scholarly journals Effect of Buoyancy and Inertia on Viscoplastic Fluid–Fluid Displacements in a Regular and an Irregular Eccentric Annulus

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
Hans Joakim Skadsem ◽  
Steinar Kragset
Keyword(s):  
Drilling Fluid ◽  
Mass Density ◽  
Three Dimensional ◽  
Density Difference ◽  
Viscoplastic Fluid ◽  
Positive Density ◽  
Displacement Efficiency ◽  
Cement Slurry ◽  
Eccentric Annulus ◽  
Narrow Side

Abstract Casing strings and liners are important subsurface structural components in petroleum and in geothermal wells. After the casing string has been run in hole, it is cemented to the formation by pumping a sequence of spacer fluids and cement slurry into the annulus outside the string. Spacer fluids are usually pumped ahead of the cement slurry to displace the drilling fluid from the annulus that is to be cemented and thereby avoid contamination of the cement slurry. Fluid displacements are governed by inertia, buoyancy, and viscosity effects, in addition to being strongly influenced by the annular geometry. Poor centralization of the casing or irregularities such as washouts can influence the displacement flows both locally and over long axial distances. We present three-dimensional numerical simulations of the displacement flow involving two viscoplastic fluids in the vicinity of a symmetric local hole enlargement. We focus on laminar flow regimes in the regular part of the annulus and investigate how the volumetric flowrate and the mass density difference between the fluids affect the displacement efficiency in the regular and the irregular parts of the annulus. This study considers viscoplastic displacement flows in a near-vertical, irregular annulus and is an extension of a previous publication that focused on a near-horizontal annulus. We contextualize our simulations by comparison to industry guidelines for effective and steady laminar displacements in the regular, near-vertical annulus. Here, eccentricity favors flow in the wider sector of the annulus, while a positive density difference between the fluids generates secondary, azimuthal flow toward the narrow side of the annulus. In the enlarged and irregular section, both the axial bulk velocity and casing eccentricity decrease sharply and buoyancy becomes more pronounced compared to in the regular annulus. We quantify and discuss the effects of local hole enlargements on displacement efficiencies. Simulations of cementing flows can aid in optimizing fluid properties and pump rates, including when the wellbore has suspected or confirmed zones of irregular geometries.

Effect of Buoyancy and Inertia on Viscoplastic Fluid-Fluid Displacement in an Eccentric Annulus With an Irregular Section: Part 2 — Displacements in Vertical Annulus

2019 ◽  
Author(s):  
Hans Joakim Skadsem ◽  
Steinar Kragset
Keyword(s):  
Drilling Fluid ◽  
Mass Density ◽  
Volumetric Flow Rate ◽  
Density Difference ◽  
Viscoplastic Fluid ◽  
Positive Density ◽  
Displacement Efficiency ◽  
Cement Slurry ◽  
Narrow Side ◽  
Vertical Annulus

Abstract Casing strings and liners are important subsurface structural components in petroleum and in geothermal wells. After the casing string has been run in hole, it is cemented to the formation by pumping a sequence of spacer fluids and cement slurry into the annulus outside the string. Spacer fluids are usually pumped ahead of the cement slurry in order to displace the drilling fluid from the annulus that is to be cemented, and thereby avoid contamination of the cement slurry. Fluid displacements are governed by inertia, buoyancy and viscosity effects, in addition to being strongly influenced by the annular geometry. Poor centralization of the casing or irregularities such as washouts can influence the displacement flows both locally and over long axial distances. We present three dimensional numerical simulations of the displacement flow involving two viscoplastic fluids in the vicinity of a symmetric local hole enlargement. We focus on laminar flow regimes in the regular part of the annulus and investigate how the volumetric flow rate and the mass density difference between the fluids affect the displacement efficiency in the regular and the irregular parts of the annulus. This study considers viscoplastic displacement flows in a near-vertical, irregular annulus and is an extension of a previous publication that focused on a near-horizontal annulus. We contextualize our simulations by comparison to industry guidelines for effective and steady laminar displacements in the regular, near-vertical annulus. Here, eccentricity favors flow in the wider sector of the annulus while a positive density difference between the fluids generates secondary, azimuthal flow toward the narrow side of the annulus. In the enlarged and irregular section, both the axial bulk velocity and casing eccentricity decrease sharply and buoyancy becomes more pronounced compared to in the regular annulus. We quantify and discuss the effects of local hole enlargements on displacement efficiencies. Simulations of cementing flows can aid in optimizing fluid properties and pump rates, including when the wellbore has suspected or confirmed zones of irregular geometries.

Effect of Buoyancy and Inertia on Viscoplastic Fluid: Fluid Displacement in an Inclined Eccentric Annulus With an Irregular Section

2018 ◽  
Author(s):  
Steinar Kragset ◽  
Hans Joakim Skadsem
Keyword(s):  
Drilling Fluid ◽  
Mass Density ◽  
Density Difference ◽  
Regular Part ◽  
Viscoplastic Fluid ◽  
Drilling Fluids ◽  
Displacement Efficiency ◽  
Cement Slurry ◽  
Horizontal Section ◽  
Primary Cementing

Primary cementing is an important well construction process that should establish well control barriers and zonal isolation. Critical for primary cementing is the successful displacement of drilling fluid from the annulus between casing and formation by a sequence of spacer fluids and cement slurry. Failure to displace the drilling fluid may compromise the annular cement integrity and result in contaminated cement with degraded mechanical properties. Issues such as eccentricity, washouts and other geometric irregularities in the wellbore can complicate the displacement processes, and their effect on the quality of the cementing job and the final result is linked to uncertainty. We present numerical simulations of the displacement process between two viscoplastic fluids in the vicinity of a symmetric local hole enlargement. The study is limited to laminar flow regimes in the regular part of the annulus, and we focus on a near-horizontal section with significant eccentricity and small annular clearance. We vary the volumetric flow rate and the mass density difference between the fluids, and study how the irregularity affects the displacement efficiency and the presence of residual fluid in and after the irregularity. In the regular part of the geometry, eccentricity favors flow in the wider, upper part of the annulus, while density difference leads to azimuthal flow from the top to the low side of the annulus. The results support the assumption that increasing the mass density difference improves the displacement efficiency. In the laminar regime, lower flow rates can be favorable over higher ones in terms of efficiency measured as a function of volume that is pumped into the enlarged section. Displacement of drilling fluids for primary cementing is a rich flow problem involving different non-Newtonian fluids and possibly irregular geometry. Simulations of the displacement process can aid in optimizing fluid properties and injection rates for primary cementing operations, and assist cement log interpretation after the operation.

Experimental Investigation of Wellbore Fluid Displacement in Concentric and Eccentric Annulus

2017 ◽  
Author(s):  
Jan David Ytrehus ◽  
Bjørnar Lund ◽  
Ali Taghipour ◽  
Shreyansh Divyankar ◽  
Arild Saasen
Keyword(s):  
Test Section ◽  
Drilling Fluid ◽  
Realistic Model ◽  
Outer Diameter ◽  
Cement Slurry ◽  
Fluid Displacement ◽  
Eccentric Annulus ◽  
Production Phase ◽  
Concentric Annulus ◽  
Displacement Front

One of the most critical operations during well construction is the cementing procedure. Due to the curing nature of the cement slurry there will be only one opportunity to cement the well properly. Although one for top hole cases can fill cement in from the top in a remedial operation, this possibility cannot fully compensate for a non-optimal initial cement job. Furthermore, it cannot be applied to other well sections. In those sections, complex squeeze cementing operations may be necessary. Consequences of improper annular cement can be leakage during production phase and extensive costs when the well is to be plugged for abandonment after the production phase. To ensure that the risk of poor cement is minimised it is important to use the best procedures to place the cement properly. To be able to select the optimum procedures, it is necessary to improve the understanding of the displacement in the wellbore annulus. All wells will be cemented in several sections. Findings and improvements that can reduce risk of poor cementing results are thus highly relevant for a large number of operations every year. The article is based on analysing experimental results that illustrates a drilling fluid being displaced by a cement slurry. These fluids are represented by realistic model fluids and circulated through a transparent annular section. The geometry used is a 6,5″outer diameter with an inner string of 5″that also can rotate. The selected pipe sizes may normally be found in the lower parts of a well and often in deviated sections where the inner pipe cannot be assumed concentric at all times. Both concentric and eccentric inner pipe positions have therefore been selected. The test section was run both in horizontal and in inclined position. The test section was 10 meters long and instrumented with conductivity probes in an array around the perimeter at 4 separate positions along the pipe. Together with cameras along the test section the fluid interphases was observed along the test section. Results presented in the article show that inner string rotation provides a steeper displacement front, On the other hand such rotation will also cause more mixing at the interphase. Results also show that the displacement front in a concentric annulus is significantly affected by gravity. While for an eccentric annulus, with the low side at the bottom, the narrow gap is poorly displaced when realistic fluids are applied. It was also observed that the displacement front in concentric annulus was more stable when the test section was inclined than in horizontal position.

Successful Off Bottom Cementation of a Highly Deviated 4 ½ in Production Liner in UAE

2021 ◽  
Author(s):  
Ahmedagha Hamidzada ◽  
Ahmed Rashed Alaleeli ◽  
Azza El Hassan ◽  
Fatima Bin Tarsh ◽  
Islam Abdelkarim
Keyword(s):  
Drilling Fluid ◽  
High Viscosity ◽  
High Yield ◽  
Cement Slurry ◽  
Engineering Approach ◽  
Main Challenge ◽  
Narrow Side ◽  
Fluid Properties ◽  
Zonal Isolation ◽  
Cement Integrity

Abstract Cementing a highly deviated production liner is associated with cement placement challenge that can compromise zonal isolation. A major operator in UAE, was facing a challenge to cement 4 ½ in slim production liner set at + 5000 ft off-bottom. The corresponding 6 in. section was drilled with a relatively high mud weight in the range of 12 to 13 PPG. One of the main challenge was the risk of solids settling on the low side of the wellbore, making mud displacement difficult to achieve while cementing. Additionally, cementing off-bottom without an ECP in a highly deviated wellbore with multiple exposed production zones, further increased cement placement complexity. A holistic engineering approach was integrated to ensure successful zonal isolation. Wellbore parameters and fluid properties were critically evaluated. To overcome off-bottom cementing and prevent slurry fallback risks, a weighted high viscosity pill with high yield point was placed as a temporary basement to support the cement column and isolate the reservoir during 4 ½ in liner job. After placement of the pill, the wellbore was observed for flow checks to ensure stable downhole conditions prior to displacing the drilling fluid across the liner interval to brine within the same density. A centralization program was implemented to achieve more than 70% stand-off which required a minimum centralization pattern of two rigid centralizers per joint which helped minimize the presence of mud channels on the narrow side. Effective mud removal was ensured through implementation of a spacer train in front of the cement. The first spacer was pumped with same mud density to reduce ECD followed by another advanced low invasion loss circulation spacer to mitigate losses as well as provide a sustained downhole rheology. A resilient, expandable and gas tight cement slurry, was selected to target long-term zonal isolation. Multiple hydraulic simulations were performed to optimize ECDs and ensure safe margins during placement A CFD (computational fluid dynamics) model was utilized to simulate hydraulics, expected mud removal and fluids inter-mixing especially during liner rotation. In addition, the model simulated high-calculated torques based on flow restrictions through liner hanger assembly. Lack of mechanical liner movement was compensated by additional pre-job circulation to fully condition the wellbore. The job was executed with no losses during cementing, and spacer and cement returns were received on the surface during reverse out. Utilizing the best engineering approach, practices, and techniques from this job is implemented in the future wells as the production of the well is directly affected by the cement quality. Post job cement integrity evaluation via a cement bond log confirmed excellent bonding of cement to the liner and reservoirs across the entire open-hole interval.

Image formation analysis of thick biological specimens using three-dimensional power-spectra of through focus series

1994 ◽  
Vol 52 ◽  
pp. 124-125
Author(s):  
Karen F. Han
Keyword(s):  
Inelastic Scattering ◽  
Imaging Techniques ◽  
Mass Density ◽  
Relative Proportion ◽  
Three Dimensional ◽  
Power Spectra ◽  
Image Formation ◽  
Energy Filtering ◽  
Ewald Sphere ◽  
Nonlinear Imaging

The primary focus in our laboratory is the study of higher order chromatin structure using three dimensional electron microscope tomography. Three dimensional tomography involves the deconstruction of an object by combining multiple projection views of the object at different tilt angles, image intensities are not always accurate representations of the projected object mass density, due to the effects of electron-specimen interactions and microscope lens aberrations. Therefore, an understanding of the mechanism of image formation is important for interpreting the images. The image formation for thick biological specimens has been analyzed by using both energy filtering and Ewald sphere constructions. Surprisingly, there is a significant amount of coherent transfer for our thick specimens. The relative amount of coherent transfer is correlated with the relative proportion of elastically scattered electrons using electron energy loss spectoscopy and imaging techniques.Electron-specimen interactions include single and multiple, elastic and inelastic scattering. Multiple and inelastic scattering events give rise to nonlinear imaging effects which complicates the interpretation of collected images.

Solidifying Mud Cake to Improve Cementing Quality of Shale Gas Well: A Case Study

2015 ◽  
Vol 8 (1) ◽  
pp. 149-154 ◽  
Author(s):  
Jun Gu ◽  
Ju Huang ◽  
Su Zhang ◽  
Xinzhong Hu ◽  
Hangxiang Gao ◽  
...  
Keyword(s):  
Shale Gas ◽  
Calcium Silicate Hydrate ◽  
Drilling Fluid ◽  
Cement Slurry ◽  
Gas Well ◽  
Safety Requirements ◽  
Mud Cake ◽  
Gas Bearing

The purpose of this study is to improve the cementing quality of shale gas well by mud cake solidification, as well as to provide the better annular isolation for its hydraulic fracturing development. Based on the self-established experimental method and API RP 10, the effects of mud cake solidifiers on the shear strength at cement-interlayer interface (SSCFI) were evaluated. After curing for 3, 7, 15 and 30 days, SSCFI was remarkably improved by 629.03%, 222.37%, 241.43% and 273.33%, respectively, compared with the original technology. Moreover, the compatibility among the mud cake solidifier, cement slurry, drilling fluid and prepad fluid meets the safety requirements for cementing operation. An application example in a shale gas well (Yuanye HF-1) was also presented. The high quality ratio of cementing quality is 93.49% of the whole well section, while the unqualified ratio of adjacent well (Yuanba 9) is 84.46%. Moreover, the cementing quality of six gas-bearing reservoirs is high. This paper also discussed the mechanism of mud cake solidification. The reactions among H3AlO42- and H3SiO4- from alkali-dissolved reaction, Na+ and H3SiO4- in the mud cake solidifiers, and Ca2+ and OH- from cement slurry form the natrolite and calcium silicate hydrate (C-S-H) with different silicate-calcium ratio. Based on these, SSCFI and cementing quality were improved.

Ice-Phase Precipitation

2017 ◽  
Vol 58 ◽  
pp. 6.1-6.36 ◽  
Author(s):  
I. Gultepe ◽  
A. J. Heymsfield ◽  
P. R. Field ◽  
D. Axisa
Keyword(s):  
Collection Efficiency ◽  
Numerical Models ◽  
Mass Density ◽  
Three Dimensional ◽  
Phase Precipitation ◽  
Microphysical Parameters ◽  
Mass Size ◽  
Ice Water ◽  
Ice Phase

AbstractIce-phase precipitation occurs at Earth’s surface and may include various types of pristine crystals, rimed crystals, freezing droplets, secondary crystals, aggregates, graupel, hail, or combinations of any of these. Formation of ice-phase precipitation is directly related to environmental and cloud meteorological parameters that include available moisture, temperature, and three-dimensional wind speed and turbulence, as well as processes related to nucleation, cooling rate, and microphysics. Cloud microphysical parameters in the numerical models are resolved based on various processes such as nucleation, mixing, collision and coalescence, accretion, riming, secondary ice particle generation, turbulence, and cooling processes. These processes are usually parameterized based on assumed particle size distributions and ice crystal microphysical parameters such as mass, size, and number and mass density. Microphysical algorithms in the numerical models are developed based on their need for applications. Observations of ice-phase precipitation are performed using in situ and remote sensing platforms, including radars and satellite-based systems. Because of the low density of snow particles with small ice water content, their measurements and predictions at the surface can include large uncertainties. Wind and turbulence affecting collection efficiency of the sensors, calibration issues, and sensitivity of ground-based in situ observations of snow are important challenges to assessing the snow precipitation. This chapter’s goals are to provide an overview for accurately measuring and predicting ice-phase precipitation. The processes within and below cloud that affect falling snow, as well as the known sources of error that affect understanding and prediction of these processes, are discussed.

A Study of Downhole Drillable Pulsing Cementing Device with Low Frequency Self-Excited Hydraulic Oscillation and its Field Application

2012 ◽  
Vol 450-451 ◽  
pp. 1536-1539
Author(s):  
Cui Ping Nie ◽  
Deng Sheng Ye
Keyword(s):  
Setting Time ◽  
Low Frequency ◽  
Field Application ◽  
Displacement Efficiency ◽  
Cement Slurry ◽  
Gas Reservoirs ◽  
Gas Field ◽  
Gas Well ◽  
Hydraulic Oscillation ◽  
Injection Technology

Abstract: Usually we pay more attention on how to improve gas well cementing quality in engineering design and field operations, and there are so many studies on cement agents but few researches on cement slurry injection technology. The field practice proved that conventional cementing technology can not ensure the cementing quality especially in gas well and some abnormal pressure wells. Most of the study is concentrated on cement agents and some cementing aspects such as wellbore condition, casing centralization etc. All the factors analysis on cementing quality has pointed out that a combination of good agents and suitable measurements can improve cementing quality effectively. The essential factor in cementing is to enhance the displacement efficiency, but normal hole condition and casing centralization are the fundamental for cementing only. Pulsing cementing is the technology that it can improve the displacement efficiency especially in reservoir well interval, also it can shorten the period from initial to ultimate setting time for cement slurry or improve thickening characteristics, and then to inhibit the potential gas or water channeling. Based on systematically research, aiming at improving in 7″ liner cementing, where there are multi gas reservoirs in long interval in SiChuan special gas field, well was completed with upper 7″ liner and down lower 5″ liner, poor cementing bonding before this time. So we stressed on the study of a downhole low frequency self-excited hydraulic oscillation pulsing cementing drillable device and its application, its successful field utilization proved that it is an innovative tool, and it can improve cementing quality obviously.

scholarly journals Measuring the Autocorrelation Function of Nanoscale Three-Dimensional Density Distribution in Individual Cells Using Scanning Transmission Electron Microscopy, Atomic Force Microscopy, and a New Deconvolution Algorithm

2017 ◽  
Vol 23 (3) ◽  
pp. 661-667 ◽  
Author(s):  
Yue Li ◽  
Di Zhang ◽  
Ilker Capoglu ◽  
Karl A. Hujsak ◽  
Dhwanil Damania ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Density Distribution ◽  
Scanning Transmission Electron Microscopy ◽  
Mass Density ◽  
Three Dimensional ◽  
Force Microscopy ◽  
Statistical Measures ◽  
Atomic Force ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractEssentially all biological processes are highly dependent on the nanoscale architecture of the cellular components where these processes take place. Statistical measures, such as the autocorrelation function (ACF) of the three-dimensional (3D) mass–density distribution, are widely used to characterize cellular nanostructure. However, conventional methods of reconstruction of the deterministic 3D mass–density distribution, from which these statistical measures can be calculated, have been inadequate for thick biological structures, such as whole cells, due to the conflict between the need for nanoscale resolution and its inverse relationship with thickness after conventional tomographic reconstruction. To tackle the problem, we have developed a robust method to calculate the ACF of the 3D mass–density distribution without tomography. Assuming the biological mass distribution is isotropic, our method allows for accurate statistical characterization of the 3D mass–density distribution by ACF with two data sets: a single projection image by scanning transmission electron microscopy and a thickness map by atomic force microscopy. Here we present validation of the ACF reconstruction algorithm, as well as its application to calculate the statistics of the 3D distribution of mass–density in a region containing the nucleus of an entire mammalian cell. This method may provide important insights into architectural changes that accompany cellular processes.

The Research and Application of Cementing Isolation Technology in High Porosity and Permeability of Developed Clastic Rock Reservoir in Tarim Basin

2021 ◽  
Author(s):  
Hongtao Liu ◽  
Zhengqing Ai ◽  
Jingcheng Zhang ◽  
Zhongtao Yuan ◽  
Jianguo Zeng ◽  
...  
Keyword(s):  
Drilling Fluid ◽  
Water Layer ◽  
High Porosity ◽  
Self Healing ◽  
Cement Slurry ◽  
Clastic Rock ◽  
Pump Rate ◽  
Porosity And Permeability ◽  
Zonal Isolation ◽  
High Pump

Abstract The average porosity and permeability in the developed clastic rock reservoir in Tarim oilfield in China is 22.16% and 689.85×10-3 μm2. The isolation layer thickness between water layer and oil layer is less than 2 meters. The pressure of oil layer is 0.99 g/cm3, and the pressure of bottom water layer is 1.22 g/cm3, the pressure difference between them is as bigger as 12 to 23 MPa. It is difficult to achieve the layer isolation between the water layer and oil layer. To solve the zonal isolation difficulty and reduce permeable loss risk in clastic reservoir with high porosity and permeability, matrix anti-invasion additive, self-innovate plugging ability material of slurry, self-healing slurry, open-hole packer outside the casing, design and control technology of cement slurry performance, optimizing casing centralizer location technology and displacement with high pump rate has been developed and successfully applied. The results show that: First, the additive with physical and chemical crosslinking structure matrix anti-invasion is developed. The additive has the characteristics of anti-dilution, low thixotropy, low water loss and short transition, and can seal the water layer quickly. Second, the plugging material in the slurry has a better plugging performance and could reduce the permeability of artificial core by 70-80% in the testing evaluation. Third, the self-healing cement slurry system can quickly seal the fracture and prevent the fluid from flowing, and can ensuring the long-term effective sealing of the reservoir. Fourth, By strict control of the thickening time (operation time) and consistency (20-25 Bc), the cement slurry can realize zonal isolation quickly, which has achieved the purpose of quickly sealing off the water layer and reduced the risk of permeable loss. And the casing centralizers are used to ensure that the standoff ratio of oil and water layer is above 67%. The displacement with high pump rate (2 m3/min, to ensure the annular return velocity more than 1.2 m/s) can efficiently clean the wellbore by diluting the drilling fluid and washing the mud cake, and can improve the displacement efficiency. The cementing technology has been successfully applied in 100 wells in Tarim Oilfield. The qualification rate and high quality rate is 87.9% and 69% in 2019, and achieve zone isolation. No water has been produced after the oil testing and the water content has decreased to 7% after production. With the cementing technology, we have improved zonal isolation, increased the crude oil production and increased the benefit of oil.

Sign in / Sign up

Export Citation Format

Share Document