Best Practices for Wellbore Cleanup and Displacements in Openhole Sand-Control Completions

Abstract

Summary At some stage after drilling to target depth and before pumping the gravel-packing treatment or before putting the well on production, the drilling fluid is typically displaced from the wellbore. Practices in the industry vary significantly depending on the primary drivers of the completion engineers, sometimes with undesirable results. Inefficient wellbore displacements can cause a variety of problems, including increased nonproductive time, reduced well productivity, and incomplete gravel packing through various mechanisms. In this paper, we detail our best practices to ensure efficient wellbore displacements for sand-control completions on the basis of learnings from more than 500 openhole completions throughout the world from 2013 through 2016. In the design phase, these involve various compatibility tests, some of which are not commonly performed, and/or potential problems that cannot be identified easily when they are performed using conventional test procedures. Additional considerations include the modeling of fluid/fluid displacements and determining the fluid properties, pump rates, and fluid volumes required for effective displacements in a given wellbore geometry and flow paths. On the rigsite, they involve several quality-control tests, some of which have not been implemented previously.

Distributed viscosity and flow velocity measurements using a fiber-optic shear stress sensor

“…Over these longer distances, fluid mixing, temperature and pressure changes, chemical alterations of the process fluid and varying cross sectional flow areas are present which can all vary the fluid pumping and fluid displacement efficiency. Analytical and numerical models available in literature to model the fluid displacement are not capable to access the full complexity of downhole conditions [21]. Also, modeling approaches are difficult to validate if data from the subsurface is sparse.…”