Optimization of Plug-and-Perforate Completions for Balanced Treatment Distribution and Improved Reservoir Contact

SPE Journal ◽  
2019 ◽  
Vol 25 (02) ◽  
pp. 558-572
Author(s):  
Sophie Yi ◽  
Chu-Hsiang Wu ◽  
Mukul M. Sharma
Keyword(s):  
Surface Area ◽  
Transport Model ◽  
Weighted Average ◽  
Displacement Discontinuity ◽  
Design Solution ◽  
Base Case ◽  
Stress Shadow ◽  
Final Treatment ◽  
Pumping Schedules ◽  
The Impact

Summary Heel-dominated treatment distribution among multiple perforation clusters is frequently observed in plug-and-perforate (plug-and-perf) stages, causing small propped surface areas, suboptimal production, and unexpected fracture hits. A multifracture simulator with a novel wellbore-fluid and proppant-transport model is applied to quantify treatment distribution among multiple perforation clusters in a plug-and-perf operation. A simulation base case is set up on the basis of a field treatment design with four clusters. Simulation results show that the two toe-side clusters screened out early in the treatment and the two heel-side clusters were dominant. The simulated proppant placement is consistent with distributed-acoustic-sensing observations. The impact of different perforating strategies and pumping schedules on final treatment distribution is investigated. Two criteria are defined that quantify the proppant distribution and fracture area: the weighted average (WA) and standard deviation (SD) of the final fluid and proppant distribution, as well as the hydraulic surface area (HSA) and propped surface area (PSA) of the created fractures. An optimal plug-and-perf design is defined as one that minimizes the SD of the treatment distribution among perforation clusters, and maximizes the PSA. Both perforating strategy and pumping schedule are found to affect the final treatment distribution significantly, and uniform treatment distribution is shown to create more PSA. Having fewer perforations per cluster was found to promote uniform fluid and proppant placement. Other helpful strategies include reducing the number of perforations near the heel and using small, lightweight proppant. The stress shadow effect is accounted for using the displacement discontinuity method (DDM) and was found to play a smaller role than perforation friction and proppant inertia in most cases. An automated process is developed to optimize plug-and-perf completion design with multiple decision variables using a genetic algorithm (GA). Thirteen parameters are optimized simultaneously. The optimal design solution creates an almost even treatment distribution and more than doubles the PSA compared with the base case. The multifracture model presented in this paper provides a way to quantify fluid and proppant distribution for any perforating strategy and pumping schedule, and provides more insight into the physics relevant to plug-and-perf treatment distribution. The perforation and pumping schedule recommendations presented in this paper provide directional guidance for the design of fracturing jobs with balanced treatment distribution and large PSA.

scholarly journals Influence of aquifer and streambed heterogeneity on the distribution of groundwater discharge

2009 ◽  
Vol 13 (1) ◽  
pp. 69-77 ◽  
Author(s):  
E. Kalbus ◽  
C. Schmidt ◽  
J. W. Molson ◽  
F. Reinstorf ◽  
M. Schirmer
Keyword(s):  
Groundwater Flow ◽  
Transport Model ◽  
Regional Scale ◽  
Base Case ◽  
Case Scenario ◽  
Base Case Scenario ◽  
Heterogeneous Distribution ◽  
Heterogeneous Aquifer ◽  
The Impact ◽  
Low K

Abstract. The spatial distribution of groundwater fluxes through a streambed can be highly variable, most often resulting from a heterogeneous distribution of aquifer and streambed permeabilities along the flow pathways. Using a groundwater flow and heat transport model, we defined four scenarios of aquifer and streambed permeability distributions to simulate and assess the impact of subsurface heterogeneity on the distribution of groundwater fluxes through the streambed: (a) a homogeneous low-K streambed within a heterogeneous aquifer; (b) a heterogeneous streambed within a homogeneous aquifer; (c) a well connected heterogeneous low-K streambed within a heterogeneous aquifer; and (d) a poorly connected heterogeneous low-K streambed within a heterogeneous aquifer. The simulation results were compared with a base case scenario, in which the streambed had the same properties as the aquifer, and with observed data. The results indicated that the aquifer has a stronger influence on the distribution of groundwater fluxes through the streambed than the streambed itself. However, a homogeneous low-K streambed, a case often implemented in regional-scale groundwater flow models, resulted in a strong homogenization of fluxes, which may have important implications for the estimation of peak mass flows. The flux distributions simulated with heterogeneous low-K streambeds were similar to the flux distributions of the base case scenario, despite the lower permeability. The representation of heterogeneous distributions of aquifer and streambed properties in the model has been proven to be beneficial for the accuracy of flow simulations.

scholarly journals Simulation of the evolution of biomass burning organic aerosol with different volatility basis set schemes in PMCAMx-SRv1.0

2020 ◽  
Author(s):  
Georgia N. Theodoritsi ◽  
Giancarlo Ciarelli ◽  
Spyros N. Pandis
Keyword(s):  
Biomass Burning ◽  
Transport Model ◽  
Three Dimensional ◽  
Organic Aerosol ◽  
Basis Set ◽  
Base Case ◽  
Chemical Transport Model ◽  
Alternative Scheme ◽  
Average Maximum ◽  
The Impact

Abstract. A source-resolved three-dimensional chemical transport model, PMCAMx-SR, was applied in the continental U.S. to investigate the contribution of the various components (primary and secondary) of biomass burning organic aerosol (bbOA) to organic aerosol levels. Two different schemes based on the volatility basis set were used for the simulation of the bbOA during different seasons. The first is the default scheme of PMCAMx-SR and the second is a recently developed scheme based on laboratory experiments of the bbOA evolution. The simulations with the alternative bbOA scheme predict much higher total bbOA concentrations when compared with the base case ones. This is mainly due to the high emissions of intermediate volatility organic compounds (IVOCs) assumed in the alternative scheme. The oxidation of these compounds is predicted to be a significant source of secondary organic aerosol. The impact of the other parameters that differ in the two schemes is low to negligible. The monthly average maximum predicted concentrations of the alternative bbOA scheme were approximately an order of magnitude higher than those of the default scheme during all seasons. The performance of the two schemes was evaluated against observed total organic aerosol concentrations from several measurement sites across the US. The results were mixed. The default scheme performed better during July and September while the alternative scheme performed a little better during April. These results illustrate the uncertainty of the corresponding predictions, the need to quantify the emissions and reactions of IVOCs from specific biomass sources, and to better constrain the total (primary and secondary) bbOA levels.

scholarly journals Simulation of the evolution of biomass burning organic aerosol with different volatility basis set schemes in PMCAMx-SRv1.0

2021 ◽  
Vol 14 (4) ◽  
pp. 2041-2055
Author(s):  
Georgia N. Theodoritsi ◽  
Giancarlo Ciarelli ◽  
Spyros N. Pandis
Keyword(s):  
Biomass Burning ◽  
Transport Model ◽  
Organic Aerosol ◽  
Basis Set ◽  
Base Case ◽  
Air Quality Model ◽  
Alternative Scheme ◽  
Average Maximum ◽  
Different Seasons ◽  
The Impact

Abstract. A source-resolved three-dimensional chemical transport model, PMCAMx-SR (Particulate Matter Comprehensive Air-quality Model with extensions – Source Resolved), was applied in the continental US to investigate the contribution of the various components (primary and secondary) of biomass burning organic aerosol (bbOA) to organic aerosol levels. Two different schemes based on the volatility basis set were used for the simulation of the bbOA during different seasons. The first is the default scheme of PMCAMx-SR, and the second is a recently developed scheme based on laboratory experiments of the bbOA evolution. The simulations with the alternative bbOA scheme predict much higher total bbOA concentrations when compared with the base case ones. This is mainly due to the high emissions of intermediate-volatility organic compounds (IVOCs) assumed in the alternative scheme. The oxidation of these compounds is predicted to be a significant source of secondary organic aerosol. The impact of the other parameters that differ in the two schemes is low to negligible. The monthly average maximum predicted concentrations of the alternative bbOA scheme were approximately an order of magnitude higher than those of the default scheme during all seasons. The performance of the two schemes was evaluated against observed total organic aerosol concentrations from several measurement sites across the US. The results were different for the different seasons examined. The default scheme performed better during July and September, while the alternative scheme performed a little better during April. These results illustrate the uncertainty of the corresponding predictions and the need to quantify the emissions and reactions of IVOCs from specific biomass sources and to better constrain the total (primary and secondary) bbOA levels.

scholarly journals Impacts of mechanistic changes on HO<sub>x</sub> formation and recycling in the oxidation of isoprene

2010 ◽  
Vol 10 (3) ◽  
pp. 5863-5910 ◽  
Author(s):  
A. T. Archibald ◽  
M. C. Cooke ◽  
S. R. Utembe ◽  
D. E. Shallcross ◽  
R. G. Derwent ◽  
...  
Keyword(s):  
Transport Model ◽  
Numerical Models ◽  
Box Model ◽  
Chemical Mechanism ◽  
Base Case ◽  
Emission Rates ◽  
Input Rate ◽  
Wide Range ◽  
The Impact ◽  
Model Measurement

Abstract. Recently reported model-measurement discrepancies for the concentrations of the HOx radical species (OH and HO2) in locations characterized by high emission rates of isoprene have indicated possible deficiencies in the representation of OH recycling and formation in isoprene mechanisms currently employed in numerical models; particularly at low levels of NOx. Using version 3.1 of the Master Chemical Mechanism (MCM v3.1) as a base mechanism, the sensitivity of the system to a number of detailed mechanistic changes is examined for a wide range of NOx levels, using a simple box model. These studies place emphasis on processes for which experimental or theoretical evidence has been reported in the peer-reviewed literature, in addition to examining the impact of an intrinsic simplification in the MCM v3.1 chemistry. Although all the considered mechanistic changes lead to simulated increases in the concentrations of OH at low NOx levels, the greatest impact is achieved by implementation of a recently postulated mechanism involving isomerisation of the δ-hydroxyalkenyl peroxy radical isomers, formed from the sequential addition of OH and O2 to isoprene. In conjunction with necessary rapid photolysis of the resultant hydroperoxyaldehyde products, this mechanism yields approximately a factor of three increase in the simulated OH concentration at low NOx, and is the only considered mechanism which achieves enhancements which approach those necessary to explain the reported model-measurement discrepancies. Combination of all the considered mechanistic changes has an effect which is approximately additive, yielding an overall enhancement of about a factor of 3.2 in the simulated OH concentration at the lowest NOx input rate considered, with the simulated mean NOx mixing ratios at this input rate being 42 ppt and 29 ppt with the base case and modified mechanisms respectively. A parameterized representation of the mechanistic changes is optimized and implemented into a reduced variant of the Common Representative Intermediates mechanism (CRI v2-R5), for use in the STOCHEM global chemistry-transport model. The impacts of the modified chemistry in the global model are shown to be consistent with those observed in the box model sensitivity studies, and the results are illustrated and discussed with a particular focus on the tropical forested regions of the Amazon and Borneo where unexpectedly elevated concentrations of OH have recently been reported.

Impact of roof shading on building energy performance in warm & humid climatic places of India

2020 ◽  
pp. 50-64
Author(s):  
Kuladeep Kumar Sadevi ◽  
Avlokita Agrawal
Keyword(s):  
Energy Consumption ◽  
Energy Conservation ◽  
Energy Performance ◽  
General Assumption ◽  
Climatic Conditions ◽  
Building Envelope ◽  
Passive Cooling ◽  
Base Case ◽  
U Value ◽  
The Impact

With the rise in awareness of energy efficient buildings and adoption of mandatory energy conservation codes across the globe, significant change is being observed in the way the buildings are designed. With the launch of Energy Conservation Building Code (ECBC) in India, climate responsive designs and passive cooling techniques are being explored increasingly in building designs. Of all the building envelope components, roof surface has been identified as the most significant with respect to the heat gain due to the incident solar radiation on buildings, especially in tropical climatic conditions. Since ECBC specifies stringent U-Values for roof assembly, use of insulating materials is becoming popular. Along with insulation, the shading of the roof is also observed to be an important strategy for improving thermal performance of the building, especially in Warm and humid climatic conditions. This study intends to assess the impact of roof shading on building’s energy performance in comparison to that of exposed roof with insulation. A typical office building with specific geometry and schedules has been identified as base case model for this study. This building is simulated using energy modelling software ‘Design Builder’ with base case parameters as prescribed in ECBC. Further, the same building has been simulated parametrically adjusting the amount of roof insulation and roof shading simultaneously. The overall energy consumption and the envelope performance of the top floor are extracted for analysis. The results indicate that the roof shading is an effective passive cooling strategy for both naturally ventilated and air conditioned buildings in Warm and humid climates of India. It is also observed that a fully shaded roof outperforms the insulated roof as per ECBC prescription. Provision of shading over roof reduces the annual energy consumption of building in case of both insulated and uninsulated roofs. However, the impact is higher for uninsulated roofs (U-Value of 3.933 W/m2K), being 4.18% as compared to 0.59% for insulated roofs (U-Value of 0.33 W/m2K).While the general assumption is that roof insulation helps in reducing the energy consumption in tropical buildings, it is observed to be the other way when insulation is provided with roof shading. It is due to restricted heat loss during night.

Evaluation of Nanotechniques and Conventional Techniques for the Removal of Dioxins

2018 ◽  
Vol 9 (1) ◽  
pp. 79-84
Author(s):  
Vaishali V. Shahare ◽  
Rajni Grover ◽  
Suman Meena
Keyword(s):  
Soil Sample ◽  
Human Health ◽  
Surface Area ◽  
Contaminated Soil ◽  
Conventional Treatment ◽  
Volume Ratio ◽  
Soil Samples ◽  
Dioxins And Furans ◽  
Palladized Iron ◽  
The Impact

Background: The persistent dioxins/furans has caused a worldwide concern as they influence the human health. Recent research indicates that nonmaterial may prove effective in the degradation of Dioxins/furans. The nanomaterials are very reactive owing to their large surface area to volume ratio and large number of reactive sites. However, nanotechnology applications face both the challenges and the opportunities to influence the area of environmental protection. Objective: i) To study the impact of oil mediated UV-irradiations on the removal of 2,3,7,8-TCDD, 2,3,7,8-TCDF, OCDD and OCDF in simulated soil samples. ii) To compare the conventional treatment methods with the modern available nanotechniques for the removal of selected Dioxins/furans from soil samples. Methods: The present work has investigated an opportunity of the degradation of tetra and octachlorinated dioxins and furans by using oil mediated UV radiations with subsequent extraction of respective dioxins/furans from soils. The results have been compared with the available nanotechniques. Results: The dioxin congeners in the simulated soil sample showed decrease in concentration with the increase in the exposure time and intensity of UV radiations. The dechlorination of PCDD/Fs using palladized iron has been found to be effective. Conclusion: Both the conventional methods and nanotechnology have a dramatic impact on the removal of Dioxins/furans in contaminated soil. However, the nanotechniques are comparatively costlier and despite the relatively high rates of PCDDs dechlorination by Pd/nFe, small fraction of the dioxins are recalcitrant to degradation over considerable exposure times.

scholarly journals Autism Tsunami: the Impact of Rising Prevalence on the Societal Cost of Autism in the United States

2021 ◽  
Author(s):  
Mark Blaxill ◽  
Toby Rogers ◽  
Cynthia Nevison
Keyword(s):  
Forecast Model ◽  
The United States ◽  
Population Projections ◽  
Base Case ◽  
Prevention Strategies ◽  
Total Base ◽  
Cost Categories ◽  
The Cost ◽  
The Impact ◽  
First Time

AbstractThe cost of ASD in the U.S. is estimated using a forecast model that for the first time accounts for the true historical increase in ASD. Model inputs include ASD prevalence, census population projections, six cost categories, ten age brackets, inflation projections, and three future prevalence scenarios. Future ASD costs increase dramatically: total base-case costs of $223 (175–271) billion/year are estimated in 2020; $589 billion/year in 2030, $1.36 trillion/year in 2040, and $5.54 (4.29–6.78) trillion/year by 2060, with substantial potential savings through ASD prevention. Rising prevalence, the shift from child to adult-dominated costs, the transfer of costs from parents onto government, and the soaring total costs raise pressing policy questions and demand an urgent focus on prevention strategies.

scholarly journals Impact of Passive Energy Efficiency Measures on Cooling Energy Demand in an Architectural Campus Building in Karachi, Pakistan

2021 ◽  
Vol 13 (13) ◽  
pp. 7251
Author(s):  
Mushk Bughio ◽  
Muhammad Shoaib Khan ◽  
Waqas Ahmed Mahar ◽  
Thorsten Schuetze
Keyword(s):  
Energy Efficiency ◽  
Energy Demand ◽  
Electricity Consumption ◽  
Information Modeling ◽  
Base Case ◽  
Energy Efficiency Measures ◽  
Efficiency Measures ◽  
The Impact ◽  
Cooling Energy Demand ◽  
Campus Building

Electric appliances for cooling and lighting are responsible for most of the increase in electricity consumption in Karachi, Pakistan. This study aims to investigate the impact of passive energy efficiency measures (PEEMs) on the potential reduction of indoor temperature and cooling energy demand of an architectural campus building (ACB) in Karachi, Pakistan. PEEMs focus on the building envelope’s design and construction, which is a key factor of influence on a building’s cooling energy demand. The existing architectural campus building was modeled using the building information modeling (BIM) software Autodesk Revit. Data related to the electricity consumption for cooling, building masses, occupancy conditions, utility bills, energy use intensity, as well as space types, were collected and analyzed to develop a virtual ACB model. The utility bill data were used to calibrate the DesignBuilder and EnergyPlus base case models of the existing ACB. The cooling energy demand was compared with different alternative building envelope compositions applied as PEEMs in the renovation of the existing exemplary ACB. Finally, cooling energy demand reduction potentials and the related potential electricity demand savings were determined. The quantification of the cooling energy demand facilitates the definition of the building’s electricity consumption benchmarks for cooling with specific technologies.

scholarly journals Development of a Component-Level Hydrogen Transport Model with OpenFOAM and Application to Tritium Transport Inside a DEMO HCPB Breeder

2021 ◽  
Vol 11 (8) ◽  
pp. 3481
Author(s):  
Volker Pasler ◽  
Frederik Arbeiter ◽  
Christine Klein ◽  
Dmitry Klimenko ◽  
Georg Schlindwein ◽  
...  
Keyword(s):  
Transport Model ◽  
Tritium Concentration ◽  
Minor Role ◽  
Specific Rate ◽  
Component Level ◽  
Diffusion Limited ◽  
Purge Gas ◽  
Choice Of Species ◽  
The Impact ◽  
Tritium Transport

This work continues the development of a numerical model to simulate transient tritium transport on the breeder zone (BZ) level for the EU helium-cooled pebble bed (HCPB) concept for DEMO. The basis of the model is the open-source field operation and manipulation framework, OpenFOAM. The key output quantities of the model are the tritium concentration in the purge gas and in the coolant and the tritium inventory inside the BZ structure. New model features are briefly summarized. As a first relevant application a simulation of tritium transport for a single pin out of the KIT HCPB design for DEMO is presented. A variety of scenarios investigates the impact of the permeation regime (diffusion-limited vs. surface-limited), of an additional hydrogen content of 300 Pa H2 in the purge gas, of the released species (HT vs. T2), and of the choice of species-specific rate constants (recombination constant of HT set twice as for H2 and T2). The results indicate that the released species plays a minor role for permeation. Both permeation and inventory show a considerable dependence on a possible hydrogen addition in the purge gas. An enhanced HT recombination constant reduces steel T inventories and, in the diffusion-limited case, also permeation significantly. Scenarios with 80 bar vs. 2 bar purge gas pressure indicate that purge gas volumetric flow is decisive for permeation.

scholarly journals The Environmental Effects of the April 2020 Wildfires and the Cs-137 Re-Suspension in the Chernobyl Exclusion Zone: A Multi-Hazard Threat

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 467
Author(s):  
Rocío Baró ◽  
Christian Maurer ◽  
Jerome Brioude ◽  
Delia Arnold ◽  
Marcus Hirtl
Keyword(s):  
Air Quality ◽  
Nuclear Power ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Point Of View ◽  
Plume Dispersion ◽  
Exclusion Zone ◽  
Fire Plume ◽  
Mean Values ◽  
The Impact

This paper demonstrates the environmental impacts of the wildfires occurring at the beginning of April 2020 in and around the highly contaminated Chernobyl Exclusion Zone (CEZ). Due to the critical fire location, concerns arose about secondary radioactive contamination potentially spreading over Europe. The impact of the fire was assessed through the evaluation of fire plume dispersion and re-suspension of the radionuclide Cs-137, whereas, to assess the smoke plume effect, a WRF-Chem simulation was performed and compared to Tropospheric Monitoring Instrument (TROPOMI) satellite columns. The results show agreement of the simulated black carbon and carbon monoxide plumes with the plumes as observed by TROPOMI, where pollutants were also transported to Belarus. From an air quality and health perspective, the wildfires caused extremely bad air quality over Kiev, where the WRF-Chem model simulated mean values of PM2.5 up to 300 µg/m3 (during the first fire outbreak) over CEZ. The re-suspension of Cs-137 was assessed by a Bayesian inverse modelling approach using FLEXPART as the atmospheric transport model and Ukraine observations, yielding a total release of 600 ± 200 GBq. The increase in both smoke and Cs-137 emissions was only well correlated on the 9 April, likely related to a shift of the focus area of the fires. From a radiological point of view even the highest Cs-137 values (average measured or modelled air concentrations and modelled deposition) at the measurement site closest to the Chernobyl Nuclear Power Plant, i.e., Kiev, posed no health risk.

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