In cementing operations, the performance of cement slurry plays a decisive role in determining cementing quality, and fluid loss is a critical factor that must not be overlooked. When cement slurry flows through permeable formations under pressure, its liquid phase tends to leak into the formation-this phenomenon is known as fluid loss. If not properly controlled, fluid loss can lead to a series of serious consequences, such as changes in cement slurry density, deviations in thickening time and rheology from the design parameters, and in extreme cases, failure of the cementing operation.
Cementing fluid loss additivesare specifically developed to address this issue. These additives effectively prevent the loss of water from the slurry, providing key assurance for the success of cementing operations.
The effectiveness of fluid loss additives is achieved through several mechanisms. On one hand, they reduce the mobility of water molecules, making it harder for the water to freely migrate and penetrate the formation. On the other hand, they bond tightly with the surface of cement particles, promoting water adsorption onto the cement surface, thereby preventing it from being squeezed into the formation.
In practical applications, due to varying well conditions and operational needs, a variety of fluid loss additives have been developed:
1. General-Purpose Fluid Loss Additives
These additives are broadly applicable to conventional, low-density, and high-density cement slurries. They perform particularly well in medium to high-temperature wells (typically ≤180°C) and exhibit excellent salt tolerance, effectively reducing fluid loss even in saturated saltwater slurry systems. For example, KELIOIL's CG610 is a widely used general-purpose fluid loss additive that has gained significant market recognition.
2. Anti-Reversal Fluid Loss Additives
Some AMPS-based polymer additives may cause thickening reversal during use, posing a significant safety risk. In such cases, the cement slurry at the top-being cooler-may set earlier than the hotter slurry at the bottom. This "top-set" issue weakens the lower cement sheath, failing to isolate formations effectively and potentially leading to gas migration, reservoir contamination, and casing corrosion. KELIOIL's CG613 anti reversal fluid loss additive addresses this challenge by minimizing thickening reversal at critical low-to-medium temperatures (especially around 70°C and 90°C). It is suitable for standard density cement slurries and compatible with both domestic and international oil well cement types. The additive also imparts mild dispersibility to maintain pumpability and is effective up to 180°C, working well in fresh to semi-saturated saltwater systems. It is widely used in oilfields such as Liaohe, Jidong, Dagang, and Jianghan in China.
3. Anti-Settling Fluid Loss Additives
In low-density or highly dispersive standard cement slurry systems, sedimentation can impair cement quality and operational outcomes. Anti-settling fluid loss additives utilize specialized polymer technologies to control fluid loss while significantly improving slurry stability and thickening behavior. For instance, KELIOIL's CG212 enhances slurry viscosity and suspension, effectively preventing settling while maintaining adequate strength in low-density systems.
4. Dispersive Fluid Loss Additives
Designed for freshwater, seawater, and cement systems containing specific salts (e.g., 2% CaCl₂), these additives reduce water loss while preserving slurry stability and flowability. They are compatible with both high- and standard-density cement systems, particularly excelling in seawater-based slurries. KELIOIL's CG116 dispersive fluid loss additive meets the demands of various complex slurry formulations.
5. Low-Temperature Accelerating Fluid Loss Additives
In low-temperature environments (e.g., -30°C to 60°C), conventional additives may not suffice. These specialized additives combine fluid loss control with set acceleration, shortening initial set times and enhancing early compressive strength. KELIOIL's CG910S, which leverages nano-nucleation and intelligent temperature-sensitive technology, reduces initial set time by 65% and improves 8-hour compressive strength by 210%. It significantly enhances efficiency and safety in polar wells and permafrost zones.
With 19 years of experience, KELIOILhas developed a strong foundation in the field of cementing fluid loss additives, offering tailored solutions to meet diverse customer needs. Its formulations are both cost-effective and environmentally conscious, aiming to reduce environmental impact during both production and application. By delivering high-performance, eco-friendly fluid loss solutions, KELIOIL supports the sustainable development of the oil and gas industry.
