We explore the effect of dimensionality on the nearest neighbor problem. We show that under a broad set of conditions (much broader than independent and identically distributed dimensions), as dimensionality increases, the distance to the nearest data point approaches the distance to the farthest data point. To provide a practical perspective, we present empirical results on both real and synthetic data sets that demonstrate that this effect can occur for as few as 10-15 dimensions. These results should not be interpreted to mean that high-dimensional indexing is never meaningful; we illustrate this point by identifying some high-dimensional workloads for which this effect does not occur. However, our results do emphasize that the methodology used almost universally in the database literature to evaluate high-dimensional indexing techniques is flawed, and should be modified. In particular, most such techniques proposed in the literature are not evaluated versus simple linear scan, and are evaluated over workloads for which nearest neighbor is not meaningful. Often, even the reported experiments, when analyzed carefully, show that linear scan would outperform the techniques being proposed on the workloads studied in high (10-15) dimensionality!.

When is nearest neighbor meaningful

Effect of CuO and ZnO nanofluids in xanthan gum on thermal, electrical and high pressure rheology of water-based drilling fluids

CFD–DEM approach to investigate the effect of drill pipe rotation on cuttings transport behavior

Effect of a novel clay/silica nanocomposite on water-based drilling fluids: Improvements in rheological and filtration properties

Mathematical modeling of thixotropic drilling mud and crude oil flow in wells and pipelines—A review

Effect of Pipe Rotation on Hole Cleaning for Water-Based Drilling Fluids in Horizontal and Deviated Wells

This study aims to estimate the critical fluid flow velocity for preventing the development of a stationary bed using empirical correlations valid for horizontal and highly inclined wellbores that can be easily used at the field. For this purpose, experiments have been conducted at METU-PETE Cuttings Transport Flow Loop for various conditions. Observations showed that a stationary bed is developed when the fuid velocity is less than 6.0 ft/s, and a critical fluid velocity of 8.0 ft/s is required to establish a no-bed condition. Results showed that the critical velocity and the thickness of the stationary bed, if developed, could be estimated with a reasonable accuracy.

Critical Fluid Velocities for Removing Cuttings Bed Inside Horizontal and Deviated Wells

The annular frictional performance of non-Newtonian fluids is among the major considerations during development of hydraulic programs for drilling operations Proper estimation of the frictional pressure losses become more critical when determining hydraulic horsepower requirements and selecting proper mud pump systems to foresee any serious problems that might occur with hydraulics during drilling operations Because the rheological behaviour of the non-Newtonian fluids is known to be challenging, it becomes even more complicated during pipe rotation, especially in eccentric wellbores In many cases, significant differences are observed when theoretical calculations and measurements for pressure losses are compared This study aims to develop correction factors for determining the frictional pressure losses accurately in eccentric horizontal annulus for non-Newtonian fluid, including the effect of pipe rotation Extensive experimental work has been conducted on METU-PETE Flow Loop for numerous non-Newtonian drilling fluids, including KCl-polymer muds and PAC systems for different flow rates and pipe rotation speeds, and frictional pressure losses are recorded during each test Rheological characteristics of the drilling fluids are determined using a rotational viscometer Observations showed that pipe rotation has a significant influence on frictional pressure loss, especially at lower flow rates Up to a point, as the pipe rotation increases, the frictional pressure losses also increase As the flow rates are increased, the effect of pipe rotation on frictional pressure losses diminishes Also, after a certain pipe rotation speed, no additional contribution of pipe rotation on frictional pressure loss is observed When the developed friction factors are used, there is a good agreement between the calculated and observed frictional pressure losses for any pipe rotation speed

Frictional Pressure Loss Estimation of Non-Newtonian Fluids in Realistic Annulus With Pipe Rotation

Friction factors for hydraulic calculations considering presence of cuttings and pipe rotation in horizontal/highly-inclined wellbores

Accurate estimation of the frictional pressure losses for non-Newtonian drilling fluids inside annulus is quite important to determine pump rates and select mud pump systems during drilling operations. The purpose of this study is to estimate frictional pressure loss and velocity profile of non-Newtonian drilling fluids in both concentric and eccentric annuli using an Eulerian-Eulerian computational fluid dynamics (CFD) model. An extensive experimental program was performed in METU-PETE Flow Loop using two non-Newtonian drilling fluids including different concentrations of xanthan biopolimer, starch, KCl and soda ash, weighted with barite for different flow rates and frictional pressure losses were recorded during each test. This study aims to simulate non-Newtonian fluids flow through both horizontal concentric and eccentric annulus and to predict frictional pressure losses using an Eulerian-Eulerian computational fluid dynamics (CFD) model. Computational fluid dynamic simulations were performed...

Mehmet Sorgun

Papers

Effect of Pipe Rotation on Hole Cleaning for Water-Based Drilling Fluids in Horizontal and Deviated Wells

Critical Fluid Velocities for Removing Cuttings Bed Inside Horizontal and Deviated Wells

Frictional Pressure Loss Estimation of Non-Newtonian Fluids in Realistic Annulus With Pipe Rotation

Friction factors for hydraulic calculations considering presence of cuttings and pipe rotation in horizontal/highly-inclined wellbores

Predicting Frictional Pressure Loss During Horizontal Drilling for Non-Newtonian Fluids