What are the specific measures for protecting oil and gas reservoirs with drilling fluid

The specific measures for protecting oil and gas reservoirs with drilling fluid mainly include the following aspects:

1. Selecting the appropriate drilling fluid type: Choose the suitable drilling fluid type based on the formation characteristics to minimize damage to the oil and gas reservoir. Generally, drilling fluids with low solids content, low filtration, and high rheological properties cause less damage to the oil and gas reservoir. For instance, polymer drilling fluid, water-based drilling fluid, etc.

2. Control the drilling fluid density: Control the drilling fluid density to balance the formation pressure and prevent accidents such as lost circulation and blowout. Drilling fluid with too high a density may cause formation fracture, resulting in damage to the oil and gas reservoir; while drilling fluid with too low a density may cause formation collapse, affecting the productivity of the oil and gas reservoir.

3. Optimizing drilling fluid performance: Optimize the rheological, filtration, shear, and other performance indicators of drilling fluid to reduce damage to the oil and gas reservoir. For example, by adding rheological modifiers, filtration reducers, and other treatment agents, the performance of drilling fluid can be improved.

4. Enhance the rock-carrying capacity of drilling fluid: Improve the rock-carrying capacity of drilling fluid to reduce the deposition of drill cuttings in the wellbore and minimize wear on the oil and gas reservoir. This can be achieved by adjusting the rheological properties, viscosity, and other indicators of the drilling fluid, or by adding an appropriate amount of weighting agent.

5. Control the filtration loss of drilling fluid: Control the filtration loss of drilling fluid to reduce the formation of filter cake and minimize the blockage of oil and gas reservoirs. This can be achieved by adding filtration loss reducers, adjusting the rheological properties of the drilling fluid, and other methods.

6. Adopting oil and gas reservoir protection technology: Adopting oil and gas reservoir protection technology, such as prepad fluid, temporary plugging agent, anti-sloughing agent, etc., to reduce damage to the oil and gas reservoir. These technologies can form a protective film during the drilling process, reducing direct contact between the drilling fluid and the oil and gas reservoir, thereby minimizing damage to the reservoir.

7. Strictly follow drilling operation procedures: Operate strictly in accordance with drilling operation procedures to avoid damage to the oil and gas reservoir caused by misoperation. For example, follow the principle of "one quick start, two stable drilling, and three slow stops", which means starting the drill quickly, drilling steadily, and stopping the drill slowly.

8. Strengthen the maintenance and management of drilling fluid: Enhance the maintenance and management of drilling fluid, regularly test various performance indicators of the drilling fluid, promptly adjust the dosage of treatment agents, and ensure the stability of drilling fluid performance.

9. Train drilling personnel: Strengthen the training of drilling personnel, enhance their understanding of oil and gas reservoir protection, and increase their emphasis on oil and gas reservoir protection during the drilling process.

Through the above measures, the oil and gas reservoir can be effectively protected during the drilling process, reducing damage to the reservoir and enhancing the productivity and recovery rate of the oil and gas well.