The low oil-water ratio oil-based drilling fluid is a drilling fluid system specially designed for modern drilling projects. Its main characteristic is the relatively low ratio of oil phase to water phase, typically controlled between 70:30 and 60:40. This design aims to reduce the cost of the drilling fluid while maintaining or enhancing its key performances, such as rheology, emulsification stability, contamination resistance, and lubricating properties. The low oil-water ratio oil-based drilling fluid has become the preferred choice for drilling challenging horizontal wells, high-angle directional wells, high-temperature deep wells, and complex formations.

Features

1.    Low Oil-Water Ratio: By optimizing the oil-water ratio, the base oil consumption of the drilling fluid is reduced, significantly lowering costs, with the minimum oil-water ratio controllable at 60:40.

2.    Improve Drilling Efficiency: Excellent rheological and lubricating properties help to reduce resistance and energy consumption during the drilling process, thereby improving drilling efficiency.

3.    Enhance Wellbore Stability: The film-forming plugging agents in the drilling fluid can form a non-permeable isolation membrane on the surface of the wellbore rock, effectively preventing wellbore collapse.

4.    Strong Adaptability: This system is suitable for various complex formations and drilling conditions, exhibiting high flexibility and adaptability.

5.    Reduce Environmental Pollution: The low oil-water ratio design reduces the moisture content in the drilling fluid, lowering the potential risk of environmental pollution.

Advantages

1.    Cost Reduction: By lowering the oil-to-water ratio and base oil consumption, the cost of the drilling fluid is significantly reduced.

2.    Increased Drilling Efficiency: Excellent rheological and lubricating properties help reduce resistance and energy consumption during the drilling process, improving drilling efficiency.

3.    Enhanced Wellbore Stability: The film-forming sealing agents in the drilling fluid can create an impermeable barrier on the surface of the wellbore rocks, effectively preventing wall collapse.

4.    Strong Adaptability: This system is suitable for various complex formations and drilling conditions, offering high flexibility and adaptability.

5.    Reduced Environmental Pollution: The low oil-to-water ratio design reduces the moisture content in the drilling fluid, lowering the potential risk of environmental contamination.

Applications

1.    High-Temperature, High-Pressure Wells: In high-temperature, high-pressure wells, the drilling fluid needs to possess good high-temperature and high-pressure resistance and stability. Low oil-water ratio oil-based drilling fluids can maintain stable performance and rheological properties in high-temperature, high-pressure environments, ensuring the smooth progress of drilling operations.

2.    Shale Formations: Low oil-water ratio oil-based drilling fluids can effectively protect wellbore stability through their excellent inhibiting and plugging properties, reducing the instability of shale formations. At the same time, they consider the effects of different formation shale fluids and rock properties on drilling fluid performance, providing reliable drilling fluid solutions for shale gas drilling.

3.    High-Angle Directional Wells: In high-angle directional wells, high torque and significant friction can easily occur during drilling. Low oil-water ratio oil-based drilling fluids can significantly reduce the friction and wear between the drill string and the wellbore through their lubricating properties, decreasing torque and friction.

Low oil-water ratio oil-based drilling fluids have been widely used in various complex formation drilling operations, including high-temperature deep wells, high-angle directional wells, and horizontal wells. Their excellent performance and lower costs make this system highly valuable in oilfield development. By optimizing the drilling fluid formulation and construction processes, further improvements in drilling efficiency and cost reductions can be achieved while protecting oil and gas reservoir resources.

System Supporting Additives

HIWAEMUL Main Emulsifier

HIWACOAT Auxiliary Emulsifier

Key Additive HIWAEMUL Main Emulsifier Introduction:

HIWAEMUL main emulsifier is a high-performance primary emulsifier specifically designed for low oil-water ratio oil-based drilling fluid systems. Its primary role in the drilling fluid is to facilitate the effective mixing of the oil and water phases, forming a stable emulsion to meet the drilling operation's requirements.

Functions

1.    Emulsification: HIWAEMUL main emulsifier can effectively disperse water in the oil phase, forming a stable water-in-oil (W/O) emulsion, preventing oil-water separation.

2.    Stability Enhancement: Enhances the physical and chemical stability of the drilling fluid, preventing stratification or sedimentation under high temperature, high pressure, and complex geological conditions.

3.    Temperature Resistance: Possesses good high-temperature resistance, ensuring the stability of the drilling fluid in high-temperature environments during drilling.

4.    Contamination Resistance: Improves the drilling fluid's resistance to external contaminants, such as salts and calcium ions, maintaining the cleanliness and performance of the drilling fluid.

5.    Reduce Friction and Wear: By providing lubrication, it reduces friction between the drill bit and wellbore, decreases wear, and improves drilling efficiency.

Applicable Range

1.    Temperature: Generally, HIWAEMUL main emulsifier can work stably at temperatures exceeding 200°C.

2.    System: HIWAEMUL main emulsifier is suitable for various low oil-water ratio oil-based drilling fluid systems, including but not limited to diesel-based, white oil-based, and synthetic-based drilling fluids. Its application range is broad and can be adjusted and optimized according to specific drilling needs.

Key Additive HIWACOAT Auxiliary Emulsifier Introduction

HIWACOAT auxiliary emulsifier is designed specifically for the HIWADRIL low oil-water ratio oil-based drilling fluid technology. It typically works in synergy with the main emulsifier to form a more stable and higher-performing emulsion system.

Functions

1.    Improve Emulsion Stability: HIWACOAT auxiliary emulsifier can enhance the stability of the water-in-oil (W/O) emulsion, preventing emulsion breaking during drilling due to environmental changes (e.g., temperature, pressure).

2.    Enhance Interfacial Film Strength: Through its special molecular structure, HIWACOAT can form a strong interfacial film at the oil-water interface, further enhancing emulsion stability.

3.    Reduce Oil/Water Interfacial Tension: Reduces the interfacial tension between oil and water, helping to form smaller and more uniform oil droplets, improving emulsion uniformity and stability.

4.    Improve Drilling Fluid Performance: The addition of the auxiliary emulsifier can improve the lubricating properties, temperature resistance, salt resistance, and other characteristics of the drilling fluid, thus enhancing the efficiency and quality of drilling operations.

Applicable Range

1.    Temperature: It possesses high-temperature resistance to adapt to the high-temperature environment during drilling.

2.    System: Suitable for the HIWADRIL low oil-water ratio oil-based drilling fluid system.

Case Studies

This system has been successfully applied in over 60 wells in the Fuling Shale Gas Demonstration Area, where it demonstrated strong inhibition against the hydration and dispersion characteristics of mud shales in the reef dam block. It is environmentally friendly.

The shale gas reservoir in the reef dam block is predominantly mud shale with high clay content, developed stratification, and micro-fractures, leading to issues such as wellbore instability and drilling fluid invasion during drilling. Additionally, the formation pressure coefficient is high, posing significant construction risks and complicating drilling and completion processes. The application of low oil-water ratio oil-based drilling fluid in the reef dam block has shown good stability, inhibition, strong lubrication, good wellbore stability, and strong contamination resistance.

The Jiao Well 26-Z7 completed drilling to a depth of 5996m, with a penetration of 3273m using low oil-water ratio oil-based drilling fluid, a horizontal section of 2831m, and a drilling cycle of 22 days. During the drilling, the oil-water ratio was maintained at 60/40, and the demulsification voltage reached 500-800V. No downhole failures caused by the drilling fluid occurred during the drilling process, and there were no blockages. The diameter expansion rate in the logging section was less than 2%. This fully demonstrates the applicability and superiority of the low oil-water ratio oil-based drilling fluid system in shale gas horizontal well drilling in the reef dam block. The low oil-water ratio drilling fluid has demonstrated excellent economic and environmental protection functions in field applications.