scholarly journals Comparison of Crushed-Zone Skin Factor for Cased and Perforated Wells Calculated with and without including a Tip-Crushed Zone Effect

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Ekhwaiter Abobaker ◽  
Abadelhalim Elsanoose ◽  
Faisal Khan ◽  
Mohammad Azizur Rahman ◽  
Amer Aborig ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Axial Direction ◽  
Core Sample ◽  
Plane Flow ◽  
Skin Factor ◽  
Lower Productivity ◽  
Horizontal Flows ◽  
Perforated Completions ◽  
Crushed Zone ◽  
Set Up

A number of different factors can affect flow performance in perforated completions, such as perforation density, perforation damage, and tunnel geometry. In perforation damage, any compaction at the perforation tunnels will lead to reduced permeability, more significant pressure drop, and lower productivity of the reservoir. The reduced permeability of the crushed zone around the perforation can be formulated as a crushed-zone skin factor. For reservoir flow, earlier research studies show how crushed (compacted) zones cause heightened resistance in radially converging vertical and horizontal flow entering perforations. However, the effects related to crushed zones on the total skin factor are still a moot point, especially for horizontal flows in perforations. Therefore, the present study will look into the varied effects occurring in the crushed zone in relation to the vertical and horizontal flows. The experimental test was carried out using a geotechnical radial flow set-up to measure the differential pressure in the perforation tunnel with a crushed zone. Computational fluid dynamics (CFD) software was used for simulating pressure gradient in a cylindrical perforation tunnel. The single-phase water was radially injected into the core sample with the same flow boundary conditions in the experimental and numerical procedures. In this work, two crushed zone configuration scenarios were applied in conjunction with different perforation parameters, perforation length, crushed zone radius, and crushed zone permeability. In the initial scenario, the crushed zone is assumed to be located at the perforation tunnel’s side only, while in the second scenario, the crushed zone is assumed to be located at a side and the tip of perforation (a tip-crushed zone). The simulated results indicate a good comparison with regard to the two scenarios’ pressure gradients. Furthermore, the simulations’ comparison reveals another pressure drop caused by the tip crushed zone related to the horizontal or plane flow in the perforations. The differences between the two simulations’ results show that currently available models for estimating the skin factor for vertical perforated completions need to be improved based on which of the two cases is closer to reality. This study has presented a better understanding of crushed zone characteristics by employing a different approach to the composition and shape of the crushed zone and permeability reduction levels for the crushed zone in the axial direction of the perforation.

Analytical treatment of two-dimensional supersonic flow. II. Flow with weak shocks

1956 ◽  
Vol 248 (952) ◽  
pp. 499-515 ◽  
Keyword(s):  
Solution Process ◽  
Wave Interaction ◽  
Analytical Treatment ◽  
Plane Flow ◽  
Flow Equations ◽  
Interaction Regions ◽  
Steady Plane ◽  
Set Up ◽  
Downstream Flow ◽  
Weak Shocks

A scheme of approximate solution is presented for the treatment of shock waves in the steady, plane flow of a perfect gas. It is based on the neglect of any entropy variations produced by the shocks and hence is applicable only when the shocks are weak. The method provides an extension of Friedrichs’s (1948) results for simple waves to wave-interaction regions. By an examination of the solution of the continuous-flow equations in the neighbourhood of a known shock wave it is shown how the downstream flow may be calculated without reference to the particular shock shape (§2). There are certain cases in which this approach fails and they are discussed by means of a typical example in §3.3. Once the downstream flow has been calculated, it is possible to set up general equations for the determination of the shock (§ 2). Examples of the solution of these equations for typical problems are given in §3. In §4 there is a brief discussion of the validity of using homentropic theory and estimates of the errors involved in the solution process are obtained.

scholarly journals Experiments of Ultrasonic Sensing Using FBG Sensors

2011 ◽  
Vol 2-3 ◽  
pp. 148-152
Author(s):  
Wei Wei Shi ◽  
Ting Ting Hu ◽  
Yue Gang Tan
Keyword(s):  
Tunable Laser ◽  
Angular Separation ◽  
Axial Direction ◽  
Laser Source ◽  
Testing System ◽  
Linear Change ◽  
Ultrasonic Signals ◽  
Response Characteristics ◽  
Ultrasonic Sensing ◽  
Set Up

This research aims at investigating the response characteristics of fiber Bragg grating sensors (FBGs) to ultrasonic signals. The testing system was set up with a tunable laser source and the FBGs installed on the surface of an aluminum plate. Then the response characteristics of FBGs were compared, in condition of putting the ultrasonic driving source in the different longitudinal, lateral and angular separation. Measurements were taken by changing the distance between the sensor and the transducer from 60 mm to 200 mm with a step of 20 mm. Then keeping the distance at 100 mm and 200 mm respectively, do the angular experiment with the angle from 0° to 90° by the step of 10°. Experiment results show that FBG can get better signals when the transducer is along its axial direction. When the location of the transducer is changed linearly, no obvious linear change of the signal strength has been found.

Modelling and Experimental Validation of a Controllable Energy Harvester for Pressure Regulation

2019 ◽  
Author(s):  
Youngmok Ko ◽  
Shi Miao Yu ◽  
Amy M. Bilton
Keyword(s):  
Pressure Drop ◽  
Energy Harvester ◽  
Guide Vane ◽  
Electrical Power ◽  
Computational Cost ◽  
Control Valve ◽  
Francis Turbine ◽  
Pressure Regulation ◽  
Cfd Model ◽  
Set Up

Abstract A pico-scale Francis turbine (or energy harvester) was designed, fabricated and tested for pressure regulation and power generation application. The prototype energy harvester contains pivotable guide vanes and a controllable load to change the runner speed. This allows the simultaneous variation of the pressure drop and the output power. A computational fluid dynamics (CFD) model of the turbine was developed in ANSYS CFX 18.1 to evaluate the turbine’s sensitivity to geometric parameters such as the clearance gap size of the guide vane and its modularity. In conjunction to the CFD model, the electric generator’s characteristics were used to predict the turbine performance at varying guide vane angles. The turbine was prototyped and tested using a custom-built experimental set-up. The pico-scale turbine, with a runner diameter of 1.42 inches, was able to output up to 100 W of electrical power at its rated flowrate of 29 GPM. By varying the guide vane angles, the pressure drop and the hydraulic efficiency varied between 3–22 psi and up to 60% respectively. When validated against the experimental results, the CFD model showed a good agreement despite its low computational cost. The energy harvester’s initial characteristics demonstrate its potential as a game changer in the control valve market.

scholarly journals Inflation and rupture of vaginal tissue

2019 ◽  
Vol 9 (4) ◽  
pp. 20190029 ◽  
Author(s):  
Jeffrey A. McGuire ◽  
Christie L. Crandall ◽  
Steven D. Abramowitch ◽  
Raffaella De Vita
Keyword(s):  
Axial Direction ◽  
Image Correlation ◽  
Correlation Technique ◽  
Vaginal Tissue ◽  
Free Extension ◽  
Incorrect Diagnosis ◽  
Failure Properties ◽  
Set Up ◽  
Term Baby ◽  
Hoop Direction

Around 80% of women experience vaginal tears during labour when the diameter of the vagina must increase to allow the passage of a full-term baby. Current techniques for evaluating vaginal tears are qualitative and often lead to an incorrect diagnosis and inadequate treatment, severely compromising the quality of life of women. In order to characterize the failure properties of the vaginal tissue, whole vaginal tracts from rats ( n = 18) were subjected to free-extension inflation tests until rupture using a custom-built experimental set-up. The resulting deformations were measured using the digital image correlation technique. Overall, the strain and changes in curvature in the hoop direction were significantly larger relative to the axial direction. At a failure pressure of 110 ± 23 kPa (mean ± s.d.), the hoop and axial stresses were computed to be 970 ± 340 kPa and 490 ± 170 kPa, respectively. Moreover, at such pressure, the hoop and axial strains were found to be 12.8 ± 4.4 % and 6.4 ± 3.7 % , respectively. Rupture of the vaginal specimens always occurred in the hoop direction by tearing along the axial direction. This knowledge about the rupture properties of the vaginal tissue will be crucial for the development of clinical approaches for preventing and mitigating vaginal tearing and the associated short- and long-term traumatic conditions.

A Study of the Effect of Mixed Cores on the Stability of BWRs

2010 ◽  
Author(s):  
Jose March-Leuba ◽  
Weidong Wang ◽  
Tai L. Huang
Keyword(s):  
Pressure Drop ◽  
Natural Circulation ◽  
Strong Dependence ◽  
Stability Margin ◽  
Fuel Type ◽  
Stability Margins ◽  
Full Power ◽  
Set Up ◽  
The Stability ◽  
Fuel Elements

Cores loaded with a mixture of fuel types are known to reduce stability margins. Mixed fuel cores have become more common as utilities change fuel suppliers, or when fuel vendors upgrade their fuel designs to take advantage of improved thermal and mechanical margins. This paper studies some of the physical processes that reduce the stability of mixed cores. A number of runs have been performed using the LAPUR6 stability code to evaluate the effect on mixed cores on the stability of a typical BWR. To this end, two fuel types have been set up with two different single-phase to two-phase pressure drop ratios by artificially adjusting the spacer and inlet orifice friction coefficients. The flow and pressure drop characteristics of both fuels have been matched at full flow, full power conditions. All manufacturers match the pressure drop of new fuels so that the flow distributions among the new and old fuel elements operating at the same power are approximately constant. The critical power ratio and thermo-mechanical criteria are typically limiting at full power; therefore matching the flow performance at full power maximizes the margin to these criteria. Stability is of concern at low flows, especially at natural circulation, where the thermal-hydraulic conditions are significantly different from full flow and power. Our simulations show that even if two fuel elements are perfectly matched at full flow, the axial void fraction distribution changes significantly when the flow is reduced to natural circulation conditions and the two fuel elements are not fully thermal-hydraulically compatible at the reduced flows. Basically, the two fuel types set up two separate natural circulation lines, and one of the fuel types essentially starves the other from flow. Since stability has such a strong dependence with channel flow, the reactor stability is controlled by the fuel type that has the smaller flow at natural circulation. A counterintuitive result of this study shows that, in general, loading a more stable fuel type into a mixed core has the opposite effect, and the stability margin of that mixed core is lower until the new, more stable fuel becomes dominant. Because of the burnable Gadolinium in most modern BWR fuels, the highest reactivity fuel elements are the once-burned. Loading a more stable fuel type starves the flow of the high-reactivity older fuel, reducing the stability margin.

Pressure-driven radial flow in a Taylor–Couette cell

2010 ◽  
Vol 660 ◽  
pp. 527-537 ◽  
Author(s):  
NILS TILTON ◽  
DENIS MARTINAND ◽  
ERIC SERRE ◽  
RICHARD M. LUEPTOW
Keyword(s):  
Pressure Drop ◽  
Radial Flow ◽  
Outer Cylinder ◽  
Axial Direction ◽  
Generalized Solution ◽  
Transmembrane Pressure ◽  
Flow Through ◽  
Couette Cell ◽  
Pressure Driven Flow ◽  
Pressure Driven

A generalized solution for pressure-driven flow through a permeable rotating inner cylinder in an impermeable concentric outer cylinder, a situation used commercially in rotating filtration, is challenging due to the interdependence between the pressure drop in the axial direction and that across the permeable inner cylinder. Most previous approaches required either an imposed radial velocity at the inner cylinder or radial throughflow with both the inner and outer cylinders being permeable. We provide an analytical solution for rotating Couette–Poiseuille flow with Darcy's law at the inner cylinder by using a small parameter related to the permeability of the inner cylinder. The theory works for suction, injection and even combined suction/injection, when the axial pressure drop in the annulus is such that the transmembrane pressure difference reverses sign along the axial extent of the system. Corresponding numerical simulations for finite-length systems match the theory very well.

Compound transmission principle analysis of eccentric curve-face gear pair with curvilinear-shaped teeth based on tooth contact analysis

2021 ◽  
pp. 095440622110470
Author(s):  
Chao Lin ◽  
Yu Wang ◽  
Yanan Hu ◽  
Yongquan Yu
Keyword(s):  
Axial Direction ◽  
Contact Analysis ◽  
Gear Pair ◽  
Face Gear ◽  
Tooth Contact Analysis ◽  
Tooth Contact ◽  
Contact Points ◽  
Tooth Surfaces ◽  
Set Up ◽  
Curve Face

A new type of compound transmission gear pair was put forward, called eccentric curve-face gear pair with curvilinear-shaped teeth. It could realize reciprocating motion of the gear shaft when the intersecting shafts achieve transferring motion and power through its unique tooth profile. The compound transmission principle of this gear pair was fully established based on the profile-closure process of axial direction and meshing process of the end face. The tooth surfaces of the eccentric curve-face gear and non-circular gear were generated. The contact paths of different teeth were obtained, and the compound transmission principle of eccentric curve-face gear pair with curvilinear-shaped teeth was verified by tooth contact analysis. By analyzing the mechanical characteristics of time-varying contact points, the changing rule of contact force was studied, and the compound transmission principle of the gear pair was further revealed from mechanics. Moreover, the experimental platform for transmission of eccentric curve-face gear pair with curvilinear-shaped teeth was set up to measure the motion law and contact area, and the correctness of the analysis results was verified.

Design for Reliability: Experimental and Numerical Simulation of Cased and Perforated Completions with Standalone Screen

2021 ◽  
pp. 1-27
Author(s):  
Morteza Roostaei ◽  
Mohammad Soroush ◽  
Farshad Mohammadtabar ◽  
Mohammad Mohammadtabar ◽  
Seyed Abolhassan Hosseini ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Cfd Simulation ◽  
Control Method ◽  
Simulation Models ◽  
Cost Effective ◽  
Optimized Design ◽  
Annular Gap ◽  
Sand Control ◽  
Wellbore Pressure ◽  
Perforated Completions

Summary The historical challenges and high failure rate of using standalone screen in cased and perforated wellbores pushed several operators to consider cased-hole gravel packing or frac packing as the preferred completion. Despite the reliability of these options, they are more expensive than a standalone screen completion. In this paper, we employ a combined physical laboratory testing and computational fluid dynamics (CFD) for laboratory scale and field scale to assess the potential use of the standalone screen in completing the cased and perforated wells. The aim is to design a fit-to-purpose sand control method in cased and perforated wells and provide guidelines in perforation strategy and investigate screen and perforation characteristics. More specifically, the simultaneous effect of screen and perforation parameters, near wellbore conditions on pressure distribution and pressure drop are investigated in detail. A common mistake in completion operation is to separately focus on the design of the screen based on the reservoir sand print and design of the perforation. If sand control is deemed to be required, the perforation strategy and design must go hand in hand with sand control design. Several experiments and simulation models were designed to better understand the effect of perforation density, the fill-up of the annular gap between the casing and screen, perforation collapse, and formation and perforation damage on pressure drop. The experiments consisted of a series of step-rate tests to investigate the role of fluid rate on pressure drop and sand production. There is a critical rate at which the sand filling up the annular gap will fluidize. Both test results and CFD simulation scenarios are comparatively capable to establish the relation between wellbore pressure drop and perforation parameters and determine the optimized design. The results of this study highlight the workflow to optimize the standalone screen design for the application in cased and perforated completions. The proper design of standalone screen and perforation parameters allows maintaining cost-effective well productivity. Results of this work could be used for choosing the proper sand control and perforation strategy.

Effects of Formation Damage and High- Velocity Flow on the Productivity of Perforated Horizontal Wells

2005 ◽  
Vol 8 (04) ◽  
pp. 315-324 ◽  
Author(s):  
Yula Tang ◽  
Turhan Yildiz ◽  
Erdal Ozkan ◽  
Mohan G. Kelkar
Keyword(s):  
Pressure Drop ◽  
High Velocity ◽  
Horizontal Wells ◽  
Formation Damage ◽  
Gas Wells ◽  
Skin Factor ◽  
High Velocity Flow ◽  
Additional Pressure ◽  
Velocity Flow ◽  
The Individual

Summary A comprehensive semianalytical model has been built to investigate the effects of drilling and perforating damage and high-velocity flow on the performance of perforated horizontal wells. The model incorporates the additional pressure drop caused by formation damage and high-velocity flow into a semianalytical coupled wellbore/reservoir model. The reservoir model considers the details of flow in the vicinity of the wellbore, including 3Dconvergent flow into individual perforations, flow through the damaged zone around the wellbore and the crushed zone around the perforation tunnels, and non-Darcy flow in the near-wellbore region. The wellbore flow model includes the effect of frictional pressure drop. Both oil and gas wells are considered. The expressions provided in this paper for additional pressure losses caused by perforating damage, drilling damage, and high-velocity flow can be used to optimize perforating parameters and decompose the total skin into its components (perforation pseudoskin, damage skin, and non-Darcy skin). Introduction The performance of oil and gas wells may be influenced by the simultaneous effect of mechanical skin, high-velocity (non-Darcy) skin, and completion pseudoskin factors. The skin factors caused by formation damage and perforating damage constitute the mechanical-skin factor. The extra pressure drop caused by high-velocity flow is known as the rate-dependent or non-Darcy flow factor. Compared to an ideal open hole, the wells with completions and other geometries such as perforations, slotted liner, or partial penetration may experience additional pressure loss or gain. The additional pressure change caused by wellcompletion and geometry is quantified in terms of pseudoskin factor. The combined effects of all the skin factors lead to a total skin factor that maybe estimated from pressure-transient data. The total skin factor, however, is not simply the sum of the individual skin components, and the computation of the individual skin components is not straightforward (the interaction between the individual components of total skin is nonlinear). Many studies have concentrated on the effects of formation damage and high-velocity (non-Darcy) flow on well performance. For perforated vertical wells, McLeod's analytical model has been a widely accepted approximation to account for the additional pressure drop caused by formation damage and high-velocity flow. Karakas and Tariq presented a semianalytical model to predict the pseudoskin and productivity of perforated vertical wells with formation damage. The models suggested by McLeod and Tariq, however, may not work for selectively completed wells in which the flux distribution may be nonuniform. An example of this case is selectively perforated horizontal wells. Tang et al. presented models for horizontal wells completed with slottedliners or perforations. The additional pressure drop in the vicinity of the wellbore because of formation damage, perforating, flow convergence, and high-velocity flow was included in their models in the form of a total-skinterm. The existing horizontal-well models are not capable of explicitly relating the skin factor to the physical parameters controlling the additional pressure drop around the wellbore. In addition, the interplay between the skin and flux distribution and its impact on the productivity of perforated horizontal wells have not been discussed, especially for selectively perforated horizontal wells. Non-Darcy flow effect in perforated horizontal wells is another topic that has not been addressed adequately in the literature. In this study, we present a semianalytical model to predict the productivity of perforated horizontal wells under the influence of formation damage, perforating damage, and high-velocity flow. The nonlinear interaction between the individual skin components is accurately represented in the model. The model is applicable to both single-phase oil and gas wells (the pseudo pressure concept is used to extend the oil-flow model to the gas wells). Using the model, the combined effects of formation damage, the crushed zone around the perforation tunnels, and the high-velocity flow on the horizontal-well performance have been investigated in detail. The completion and damage parameters controlling the well productivity were identified through sensitivity studies.

Numerical Analysis of Inner Flow Field for Disk MRF Brake

2011 ◽  
Vol 181-182 ◽  
pp. 251-256
Author(s):  
Cheng Ye Liu ◽  
Feng Yan Yi ◽  
Ke Jun Jiang
Keyword(s):  
Numerical Analysis ◽  
Flow Field ◽  
Velocity Distribution ◽  
Theoretical Data ◽  
Numerical Data ◽  
Axial Direction ◽  
Analysis Data ◽  
Brake Torque ◽  
Set Up ◽  
Volume Method

According to structure of disk MRF brake computational model of inner flow field for MRF was set up at simplified condition when MRF was regarded as Bingham model. Velocity distribution in inner flow field had been analyzed at different brake velocities and magnetic intensity using finite volume method (FVM), and brake torque and power had also been received at the same condition by integral method. Numerical analysis data were compared with theoretical data. Result showed that velocity distribution of inner flow field was not linear at axial direction, and that brake torque of disk MRF brake was constant approximately, and that numerical data and theoretic data were identical and it can provide reference for design.

Sign in / Sign up

Export Citation Format

Share Document