Abstract

In this paper, the integrity of sand screen is evaluated for various depletions using fluid-mechanical coupling analysis. The interaction between the screen and reservoir is captured by rock-structure interaction model, based on laboratory tests that measured the mechanical properties of ceramic proppant, the formation sandstone and sand screen. The frictional hardening properties of the ceramic proppant and sandstone core plugs are measured by performing constant mean-stress tests in rock mechanics laboratory. The volumetric hardening curve of sandstone is measured in isotropic compression tests (with unloading excursions). The elasto-plastic mechanical properties of sand screen are determined by calibrating the laboratory crushing test data. For a given maximum depletion, this model can be used to select appropriate sand screens; conversely, for a given sand screen, this model can be used to estimate the depletion where failure is likely.

1. INTRODUCTION

The reduction of formation pore pressure induced by fluid production in water and hydrocarbon reservoirs could result in many serious consequences, including subsidence of earth surface, loss of overburden integrity, reduction of porosity and permeability of formation, damage of well construction and production parts such as casing and tubing strings (Schutjens et al., 2004, 2008).

Open-hole standalone screens and gravel packs are often-used sand control methods in unconsolidated sandstone. As reservoir pressure depletes, the effective stresses in the formation increase. The depletion-induced increase in effective stresses are further magnified by the near wellbore stress concentration. Because the strength of unconsolidated sandstone is low and the gravel pack provides only a limited support to the wellbore wall, plastic deformation near the well seems inevitable in many wells. As a result, the forces acting on the sand screen increase. When formation loads exceed the loading capacity of the sand screen, the integrity of the screen is lost resulting in sand control failure and lost production.

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