scholarly journals Effect of Isolated Fracture on the Carbonate Acidizing Process

2021 ◽  
Vol 9 ◽  
Author(s):  
Cunqi Jia ◽  
Tao Huang ◽  
Jun Yao ◽  
Hongchuan Xing ◽  
Haiyang Zhang
Keyword(s):  
Core Sample ◽  
Carbonate Reservoirs ◽  
Scale Model ◽  
Target System ◽  
Physical Parameters ◽  
Fracture Geometry ◽  
The Core ◽  
Isolated Fracture ◽  
Carbonate Acidizing ◽  
Rotation Groups

Carbonate reservoirs are one of the most important fossil fuel sources, and the acidizing stimulation is a practical technique for improving the recovery of carbonate reservoirs. In this study, the improved two-scale continuum model, including the representative elementary volume (REV) scale model and the upscaling model, is used to study the acidizing process with an isolated fracture. Based on this model, a comprehensive discussion is presented to study the effect of the physical parameters of the isolated fracture on the acidizing results and dissolution images, including the isolated fracture geometry, location, and morphology. Results show that the isolated fracture system is still the target system for the acidizing stimulation. The isolated fracture provides a limited contribution to the core porosity. The permeability of the core sample with fracture can be obviously increased only when the fracture penetrates through the whole sample. The existence of the isolated fracture reduces the consumption of acid solution to achieve a breakthrough. The acidizing curve is sensitive to the change of the length, aperture, and position of the isolated fracture. The acidizing curve difference corresponding to different rotation angles has not changed significantly for clockwise rotation and anticlockwise rotation groups.

scholarly journals CO2-brine injectivity tests in high co2 content carbonate field, sarawak basin, offshore east Malaysia

2019 ◽  
Vol 89 ◽  
pp. 04005 ◽  
Author(s):  
A Giwelli ◽  
MZ Kashim ◽  
MB Clennell ◽  
L Esteban ◽  
R Noble ◽  
...  
Keyword(s):  
Packed Column ◽  
Core Sample ◽  
Chemical Analyses ◽  
Core Flooding ◽  
Flow Rates ◽  
X Ray ◽  
The Core ◽  
Reservoir Conditions ◽  
Post Test ◽  
Porosity And Permeability

We conducted relatively long duration core-flooding tests on three representative core samples under reservoir conditions to quantify the potential impact of flow rates on fines production/permeability change. Supercritical CO2 was injected cyclically with incremental increases in flow rate (2─14 ml/min) with live brine until a total of 7 cycles were completed. To avoid unwanted fluid-rock reaction when live brine was injected into the sample, and to mimic the in-situ geochemical conditions of the reservoir, a packed column was installed on the inflow accumulator line to pre-equilibrate the fluid before entering the core sample. The change in the gas porosity and permeability of the tested plug samples due to different mechanisms (dissolution and/or precipitation) that may occur during scCO2/live brine injection was investigated. Nuclear magnetic resonance (NMR) T2 determination, X-ray CT scans and chemical analyses of the produced brine were also conducted. Results of pre- and post-test analyses (poroperm, NMR, X-ray CT) showed no clear evidence of formation damage even after long testing cycles and only minor or no dissolution (after large injected pore volumes (PVs) ~ 200). The critical flow rates (if there is one) were higher than the maximum rates applied. Chemical analyses of the core effluent showed that the rock samples for which a pre-column was installed do not experience carbonate dissolution.

scholarly journals Moisture Absorption Effects on the Mechanical Properties of Sandwich Biocomposites with Cork Core and Flax/PLA Face Sheets

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7295
Author(s):  
Hom Nath Dhakal ◽  
Chulin Jiang ◽  
Moumita Sit ◽  
Zhongyi Zhang ◽  
Moussa Khalfallah ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Failure Modes ◽  
Moisture Absorption ◽  
Mechanical Performance ◽  
Core Sample ◽  
Environmental Benefits ◽  
Matrix Cracking ◽  
Core Material ◽  
Poly Lactic Acid ◽  
The Core

The aim of this study was to evaluate the moisture absorption behaviour and its influence on the mechanical properties of newly developed sandwich biocomposites with flax fibre-reinforced poly-lactic acid (PLA) face sheets and soft cork as the core material. Three different types of sandwich biocomposite laminates comprised of different layup configurations, namely, non-woven flax/PLA (Sample A), non-woven flax/PLA and cork as core (Sample B) and non-woven flax/paper backing/PLA, cork as core (Sample C), were fabricated. In order to evaluate the influence of moisture ingress on the mechanical properties, the biocomposites were immersed in seawater for a period of 1200 h. The biocomposites (both dry and water immersed) were then subjected to tensile, flexural and low-velocity falling weight impact tests. It was observed from the experimental results that the moisture uptake significantly influenced the mechanical properties of the biocomposites. The presence of the cork and paper in sample C made it more susceptible to water absorption, reaching a value of 34.33%. The presence of cork in the core also has a considerable effect on the mechanical, as well as energy dissipation, behaviours. The results of sample A exhibited improved mechanical performance in both dry and wet conditions compared to samples B and C. Sample A exhibits 32.6% more tensile strength and 81.4% more flexural strength in dry conditions than that in sample C. The scanning electron microscopy (SEM) and X-ray micro-CT images revealed that the failure modes observed are a combination of matrix cracking, core crushing and face core debonding. The results from this study suggest that flax/PLA sandwich biocomposites can be used in various lightweight applications with improved environmental benefits.

Modeling Acid Fracturing Treatments with Multi-Stage Alternating Injection of Pad and Acid Fluids

2021 ◽  
Author(s):  
Rencheng Dong ◽  
Mary F. Wheeler ◽  
Hang Su ◽  
Kang Ma
Keyword(s):  
Viscous Fingering ◽  
High Viscosity ◽  
Carbonate Reservoirs ◽  
Acid Etching ◽  
Fracture Geometry ◽  
Fracture Conductivity ◽  
Acid Fracturing ◽  
Fracture Surfaces ◽  
Low Viscosity ◽  
Multi Stage

Abstract Acid fracturing technique is widely applied to stimulate the productivity of carbonate reservoirs. The acid-fracture conductivity is created by non-uniform acid etching on fracture surfaces. Heterogeneous mineral distribution of carbonate reservoirs can lead to non-uniform acid etching during acid fracturing treatments. In addition, the non-uniform acid etching can be enhanced by the viscous fingering mechanism. For low-perm carbonate reservoirs, by multi-stage alternating injection of a low-viscosity acid and a high-viscosity polymer pad fluid during acid fracturing, the acid tends to form viscous fingers and etch fracture surfaces non-uniformly. To accurately predict the acid-fracture conductivity, this paper developed a 3D acid fracturing model to compute the rough acid fracture geometry induced by multi-stage alternating injection of pad and acid fluids. Based on the developed numerical simulator, we investigated the effects of viscous fingering, perforation design and stage period on the acid etching process. Compared with single-stage acid injection, multi-stage alternating injection of pad and acid fluids leads to narrower and longer acid-etched channels.

scholarly journals Seasonal dynamics of Daphnia laevisBirge, 1878 ephippia in a tropical lake with a description of a new methodology for in situ evaluation

2014 ◽  
Vol 74 (3) ◽  
pp. 642-648 ◽  
Author(s):  
LPM Brandão ◽  
DGF Pujoni ◽  
PM Maia-Barbosa
Keyword(s):  
Water Column ◽  
Seasonal Dynamics ◽  
Thermal Stratification ◽  
Core Sample ◽  
Hatching Rate ◽  
The Core ◽  
Significant Difference ◽  
Chi Squared ◽  
Hatching Rates

The effect of dormancy in zooplankton populations is still unknown, largely because of the lack of methods to estimate hatching and production of the dormant stages. This study aimed to compare the production and hatching rates of ephippia of Daphnia laevis between thermal stratification and mixing periods in Jacaré Lake (Middle Rio Doce, Minas Gerais, Brazil). For this, we collected ephippia on the sediment with core sampler and we created a device called the “Ephippial Collector”. There was a significant difference in ephippia hatching in situ between stratification and mixing periods (Pearson's Chi-squared test p <0.001), being higher in the second one. Significant differences in the hatching rates between periods was observed in the laboratory only for ephippia collected with Ephippial Collectors (Pearson's Chi-squared test p <0.001), being higher during the mixing period (∼8%). The core sample allows the collection of a certain fraction of the sediment that may contain a mixture of ephippia produced in different periods, i.e., may contain old and not viable ephippia, which masks the hatching rate. Thus, seasonality in hatching rates of ephippia was reported only by Ephippial Collectors. The higher hatching rate observed during the mixing period in the lake suggests that individuals hatched from ephippia may contribute to the increase in the population of D. laevis in the water column at this time.

A physically motivated core definition applied to dust emission observations of the Pipe nebula

2018 ◽  
Vol 14 (S345) ◽  
pp. 259-260
Author(s):  
Birgit Hasenberger ◽  
João Alves
Keyword(s):  
Star Formation ◽  
Formation Process ◽  
Molecular Clouds ◽  
Dust Emission ◽  
Core Sample ◽  
Critical Stage ◽  
The Core ◽  
Dense Cores ◽  
A New Technique ◽  
Cloud Medium

AbstractDense cores represent a critical stage in the star-formation process, but are not physically well-defined entities. We present a new technique to define core boundaries in observations of molecular clouds based on the physical properties of the cloud medium. Applying this technique to regions in the Pipe nebula, we find that our core boundaries differ from previous analyses, with potentially crucial implications for the statistical properties of the core sample.

scholarly journals Core Metabolism Shifts during Growth on Methanol versus Methane in the Methanotroph Methylomicrobium buryatense 5GB1

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Yanfen Fu ◽  
Lian He ◽  
Jennifer Reeve ◽  
David A. C. Beck ◽  
Mary E. Lidstrom
Keyword(s):  
Flux Balance Analysis ◽  
Metabolic Pathways ◽  
Scale Model ◽  
Obligate Methylotroph ◽  
Content Type ◽  
Advantages And Disadvantages ◽  
The Core ◽  
Flux Balance ◽  
Balance Analysis ◽  
Core Metabolism

ABSTRACT Methylomicrobium buryatense 5GB1 is an obligate methylotroph which grows on methane or methanol with similar growth rates. It has long been assumed that the core metabolic pathways must be similar on the two substrates, but recent studies of methane metabolism in this bacterium suggest that growth on methanol might have significant differences from growth on methane. In this study, both a targeted metabolomics approach and a 13C tracer approach were taken to understand core carbon metabolism in M. buryatense 5GB1 during growth on methanol and to determine whether such differences occur. Our results suggest a systematic shift of active core metabolism in which increased flux occurred through both the Entner-Doudoroff (ED) pathway and the partial serine cycle, while the tricarboxylic acid (TCA) cycle was incomplete, in contrast to growth on methane. Using the experimental results as constraints, we applied flux balance analysis to determine the metabolic flux phenotype of M. buryatense 5GB1 growing on methanol, and the results are consistent with predictions based on ATP and NADH changes. Transcriptomics analysis suggested that the changes in fluxes and metabolite levels represented results of posttranscriptional regulation. The combination of flux balance analysis of the genome-scale model and the flux ratio from 13C data changed the solution space for a better prediction of cell behavior and demonstrated the significant differences in physiology between growth on methane and growth on methanol. IMPORTANCE One-carbon compounds such as methane and methanol are of increasing interest as sustainable substrates for biological production of fuels and industrial chemicals. The bacteria that carry out these conversions have been studied for many decades, but gaps exist in our knowledge of their metabolic pathways. One such gap is the difference between growth on methane and growth on methanol. Understanding such metabolism is important, since each has advantages and disadvantages as a feedstock for production of chemicals and fuels. The significance of our research is in the demonstration that the metabolic network is substantially altered in each case and in the delineation of these changes. The resulting new insights into the core metabolism of this bacterium now provide an improved basis for future strain design.

Magnetic properties of a bi-fullerene-like structure, X60-Y60, with RKKY interactions in the Blume–Capel model

2018 ◽  
Vol 32 (04) ◽  
pp. 1850031 ◽  
Author(s):  
T. Sahdane ◽  
A. Mhirech ◽  
L. Bahmad ◽  
B. Kabouchi
Keyword(s):  
Monte Carlo ◽  
Magnetic Properties ◽  
Physical Parameters ◽  
Nano Particle ◽  
Interaction Type ◽  
The Core ◽  
Spherical Surfaces ◽  
Metropolis Monte Carlo

In this paper, we study the influence of the physical parameters on the thermal and magnetic properties of a nano-particle of bi-fullerene-like structure X[Formula: see text]-Y[Formula: see text] separated by nonmagnetic spherical surfaces, using the Metropolis Monte Carlo (MC) simulations. The coupling between the two spheres containing the spins [Formula: see text] = 3/2 and the spins S = 7/2 belongs to the core and shell, respectively. This study is based on the RKKY (Ruderman–Kittel–Kasuya–Yoshida) interaction type. To complete this work, we carry out the hysteresis cycles of the studied system for different nonmagnetic surface (NMS) numbers.

Comparison of Test and Analytical Results on CAP1400 Reactor Flow Distributor Designs

2017 ◽  
Author(s):  
Zhang Wei ◽  
Zhang Ming ◽  
Yu Hao ◽  
Yu Qing ◽  
Lin Shaoxuan
Keyword(s):  
Effective Means ◽  
Flow Distribution ◽  
Scale Model ◽  
Test Results ◽  
Hydraulic Test ◽  
Inlet Flow ◽  
The Core ◽  
Fuel Assemblies ◽  
Flow Distributor ◽  
Better Than

The CAP1400 reactor internal is going to use a new component termed the “Even Flow Distributor (EFD)”, instead of the existing flow skirt (FS) design, to help distribute the incoming flow more evenly to the fuel assemblies. To verify the effect of the EFD, a scale model of the reactor and internals was built and hydraulic tests of both the EFD and the FS configurations were conducted. In addition, numerical simulations of the flow fields, using CFD, of both designs were also carried out. From the scale model test results, the overall flow distribution of EFD is better than that of the FS. The core inlet flow distribution taken from the CFD results is slightly better than that from the hydraulic test. The differences between CFD result and test results are less than 3 percent for the most of fuel assemblies, and about 5 percent for a few assemblies. Based on this study, it is concluded that the EFD is a very effective means of controlling core inlet flow distribution in a CAP1400 reactor.

INVESTIGATION OF THE USE OF A VORTEX FLOW TO SEPARATE OIL FROM AN OIL-WATER MIXTURE

1971 ◽  
Vol 1971 (1) ◽  
pp. 361-368 ◽  
Author(s):  
Arthur E. Mensing ◽  
Richard C. Stoeffler
Keyword(s):  
Vortex Tube ◽  
Scale Model ◽  
Water Mixture ◽  
The Core ◽  
Heating Fuel ◽  
Prime Movers ◽  
Vortex Separator ◽  
Oil Water ◽  
Flow Vortex ◽  
Vortex Axis

ABSTRACT The use of a continuous-flow vortex separator as a component of an oil spill clean-up system was investigated. Tangential injection of the oil-water mixture into the vortex tube produces buoyant forces which accelerate the lighter oil to the vortex axis. The cleansed water and the core containing the oil are exhausted through exit ports in opposite end walls of the vortex tube. The cleansed water would be returned to the sea and the core flow containing the oil would be stored. Tests of laboratory-scale model vortex separators were made using oil-water mixtures having inlet oil-to-total-flow ratios between 0.002 and 0.3 and for a variety of geometric and flow conditions. The tests were made using four types of oil (napthene-base crude, paraffin-base crude, diesel and No. 6 heating fuel) having viscosities between 3 and 4250 cps (measured at 75 F) and specific gravities between 0.83 and 0.97. The results showed that separator performance may be optimized by proper control of the oil exhaust flow. Under optimum conditions, approximately 90 percent of the injected oil was separated and captured, and the captured flow contained approximately 90 percent oil. Studies were also made to determine the sizes and weights of components for full-scale vortex separators, including the necessary pumps and prime movers.

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