Intermixing of Cementing Fluids: Understanding Mud Displacement and Cement Placement

Abstract

Mud removal and cement placement during a cementing operation are key factors to ensuring zonal isolation. Actual well testing results show that majority of wells have zonal communication during the life of production. The communication between water and oil zones may significantly affect oil production and require expensive remedial squeeze treatments. Fully understanding the flow characteristics and interactive behaviors in mud, spacer, and cement is an important step to ensure critical zonal isolation.A newly developed computational fluid dynamics model helps end users better understand the transport phenomena of intermixing multiple fluids. Fluid decay resulting from the intermixing involving the mud, spacer, and cement systems is quantified for given downhole conditions of wellbore geometry, fluid properties, pump rates and casing centralization. The robust method allows the analysis of potential hydrocarbon production zonal isolation success and optimization of cement placement. This advanced fluid displacement simulator has been field verified with impressive results for a wide range of annuli. A recently developed pseudo 3-D visualization module aids in understanding the complex phenomena as well.Some field cases used for verification are included. The detailed job analysis demonstrates the methodology used to study the effects of fluid systems, pump rates, and centralization configurations and provides application engineers the opportunity to understand different scenarios while optimizing key parameters to achieve top tier results.

Bingham’s model in the oil and gas industry

“…Such models are appropriate for process design and predict well the dominant effects of wellbore eccentricity, rheology, density differences, and inclination. Variants of this approach are increasingly widely used in industry, e.g., Tardy and Bittleston (2015), Guillot et al (2007), Chen et al (2014), and Bogaerts et al (2015). It is interesting to reflect that the above approach is mathematically analogous to the LPG reservoir flows outlined in "Reservoir flows of visco-plastic heavy oils," with varying annular gap width corresponding varying permeability.…”

Cement Placement: An Overview of Fluid Displacement Techniques and Modelling

“…Moran and Savery [24] presented a comprehensive experimental study on the effect of eccentricity and affirmed the importance of centralization. There have been indeed numerous works, such as the ones by McLean et al [23], Couturier et al [29], Jakobsen et al [19], Guillot et al [33], Chen et al [34], Foroushan et al [13], Ytrehus et al [22], Skadsem et al [35], Lund et al [26], where the importance of proper centralization and the adverse influence of eccentricity is emphasized.…”

Fundamentals of Plug Placement

“…The analysis of removing drilling fluid and replacing it with cement can be performed properly by simulating multiphase flow. In a multiphase flow simulation, interfaces between cement and space fluid, and spacer fluid and drilling mud are presented by solutions of the governing equations [2,[34][35][36][37].…”

“…To achieve the objectives, drilling fluid and pre-flushes must be fully removed from the openhole interval and be exchanged fully with cement or any plugging material. The fluid removal process is a function of borehole quality, circulation and displacement efficiency, fluid conditioning and properties of drilling fluids, spacers and washes [1][2][3][4][5][6]. Fluid removal process can be carried out in two main different ways: hydraulically or mechanically.…”