The weighting agents for oil drilling fluids mainly include barite powder, iron ore powder, limestone powder, galena powder and manganese trioxide powder, among which barite powder is the most widely used weighting agent for drilling fluids at present. 
1. Barite (Barium Sulfate, BaSO₄)
Density: 4.2–4.6 g/cm³, commonly used density is 3.9–4.2 g/cm³
Characteristics: Stable chemical properties, low cost, easily accessible, insoluble in water, acids or alkalis, has little impact on drilling fluid performance
Applications: Can increase the density of drilling fluid to 2.4 g/cm³ (approximately 20 lb/gal), widely used in water-based and oil-based drilling fluids
Standard requirements: BaSO₄ content ≥ 92%, more than 97% of particles need to pass through a 200-mesh sieve (approximately 74 μm), in line with API 13A standard
Advantages: Low wear, good suspension, is used for 80%–90% of barite applications, especially suitable for deep wells and high-pressure formations
2. Hematite (Ferrous Oxide, Fe₂O₃)
Density: 4.9–5.3 g/cm³, higher than barite
Characteristics: High hardness (Mohs 5.5–6.5), resistant to grinding, but prone to wear on drill bits and pump valves
Applications: Can increase the density of drilling fluid to above 2.7 g/cm³, suitable for complex well conditions with high-density requirements
Limitations: Due to high hardness, it is prohibited in some conditions and needs to be replaced with activated barite
3. Calcite (Calcium Carbonate, CaCO₃)
Density: 2.7–2.9 g/cm³, relatively low
Characteristics: Soluble in acids, suitable for acidizing operations in producing layers
Applications: Mainly used in oil-based drilling fluids or well servicing fluids, can increase the density to approximately 1.9 g/cm³ (11 lb/gal)
Advantages: Good acid solubility, does not permanently block oil and gas channels, suitable for sensitive reservoir protection
4. Galena (PbS)
Density: 7.4–7.7 g/cm³, the highest density among all weighting agents
Characteristics: Can be used to prepare ultra-high density drilling fluids (above 3.0 g/cm³), for controlling abnormal high-pressure formations
Limitations: High cost, scarce resources, and certain toxicity, only used in extremely high-pressure wells under special circumstances
5. Manganese Trioxide (Mn₃O₄)
Density: Approximately 4.9 g/cm³
Characteristics: Non-magnetic, high hardness, acid-soluble, superior sediment stability by 40% compared to traditional materials
Applications: As a new type of high-density acid-soluble weighting agent, suitable for well sections requiring later acidization treatment, and does not damage downhole tubing
Challenges: High cost, requires reasonable control of particle size to improve efficiency 
Furthermore, cesium fluoride, as a liquid weighting agent, is also used in certain high-end drilling operations. In 2023, China's usage of it in the oil drilling sector reached 1,200 tons, mainly for drilling fluid systems in high-density and high-temperature environments.