Detailed explanation of the production process of polyethylene glycol drilling fluid

I. Overview

Polyethylene glycol drilling fluid is an environmentally friendly, high-performance water-based drilling fluid, the core component is polyethylene glycol (PEG), and its formulation involves a variety of chemical treatment agents and strict process flow. The key to the production process is to achieve the stability, rheological properties and environmental performance of the drilling fluid to meet the complex needs of oil and gas drilling operations. The following is a systematic introduction to the production process of polyethylene glycol drilling fluid.

Second, the production process

The production of polyethylene glycol drilling fluid can be divided into five main stages: raw material preparation, base fluid preparation, performance optimization, performance testing, and storage and transportation.

1. Raw material preparation

(1) Core raw materials

Polyethylene glycol (PEG): Choose the right molecular weight range (typically between 200-8000) for different needs.
Water: As the primary dispersion medium, deionized water or high-purity water is required to reduce the impact of impurities on the performance of the drilling fluid.

(2) Supporting Materials**

Lubricants: such as paraffin emulsions, ester lubricants, to enhance the lubricity of drilling fluids.
Inhibitors: such as potassium chloride (KCl), sodium salts, or organic inhibitors to prevent shale swelling.
Plugging agent: such as calcium carbonate and cellulose materials, used to plug fractures in the formation.
Rheology regulators: e.g. bentonite, polyacrylamide (PAM) to regulate rheological properties and shear thinning properties.

2. Base Fluid Preparation

The base fluid is the core of the drilling fluid system and determines its basic performance.
(1) Preparation equipment

Mixing tank: for mixing and dissolving polyethylene glycol.
Mixing equipment: high-speed agitator ensures that all components are evenly dispersed.
Heating device: The heating system controls the temperature of the liquid and improves the dissolution efficiency.

(2) Preparation step

Water pretreatment: Inject deionized water into the mixing tank to maintain the water temperature at 30-50°C to avoid the degradation of polyethylene glycol due to excessive temperature.
Dissolve polyethylene glycol: Add PEG gradually, stirring slowly to dissolve it completely until a homogeneous solution is formed. Low-molecular-weight PEGs dissolve more quickly, while high-molecular-weight PEGs require longer and moderate heating.
Adjust viscosity: Add an appropriate amount of rheology regulator such as bentonite, and stir continuously until completely dispersed.

3. Performance Optimization

After the completion of the base fluid, the performance of the drilling fluid is further optimized according to the specific formation conditions.

(1) Add lubricant

Under agitation conditions, lubricants (such as esters or silicone oils) are added slowly to enhance the lubrication of the drilling fluid.
The lubricant is typically added at a rate of 2%-5%, depending on the friction needs of the formation.

(2) Add inhibitors

Add inorganic salt inhibitors (e.g., potassium chloride) or organic inhibitors (e.g., polyamines) in the designed ratio.
The inhibitor can effectively control the hydration swelling of water-sensitive formations and ensure the stability of the wellbore.

(3) Add occluder

Introducing fine particles and fibrous materials such as calcium carbonate and cellulose into drilling fluids to form dense mud cakes and plug formation fractures and pores.

(4) High temperature and high pressure treatment

If it is used in high-temperature and high-pressure well sites, high-temperature stabilizers (such as sulfonating resins) should be added to enhance the heat resistance of the system.

4. Performance Test

After the formulation is completed, the performance of the drilling fluid needs to be fully tested to ensure that it meets the requirements for field use.

(1) Rheological properties

Test the viscosity, dynamic shear and shear thinning properties of the drilling fluid to ensure that the fluid has good rheological properties.
Commonly used instruments: rotational viscometer, rheometer, etc.

(2) Inhibition Performance**

Shale expansion test was used to test the inhibition effect of drilling fluid on water-sensitive formations.

(3) Filtration performance

API filtration test to evaluate the filtration of drilling fluids under high temperature and pressure conditions.

(4) Environmental performance

Toxicity testing and biodegradability analysis to ensure that products meet environmental standards.

5. Storage & Transportation

(1) Storage Requirements**

Drilling fluids should be stored in airtight containers to avoid contamination of impurities.
Temperature control at 10-40°C to avoid the effects of high temperatures or freezing on the stability of the liquid.

(2) Shipping Specifications**

Dedicated transport tankers are used to prevent spillage or contamination.
During transportation, regularly check the condition of the liquid to prevent delamination or settling.

Third, the key points of the production process

Dissolution control of polyethylene glycol

Adjust dissolution conditions based on molecular weight: Low molecular weight PEGs dissolve quickly at room temperature, while high molecular weight PEGs require heat stirring.
Ensure the homogeneity of the solution and avoid agglomeration or precipitation.

Group Assignment Compatibility Test

The compatibility of polyethylene glycol with other treatment agents has a direct impact on the performance of drilling fluids and must be repeatedly tested in the laboratory.
Special attention is paid to chemical stability in high-salt, high-temperature environments.

Rheological Properties Optimization

Adjust the type and concentration of the rheology regulator to ensure that the drilling fluid exhibits stable rheological properties at different shear rates.

Environmental Requirements

Polyethylene glycol and its formulated components should comply with international environmental standards to avoid contamination of groundwater and soil.

Fourth, adjustments in practical application

Dealing with complex strata

In collapse-prone formations, the proportion of inhibitors and plugging agents can be appropriately increased.
For deep and horizontal wells, increase the molecular weight and lubricant content of PEG to enhance anti-friction properties.

Temperature Adaptability Improvement

In high-temperature working environments, highly heat-resistant treatment agents are selected and the PEG system is modified.

V. Summary

The production process of polyethylene glycol drilling fluid is a systematic project integrating chemical formulation, engineering design and environmental protection. Through rigorous raw material selection, scientific formulation design and comprehensive performance testing, we can ensure that products meet the needs of complex formations and operating conditions while minimizing environmental impact. With the advancement of oil and gas exploitation technology, the production process of polyethylene glycol drilling fluid will be further optimized to promote the sustainable development of the oil drilling industry.

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