What is a GRE Screen/Sieve Tube, and Its Role in Oil Wells and Mines?

This is a very specialized and important question. GRE screens are critical components in oil and gas wells, as well as in mine dewatering wells.

Its structure typically consists of:

• Matrix Material: Epoxy resin, which provides corrosion resistance and the overall shape.

• Reinforcement Material: Continuous glass fibers, which provide very high tensile and compressive strength.

• Key Feature: The pipe wall contains accurately machined, narrow, slit-like openings called "screen slots" or "gaps". The slot width (e.g., 0.15mm, 0.2mm, 0.3mm) is customized based on the size of the sand particles to be blocked.

The fundamental difference from traditional metal screens lies in the material:

• Traditional Metal Screens: Made of stainless steel, carbon steel, etc., they rely on their strength and the formation of a "sand bridge" downhole for sand control.

• GRE Screens: Made of composite materials, their sand control mechanism is direct blocking. They use the precise slots to physically prevent formation sand grains from passing through, while allowing fluids to enter.

The Role of GRE Screens in Oil Wells and Mines

The core function of a GRE screen is "sand control" and "corrosion prevention", ensuring unimpeded flow paths and extending the service life of the wellbore. The table below clearly compares its applications in oil wells and mines.

Key Advantages of GRE Screens Explained

Why choose GRE screens over metal ones in these demanding environments? Primarily because their material properties solve the pain points of traditional technology:

1. Excellent Corrosion Resistance (Core Advantage)

◦ In Oil Wells: Produced fluids often contain corrosive substances (e.g., H₂S, CO₂, chlorides) that rapidly corrode steel screens, leading to slot enlargement, sand control failure, or even pipe failure. GRE screens fundamentally eliminate electrochemical corrosion and pitting.

◦ In Mine Wells: Groundwater is often acidic or highly saline, severely corroding metal filter pipes. GRE screens can last for decades, far exceeding the lifespan of metal filters.

2. Accurate and Stable Sand Control Performance

◦ The slots on a GRE screen are machined precisely during manufacturing, ensuring accurate and uniform dimensions. Metal screens can have their slots deformed or damaged during installation or by corrosion, compromising sand control accuracy.

3. Lightweight yet High-Strength, Easy Installation

◦ They weigh only about a quarter of equivalent steel screens. This dramatically reduces hoisting difficulty, operational risk, and labor intensity during installation in wells hundreds or even thousands of meters deep.