An Innovative Approach to the Selection of Critical Design Parameters Influencing Sand Control Efficacy in Standalone Sand Screens Deployed in Oil and Gas Wells

Abstract

The objective of screen testing and selection is to minimise sand production while maintaining acceptable filter permeability, however, screen failures during operation are common and difficult or expensive to fix. Our research improves current selection tests and considers the expected time to failure for the screen. Experimental tests for screen selection compare retained permeability and produced solids for different screen apertures and weave types. Our study suggests that performance is only minimally dependent on aperture and weave, but more strongly dependent on the structure of the filter-bed that builds up on the screen. We also show that screen failures are directly linked to the structure of the deposited filter-bed. The aim of our work is to develop a relationship between filter bed packing, filter bed thickness, and screen stresses, to introduce preliminary quantification of the required strength of a screen and extend its operating life. Our methodology uses a CFD-DEM model to simulate four common screen types. The numerical model is calibrated using an innovative laboratory experimental result and the corresponding micro-CT image of the deposited filter-bed at, using sand samples from wells offshore Brunei. The metric used for calibration is the single-phase permeability parameter. The retained permeability and the rate of sand production is only weakly dependent on the weave and aperture of screen coupons in both experimental tests and numerical simulations. The behaviour of the screen is better correlated with the structure and composition of the filter-bed. Numerical simulations of behaviour of the screen and the filter-bed allowed us to analyse the stress on the screen, which is not normally measured in experimental screen retention tests. As the filter-bed is a granular media, the forces transmitted through the filter-bed are spatially highly variable with some locations on the screen receiving extremely high point forces which are above the manufacturers specified collapse pressure. Our advanced numerical method that involves stress analyses on sand screens allows us to develop a more comprehensive set of criteria for screen selection which should reduce the occurrence of screen failure or extended the expected time to failure. The novelty of this research is the development of new techniques to investigate the screens’ ability to resist collapse due to non-uniform forces on the screen. During this research, it also became apparent that screens with different weaves and apertures perform broadly the same in terms of produced sand and retained permeability. As a result of these observations, we suggest a more rigorous comparative test that considers the expected life of the screen and its susceptibility to failure.