Rogaland Research Institute Stavanger - Erosionstest

Vergleich zwischen

  1. Baker Excluder Screen
  2. Baker Pre-pack Screen 12/20 and 20/40
  3. con-slot Single Wire Wrap Screen

Bitte lesen Sie zwischen den Zeilen den Kommentar über den con-slot Filter:

Nach 50 Tagen war der Filter noch nicht erodiert, aber die Tauglichkeit der anderen Filter bereits innerhalb von Stunden stark eingeschränkt! Wann und ob ein con-slot Filter erodiert konnte mit dieser Untersuchung nicht festgestellt werden.




Erosion of sand screens by relatively dilute, 1% by weight, sand slurry was investigated in laboratory tests for Single Wire Wrap Screens and Baker Hughes Inteq Excluder and Pre-pack Screens.

The erosive effect of the sand slurry is strongly dependent on the velocity of the liquid fluid through the screen, and thus on the pressure drop over the screen. The magnitude of erosion increased with the pressure drop to the power of about 1.75 over the Single Wire Wrap Screen, and to the power of about 2.3 over the vector weave in the Excluder Screen.

As may be expected, the rugged design of the Single Wire Wrap Screen makes it relatively resistant against sand erosion. However, with a pressure drop of 1 bar and a sand concentration in the fluid of 1wt% at local "hot spots", 10% of the screen material may become eroded away at such places in about 50 days.

The vector weave layer in the Excluder Screen turned out to be quite vulnerable to sand erosion. After 3.6 days with 0.6 bar pressure drop over the screen 4% of the weave material had eroded away. With 1.5 bar pressure drop 5% had eroded away already after 7.6 hours.

In the Pre-pack Screens, both with 12/20 and 20/40 gravel, the fine mesh netting between the base pipe and the cured gravel layer was relatively quickly eroded at pressure drops of 1.5 bar  and higher, while no damage could be observed on the gravel matrix or the other components of the screen. The cured gravel layer thus seems relatively robust against erosion. Quantitative measurements on the gravel layer were not performed. Whether the loss of the supporting retting turns out serious depends on the integrity of the gravel matrix.

The sand content of 1 wt% used in the slurries of the tests may normally be unrealistically high relative to the total flow from a well. However, at local "hot-spots" one may very well have concentrations this high and higher. If a sand screen partially plugs during the production of well fluids the practice is to lower the well pressure, with several bars or even several tenth of bars, in order to keep up the production. The tests show that one then runs a serious risk of damaging a sand screen within a short time.

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