I. Introduction

Drilling fluid is the "blood" in oil and gas drilling projects and plays a crucial role in the drilling process. As a key treatment agent for drilling fluids, polymers can significantly improve the performance of drilling fluids, enhance drilling efficiency and reduce drilling costs. With the continuous development of drilling technology and the increasingly strict environmental protection requirements, polymers used in drilling fluids are evolving towards high performance, environmental friendliness and multi-functionality.

Ii. Classification of Polymers for Drilling Fluids

1.Classification by chemical structure

(1).Natural polymers and their modified products

Plant gums: Guar gum, turnip gum, konjac gum, etc

Cellulose types: carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), polyanionic cellulose (PAC), etc

Starches: carboxymethyl starch (CMS), hydroxypropyl starch (HPS), etc

Lignin types: sulfonated lignin, lignosulfonate, etc

(2).Synthetic polymers

Polyacrylamide types: hydrolyzed polyacrylamide (HPAM), partially hydrolyzed polyacrylamide (PHPA), sulfonated polyacrylamide (SPAM), etc

Vinyl polymers: polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), etc

Amphoteric polymer: A polymer containing anionic and cationic groups

Hydrophobic associative polymers: Water-soluble polymers with hydrophobic groups

2.Classification by function

(1) Viscosity enhancer

Increase the viscosity of drilling fluids, such as XC biopolymers, HPAM, etc

(2) Filter loss reducing agent

Control the fluid loss of drilling fluids, such as PAC, CMS, SPNH, etc

(3) Shale inhibitors

Inhibit the hydration and expansion of shale, such as polyetheramine and polyamine polymers

(4) Flow pattern regulator

Improve the rheological properties of drilling fluids, such as XC, PHPA, etc

(5) Lubricant

Reduce the coefficient of friction, such as polymer lubricants

(6) Leak sealing agent

Seal the pores of the formation, such as polymer gel leak-stopping agents

Iii. Main Uses of Polymers for Drilling Fluids

1.Enhance the carrying capacity of drilling fluid

Polymers significantly enhance the cutting-carrying capacity of drilling fluid by increasing its viscosity and dynamic shear force, ensuring wellbore cleanliness. For instance, XC biopolymers and PHPA perform exceptionally well in this aspect.

2.Control the filtration loss

Polymer fluid loss reduction agents effectively reduce the fluid loss of drilling fluid to the formation by forming a dense filter cake on the wellbore, protecting the oil and gas layers. Cellulose-based polymers such as PAC and CMS are commonly used fluid loss reducers.

3.Stabilize the well wall

Polymer shale inhibitors inhibit the hydration and expansion of clay by adsorbing on its surface, preventing wellbore collapse. Polyetheramine and polyamine polymers have a good inhibitory effect on shale.

4.Adjust rheological properties

Polymers can optimize the rheological parameters of drilling fluids, endowing them with appropriate shear dilution and suspension stability to meet the requirements of different drilling conditions.

5.Protect the oil and gas layers

Polymers reduce the damage of drilling fluid to the reservoir by forming temporary blockage zones and increase the production of oil and gas Wells. Degradable polymers have unique advantages in this field.

6.Deal with complex strata

For complex formations such as high temperature and high pressure, salt paste layers, etc., temperature-resistant and salt-resistant polymers can maintain the stability of drilling fluid performance and ensure drilling safety.

Iv. Development Trends of Polymers for New Drilling Fluids

High-temperature and salt-resistant polymers: Develop polymers that can operate stably in high-temperature (>200°C) and high-salt environments

Intelligent responsive polymers: Polymers that are responsive to environmental factors such as temperature, pH value, and salinity

Environmentally friendly polymers: Biodegradable, low-toxic or non-toxic polymers that are friendly to the environment

Nanocomposite polymers: Composite polymers that combine the excellent properties of nanomaterials

Multifunctional integrated polymer: A highly efficient polymer that integrates multiple functions

V. Conclusion

Polymers for drilling fluids, as an important component of modern drilling technology, have increasingly diverse types and functions. With the development of the petroleum industry towards deep Wells, ultra-deep Wells and the exploitation of unconventional oil and gas resources, higher requirements have been put forward for polymers used in drilling fluids. In the future, polymers used in drilling fluids will develop in the direction of high performance, multi-functionality and environmental friendliness, providing strong support for safe and efficient drilling.