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The Role of the Annular Gap in Expandable Sand Screen Completions SPE 86463.

The Role of the Annular Gap in Expandable Sand Screen Completions SPE 86463. . J. Heiland, J. Cook, A. Johnson, B. Jeffryes. Schlumberger Cambridge Research. Outline. Where does the gap come from? How does it influence the mechanics of the completion? experiments theory

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The Role of the Annular Gap in Expandable Sand Screen Completions SPE 86463.

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  1. The Role of the Annular Gap in Expandable Sand Screen Completions SPE 86463. J. Heiland, J. Cook, A. Johnson, B. Jeffryes. Schlumberger Cambridge Research

  2. Outline • Where does the gap come from? • How does it influence the mechanics of the completion? • experiments • theory • How does it influence the hydraulics? • Conclusions.

  3. Origins of the gap • State of the hole after drilling (enlargement, tortuosity, rugosity). • Nature of the screen - expansion ratio. • Nature of the expansion process - fixed diameter or compliant.

  4. Possible consequences of a gap: short- and long-term Rock failure behind screen with gap: • generating load on screen. • releasing grains and fines. • transport, and erosion of screen • plugging of screen • changing permeability ( or ). Fluid flow in annular gap: • intervention or production logging more difficult. This paper addresses the first two of these.

  5. Views of the system Transverse Collapse; closure; inflow Inflow; fluid and sand transport Axial

  6. Transverse view - experimental • Aim: observe how the gap influences closure and collapse • using full-size screens in simulated boreholes in weak rock. • Sample is 600 mm OD, 215 mm ID, 1000 mm long. NB: no fluid flow through rock pores. Camera Rock Screen Pressure Kerosene

  7. Summary of conditions for the screen closure experiments.

  8. Example: Test 4. Full screen, close fit Pressure in bars (500 bars = 7250 psi)

  9. Closure data from all the experiments

  10. Transverse view - modelling • Simple rock deformation model, incorporating support stress (isotropic stress, perfect plasticity, no pore pressure gradients). • Couples deformation of rock to that of screen. • Allows study of effects of stiffness, gap, rock properties….

  11. Typical results from modelling Result:Optimum gap for mechanical stability: zero to few mm

  12. Axial view - modelling • Accounts for • radial flow from formation into well • axial flow along gap • radial flow through screen wall • axial flow in basepipe. • Tracks movement of sand (if annulus velocity is above threshold value). • Allows blockage of screen or annulus.

  13. Effect of gap size:hole ID 0.2 m, screen OD 0.195 m. Toe Heel

  14. Effect of gap size:hole ID 0.2 m, screen OD 0.185 m. Toe Heel

  15. Conclusions • Most stable system when movement of both grains and larger fragments is prevented. • Small gap (few mm) allows mobilization of rock strength to assist stability. • Sand movement in annulus prevented by smaller gap, because of lower annulus velocity. • Sand accumulations, plugged screen sections, and enlarged holes lead to local hotspots and potential erosion. Very small or zero gap is therefore best for long-term integrity of completion.

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