Laminar Displacement Flows in Vertical Eccentric Annuli: Experiments and Simulations

Abstract

We present a numerical investigation of laminar miscible displacement flows in narrow, vertical, eccentric annuli. This study is motivated by the primary cementing stage of oil and gas well production, where successful displacement of drilling mud is crucial for the well integrity and zonal isolation. The large number of characterizing parameters makes a complete description of such flows challenging. In turn, this means that the design of effective strategies for primary cementing is a difficult task. As a result the existing literature is mostly based on non-inertial Hele-Shaw models and experiments in narrow annuli, where the dimensionality of the problem is reduced. In this preliminary study, we run a series of three-dimensional numerical simulations, using a Volume of Fluid (VOF) method to capture the interface between the fluids. Both Newtonian and non-Newtonian fluids are considered, and a variety of different phenomena are observed, e.g. dispersive spikes, static layers, instabilities and secondary flows. The range of flow parameters used in the simulations are similar to existing experimental data to allow for a preliminary comparison. The results show qualitative agreement with the experiments and gap-averaged models.

Primary cementing of vertical wells: displacement and dispersion effects in narrow eccentric annuli

“…b). For other parameters we can also find contact shocks on the narrow side, as well as experimentally (Etrati & Frigaard 2019). We have focused on wide and narrow side here, where the 2-D models have velocity only along the annulus (due to the imposition of symmetry).…”

“…A number of recent studies have looked at fully 3-D flows in the cementing context (Kragset & Skadsem 2018;Etrati & Frigaard 2019;Skadsem et al 2019a;Skadsem, Kragset & Sørbø 2019b), and in particular for studying local irregularity effects. These occur when, for example, the surrounding formation is poorly consolidated and/or the drilling operation has anomalies, leading to washouts, i.e.…”

Primary cementing of horizontal wells. Displacement flows in eccentric horizontal annuli. Part 1. Experiments

“…In recent years interest has revived in these methods as open source and other computational codes have become widely accessible and multi-processor computations have made such calculations manageable at reasonable resolutions over increasingly long annuli and even for non-Newtonian fluids, e.g. Kragset & Skadsem (2018), Etrati & Frigaard (2019) and Skadsem et al (2019). Those 3-D simulations that have been published certainly expose flow features not present in Hele-Shaw models: inertial effects and flow features on the scale of the annular gap.…”

Primary cementing of vertical wells: displacement and dispersion effects in narrow eccentric annuli. Part 2. Flow behaviour and classification

“…we are not in the Taylor dispersion regime. Instead, we do see dispersive flows develop on the annular gap-scale, in both lab-scale experiments and in fully three-dimensional (3-D) computations (Kragset & Skadsem 2018;Etrati & Frigaard 2019;Skadsem et al 2019a;Skadsem, Kragset & Sørbø 2019b;Sarmadi, Renteria & Frigaard 2021;Zhang & Frigaard 2021;Sarmadi et al 2022). The challenge therefore is to resolve dispersion on the gap-scale, while retaining the two-dimensional (2-D) formulation.…”