The common types of water loss agents mainly include water-soluble polymers, granular materials, and environmentally friendly water loss agents. Among them, water-soluble polymers are the most widely used, with high technological maturity and strong adaptability.

1、 Water soluble polymer water loss agent
This type of water loss reducing agent controls water loss through adsorption, thickening, film formation, and other methods. It is currently the mainstream product and can be further divided into the following two categories:
1. Modified natural products
Using natural polymers as raw materials and chemically modified to enhance performance, it has advantages such as low cost and biodegradability, but its temperature resistance and water solubility are relatively limited.
Carboxymethyl cellulose (CMC): The most commonly used and can effectively reduce water loss under low to medium temperature conditions, but it is prone to degradation at high temperatures.
Hydroxyethyl cellulose (HEC): It has good salt resistance, is suitable for high salt environments, and has the ability to increase viscosity and suspend.
Carboxymethyl hydroxyethyl cellulose (CMHEC): Combining the advantages of CMC and HEC, it can withstand temperatures up to 120 ℃ or above.
In practical applications, its water solubility and thermal stability can be improved through graft copolymerization.
2. Synthetic polymers
Artificially synthesized, with strong structural designability and excellent high temperature and salt resistance, suitable for complex working conditions such as deep wells and high temperature and pressure.
Non ionic polymers, such as polyvinyl alcohol (PVA), require cross-linking to form a membrane like structure for efficient water loss reduction.
Anionic copolymer:
The copolymer containing acrylamido-2-methylpropanesulfonic acid (AMPS) can withstand temperatures exceeding 120 ℃, and some products such as C-FL72L can withstand temperatures above 300 ℃.
Acrylic acid (AA)/acrylamide (AM) copolymer: By adsorbing carboxylate ions onto cement particles, a thick hydration film is formed, significantly reducing filtration loss.
2、 Particle material based water loss agent
Mainly through physical filling, the pores of the filter cake are blocked to form a low-permeability barrier.
Bentonite: The earliest particle type water loss agent used, with small particles that can enter the gaps between cement particles and reduce the permeability of the filter cake.
Latex materials (such as styrene butadiene latex): They have the functions of reducing water loss, preventing gas channeling, and toughening, and are a hot research topic in deep well drilling.
There are already mature products abroad, such as Halliburton Latex2000 and Schlumberger D-series latex, which can be used at temperatures up to 191 ℃.
Micro silicon powder, limestone powder, talc powder and other ultrafine particles: often used in combination with other polymers to enhance the sealing effect.
3、 Environmentally friendly water loss agent
In order to meet the requirements of green operations, it has developed rapidly in recent years, emphasizing biodegradability and low ecological toxicity.
Etherified starch modified product: stable under strong alkali and degradable in neutral water.
Degradable crosslinking agent system: Based on bio derived polymers, it achieves functional controllability and environmental friendliness through breakable crosslinking bonds.
Medical white oil suspension system: non-toxic, biodegradable, suitable for sensitive formations or offshore operations.