### I. Technical Background

Ultra-short radius drilling technology is an important technology in oil and gas production and mining development, characterized by low cost, short cycle, and minimal formation pollution. It can significantly increase oil well output and crude oil production. For example, in the enhancement of old wells in oil and gas fields and the extraction of gas from coal mines, ultra-short radius drilling technology is of great significance. Especially in the later stages of oil field development, some old oil fields face technical pressures related to the transformation of old wells, the extraction of residual oil in thin oil layers, and maintaining stable production. The ultra-short radius horizontal well technology can effectively address these challenges.

### II. Principle of Deflection Tool

The deflection tool refers to a tool that can change the direction of the wellbore. The principle of deflection is designed based on the principle of wellbore direction change, which involves asymmetric cutting of the drill bit against the well bottom or lateral cutting against the well wall. During drilling, if one side of the drill bit has a faster cutting speed while the other side has a slower cutting speed, the direction of the wellbore will change, bending towards the side with the slower cutting speed.

### III. Structural Characteristics of Ultra-Short Radius Deflection Tool

The structural design of the ultra-short radius deflection tool is complex, aimed at achieving precise control over the deflection trajectory and curvature. Below are several typical structural characteristics of ultra-short radius deflection tools:

1. **Variable Angle Deflection Joint**: Includes a first stable end and a second stable end, connected through bearings and coaxial mating surfaces, allowing for angle adjustment within a certain range to achieve deflection. This joint also includes a locking structure and locking components to ensure stability during the deflection process.

2. **Flexible Drill Rod**: Used for drilling in the deflection and horizontal sections, the flexible drill rod can bend during the drilling process to meet the demands of high curvature deflection.

3. **Deflection Short Section and Deflection Rod**: The deflection short section is equipped with a deflection rod made of elastic material, which tends to bend upwards under drilling pressure, providing support for the deflection short section and ensuring the drilling trajectory.

### IV. Application Examples

In oil field applications, ultra-short radius deflection tools are usually used in conjunction with rotating self-sealing devices, guiding anchor systems, multifunctional guiding pipes, and other tools. The specific operational process includes:

1. Performing window opening operations at the position of the oil layer inside the original well casing.

2. Using the ultra-short radius deflection tool for drilling in the deflection section, achieving precise control of the deflection trajectory by adjusting the angle of the deflection tool and drilling parameters.

3. After completing the deflection, continue drilling in the horizontal section to achieve the goal of extracting residual oil.

### V. Technical Advantages

1. **Improved Deflection Accuracy**: Achieving precise control of the deflection trajectory through accurate control of the angle and drilling parameters of the deflection tool.

2. **Ensuring Drilling Trajectory**: Using designs such as flexible drill rods and elastic deflection rods to ensure stability and accuracy of the trajectory during the drilling process.

3. **Reducing Operational Risks**: Avoiding traditional deflection