Glass Bubble Application and Advantages in Oilfield Cementing
Glass bubble(Hollow glass microspheres) are mainly used in two parts of oilfield cementing operations: drilling fluid and cementing slurry. Adding hollow glass microspheres to drilling fluid and cementing slurry can produce low-density, high-strength products.
I. Functions and Advantages of Glass bubble in Low-Density Drilling Fluids:
1. Reducing Drilling Fluid Density. Hollow glass microspheres (CL42) have extremely low density (0.40~0.44 g/cm³) and a compressive strength of 8000 Psi. It can significantly reduce drilling fluid density without affecting its strength. This ensures stable drilling fluid density for deep well drilling.
2. Hollow glass microspheres is a kind of stable borosilicate glass bubble. This inorganic non-metallic material does not chemically react with other substances in the mud, ensuring the chemical stability of the drilling fluid.
3. Improving Lubrication and Equipment Lifespan. Hollow glass microspheres, being closed spheres, act like ball bearings in drilling fluid. Thus, it effectively reduces frictional resistance between the drill string and the wellbore. Simultaneously, they reduce friction between equipment, thus extending the service life of drill pipes, drill bits, and other equipment.
4. Hollow glass microspheres used in drilling fluid can be recycled, thereby reducing oilfield production costs.
II. Adding hollow glass microspheres to oilfield cement slurry can solve the problems of low pressure, easily leaking wells, and low return of cement slurry. Its main functions and advantages are as follows:
1. Glass bubble is suitable for producing cement slurry with a density below 1.60 g/cm³ (even as low as 1.20~1.40 g/cm³). Due to their low density, hollow glass microspheres can significantly reduce the slurry density without increasing the water volume, effectively controlling the water loss rate.
2. Preventing Loss of Formation: In cementing sections with low formation fracture pressure (shallow formations, loose formations, fractured zones), high-density cement slurry can easily cause formation leakage. The low density of microsphere cement slurry reduces the equivalent circulating density, preventing loss of formation.
3. Improving the Compressive Strength of Cement Stone: Compared to low-density cement with a high water-cement ratio, cement slurry with hollow glass microspheres maintains higher compressive and flexural strength at the same density. The microspheres act as “micro-air pockets” within the cement stone, absorbing and dispersing stress, preventing cement stone brittleness.
4. Improving the Rheological Properties and Stability of Cement Slurry: Hollow glass microspheres improve the fluidity of the cement slurry, facilitating pumping and displacement, thus increasing cementing displacement efficiency.
5. High Temperature Resistance, High Pressure Resistance, and Low Thermal Conductivity. Hollow glass microspheres improve the thermal stability and high pressure resistance of cement slurry, reducing heat transfer to the casing and protecting other downhole equipment.
5. The addition of hollow glass microspheres can adjust the thickening time according to construction needs, which facilitates operation and improves cementing quality.
