How to evaluate whether FRP downhole oil pipes are qualified?

The evaluation of whether the FRP downhole oil pipe is qualified requires a comprehensive judgment from multiple links such as design, production, testing and use. According to relevant standards and technical requirements, it mainly includes the following aspects:

1. Material quality inspection

  1. Resin and glass fiber performance testing :

    • Resin content : The proportion of resin in FRP is determined by standard methods (such as GB/T 2577-2005) to ensure that it is within the specified range. The resin content directly affects the corrosion resistance and mechanical properties of the pipe.
    • Fiberglass reinforcements : Check the strength, modulus and surface finish quality of the fibers to ensure they meet design requirements.

  2. Quality of lining and impermeable layer :

    • The lining material needs to have good ductility and impermeability to meet the sealing requirements under complex working conditions.
    • Check whether the inner and outer anti-seepage layers are uniform and free of defects to ensure that they have sufficient corrosion and pressure resistance.

2. Structure and size inspection

  1. Geometric dimension detection :

    • Measure pipe OD, ID, wall thickness and length to ensure design specifications are met.
    • Check the accuracy of threaded joints and measure thread size and tightness using gauges or instruments.

  2. Appearance quality :

    • Inspect the surface for cracks, delamination, bubbles, or obvious mechanical damage.
    • The color and surface finish of the tube body should be uniform and free of defects that affect performance.

3. Mechanical properties test

  1. Tensile strength and axial load :

    • Test the tensile strength and modulus of FRP pipes according to standard methods (such as ISO 527) to ensure that they meet the axial load requirements of downhole conditions.

  2. Ring stiffness test :

    • By testing the deformation capacity of the pipe under radial load, it is verified whether its ring stiffness meets the standard requirements, especially for high external pressure environments.

  3. Fatigue resistance test :

    • Under conditions simulating downhole pressure and temperature, multiple pressure cycle tests are carried out to evaluate the fatigue resistance of the pipe in long-term use.

4. Pressure performance test

  1. Hydrostatic Pressure Test :

    • Test the sealing and durability of FRP oil pipes at rated pressure and ultimate pressure to observe whether there is leakage or rupture.

  2. Internal and external pressure composite test :

    • Internal and external pressures are applied simultaneously to simulate actual downhole conditions and ensure the reliability of the pipeline in complex pressure environments.

  3. Instantaneous stress test :

    • Apply a rapid pressure increase to test the pipe's resistance to rupture under sudden pressure conditions.

5. High temperature resistance and corrosion resistance test

  1. High temperature resistance test :

    • The mechanical properties and sealing performance of the pipe are tested in a set high temperature environment (such as 100°C) to ensure that it does not fail under high temperature conditions.

  2. Corrosion resistance test :

    • The pipe is immersed in a simulated downhole corrosive medium (such as a solution containing hydrogen sulfide and carbon dioxide) to evaluate its corrosion resistance.

6. Joint quality inspection

  1. Interface bonding strength between FRP and metal joints :

    • Test the interfacial bonding strength of FRP and embedded metal joints to ensure that they meet the requirements of internal and external pressure and axial load.

  2. Joint sealing :

    • Through air tightness test or water tightness test, evaluate whether the sealing performance of the joint meets the standard requirements.

  3. Joint fatigue resistance :

    • Test the reliability of the connector during multiple installation, removal and pressure cycles.

VII. Production and Manufacturing Process Control

  1. Winding process :

    • Check whether the glass fiber winding angle and number of layers meet the design requirements to ensure the mechanical properties and structural stability of the pipe.

  2. Curing quality :

    • Use differential thermal analysis or glass transition temperature (Tg) testing methods to verify that the pipe is fully cured.

  3. Non-destructive testing :

    • Use ultrasonic testing or X-ray testing to check the inside of the tube for bubbles, delamination or other defects.

8. Standards Compliance Review

  1. International Standards :

    • Check whether the pipe meets the requirements of API Spec 15HR, API Spec 15LR or ISO 14692.

  2. Industry Standards :

    • Verify whether it complies with domestic industry standards such as SY/T 7043 and SY/T 6267.

IX. On-site test and acceptance

  1. On-site installation and testing :

    • Check the installability of the pipe, including its matching with the casing, the connection accuracy of the joints and the convenience of construction.

  2. Run the tests :

    • On a test platform that simulates underground working conditions, its performance, including pressure resistance, corrosion resistance and fatigue resistance, is evaluated after running for a certain period of time.

Through the above series of inspections and tests, the quality of FRP downhole oil pipes can be comprehensively evaluated to ensure that they can operate reliably for a long time in complex working conditions underground in oil fields.