Abstract: In this paper we describe the design and implementation of a parallel algorithm for data assimilation with ensemble Kalman filter (EnKF) for oil reservoir history matching problem. The use of large number of observations from time-lapse seismic leads to a large turnaround time for the analysis step, in addition to the time consuming simulations of the realizations. For efficient parallelization it is important to consider parallel computation at the analysis step. Our experiments show that parallelization of the analysis step in addition to the forecast step has good scalability, exploiting the same set of resources with some additional efforts.
Abstract: In view of geological origin, formation of the shallow
gas reservoir of the Hangzhou Bay, northern Zhejiang Province,
eastern China, and original occurrence characteristics of the gassy
sand are analyzed. Generally, gassy sand in scale gas reservoirs is in
the state of residual moisture content and the approximate scope of
initial matric suction of sand ranges about from 0kPa to100kPa.
Results based on GDS triaxial tests show that the classical shear
strength formulas of unsaturated soil can not effectively describe basic
strength characteristics of gassy sand; the relationship between
apparent cohesion and matric suction of gassy sand agrees well with
the power function, which can reasonably be used to describe the
strength of gassy sand. In the stress path of gas release, shear strength
of gassy sand will increase and experimental results show the formula
proposed in this paper can effectively predict the strength increment.
When saturated strength indexes of the sand are used in engineering
design, moderate reduction should be considered.
Abstract: The degradation of selected pharmaceuticals in some
water matrices was studied by using several chemical treatments. The
pharmaceuticals selected were the beta-blocker metoprolol, the
nonsteroidal anti-inflammatory naproxen, the antibiotic amoxicillin,
and the analgesic phenacetin; and their degradations were conducted
by using UV radiation alone, ozone, Fenton-s reagent, Fenton-like
system, photo-Fenton system, and combinations of UV radiation and
ozone with H2O2, TiO2, Fe(II), and Fe(III). The water matrices, in
addition to ultra-pure water, were a reservoir water, a groundwater,
and two secondary effluents from two municipal WWTP. The results
reveal that the presence of any second oxidant enhanced the
oxidation rates, with the systems UV/TiO2 and O3/TiO2 providing the
highest degradation rates. It is also observed in most of the
investigated oxidation systems that the degradation rate followed the
sequence: amoxicillin > naproxen > metoprolol > phenacetin. Lower
rates were obtained with the pharmaceuticals dissolved in natural
waters and secondary effluents due to the organic matter present
which consume some amounts of the oxidant agents.
Abstract: This paper discusses on the use of Spline Interpolation
and Mean Square Error (MSE) as tools to process data acquired from
the developed simulator that shall replicate sea bed logging environment.
Sea bed logging (SBL) is a new technique that uses marine
controlled source electromagnetic (CSEM) sounding technique and is
proven to be very successful in detecting and characterizing hydrocarbon
reservoirs in deep water area by using resistivity contrasts. It uses
very low frequency of 0.1Hz to 10 Hz to obtain greater wavelength.
In this work the in house built simulator was used and was provided
with predefined parameters and the transmitted frequency was varied
for sediment thickness of 1000m to 4000m for environment with and
without hydrocarbon. From series of simulations, synthetics data were
generated. These data were interpolated using Spline interpolation
technique (degree of three) and mean square error (MSE) were
calculated between original data and interpolated data. Comparisons
were made by studying the trends and relationship between frequency
and sediment thickness based on the MSE calculated. It was found
that the MSE was on increasing trends in the set up that has the
presence of hydrocarbon in the setting than the one without. The MSE
was also on decreasing trends as sediment thickness was increased
and with higher transmitted frequency.
Abstract: Nanoemulsions are a class of emulsions with a droplet
size in the range of 50–500 nm and have attracted a great deal of
attention in recent years because it is unique characteristics. The
physicochemical properties of nanoemulsion suggests that it can be
successfully used to recover the residual oil which is trapped in the
fine pore of reservoir rock by capillary forces after primary and
secondary recovery. Oil-in-water nanoemulsion which can be formed
by high-energy emulsification techniques using specific surfactants
can reduce oil-water interfacial tension (IFT) by 3-4 orders of
magnitude. The present work is aimed on characterization of oil-inwater
nanoemulsion in terms of its phase behavior, morphological
studies; interfacial energy; ability to reduce the interfacial tension and
understanding the mechanisms of mobilization and displacement of
entrapped oil blobs by lowering interfacial tension both at the
macroscopic and microscopic level. In order to investigate the
efficiency of oil-water nanoemulsion in enhanced oil recovery
(EOR), experiments were performed to characterize the emulsion in
terms of their physicochemical properties and size distribution of the
dispersed oil droplet in water phase. Synthetic mineral oil and a series
of surfactants were used to prepare oil-in-water emulsions.
Characterization of emulsion shows that it follows pseudo-plastic
behaviour and drop size of dispersed oil phase follows lognormal
distribution. Flooding experiments were also carried out in a
sandpack system to evaluate the effectiveness of the nanoemulsion as
displacing fluid for enhanced oil recovery. Substantial additional
recoveries (more than 25% of original oil in place) over conventional
water flooding were obtained in the present investigation.
Abstract: Simulation of the flow and sedimentation process in
the reservoir dams can be made by two methods of physical and mathematical modeling. The study area was within a region which
ranged from the Jelogir hydrometric station to the Karkheh reservoir
dam aimed at investigating the effects of stream tubes on the
GSTARS-3 model behavior. The methodologies was to run the model based on 5 stream tubes in order to observe the influence of
each scenario on longitudinal profiles, cross-section, flow velocity and bed load sediment size. Results further suggest that the use of
two stream tubes or more which result in the semi-two-dimensional
model will yield relatively closer results to the observational data
than a singular stream tube modeling. Moreover, the results of
modeling with three stream tubes shown to yield a relatively close
results with the observational data. The overall conclusion of the paper is with applying various stream tubes; it would be possible to yield a significant influence on the modeling behavior Vis-a Vis the bed load sediment size.
Abstract: The sand production problem has led researchers into making various attempts to understand the phenomenon. The generally accepted concept is that the occurrence of sanding is due to the in-situ stress conditions and the induced changes in stress that results in the failure of the reservoir sandstone during hydrocarbon production from wellbores. By using a hypothetical cased (perforated) well, an approach to the problem is presented here by using Finite Element numerical modelling techniques. In addition to the examination of the erosion problem, the influence of certain key parameters is studied in order to ascertain their effect on the failure and subsequent erosion process. The major variables investigated include: drawdown, perforation depth, and the erosion criterion. Also included is the determination of the optimal mud pressure for given operational and reservoir conditions. The improved understanding between parameters enables the choice of optimal values to minimize sanding during oil production.
Abstract: A direct search approach to determine optimal reservoir operating is proposed with ant colony optimization for continuous domains (ACOR). The model is applied to a system of single reservoir to determine the optimum releases during 42 years of monthly steps. A disadvantage of ant colony based methods and the ACOR in particular, refers to great amount of computer run time consumption. In this study a highly effective procedure for decreasing run time has been developed. The results are compared to those of a GA based model.
Abstract: Scarcity of water resources and huge costs of
establishing new hydraulic installations necessitate optimal
exploitation from existing reservoirs. Sustainable management and
efficient exploitation from existing finite water resources are
important factors in water resource management, particularly in the
periods of water insufficiency and in dry regions, and on account of
competitive allocations in the view of exploitation management. This
study aims to minimize reservoir water release from a determined
rate of demand. A numerical model for water optimal exploitation
has been developed using GAMS introduced by the World Bank and
applied to the case of Meijaran dam, northern Iran. The results
indicate that this model can optimize the function of reservoir
exploitation while required water for lower parts of the region will be
supplied. Further, allocating optimal water from reservoir, the
optimal rate of water allocated to any group of the users were
specified to increase benefits in curve dam exploitation.
Abstract: Many water supply systems in Australia are currently
undergoing significant reconfiguration due to reductions in long term
average rainfall and resulting low inflows to water supply reservoirs
since the second half of the 20th century. When water supply systems
undergo change, it is necessary to develop new operating rules,
which should consider climate, because the climate change is likely
to further reduce inflows. In addition, water resource systems are
increasingly intended to be operated to meet complex and multiple
objectives representing social, economic, environmental and
sustainability criteria. This is further complicated by conflicting
preferences on these objectives from diverse stakeholders. This paper
describes a methodology to develop optimum operating rules for
complex multi-reservoir systems undergoing significant change,
considering all of the above issues. The methodology is demonstrated
using the Grampians water supply system in northwest Victoria,
Australia. Initial work conducted on the project is also presented in
this paper.
Abstract: Protecting is the sources of drinking water is the first
barrier of contamination of drinking water. The Feitsui Reservoir
watershed of Taiwan supplies domestic water for around 5 million
people in the Taipei metropolitan area. Understanding the spatial
patterns of water quality trends in this watershed is an important
agenda for management authorities. This study examined 7 sites in the
watershed for water quality parameters regulated in the standard for
drinking water source. The non-parametric seasonal Mann-Kendall-s
test was used to determine significant trends for each parameter.
Significant trends of increasing pH occurred at the sampling station in
the uppermost stream watershed, and in total phosphorus at 4 sampling
stations in the middle and downstream watershed. Additionally, the
multi-scale land cover assessment and average land slope were used to
explore the influence on the water quality in the watershed. Regression
models for predicting water quality were also developed.
Abstract: Article devoted to the development of technologies
for medicine and agroecology by using plant organelle – spherosome.
Technological method of purification and isolation of this organelle
by using novel nanostructured carbon sorbent – “nanocarbosorb"
ARK type are presented. Also the methods of preparation of
nanocontainers based on using of spherosome with loaded isosorbide
dinitrate, piroxicam or diclofenak are exhibited. We found that the
spherosome could be applied for ecological aims as bioregulator and
also as biosensor for determination of ammonia ions in water
reservoirs at concentration range 1mM to 100mM.
Abstract: Determination of wellbore problems during a
production/injection process might be evaluated thorough
temperature log analysis. Other applications of this kind of log
analysis may also include evaluation of fluid distribution analysis
along the wellbore and identification of anomalies encountered
during production/injection process. While the accuracy of such
prediction is paramount, the common method of determination of a
wellbore temperature log includes use of steady-state energy balance
equations, which hardly describe the real conditions as observed in
typical oil and gas flowing wells during production operation; and
thus increase level of uncertainties. In this study, a practical method
has been proposed through development of a simplified semianalytical
model to apply for predicting temperature profile along the
wellbore. The developed model includes an overall heat transfer
coefficient accounting all modes of heat transferring mechanism,
which has been focused on the prediction of a temperature profile as
a function of depth for the injection/production wells. The model has
been validated with the results obtained from numerical simulation.
Abstract: Sedimentation formation is a complex hydraulic phenomenon that has emerged as a major operational and maintenance consideration in modern hydraulic engineering in general and river engineering in particular. Sediments accumulation along the river course and their eventual storage in a form of islands affect water intake in the canal systems that are fed by the storage reservoirs. Without proper management, sediment transport can lead to major operational challenges in water distribution system of arid regions like the Dez and Hamidieh command areas. The paper aims to investigate sedimentation in the Western Canal of Dez Diversion Weir using the SHARC model and compare the results with the two intake structures of the Hamidieh dam in Iran using SSIIM model. The objective was to identify the factors which influence the process, check reliability of outcome and provide ways in which to mitigate the implications on operation and maintenance of the structures. Results estimated sand and silt bed loads concentrations to be 193 ppm and 827ppm respectively. This followed ,ore or less similar pattern in Hamidieh where the sediment formation impeded water intake in the canal system. Given the available data on average annual bed loads and average suspended sediment loads of 165ppm and 837ppm in the Dez, there was a significant statistical difference (16%) between the sand grains, whereas no significant difference (1.2%) was find in the silt grain sizes. One explanation for such finding being that along the 6 Km river course there was considerable meandering effects which explains recent shift in the hydraulic behavior along the stream course under investigation. The sand concentration in downstream relative to present state of the canal showed a steep descending curve. Sediment trapping on the other hand indicated a steep ascending curve. These occurred because the diversion weir was not considered in the simulation model. The comparative study showed very close similarities in the results which explains the fact that both software can be used as accurate and reliable analytical tools for simulation of the sedimentation in hydraulic engineering.
Abstract: This research was conducted in the Pua Watershed whereas located in the Upper Nan River Basin in Nan province, Thailand. Nan River basin originated in Nan province that comprises of many tributary streams to produce as inflow to the Sirikit dam provided huge reservoir with the storage capacity of 9510 million cubic meters. The common problems of most watersheds were found i.e. shortage water supply for consumption and agriculture utilizations, deteriorate of water quality, flood and landslide including debris flow, and unstable of riverbank. The Pua Watershed is one of several small river basins that flow through the Nan River Basin. The watershed includes 404 km2 representing the Pua District, the Upper Nan Basin, or the whole Nan River Basin, of 61.5%, 18.2% or 1.2% respectively. The Pua River is a main stream producing all year streamflow supplying the Pua District and an inflow to the Upper Nan Basin. Its length approximately 56.3 kilometers with an average slope of the channel by 1.9% measured. A diversion weir namely Pua weir bound the plain and mountainous areas with a very steep slope of the riverbed to 2.9% and drainage area of 149 km2 as upstream watershed while a mild slope of the riverbed to 0.2% found in a river reach of 20.3 km downstream of this weir, which considered as a gauged basin. However, the major branch streams of the Pua River are ungauged catchments namely: Nam Kwang and Nam Koon with the drainage area of 86 and 35 km2 respectively. These upstream watersheds produce runoff through the 3-streams downstream of Pua weir, Jao weir, and Kang weir, with an averaged annual runoff of 578 million cubic meters. They were analyzed using both statistical data at Pua weir and simulated data resulted from the hydrologic modeling system (HEC–HMS) which applied for the remaining ungauged basins. Since the Kwang and Koon catchments were limited with lack of hydrological data included streamflow and rainfall. Therefore, the mathematical modeling: HEC-HMS with the Snyder-s hydrograph synthesized and transposed methods were applied for those areas using calibrated hydrological parameters from the upstream of Pua weir with continuously daily recorded of streamflow and rainfall data during 2008-2011. The results showed that the simulated daily streamflow and sum up as annual runoff in 2008, 2010, and 2011 were fitted with observed annual runoff at Pua weir using the simple linear regression with the satisfied correlation R2 of 0.64, 062, and 0.59, respectively. The sensitivity of simulation results were come from difficulty using calibrated parameters i.e. lag-time, coefficient of peak flow, initial losses, uniform loss rates, and missing some daily observed data. These calibrated parameters were used to apply for the other 2-ungauged catchments and downstream catchments simulated.
Abstract: The operation performance of a valveless micro-pump
is strongly dependent on the shape of connected nozzle/diffuser and
Reynolds number. The aims of present work are to compare the
performance curves of micropump with the original straight
nozzle/diffuser and contoured nozzle/diffuser under different back
pressure conditions. The tested valveless micropumps are assembled
of five pieces of patterned PMMA plates with hot-embracing
technique. The structures of central chamber, the inlet/outlet
reservoirs and the connected nozzle/diffuser are fabricated with laser
cutting machine. The micropump is actuated with circular-type PZT
film embraced on the bottom of central chamber. The deformation of
PZT membrane with various input voltages is measured with a
displacement laser probe. A simple testing facility is also constructed
to evaluate the performance curves for comparison.
In order to observe the evaluation of low Reynolds number
multiple vortex flow patterns within the micropump during suction
and pumping modes, the unsteady, incompressible laminar
three-dimensional Reynolds-averaged Navier-Stokes equations are
solved. The working fluid is DI water with constant thermo-physical
properties. The oscillating behavior of PZT film is modeled with the
moving boundary wall in way of UDF program. With the dynamic
mesh method, the instants pressure and velocity fields are obtained
and discussed.Results indicated that the volume flow rate is not
monotony increased with the oscillating frequency of PZT film,
regardless of the shapes of nozzle/diffuser. The present micropump
can generate the maximum volume flow rate of 13.53 ml/min when
the operation frequency is 64Hz and the input voltage is 140 volts.
The micropump with contoured nozzle/diffuser can provide 7ml/min
flow rate even when the back pressure is up to 400 mm-H2O. CFD
results revealed that the flow central chamber was occupied with
multiple pairs of counter-rotating vortices during suction and
pumping modes. The net volume flow rate over a complete
oscillating periodic of PZT
Abstract: This study was investigated on sampling and
analyzing water quality in water reservoir & water tower installed in
two kind of residential buildings and school facilities. Data of water
quality was collected for correlation analysis with frequency of
sanitization of water reservoir through questioning managers of
building about the inspection charts recorded on equipment for water
reservoir. Statistical software packages (SPSS) were applied to the
data of two groups (cleaning frequency and water quality) for
regression analysis to determine the optimal cleaning frequency of
sanitization. The correlation coefficient (R) in this paper represented
the degree of correlation, with values of R ranging from +1 to -1.After
investigating three categories of drinking water users; this study found
that the frequency of sanitization of water reservoir significantly
influenced the water quality of drinking water. A higher frequency of
sanitization (more than four times per 1 year) implied a higher quality
of drinking water. Results indicated that sanitizing water reservoir &
water tower should at least twice annually for achieving the aim of
safety of drinking water.
Abstract: Reservoirs with high pressures and temperatures
(HPHT) that were considered to be atypical in the past are now
frequent targets for exploration. For downhole oilfield drilling tools
and components, the temperature and pressure affect the mechanical
strength. To address this issue, a finite element analysis (FEA) for
206.84 MPa (30 ksi) pressure and 165°C has been performed on the
pressure housing of the measurement-while-drilling/logging-whiledrilling
(MWD/LWD) density tool.
The density tool is a MWD/LWD sensor that measures the density
of the formation. One of the components of the density tool is the
pressure housing that is positioned in the tool. The FEA results are
compared with the experimental test performed on the pressure
housing of the density tool. Past results show a close match between
the numerical results and the experimental test. This FEA model can
be used for extreme HPHT and ultra HPHT analyses, and/or optimal
design changes.
Abstract: In this survey the process of crack propagation at the
toe of concrete gravity dam is investigated by applying principals
and criteria of linear elastic fracture mechanic. Simulating process of
earthquake conditions for three models of dam with different
geometrical condition, in empty reservoir under plain stress is
calculated through special fracture mechanic software FRANNC2D
[1] for determining fracture mechanic criteria. The outcomes showed
that in spite of the primary expectations, the simultaneous existence
of fillet in both toe and heel area (model 3), the rate of maximum
principal stress has not been decreased; however, even the maximum
principal stress has increased, so it caused stress intensity factors
increase which is undesirable. On the other hand, the dam with heel
fillet has shown the best attitude and it is because of items like
decreasing the rates of maximum and minimum principal stresses and
also is related to decreasing the rates of stress intensity factors for 1st
& 2nd modes of the model.
Abstract: When acid is pumped into damaged reservoirs for
damage removal/stimulation, distorted inflow of acid into the
formation occurs caused by acid preferentially traveling into highly
permeable regions over low permeable regions, or (in general) into
the path of least resistance. This can lead to poor zonal coverage and
hence warrants diversion to carry out an effective placement of acid.
Diversion is desirably a reversible technique of temporarily reducing
the permeability of high perm zones, thereby forcing the acid into
lower perm zones.
The uniqueness of each reservoir can pose several challenges to
engineers attempting to devise optimum and effective diversion
strategies. Diversion techniques include mechanical placement and/or
chemical diversion of treatment fluids, further sub-classified into ball
sealers, bridge plugs, packers, particulate diverters, viscous gels,
crosslinked gels, relative permeability modifiers (RPMs), foams,
and/or the use of placement techniques, such as coiled tubing (CT)
and the maximum pressure difference and injection rate (MAPDIR)
methodology.
It is not always realized that the effectiveness of diverters greatly
depends on reservoir properties, such as formation type, temperature,
reservoir permeability, heterogeneity, and physical well
characteristics (e.g., completion type, well deviation, length of
treatment interval, multiple intervals, etc.). This paper reviews the
mechanisms by which each variety of diverter functions and
discusses the effect of various reservoir properties on the efficiency
of diversion techniques. Guidelines are recommended to help
enhance productivity from zones of interest by choosing the best
methods of diversion while pumping an optimized amount of
treatment fluid. The success of an overall acid treatment often
depends on the effectiveness of the diverting agents.