Experimental and Numerical Study of Drilling Fluid Removal from a Horizontal Wellbore

Abstract

After a well has been drilled, the drilling fluid should be removed and replaced with either cement and/or completion fluids. For effective zonal isolation and optimum hydrocarbon production during the life of the well, the entire drilling fluid should be removed from the annulus. Cement and completion fluids are sensitive to drilling fluid contamination, and even a thin layer of oil-based drilling fluid could prevent the cement from bonding to the formation and the casing. In addition, for optimum hydrocarbon production, the cement sheath must be able to withstand the stresses throughout the life of the well. 1 Several factors affect the success of drilling fluid removal from horizontal annuli. Under static conditions, drilling fluid usually forms a gel structure. Under positive differential pressure, the drilling fluid loses filtrate and forms a filter cake on the formation face. Sometimes the filter cake is mushy and difficult to remove, but the formation fluid can easily flow through it. The successful removal of the gel and mushy filter cake depends on the structures that form and how these structures behave under flow conditions. In addition, casing centralization affects the fluid flow profile in the annulus, which affects gel and filter-cake removal.To investigate the mechanism of drilling fluid removal, we conducted both numerical and experimental studies. In the experimental studies, chemical flushes and spacers were tested for their effectiveness in removing drilling fluid. The experiments showed that annulus cleaning begins around the inner pipe and progresses outward at increasing fluid flow rates. Analytical fluid flow models and full 3D multiphase numerical models allowed us to estimate flow profiles and the success of removing drilling fluid under downhole conditions. The large-scale ex-fax 01-972-952-9435.References at the end of the paper. periments and analytical/numerical modeling have led to a better understanding of the factors controlling drilling fluid removal from horizontal wellbores.

Microemulsions for Cleaning Applications

“…These inefficient displacements could lead to poor cement bonding, squeeze jobs, communication between zones and, in some cases, blowouts [68][69][70][71]. Fluids incompatibility is a major issue when oil and gas operators have directly displaced the oil-based drilling fluid from a wellbore with an aqueous fluid such as brine and/or cement after running a casing string.…”

Thermal Sealants Improve Cementing in SAGD Areas

“…• Free water; and • Rheology (6) . In addition to these, mechanical laboratory testing is needed to confirm the required parameters of the slurry design.…”

Use of Pressure Gauges in Liner Running Strings during Liner Cementing Operations

“…5,7 One deciding factor in ECD calculation is the geometry of the well, the equipment that has to be run and determining when the hole is ready to receive the cement slurry. The modern ECD dynamic predictions take into account complex calculations like horizontal and high angle wellbore configurations, pipe eccentricity, gelled drilling fluids and different hole diameters.…”