Changes In Holdup Research Articles

Study on the Interpretation Method of Layered Flow Imaging Logging for Oil–water, Two-Phase Flow in Horizontal Wells

In the production of oil and gas fields, horizontal wells can obtain larger reservoir drainage area. Single well production is large and the production cycle is long. Especially for the development of reservoirs with thin production layer, small porosity, and low permeability, it shows the incomparable effect of vertical wells. Due to gravity separation in horizontal wells, the distribution of fluids in horizontal cross sections is more complicated. There are many influencing factors, such as gas lock, water lock, and flow instability. In horizontal well oil–water two-phase flow, the flow separation in different flow zones complicates the reading of the turbine flowmeter due to the change the cross-sectional area of the fluid. A small deviation of the horizontal well inclination causes significant changes in holdup and flow velocity. Well deviation causes backflow and circulation. In this paper, the capacitance water holdup and turbine flowmeter data processing method of FILT in oil–water two-phase flow are studied by the oil–water, two-phase flow experiment. The stratified flow interpretation model of oil–water two-phase flow and the chart fitting calculation method are proposed and realized. This is the innovation of this paper. Through the verification of experimental data, the relative errors under various conditions are less than 10%. Only when the moisture content is 20%, the error is greater than 10%. The interpretation accuracy of oil–water two-phase flow can fully meet the actual needs of production. It provides a strong basis for accurately finding the producing water point and scientifically plugging water in horizontal wells. The findings of this study can help the better understanding of the oil–water two-phase flow stratification flow interpretation model and the chart fitting calculation method.

Dispersed-Phase Holdup and Characteristic Velocity in a Pulsed and Nonpulsed Disk-and-Doughnut Solvent Extraction Column

The dispersed-phase holdup and characteristic velocity, which are important hydrodynamic performance parameters for solvent extraction columns, were measured and compared to literature correlations under pulsing and nonpulsing conditions using a 75 mm diameter disk-and-doughnut column. The results show that the dispersed-phase holdup increased with increasing dispersed-phase flow rate, while there was no noticeable change in holdup with the continuous-phase flow rate. With increasing pulsation intensity from zero, the dispersed-phase holdup decreased at first and then increased. A minimum holdup was found in the transition from the mixer-settler to the emulsion regime, and it increased with increasing dispersed-phase velocity. The experimental holdup and minimum holdup were correlated over a range of pulsation rates to within 13.3% and 8.8%, respectively. The characteristic velocities under different pulsation conditions were calculated from the measured holdup for the pulsing conditions. The characterist...

Downstream mergers and producer's capacity choice: why bake a larger pie when getting a smaller slice?

In this article, the effect of downstream horizontal mergers on the upstream producer's capacity choice was studied. Contrary to conventional wisdom, I find a nonmonotonic relationship: horizontal mergers induce a higher upstream capacity if the cost of capacity is low, and a lower upstream capacity if this cost is high. This result is explained by decomposing the total effect into two competing effects: a change in holdup and a change in bargaining erosion.

Phase-Plane Analysis of Homogeneous Azeotropic Distillation Columns

In this paper, it is shown that despite the large number of states and equations describing a distillation column the dynamics can be analyzed by lumping the states into a few variables characterizing the total holdup. Changes in holdup are compared to the global mass balance to derive a vector field describing the trajectories of the product compositions. The vector field contains detailed information about the dynamic behavior and is obtained without performing a complete dynamic simulation. Here, the procedure is applied to homogeneous azeotropic distillation, but with appropriate adjustments, it should be applicable to any column.

Holdup Propagation Predicted by Steady-state Drift Flux Models

For actual two phase pipe systems, variations in input flows often occur naturally, or may be imposed intentionally. Changes in holdup (in-situ fluid fraction) caused by such input variation will propagate along the pipe, and may affect overall performance. The current paper describes experimental investigation of holdup propagation in oil–water flow in a vertical pipe. It is shown that larger changes in input holdup profile may either compress or rarefy as they propagate along the pipe. For the cases considered, observed behaviour could be quite accurately predicted using a non-linear, hyperbolic wave propagation relation and a drift flux model, calibrated at steady-state flow conditions. The methodology outlined enables prediction and optimization of processes where the fluid content in a pipeline, or wellbore, is displaced by another, immiscible fluid.

Flow Behavior of a Gas−Liquid−Solid Fluidized Bed in a Self-Circulating Operation through an External Conduit

Flow behavior of liquid and multicomponent mixtures of solid particles in fluidizing columns with an external conduit was investigated for a self-circulating operation by an airlift effect. Experimental and analytical results are presented for circulating rates of liquid and particles and for axial changes in holdups of gas and solid in the column. From good agreement between both results, it was found that a one-dimensional sedimentation-dispersion model and mechanical energy balance equation were successfully applied to predict the axial change in gas and solid holdups as well as the circulating rates of liquid and solid particles in the columns.

Effect of solid particles on gas holdup in flotation columns—II. Investigation of mechanisms of gas holdup reduction in presence of solids

Part I showed that the presence of solids decreased gas holdup under conditions typical of flotation in columns. Four mechanisms which might explain this effect are evaluated here: bubble coalescence, slurry density and viscosity changes, changes in radial gas holdup and flow profiles, and bubble wake effects. The first two cannot explain the holdup decrease but the second two can. It was shown experimentally that solids do not cause bubbles to coalesce in flotation columns. Using the drift flux model, changes in density and viscosity of the slurry due to the presence of solids could not account for the observed reduction in gas holdup. A drift flux analysis for the gas-slurry system suggested both that the holdup and flow were not distributed uniformly and that the bubbles rose more rapidly in the presence of solids. Two gas holdup and flow profiles were postulated which could account for the lower gas holdup. These profiles had an upward flow in the center of the collumn and an annular downward flow near the wall. The bubble wake mechanism postulates that wake stability is increased in the presence of solids due to increased viscosity. This, in turn, increases the probability of in line bubble-bubble interaction where the wake velocity of the leading bubble increases the rise velocity of the trailing bubble. The resulting higher rise velocity reduces the gas holdup. It is proposed that the effect of solids on reducing gas holdup is a combination of an increase in the rise velocity of bubbles due to stabilization of the bubble wake and a change in the holdup and flow profiles from flat to non-uniform.

Axial mixing and segregation of multicomponent coarse particles fluidized by concurrent gas-liquid flow

Multicomponent solid particles were fluidized by upward concurrent flows of air and water in vertical columns of 7 cm diameter and 4.85 m height, and of 15 cm diameter and 2.7 m height. Solid particles used were sieved glass beads (2.2, 3.1 and 4.65 mm) and mixtures thereof. Axial changes in holdups of gas and solids were determined by sectioning the whole column simultaneously with horizontal plates. The solid holdup of coarse particles was more strongly affected by the liquid velocity than was that of fine particles. A one-dimensional sedimentation-dispersion model was applied to describe the axial holdup profile of each solids component. Calculated results were in agreement with experimental ones over an entire column consisting of dense and dilute regions. Parameters used in the calculation were correlated as experimental equations.

Axial segregation of multicomponent solid particles suspended in bubble columns

Multicomponent solid particles were suspended in vertical bubble columns of 7-cm diameter and 4.85-m height and 15-cm diameter and 2.7-m height. Axial changes in holdups of gas and solids in the column were determined by sectioning the column simultaneously with 20 horizontal plates for the 7-cm-diameter column and 11 such plates for the 15-cm-diameter column. Solid particles used were sieved glass beads (118, 243, and 465 μm) and mixtures thereof. A one-dimensional sedimentation-dispersion model was applied to describe the axial holdup profile of each solid component. The parameters used in the model were all correlated with experimental equations based on the results of single-component systems

Segregation of solid particles of two sizes in bubble columns

Binary mixtures of solid particles were fluidized by a two-phase flow of gas and liquid. The changes in holdup of the two components with axial position in the column were determined. The experiments were conducted with three combinations of sieved glass beads (118 and 243 μm; 118 and 465 μm; and 243 and 465 μm diameter) in vertical columns of 7 cm diameter × 4.85 m height and 15 cm diameter × 2.7 m height under batch operation with respect to the solid phase. A sedimentation—dispersion model developed on the basis of the experiments gives a semi-empirical description of the axial distributions of segregation and solid holdup over the whole range of the column.

Power consumption of partially filled twin‐screw extruders

AbstractTwin‐screw extruders are used very effectively, when partially filled, for mixing and surface renewal of high‐viscosity fluids. The rate of energy input, often sufficiently high to be a major design consideration, determines the drive power, the heat input to the fluid, and the cooling requirements. Operating limitations may be fixed by thermal degradation of the material being processed. A simple model for the rate of energy dissipation in twin‐screw extruders predicts that the power input is proportional to the square of the screw speed. Measurements were made of shaft torque and screw speed for polyisobutylene passing through a large twin‐screw extruder having co‐rotating shafts. The experimental procedure avoids the problems of changes in holdup and temperature that accompany changes in screw speed under steady state conditions. The power input was found to be proportional to the screw speed raised to the exponent 1.90. This result was attributed to slightly pseudoplastic behavior of the fluid in the radial clearances.

Use of microwaves in the measurements of frequencies and amplitudes in liquid hold-up fluctuations

A technique based on absorption of microwave radiation by water molecules was developed for the measurement of liquid hold-up in gas-liquid systems, in particular in cocurrent flow of a gas and a water based liquid. The measuring set-up had to be empirically calibrated and the calibration line strongly depended on the mutual position of the radiation conducting waveguides and the tube containing the gas-liquid mixture: under certain circumstances a linear relationship between the amount of transmitted radiation and the value of liquid hold-up was obtained. The advantages of the technique are that a very flat beam of microwaves can be generated thus allowing to measure hold-up in a very narrow slice of the tube and that the device responds instantly to any change in hold-up. The device was then used in connection with a spectrum analyzer to investigate the frequencies and amplitudes of hold-up fiuctuations in upward cocurrent flow of air and water and air and corn sugar solution in a tube 12.9 mm i.d. It was found that the hold-up fluctuations were confined to low frequencies and that there was no particular regularity in their pattern. Only at higher gas and liquid flow rates the frequency-amplitude curves exhibited a peak value which may be associated with the occurrence of disturbance waves. The mean amplitudes of hold-up fluctuations were strongly dependent on the gas and liquid flow rates and for most liquid flow rates went through a maximum in the wavy-annular flow regime.