A Comprehensive Theoretical and Experimental Study on Fluid Displacement for Oilwell-Cementing Operations

Abstract

Summary Displacing fluids in downhole conditions and for long distances is a complex task, affecting several steps of well construction. Cementing gains relevance the moment that fluid contamination compromises cement-sheath integrity and consequently zonal isolation. Density and rheology design for all the fluids involved is essential to achieve operational success. Properties hierarchy and preferred flow regimes have been empirically defined and tend to provide reasonable generic results. Challenging operations, including ultradeep waters and their narrow operational-window scenario, require further knowledge of the physics involved to prevent undesirable events. This paper presents the in-house development of software for annular miscible fluid displacement that analyzes fluid displacement in typical vertical and directional offshore wells, for Newtonian and non-Newtonian liquids and laminar- and turbulent-flow regimes. The formulation proposed provides accurate results for a wide range of input parameters, including the cases in which the ratio of the inner radious to the outer radius of the annulus is small. The computational work is validated by unique results obtained from an experimental test rig where detailed displacement tests were conducted. Contamination degrees were measured after the displacement of a sequence of fluids through 1192 m of vertical well. Effect of fluid-density and rheology hierarchy, flow regimes, and displacement concepts was investigated. The results provide relevant information for the industry and fundamental understanding on displacement of Newtonian and non-Newtonian liquids through annular sections.

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

“…The underlying Hele-Shaw model is identical with that analysed earlier for vertical annular displacement flows (Bittleston et al 2002;Pelipenko & Frigaard 2004a,b,c) and to that recently extended towards other flow regimes (Maleki & Frigaard 2017. Variants of the underlying model are becoming widespread (Aranha et al 2012;Tardy & Bittleston 2016) as are apparently similar engineering software, developed in-house by many companies. This style of model has also become regularly used industrially for cementing case studies, job designs and post-job evaluations, e.g.…”

Evaluation of Flushing Ability of Cementing Flushing Fluids

“…The basic principle of the rotating droplet method is to fill a rotating sample tube C with a liquid B of high density ρ, add a drop A of low density ρ to suspend it in liquid B, and install it in the sample tube of the rotating droplet instrument in a closed manner. − At this time, the sample tube is parallel to the rotating axis D . After starting the machine, take the central axis of the sample tube as the rotating axis and carry the liquid to rotate at an angular velocity ω.…”

Cement Placement: An Overview of Fluid Displacement Techniques and Modelling

“…Howard and Clark [7] were probably the first to suggest that a decrease in viscosity of the drilling fluid would increase displacement efficiency. Later the effect of rheological properties of displacing and displaced fluids was studied in various works, such as Flumerfelt [8], Nguyen et al [9], Tehrani et al [10], Miranda et al [11], Aranha et al [12], and Foroushan et al [13]. There were also other investigations, such as the ones of Lockyear and Hibbert [14], Lockyear et al [15], and Silva et al [16], that discussed the effect of yield stress and gel strength of mud on the displacement process.…”

“…There have been numerous experimental works, such as the ones of Parker et al [27], McLean et al [23], Clark and Carter [17], Martin et al [37], Haut and Crook [18], Lockyear et al [15], Tehrani et al [10], Moran and Savery [24], and Aranha et al [12], conducted to study the fluid displacement processes. In this section, selected experimental setups from more recent works are described to provide an overview of scales and functionality of the referred work.…”