Hydraulic Behavior in Cased and Open-Hole Sections in Highly Deviated Wellbores

Abstract

In this paper, we present results from flow loop experiments with an oil-based drilling fluid with micronized barite as weight materials. The use of micronized barite allows using lower viscosity drilling fluid, providing non-laminar flow, which is advantageous for particle transport in near-horizontal sections. While transition to turbulence and turbulent flow of non-Newtonian fluids has been well studied both theoretically and experimentally, there are very few published results on the effect of wellbore wall properties on flow regime transition and turbulence. This is relevant because horizontal sections are often open hole with less well-defined surfaces than a steel casing surface. We have conducted a series of flow experiments with and without cuttings size particles in a 10 m long annular test section using steel and concrete material to represent the wellbore wall of a cased and open hole section. In both cases the annulus was formed by a freely rotating steel pipe of 2" outer diameter inside a 4" diameter wellbore. Experiments were conducted at 48°, 60° and 90° wellbore inclination from vertical. The two materials result in different hydraulic behavior without particles with stronger turbulence when using concrete wellbore wall material than when using steel casing. While there is negligible difference at low flow rates, at 0.8 m/s and below, there is an increasing difference as the flow rate increases and becomes transitional to turbulence. Hole cleaning is found to differ dependent on the wall material. However, the effect on hole cleaning is less clear than for the pressure loss.

Oil-Based Drilling Fluid's Cuttings Bed Removal Properties for Deviated Wellbores

“…In OBM A, a micronized barite is used as a weighting material. Further information on this fluid can be found in the study by Ytrehus et al [7,10]. For OBM C, a fine-grained barite is used as a weighting material.…”

“…In two comprehensive review articles, Li and Luft [5,6] summarized experimental studies and theoretical analyses of hole cleaning. Experiments have also shown that hole cleaning can be different in gauge open hole and inside casing [7]. Numerical simulations have also been used to evaluate hole cleaning [8,9].…”

Fundamentals and Physical Principles for Drilled Cuttings Transport—Cuttings Bed Sedimentation and Erosion

“…Similarly to the Boycott settling phenomena described in 1920 [11], which showed that blood corpuscles settle faster in inclined test tubes than in vertical ones; the drilled cuttings tend to settle faster in inclined trajectories. Among the different researchers, the common results showed that between 45 • and 60 • is the most critical angle for cuttings lifting and transport [12][13][14][15][16]. Nevertheless, the critical angle can swift between 60 • and 90 • depending on the drilling fluid type, flow rate [17] and the drill-pipe rotation and practical setup, as well as the conditions used for research.…”

“…where U mB is is the moving bed velocity, A mB is the cross-sectional area of the moving bed and C mB is the mean concentration of solids in moving bed. These two equations, ( 12) and ( 13) correspond to the mass balances for the solid and for the liquid respectively, the momentum equations, describe the suspended layer in Equation ( 14), the moving bed layer in Equation (15) and the stationary bed layer in Equation (16).…”

Experimental Study of Hydraulic Sealability and Shear Bond Strength of Cementitious Barrier Materials

“…It is insufficient to have a strong bonding to achieve proper zonal isolation; a cementitious material can have severe adhesion to the casing material, while pathways exist at the interfaces and formation fluid can easily penetrate through micro-channels. Hence, hydraulic bond strength is more critical in terms of zonal isolation, and it should be further investigated [18].…”