Experimental Methods for Investigation of Drilling Fluid Displacement in Irregular Annuli

Abstract

Experimental methods are still indispensable for fluid mechanics research, despite advancements in the modelling and computer simulation field. Experimental data are vital for validating simulations of complex flow systems. However, measuring the flow in industrially relevant systems can be difficult for several reasons. Here we address flow measurement challenges related to cementing of oil wells, where main experimental issues are related to opacity of the fluids and the sheer size of the system. The main objective is to track the propagation of a fluid-fluid interface during a two-fluid displacement process, and thereby to characterize the efficiency of the displacement process. We describe the implementation and use of an array of electrical conductivity probes, and demonstrate with examples how the signals can be used to recover relevant information about the displacement process. To our knowledge this is the most extensive use of this measurement method for studying displacement in a large-scale laboratory setup. Optical measurements and visual observations are challenging and/or costly in such large-scale systems, but can still provide qualitative information as shown in this article. Using electrical conductivity probes is a robust and fairly low-cost experimental method for characterizing fluid-fluid displacement in large-scale systems.

Experimental Study of the Use of Tracing Particles for Interface Tracking in Primary Cementing in an Eccentric Hele–Shaw Cell

“…7 in concentric geometries with the same used fluids, densities, and rheologies, it can be seen that the higher flow rate of 21.6 L/min in the eccentric geometry than 7.86 L/min in the concentric geometry causes lower effective viscosity, and the recorded pressure gradients in the eccentric geometry are higher than the concentric geometry. While it is known that frictional pressure drop in an eccentric annulus is lower than in a corresponding concentric annulus [24], due to the dominating hydrostatic pressure gradient and somewhat different fluid and flow properties from test to test, this is not apparent from our experiments here. The observed differences of pressure gradients in the eccentric and concentric Hele-Shaw cells are due to the flow rate differences and consequently equivalent viscosity differences rather than the degree of eccentricity.…”

“…The frictional pressure drop and the relation between pressure drop and flow rate during the displacement flow of non-Newtonian fluids were described as well [4,10,11]. By using large-scale eccentric annular geometry, the importance of the rheological properties of the realistic non-Newtonian fluids for fluid flow and hole cleaning performance was expressed extensively [14][15][16], and the propagation of the fluid interfaces and displacement efficiency were characterized [24]. It was indicated that an enlarged irregular section, i.e., a washout causes an improvement in displacement in some scenarios in strongly inclined wellbores [17]; while being independent of the displacement efficiency in the washout itself, the presence of washouts may lead to poorer cement quality downstream of the washouts [23].…”