) and good stability. It is suitable for deep wells, ultra-deep wells, and offshore drilling platforms. The disadvantage is complex assembly/disassembly and high transportation costs. Mast: Mostly of integral or foldable structure, with a relatively low height (20-40 meters). It can be erected and folded by hydraulic devices, featuring convenient assembly/disassembly and flexible relocation. It is suitable for shallow wells and onshore mobile rigs (e.g., workover rigs), but its load-bearing capacity is slightly lower than that of the derrick. 2. Drill Floor/Substructure It is the support structure under the derrick, used to bear core equipment such as the derrick, rotary table, and drawworks. It also provides a horizontal operation platform (drill floor) and serves as the basic load-bearing unit for drilling operations. Key Functions and Characteristics Equipment Support: It evenly transfers the load of heavy equipment such as the derrick and rotary table to the ground to avoid ground settlement. Operation Platform: The "drill floor" on the top is the core area for drilling operations, equipped with wellhead devices and drill pipe racks, facilitating operators to connect drill pipes and control drilling parameters. Height Design: It is usually elevated by 1-3 meters, which is convenient for installing blowout preventers, wellhead casings, and other equipment under the substructure. At the same time, it prevents water accumulation or debris accumulation in the operation area. Types of Substructures Classified by height and structure: Low Substructure: With a height of 1-2 meters, it has a simple structure and is suitable for shallow wells or scenarios with few surface equipment. Its advantages are low cost and fast installation, while the disadvantage is limited space under the substructure, which can only accommodate small blowout preventers. High Substructure: With a height of 2-4 meters, it reserves sufficient space under the substructure to install large blowout preventers, wellhead crosses, and pipeline systems. It is suitable for deep wells and high-pressure oil and gas wells, which can reduce interference in wellhead operations and improve safety factors. Ⅱ. Correlation Between the Two and Industry Applications Synergistic Effect The substructure provides fixed support points for the derrick. The derrick and substructure are connected by high-strength bolts to form the "main framework" of the drilling rig, jointly ensuring the vertical accuracy and structural safety of drilling operations. Typical Application Scenarios Onshore Deep Well Operations: The combination of "derrick + high substructure" is mostly used to meet the installation requirements of large drill string weight (e.g., drill string over 1000 meters) and high-pressure wellhead equipment. It is commonly used in oil and gas exploration wells. Onshore Shallow Well/Workover Operations: The combination of "mast + low substructure" is commonly used, which has the advantage of flexible relocation (can be transported as a whole) and is suitable for workover or geological exploration scenarios requiring frequent movement. Offshore Drilling Platforms: The combination of "fixed derrick + high-strength high substructure" is adopted. The substructure needs to be rigidly connected to the platform deck, and the derrick is added with anti-sway and anti-seawater corrosion designs to adapt to the offshore wind and wave environment.