This paper contrasts predicted X-band sea surface backscattering from slick-free and oil-covered sea surfaces with actual measurements acquired by the X-band satellite TerraSAR-X and COSMO-SkyMed Synthetic Aperture Ra...This paper contrasts predicted X-band sea surface backscattering from slick-free and oil-covered sea surfaces with actual measurements acquired by the X-band satellite TerraSAR-X and COSMO-SkyMed Synthetic Aperture Radar(SAR)missions.Two SAR scenes were acquired with a temporal difference of about 36 minutes,under similar met-ocean conditions,during the North Sea’s Gannet Alpha oil spill accident.The normalized radar cross section of the slick-free sea surface is predicted using the Advanced Integral Equation Model(AIEM)while the backscatter from the oiled sea surface is predicted by the AIEM augmented with the Model of Local Balance(MLB)to include the damping effect of oil slicks.Experimental results show that X-band co-polarized numerical predictions agree reasonably well with both TSX and CSK actual measurements collected over slick-free sea surfaces.When dealing with oil-covered sea surfaces,the predicted backscattering reasonably agrees with TSX measurements,while it overestimates the CSK ones.This is likely due to the different spreading conditions of the oil imaged by the two satellite missions.展开更多
The purpose of this study was to investigate the characteristics of sea surface waves as they pass through oil slicks.The parameterized first-guess spectrum method(PFSM)theory-based wave retrieval algorithm was applie...The purpose of this study was to investigate the characteristics of sea surface waves as they pass through oil slicks.The parameterized first-guess spectrum method(PFSM)theory-based wave retrieval algorithm was applied to 20 images of horizontal-horizontal(HH)polarization obtained using the phased-array L-band synthetic aperture radar(SAR)(PALSAR)on the Advanced Land Observing Satellite(ALOS-1).The images were collocated with simulations from the WAVEWATCH-Ⅲ(WW3)model in a 0.1°grid using the European Centre for Medium-Range Weather Forecasts(ECMWF)reanalysis(ERA-5)winds data as the forcing field.The validation of the model-simulated significant wave height(SWH)against the measurements from the Jason-2 altimeter produced a 0.66m root mean square error(RMSE)for the SWH,with a coefficient(COR)0.74.In this sense,the WW3-simulated waves were reliable for our work.A comparison between the SAR retrieval results and the WW3 simulations was performed using the dataset for the regions without oil slicks,which produced a 0.34m RMSE for the SWH,with a COR of 0.79,which is less than a the RMSE of 0.52 m and the COR of 0.70 for the regions with oil slicks.Moreover,it was found that the SAR-derived SWHs were significantly underestimated by about 0.2m in the areas with oil slicks.This difference is probably due to the underestimation of the SAR-derived wind speeds at moderate wind speeds(i.e.,at wind speeds of greater than 5ms^(-1)).An additional analysis compared the SAR-derived wave spectra with those from the WW3 model as waves passed through the oil slicks.The interesting finding is that the wave energy at short wave lengths(about 30m)is reduced by the oil slicks,causing the movement of the dominant wave spectrum to shift to longer wave lengths(about 80 m).展开更多
The critical angle is the angle at which the contrast of oil slicks reverse their contrasts against the surrounding oil-free seawater under sunglint.Accurate determination of the critical angle can help estimate surfa...The critical angle is the angle at which the contrast of oil slicks reverse their contrasts against the surrounding oil-free seawater under sunglint.Accurate determination of the critical angle can help estimate surface roughness and refractive index of the oil slicks.Although it’s difficult to determine a certain critical angle,the potential critical angle range help to improve the estimation accuracy.In this study,the angle between the viewing direction and the direction of mirror reflection is used as an indicator for quantifying the critical angle and could be calculated from the solar/viewing geometry from observations of the Moderate Resolution Imaging Spectroradiometer(MODIS).The natural seep oil slicks in the Gulf of Mexico were first delineated using a customized segmentation approach to remove noise and apply a morphological filter.On the basis of the histograms of the brightness values of the delineated oil slicks,the potential range of the critical angle was determined,and then an optimal critical angle between oil slicks and seawater was then determined from statistical and regression analyses in this range.This critical angle corresponds to the best fitting between the modeled and observed surface roughness of seep oil slicks and seawater.展开更多
Deep coal seams show low permeability,low elastic modulus,high Poisson’s ratio,strong plasticity,high fracture initiation pressure,difficulty in fracture extension,and difficulty in proppants addition.We proposed the...Deep coal seams show low permeability,low elastic modulus,high Poisson’s ratio,strong plasticity,high fracture initiation pressure,difficulty in fracture extension,and difficulty in proppants addition.We proposed the concept of large-scale stimulation by fracture network,balanced propagation and effective support of fracture network in fracturing design and developed the extreme massive hydraulic fracturing technique for deep coalbed methane(CBM)horizontal wells.This technique involves massive injection with high pumping rate+high-intensity proppant injection+perforation with equal apertures and limited flow+temporary plugging and diverting fractures+slick water with integrated variable viscosity+graded proppants with multiple sizes.The technique was applied in the pioneering test of a multi-stage fracturing horizontal well in deep CBM of Linxing Block,eastern margin of the Ordos Basin.The injection flow rate is 18 m^(3)/min,proppant intensity is 2.1 m^(3)/m,and fracturing fluid intensity is 16.5 m^(3)/m.After fracturing,a complex fracture network was formed,with an average fracture length of 205 m.The stimulated reservoir volume was 1987×10^(4)m^(3),and the peak gas production rate reached 6.0×10^(4)m^(3)/d,which achieved efficient development of deep CBM.展开更多
Two allyldimethylalkyl quaternary ammonium salt(AQAS)monomers,N,N-dimethylallylphenylpropylammonium bromide(AQAS1)and N,N-dimethylallylnonylammonium bromide(AQAS2),were synthesized and used to prepare modified polyacr...Two allyldimethylalkyl quaternary ammonium salt(AQAS)monomers,N,N-dimethylallylphenylpropylammonium bromide(AQAS1)and N,N-dimethylallylnonylammonium bromide(AQAS2),were synthesized and used to prepare modified polyacrylamide materials.Two new drag reducers were synthesized from acrylamide(AM),sodium acrylate(Na AA)and a cationic modified monomer(AQAS1 or AQAS2)via aqueous solution polymerization,and the copolymers were named P(AM/Na AA/AQAS1)and P(AM/Na AA/AQAS2),respectively.The structures of the drag reduction agents were confirmed by IR and1H NMR spectroscopies.The molecular weight(Mw)of P(AM/Na AA/AQAS1)was 1.79×10^(6)g/mol.When the copolymer concentration was 1000 mg/L and the flow rate was 45 L/min,in fresh water the highest drag reduction rate was 75.8%,in 10,000 mg/L Na Cl solution the drag reduction rate decreased to 72.9%.The molecular weight of P(AM/Na AA/AQAS2)was 3.17×10^(6)g/mol.When the copolymer concentration was500 mg/L and the flow rate was 45 L/min,the drag reduction rate reached 75.2%,and in 10,000 mg/L Na Cl solution the drag reduction rate was 73.3%,decreased by approximately 1.9%.The drag reduction rate for partially hydrolyzed polyacrylamide(HPAM)was also investigated,and the results showed that the drag reduction rates for 500 and 1000 mg/L HPAM solutions were merely 43.2%and 49.0%in brine,respectively.Compared with HPAM,both of the above copolymers presented better drag reduction capacities.展开更多
In this paper,we compared the normalized radar cross section in the cases of oil spill,biogenic slicks,and clean sea areas with image samples made from 11-pixel NRCS average,and determined their thresholds of the NRCS...In this paper,we compared the normalized radar cross section in the cases of oil spill,biogenic slicks,and clean sea areas with image samples made from 11-pixel NRCS average,and determined their thresholds of the NRCS of the synthetic aperture radar. The results show that the thresholds of oil and biogenic slicks exhibit good consistency with the corresponding synthetic aperture radar images. In addition,we used the normalized radar cross section of clean water from adjacent patches of oil or biogenic slicks areas to replace that of oil or biogenic slicks areas,and retrieve wind field by CMOD5.n and compare wind velocity mending of oil and biogenic slicks areas with Weather Research and Forecasting modeled data,from which the root mean squares of wind speed(wind direction) inversion are 0.89 m/s(20.26°) and 0.88 m/s(7.07°),respectively. Therefore,after the occurrence of oil spill or biogenic slicks,the real wind field could be repaired using the method we introduced in this paper. We believe that this method could improve the accuracy in assessment of a real wind field on medium and small scales at sea,and enhance effectively the monitoring works on similar oil or biogenic slicks incidents at sea surface.展开更多
Egypt is a highly populated country of about 85 million inhabitants that are concentrated on the Nile Delta and on the flood plain of the Nile River. More than 90% of this population relies on the Nile River in their ...Egypt is a highly populated country of about 85 million inhabitants that are concentrated on the Nile Delta and on the flood plain of the Nile River. More than 90% of this population relies on the Nile River in their water demand for domestic use. Currently, Egypt is facing a problem with the trans-boundary water budget coming from the Nile basin. This urges for managing the water quantity and quality to secure the water needs. This paper discusses the potential use of airborne hyperspectral data for water quality management in the form of detecting the oil contamination in the Nile River in integration with in-situ measurements including ASD spectroradiometer and eco-sounder multi-probe devices. The eco-sounder multi-probe device measured most of the water quality parameters and detected the existence of oil contamination at 1200 bb downstream of the study area. The airborne hyperspectral images were analyzed and calibrated with the spectral library determined from the in-situ spectroradiometer to map the patches of the oil contamination. The details of the findings and learning lessons are fully discussed in the paper.展开更多
Along with the rapid advance in global industrialization, oil spill events caused by offshore operations, trans- portation and accidents are increasing. Compared with ship surveys, monitoring oil spills through remote...Along with the rapid advance in global industrialization, oil spill events caused by offshore operations, trans- portation and accidents are increasing. Compared with ship surveys, monitoring oil spills through remote sensing has real-time, comprehensive, low-cost advantages, which can effectively guide cleaning and evalu- ation, and reduce the marine ecological destruction resulting from oil spills. Therefore, studying the remote sensing mechanism used to monitor marine oil spills is of great significance for ecological environmen- tal protection. This paper describes an experiment and corresponding analysis based on the above-water method, using the East China Sea coastal turbid water. The analysis shows that ＂upward short-wave＂ in ultraviolet and blue-purple bands and its displacement, along with the changing thickness, are important characteristics for distinguishing between the oil slick and the sea water, and also to differentiate oil slicks of different thicknesses. From blue to near-infrared bands, the spectrum of lube oil is flatter than that of diesel, and the diesel spectrum rises faster than the lube spectrum on the right side of the trough at 400 nm. These two features form an important basis for differentiating diesel from lube oil. These analyses will further the development of oil spill remote sensing in the East China Sea.展开更多
The dynamics of contained oil spills is investigated based on multiphase CFD (Computational Fluid Mechanics) model. The oil slick shape behind the oil boom under water current is studied. The velocity field in the oil...The dynamics of contained oil spills is investigated based on multiphase CFD (Computational Fluid Mechanics) model. The oil slick shape behind the oil boom under water current is studied. The velocity field in the oil slick is compared with the velocity field in pure water flow. The thickness of the oil slick is studied quantitatively. It is found that there is a fixed linear relationship between the oil slick relative thickness and the Froude number for different oil, different current velocity, different boom draft and different volume of oil.展开更多
To formulate fluids with flowback water,produced water directly to improve the utilization rate of recycling and reduce the adsorption damage of slick water to reservoirs,a high salt tolerance and low adsorption drag ...To formulate fluids with flowback water,produced water directly to improve the utilization rate of recycling and reduce the adsorption damage of slick water to reservoirs,a high salt tolerance and low adsorption drag reducer was designed and prepared by introducing polar cation fragments to enhance the non-covalent interactions between the chains.The drag reducer was characterized by IR and NMR.Friction resistance and viscosity tests were conducted to evaluate its salt resistance property.Static adsorption and dynamic adsorption retention tests were carried out to evaluate the damage of this reducer to shale reservoirs.The introduction of cation units into the molecular structure can weak the shielding effect of metal cations to some extent,so the drag reducer can keep a stable molecular structure and good resistant reducing performance under high salinity.The enhancement of non-covalent interaction between chains decreased the free polarity sites,further reduced the possibility of hydrogen bonding between drag reducer molecules and shale.In high salinity condition,both the adsorption capacity of the drag reducer on the shale surface and the average damage rate to the core permeability are low.Compared with the conventional salt-tolerant system,the overall liquid cost was reduced by 17%and the production per well increased by 44%.The application of this slick water system has achieved remarkable results.展开更多
The Sulige gas field is a typical low-pressure low-permeability tight sandstone gas reservoir. The reservoir has poor seepage capacity, strong heterogeneity, high mineralization of formation water and extremely scarce...The Sulige gas field is a typical low-pressure low-permeability tight sandstone gas reservoir. The reservoir has poor seepage capacity, strong heterogeneity, high mineralization of formation water and extremely scarce water resources on the site. These unfavorable factors have brought great difficulties to the on-site mining process. Now, a nano-composite green environmental protection slick water fracturing fluid system CQFR can be quickly dissolved because of the larger specific surface area, and the small molecular size makes the damage to the reservoir less than 5%, and the average drag reduction effect can reach more than 73%. It can quickly and well dissolve and maintain performance under high salinity conditions and fracturing flowback fluids. It responds well to the complex reservoir conditions on the construction site and makes the flowback fluid recyable, which greatly reduces the consumption of water resources on the construction site and effectively improves the construction efficiency and economic benefits.展开更多
A dynamic experiment for oil dispersion into a water column was performed with a 21 m long, 0.5 m wide, and 1 m high wind-driven wave tank. At wind velocity between 6-12 m/s and with the oil slide kept constant (about...A dynamic experiment for oil dispersion into a water column was performed with a 21 m long, 0.5 m wide, and 1 m high wind-driven wave tank. At wind velocity between 6-12 m/s and with the oil slide kept constant (about 1 um), the rate of the oil content increase in the water column could be approximated from the difference between the dispersion rate (R) of the oil slick and the coagulation rate (R’) of the dispersed oil slick. Assuming the coagulation rate is directly proportional to the concentration of the water dispersed oil slick (i. e. R’ =KC),, the integral form of the dynamic model can be expressed as C=R*[1-exp(-K*t)]/K and parameters R and K can be regressed with a computer. The relative deviation of model results from the experimental data was mainly less than 10%. The oil slick dispersion rate (R) had exponential relationship with the wind velocity (V), and can be fitted with a formula R=A*(U+1)B.The fitted constant of the coagulation rate, K(0.8-3.0* 10-3 min-1) did not have significant展开更多
This paper adopted an upstream FEM of 2-D unsteady flow to calculate the tidal flow in Zhoushan sea area. Based on the verification of the tidal current and environmental situation, the effects of the oily waste disch...This paper adopted an upstream FEM of 2-D unsteady flow to calculate the tidal flow in Zhoushan sea area. Based on the verification of the tidal current and environmental situation, the effects of the oily waste discharged from the oil berths on water quality have been calculated with a similar method. The isodilutions of oil pollutant are drawn from different sewage discharges. The moving loci of the slick centrepoint of oil spill have been calculated. The spreading area of the oil spill has also been forecasted. The results indicate that the set of models can predict the transport of oil spill in the sea area with reasonable accuracy.展开更多
In order to solve the difficulties in the volume fracturing stimulation of Middle Jurassic Shaximiao Formation tight sandstone reservoirs in the Qiulin Block of Central Sichuan Basin and explore the adaptability of hi...In order to solve the difficulties in the volume fracturing stimulation of Middle Jurassic Shaximiao Formation tight sandstone reservoirs in the Qiulin Block of Central Sichuan Basin and explore the adaptability of high-intensity volumefracturing technology,we selected the outcrop samples of Shaximiao Formation tight sandstone in the Qiulin Block to carry out the physical simulation experiment of true triaxial hydraulic fracturing.On this basis,horizontal well cluster perforation was optimally designed by using the production predictionmodel of staged multi-cluster fracturing horizontal wells.Then,based on the liquid control and proppant increase mode,three rounds of pilot tests were carried out on the tight sandstone reservoirs in this area.Andthe following research resultswere obtained.First,natural fractures in the ShaximiaoFormation tight sandstone reservoir of theQiulin Block are undeveloped,and hydraulic fractures are morphologically dominated by symmetric double-wing fractures,so complex fracture networks can be hardly formed.In addition,the reservoir is of medium to strong water sensitivity,so conventional volume fracturing is not adaptive to the reservoir stimulation in this block.Second,the connotation of high-intensity volume fracturing technology is to carry out multi-cluster perforation in each section to form multiple independent double-wing fractures and to implement the proppant injection mode of liquid control and proppant increase to reduce the inflowfluid while ensuring the high-intensity proppant injection,so as to reduce the damage of inflowfluid to the formation.Third,there are 10 fracturing sections inWell Qiulin 207-5-H2,with 7-12 clusters in each section,and the displacement is in the range of 16-18m^(3)/min.According to the fluid control and proppant increase mode,12146 m^(3) slick water and 4170 t proppant are injected in total.The tested production rate and absolute open flow of natural gas after the fracturing are up to 83.88×10^(4)m^(3)/d and 214.05×10^(4)m^(3)/d,respectively.Fourth,with the decrease of cluster spacing,the cumulative gas production increases gradually,but when the cluster spacing is less than 15 m,the increase amplitude of cumulative gas production decreases.Fifth,when the proppant injection intensity is lower than 6 t/m,the tested gas production per kilometer of stimulated section ina horizontal well overall presents an increasing trend with the increase of proppant injection intensity.When the proppant injection intensity is higher than 6 t/m,however,the tested gas production per kilometer of stimulated section does not increase significantly with the increase of proppant injection intensity.Sixth,as the included angle between the borehole trajectory and the direction ofmaximumhorizontal principal stress increases,the tested gas production per kilometer of stimulated section overall presents an increasing trend.When the hydraulic fracture is nearly perpendicular to the borehole,the effective drainage area is the largest and the tested gas production per kilometer of stimulated section is also the highest.In conclusion,the fracturing mode of high production well has a borehole trajectory of large included angle,perforation cluster spacing of 10 m or so,proppant injection intensity of 5 t/m and large-displacement slick water+continuous injection of combined particle size proppant.展开更多
Controlling marine pollution caused by hydrocarbons spilling from oil tanker accidents and oil rigs is urgently needed.Conventional pollution control vessels currently in service worldwide do not meet certain safety c...Controlling marine pollution caused by hydrocarbons spilling from oil tanker accidents and oil rigs is urgently needed.Conventional pollution control vessels currently in service worldwide do not meet certain safety criteria,storage capacities,and response times owing to their technical shortcomings.This study proposes a new concept of multimission and autonomous antipollution vessels capable of acting quickly and efficiently to counter such pollution threats.The objective of this study is to carry out a total and rapid recovery of the spilled oil slick in complete safety.Hence,optimizing the bulbous bow adapted to the pollution control vessel during its displacement is necessary to horizontally straighten the accompanying waves formed around the hull and to laminate the flow upstream of the side openings for the recovery of spilled oil.This optimization improves the nautical qualities specific to this ship to reduce the total resistance to progress and to standardize the flow upstream of the side openings to allow the collection of spilled oil at high speed.This optimization study can open a field of application for the construction of modern multi-mission pollution control vessels.Tests in hull basins will be planned to validate and adjust the results obtained from the simulations.展开更多
In this paper,shale gas cores from the Lower Silurian Longmaxi Formation in the Zhaotong National Shale Gas Demonstration Area were selected to study the hydration effect of differentfluids on the fracture morphology ...In this paper,shale gas cores from the Lower Silurian Longmaxi Formation in the Zhaotong National Shale Gas Demonstration Area were selected to study the hydration effect of differentfluids on the fracture morphology inside the shale,the rock tensile strength and the Brazilian tensile failure mode.Fresh water and slick water were adopted for hydration pretreatments and the CT technique was used to compare the changes of the fabric in the shale.Then,Brazilian tensile tests were carried out to study the tensile strength and tensile failure modes of the shale specimen after hydration pretreatment.Finally,two horizontal wells in the study area were selected to perform pilot tests of hydration pre-treatment in their fracturing operation sites.And the following research results were obtained.First,in the process of spontaneous imbibition,the hydration effect of fresh water is superior to that of slick water in promoting the fracture complexity of marine shale in the same hydration duration.Second,fresh water has greater surface tension and lower viscosity and its hydration effect can not only promote the propagation of original fractures but induce new micro-fractures or branches,while the hydration effect of slick water mainly promotes the propagation of original fractures.Third,due to hydration effect,marine shale is damaged and its tensile strength is reduced.After the hydration pretreatment by fresh water and slick water,the tensile strength of the shale specimens are reduced by 35.6%and 18.1%,respectively.Fourth,according to the propagation paths of main fractures,the Brazilian tensile failure modes of hydrated shale can be divided into four types(i.e.,step shaped,dog-leg shaped,branching shaped and arc shaped)or their combinations,while the tensile failure mode of unhydrated shale is only a straight line.Fifth,hydration effect can effectively increase the complexity of the hydraulic fractures in marine shale,so if the conditions permit,it is recommended to inject a certain amount of fresh water at a high pumping rate within the limited pressure after perforation and to shut in the well until the hydraulic fracturing operation.And in order to reduce the difficulties of pumping the proppant during the hydraulic fracturing operation,a pumping strategy of“low proppant concentration,large volume of slurries”can be adopted to reach the expected proppant volume.展开更多
Through the study of the theory of oil spill model, a mathematical modeling of oil spill on the sea is developed which with the consideration of spread, diffusion, drifting and attenuation of oil slick is influenced b...Through the study of the theory of oil spill model, a mathematical modeling of oil spill on the sea is developed which with the consideration of spread, diffusion, drifting and attenuation of oil slick is influenced by evaporation and emulsification factors. A model that under the effect of ocean dynamic condition of tide, wind and wave, using Monte Carlo method to simulate the movement of oil slick is established. The modeling is applied to calculate and predict pollution range of oil spill at oil quay and oil ship in Daya Bay. The prediction results have basically shown the pollution situation by emergency of oil spill on the sea.展开更多
Offshore oil slicks are significant for both the monitoring of marine spill accidents and the detection of marine oil resources.The use of remote sensing technology to detect the thickness of oil slicks is a major are...Offshore oil slicks are significant for both the monitoring of marine spill accidents and the detection of marine oil resources.The use of remote sensing technology to detect the thickness of oil slicks is a major area of research.The reflected light from oil slicks changes with the thickness of the oil.This is the theoretical basis of research on optical remote sensing of offshore oil slicks.A two-beam interference model that considers the offshore oil slick as a flat plate has been developed in this study.A quantitative remote sensing model which describes a series of processes that use oil slick thickness and reflectance as variables is established.The use of the Fresnel equation to analyze parameters in the model indicated that the key property of the quantitative relationship between the oil slick thickness and reflectance was ultimately the disappearance or extinction of the oil slick.This model has been tested and verified by data from offshore oil slick spectral response experiments.Results showed that the oil slick thickness remote sensing model can be theoretically analyzed and is efficient.The research indicated that the major cause of variations in the spectral response as a function of oil slick thickness was the different light-scattering characteristics.These characteristics can be used in remote sensing applications to identify the different types of offshore oil slicks.The theoretical interpretation of each parameter in this model led to the development of a look-up table of the model parameters which will improve the efficiency of future offshore oil slick remote sensing.展开更多
Determining oil slick thickness plays an important role in assessing oil spill volume and its environmental impacts on the ocean.In this study,we used a Hyperion image of an oil spill accident area and seawater and fr...Determining oil slick thickness plays an important role in assessing oil spill volume and its environmental impacts on the ocean.In this study,we used a Hyperion image of an oil spill accident area and seawater and fresh crude oil samples collected in the Bohai Sea of China.A well-controlled laboratory experiment was designed to simulate spectral responses to different oil slick thicknesses.Spectral resampling and normalization methods were used to reduce the differences in spectral reflectances between the experimental background seawater sample and real background seawater.Fitting the analysis with laboratory experimental data results showed a linear relationship between normalized oil slick reflectance and normalized oil slick thickness[20th band(R^(2)-0.92938,n=49,pB0.01),26th band(R^(2)=0.93806,n=49,pB0.01),29th band(R^(2)=0.93288,n=49,pB0.01)].By using these statistical models,we successfully determined the normalized oil slick thickness with the Hyperion image.Our results indicate that hyperspectral remote sensing technology is an effective method to monitor oil spills on water.The spectral ranges of visible green and red light were the optimal bands for estimating oil slick thickness in case 2 water.The high,stabilized spectral reflectance of background seawater will be helpful in oil slick thickness inversion.展开更多
基金supported by the National Key R&D Program of China[Grant number 2021YFB3901300]the ESA-NRSCC Dragon-5 cooperation project[ID 57979]+1 种基金the Agenzia Spaziale Italiana under the APPLICAVEMARS project[ASI contract n.2021-4-U.0]the China Scholarship Council.
文摘This paper contrasts predicted X-band sea surface backscattering from slick-free and oil-covered sea surfaces with actual measurements acquired by the X-band satellite TerraSAR-X and COSMO-SkyMed Synthetic Aperture Radar(SAR)missions.Two SAR scenes were acquired with a temporal difference of about 36 minutes,under similar met-ocean conditions,during the North Sea’s Gannet Alpha oil spill accident.The normalized radar cross section of the slick-free sea surface is predicted using the Advanced Integral Equation Model(AIEM)while the backscatter from the oiled sea surface is predicted by the AIEM augmented with the Model of Local Balance(MLB)to include the damping effect of oil slicks.Experimental results show that X-band co-polarized numerical predictions agree reasonably well with both TSX and CSK actual measurements collected over slick-free sea surfaces.When dealing with oil-covered sea surfaces,the predicted backscattering reasonably agrees with TSX measurements,while it overestimates the CSK ones.This is likely due to the different spreading conditions of the oil imaged by the two satellite missions.
基金supported by the National Natural Science Foundation of China(Nos.41906152 and 42076238).
文摘The purpose of this study was to investigate the characteristics of sea surface waves as they pass through oil slicks.The parameterized first-guess spectrum method(PFSM)theory-based wave retrieval algorithm was applied to 20 images of horizontal-horizontal(HH)polarization obtained using the phased-array L-band synthetic aperture radar(SAR)(PALSAR)on the Advanced Land Observing Satellite(ALOS-1).The images were collocated with simulations from the WAVEWATCH-Ⅲ(WW3)model in a 0.1°grid using the European Centre for Medium-Range Weather Forecasts(ECMWF)reanalysis(ERA-5)winds data as the forcing field.The validation of the model-simulated significant wave height(SWH)against the measurements from the Jason-2 altimeter produced a 0.66m root mean square error(RMSE)for the SWH,with a coefficient(COR)0.74.In this sense,the WW3-simulated waves were reliable for our work.A comparison between the SAR retrieval results and the WW3 simulations was performed using the dataset for the regions without oil slicks,which produced a 0.34m RMSE for the SWH,with a COR of 0.79,which is less than a the RMSE of 0.52 m and the COR of 0.70 for the regions with oil slicks.Moreover,it was found that the SAR-derived SWHs were significantly underestimated by about 0.2m in the areas with oil slicks.This difference is probably due to the underestimation of the SAR-derived wind speeds at moderate wind speeds(i.e.,at wind speeds of greater than 5ms^(-1)).An additional analysis compared the SAR-derived wave spectra with those from the WW3 model as waves passed through the oil slicks.The interesting finding is that the wave energy at short wave lengths(about 30m)is reduced by the oil slicks,causing the movement of the dominant wave spectrum to shift to longer wave lengths(about 80 m).
基金Natural Science Foundation of Jiangsu Province[Grant no.BK20160023] National Natural Science Foundation of China[Grant Nos.41771376,41371014,61675099]the National Key Research and Development Program of China[Grant no.2016YFC1400901].
文摘The critical angle is the angle at which the contrast of oil slicks reverse their contrasts against the surrounding oil-free seawater under sunglint.Accurate determination of the critical angle can help estimate surface roughness and refractive index of the oil slicks.Although it’s difficult to determine a certain critical angle,the potential critical angle range help to improve the estimation accuracy.In this study,the angle between the viewing direction and the direction of mirror reflection is used as an indicator for quantifying the critical angle and could be calculated from the solar/viewing geometry from observations of the Moderate Resolution Imaging Spectroradiometer(MODIS).The natural seep oil slicks in the Gulf of Mexico were first delineated using a customized segmentation approach to remove noise and apply a morphological filter.On the basis of the histograms of the brightness values of the delineated oil slicks,the potential range of the critical angle was determined,and then an optimal critical angle between oil slicks and seawater was then determined from statistical and regression analyses in this range.This critical angle corresponds to the best fitting between the modeled and observed surface roughness of seep oil slicks and seawater.
基金Supported by the National Natural Science Foundation of China Project(52274014)Comprehensive Scientific Research Project of China National Offshore Oil Corporation(KJZH-2023-2303)。
文摘Deep coal seams show low permeability,low elastic modulus,high Poisson’s ratio,strong plasticity,high fracture initiation pressure,difficulty in fracture extension,and difficulty in proppants addition.We proposed the concept of large-scale stimulation by fracture network,balanced propagation and effective support of fracture network in fracturing design and developed the extreme massive hydraulic fracturing technique for deep coalbed methane(CBM)horizontal wells.This technique involves massive injection with high pumping rate+high-intensity proppant injection+perforation with equal apertures and limited flow+temporary plugging and diverting fractures+slick water with integrated variable viscosity+graded proppants with multiple sizes.The technique was applied in the pioneering test of a multi-stage fracturing horizontal well in deep CBM of Linxing Block,eastern margin of the Ordos Basin.The injection flow rate is 18 m^(3)/min,proppant intensity is 2.1 m^(3)/m,and fracturing fluid intensity is 16.5 m^(3)/m.After fracturing,a complex fracture network was formed,with an average fracture length of 205 m.The stimulated reservoir volume was 1987×10^(4)m^(3),and the peak gas production rate reached 6.0×10^(4)m^(3)/d,which achieved efficient development of deep CBM.
基金supported by the National Natural Science Foundation of China(Project Nos.51774062 and 52274032)Scientific and Technological Key Research Program of Chongqing Municipal Education Commission(KJZD-K201901502)+1 种基金General Project of Chongqing Natural Science Foundation(CSTB2022NSCQMSX0349)Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN202313101)。
文摘Two allyldimethylalkyl quaternary ammonium salt(AQAS)monomers,N,N-dimethylallylphenylpropylammonium bromide(AQAS1)and N,N-dimethylallylnonylammonium bromide(AQAS2),were synthesized and used to prepare modified polyacrylamide materials.Two new drag reducers were synthesized from acrylamide(AM),sodium acrylate(Na AA)and a cationic modified monomer(AQAS1 or AQAS2)via aqueous solution polymerization,and the copolymers were named P(AM/Na AA/AQAS1)and P(AM/Na AA/AQAS2),respectively.The structures of the drag reduction agents were confirmed by IR and1H NMR spectroscopies.The molecular weight(Mw)of P(AM/Na AA/AQAS1)was 1.79×10^(6)g/mol.When the copolymer concentration was 1000 mg/L and the flow rate was 45 L/min,in fresh water the highest drag reduction rate was 75.8%,in 10,000 mg/L Na Cl solution the drag reduction rate decreased to 72.9%.The molecular weight of P(AM/Na AA/AQAS2)was 3.17×10^(6)g/mol.When the copolymer concentration was500 mg/L and the flow rate was 45 L/min,the drag reduction rate reached 75.2%,and in 10,000 mg/L Na Cl solution the drag reduction rate was 73.3%,decreased by approximately 1.9%.The drag reduction rate for partially hydrolyzed polyacrylamide(HPAM)was also investigated,and the results showed that the drag reduction rates for 500 and 1000 mg/L HPAM solutions were merely 43.2%and 49.0%in brine,respectively.Compared with HPAM,both of the above copolymers presented better drag reduction capacities.
基金Supported by the National Natural Science Foundation of China(No.41176160)the "135 Program" of Chinese Academy of Sciences(No.Y455011031)
文摘In this paper,we compared the normalized radar cross section in the cases of oil spill,biogenic slicks,and clean sea areas with image samples made from 11-pixel NRCS average,and determined their thresholds of the NRCS of the synthetic aperture radar. The results show that the thresholds of oil and biogenic slicks exhibit good consistency with the corresponding synthetic aperture radar images. In addition,we used the normalized radar cross section of clean water from adjacent patches of oil or biogenic slicks areas to replace that of oil or biogenic slicks areas,and retrieve wind field by CMOD5.n and compare wind velocity mending of oil and biogenic slicks areas with Weather Research and Forecasting modeled data,from which the root mean squares of wind speed(wind direction) inversion are 0.89 m/s(20.26°) and 0.88 m/s(7.07°),respectively. Therefore,after the occurrence of oil spill or biogenic slicks,the real wind field could be repaired using the method we introduced in this paper. We believe that this method could improve the accuracy in assessment of a real wind field on medium and small scales at sea,and enhance effectively the monitoring works on similar oil or biogenic slicks incidents at sea surface.
文摘Egypt is a highly populated country of about 85 million inhabitants that are concentrated on the Nile Delta and on the flood plain of the Nile River. More than 90% of this population relies on the Nile River in their water demand for domestic use. Currently, Egypt is facing a problem with the trans-boundary water budget coming from the Nile basin. This urges for managing the water quantity and quality to secure the water needs. This paper discusses the potential use of airborne hyperspectral data for water quality management in the form of detecting the oil contamination in the Nile River in integration with in-situ measurements including ASD spectroradiometer and eco-sounder multi-probe devices. The eco-sounder multi-probe device measured most of the water quality parameters and detected the existence of oil contamination at 1200 bb downstream of the study area. The airborne hyperspectral images were analyzed and calibrated with the spectral library determined from the in-situ spectroradiometer to map the patches of the oil contamination. The details of the findings and learning lessons are fully discussed in the paper.
基金scientific research fund of the National Key Technology Research and Development Program of China under contact No.2012BAH32B01Second Institute of Oceanography,State Oceanic Administration(SOA)under contact No.JG1016Public science and technology research funds project of ocean under contact No.200805028
文摘Along with the rapid advance in global industrialization, oil spill events caused by offshore operations, trans- portation and accidents are increasing. Compared with ship surveys, monitoring oil spills through remote sensing has real-time, comprehensive, low-cost advantages, which can effectively guide cleaning and evalu- ation, and reduce the marine ecological destruction resulting from oil spills. Therefore, studying the remote sensing mechanism used to monitor marine oil spills is of great significance for ecological environmen- tal protection. This paper describes an experiment and corresponding analysis based on the above-water method, using the East China Sea coastal turbid water. The analysis shows that ＂upward short-wave＂ in ultraviolet and blue-purple bands and its displacement, along with the changing thickness, are important characteristics for distinguishing between the oil slick and the sea water, and also to differentiate oil slicks of different thicknesses. From blue to near-infrared bands, the spectrum of lube oil is flatter than that of diesel, and the diesel spectrum rises faster than the lube spectrum on the right side of the trough at 400 nm. These two features form an important basis for differentiating diesel from lube oil. These analyses will further the development of oil spill remote sensing in the East China Sea.
文摘The dynamics of contained oil spills is investigated based on multiphase CFD (Computational Fluid Mechanics) model. The oil slick shape behind the oil boom under water current is studied. The velocity field in the oil slick is compared with the velocity field in pure water flow. The thickness of the oil slick is studied quantitatively. It is found that there is a fixed linear relationship between the oil slick relative thickness and the Froude number for different oil, different current velocity, different boom draft and different volume of oil.
基金Supported by the China National Science and Technology Major Project(2017ZX05023003)National Science Fund for Distinguished Young Scholars(51525404)
文摘To formulate fluids with flowback water,produced water directly to improve the utilization rate of recycling and reduce the adsorption damage of slick water to reservoirs,a high salt tolerance and low adsorption drag reducer was designed and prepared by introducing polar cation fragments to enhance the non-covalent interactions between the chains.The drag reducer was characterized by IR and NMR.Friction resistance and viscosity tests were conducted to evaluate its salt resistance property.Static adsorption and dynamic adsorption retention tests were carried out to evaluate the damage of this reducer to shale reservoirs.The introduction of cation units into the molecular structure can weak the shielding effect of metal cations to some extent,so the drag reducer can keep a stable molecular structure and good resistant reducing performance under high salinity.The enhancement of non-covalent interaction between chains decreased the free polarity sites,further reduced the possibility of hydrogen bonding between drag reducer molecules and shale.In high salinity condition,both the adsorption capacity of the drag reducer on the shale surface and the average damage rate to the core permeability are low.Compared with the conventional salt-tolerant system,the overall liquid cost was reduced by 17%and the production per well increased by 44%.The application of this slick water system has achieved remarkable results.
文摘The Sulige gas field is a typical low-pressure low-permeability tight sandstone gas reservoir. The reservoir has poor seepage capacity, strong heterogeneity, high mineralization of formation water and extremely scarce water resources on the site. These unfavorable factors have brought great difficulties to the on-site mining process. Now, a nano-composite green environmental protection slick water fracturing fluid system CQFR can be quickly dissolved because of the larger specific surface area, and the small molecular size makes the damage to the reservoir less than 5%, and the average drag reduction effect can reach more than 73%. It can quickly and well dissolve and maintain performance under high salinity conditions and fracturing flowback fluids. It responds well to the complex reservoir conditions on the construction site and makes the flowback fluid recyable, which greatly reduces the consumption of water resources on the construction site and effectively improves the construction efficiency and economic benefits.
文摘A dynamic experiment for oil dispersion into a water column was performed with a 21 m long, 0.5 m wide, and 1 m high wind-driven wave tank. At wind velocity between 6-12 m/s and with the oil slide kept constant (about 1 um), the rate of the oil content increase in the water column could be approximated from the difference between the dispersion rate (R) of the oil slick and the coagulation rate (R’) of the dispersed oil slick. Assuming the coagulation rate is directly proportional to the concentration of the water dispersed oil slick (i. e. R’ =KC),, the integral form of the dynamic model can be expressed as C=R*[1-exp(-K*t)]/K and parameters R and K can be regressed with a computer. The relative deviation of model results from the experimental data was mainly less than 10%. The oil slick dispersion rate (R) had exponential relationship with the wind velocity (V), and can be fitted with a formula R=A*(U+1)B.The fitted constant of the coagulation rate, K(0.8-3.0* 10-3 min-1) did not have significant
文摘This paper adopted an upstream FEM of 2-D unsteady flow to calculate the tidal flow in Zhoushan sea area. Based on the verification of the tidal current and environmental situation, the effects of the oily waste discharged from the oil berths on water quality have been calculated with a similar method. The isodilutions of oil pollutant are drawn from different sewage discharges. The moving loci of the slick centrepoint of oil spill have been calculated. The spreading area of the oil spill has also been forecasted. The results indicate that the set of models can predict the transport of oil spill in the sea area with reasonable accuracy.
基金Project supported by the Scientific Research and Technical Development Project of Postdoctoral Workstation of PetroChina Southwest Oil and Gas Field Company“Research on fracture morphology control and reconstruction technology of tight sandstone gas reservoir in Jinhua-Zhongtaishan ShaximiaoFormation”(No:20190302-15).
文摘In order to solve the difficulties in the volume fracturing stimulation of Middle Jurassic Shaximiao Formation tight sandstone reservoirs in the Qiulin Block of Central Sichuan Basin and explore the adaptability of high-intensity volumefracturing technology,we selected the outcrop samples of Shaximiao Formation tight sandstone in the Qiulin Block to carry out the physical simulation experiment of true triaxial hydraulic fracturing.On this basis,horizontal well cluster perforation was optimally designed by using the production predictionmodel of staged multi-cluster fracturing horizontal wells.Then,based on the liquid control and proppant increase mode,three rounds of pilot tests were carried out on the tight sandstone reservoirs in this area.Andthe following research resultswere obtained.First,natural fractures in the ShaximiaoFormation tight sandstone reservoir of theQiulin Block are undeveloped,and hydraulic fractures are morphologically dominated by symmetric double-wing fractures,so complex fracture networks can be hardly formed.In addition,the reservoir is of medium to strong water sensitivity,so conventional volume fracturing is not adaptive to the reservoir stimulation in this block.Second,the connotation of high-intensity volume fracturing technology is to carry out multi-cluster perforation in each section to form multiple independent double-wing fractures and to implement the proppant injection mode of liquid control and proppant increase to reduce the inflowfluid while ensuring the high-intensity proppant injection,so as to reduce the damage of inflowfluid to the formation.Third,there are 10 fracturing sections inWell Qiulin 207-5-H2,with 7-12 clusters in each section,and the displacement is in the range of 16-18m^(3)/min.According to the fluid control and proppant increase mode,12146 m^(3) slick water and 4170 t proppant are injected in total.The tested production rate and absolute open flow of natural gas after the fracturing are up to 83.88×10^(4)m^(3)/d and 214.05×10^(4)m^(3)/d,respectively.Fourth,with the decrease of cluster spacing,the cumulative gas production increases gradually,but when the cluster spacing is less than 15 m,the increase amplitude of cumulative gas production decreases.Fifth,when the proppant injection intensity is lower than 6 t/m,the tested gas production per kilometer of stimulated section ina horizontal well overall presents an increasing trend with the increase of proppant injection intensity.When the proppant injection intensity is higher than 6 t/m,however,the tested gas production per kilometer of stimulated section does not increase significantly with the increase of proppant injection intensity.Sixth,as the included angle between the borehole trajectory and the direction ofmaximumhorizontal principal stress increases,the tested gas production per kilometer of stimulated section overall presents an increasing trend.When the hydraulic fracture is nearly perpendicular to the borehole,the effective drainage area is the largest and the tested gas production per kilometer of stimulated section is also the highest.In conclusion,the fracturing mode of high production well has a borehole trajectory of large included angle,perforation cluster spacing of 10 m or so,proppant injection intensity of 5 t/m and large-displacement slick water+continuous injection of combined particle size proppant.
文摘Controlling marine pollution caused by hydrocarbons spilling from oil tanker accidents and oil rigs is urgently needed.Conventional pollution control vessels currently in service worldwide do not meet certain safety criteria,storage capacities,and response times owing to their technical shortcomings.This study proposes a new concept of multimission and autonomous antipollution vessels capable of acting quickly and efficiently to counter such pollution threats.The objective of this study is to carry out a total and rapid recovery of the spilled oil slick in complete safety.Hence,optimizing the bulbous bow adapted to the pollution control vessel during its displacement is necessary to horizontally straighten the accompanying waves formed around the hull and to laminate the flow upstream of the side openings for the recovery of spilled oil.This optimization improves the nautical qualities specific to this ship to reduce the total resistance to progress and to standardize the flow upstream of the side openings to allow the collection of spilled oil at high speed.This optimization study can open a field of application for the construction of modern multi-mission pollution control vessels.Tests in hull basins will be planned to validate and adjust the results obtained from the simulations.
基金Project supported by the National Major Science and Technology Project“Zhaotong Shale Gas Exploration and Development Demonstration Project”(No.2017ZX05063)the Science and Technology Project of CNPC Chuanqing Drilling Engineering Company Limited“Study and Application of Hydration Mechanism of Shale Reservoir”(No.CQ2018B-23-1-4).
文摘In this paper,shale gas cores from the Lower Silurian Longmaxi Formation in the Zhaotong National Shale Gas Demonstration Area were selected to study the hydration effect of differentfluids on the fracture morphology inside the shale,the rock tensile strength and the Brazilian tensile failure mode.Fresh water and slick water were adopted for hydration pretreatments and the CT technique was used to compare the changes of the fabric in the shale.Then,Brazilian tensile tests were carried out to study the tensile strength and tensile failure modes of the shale specimen after hydration pretreatment.Finally,two horizontal wells in the study area were selected to perform pilot tests of hydration pre-treatment in their fracturing operation sites.And the following research results were obtained.First,in the process of spontaneous imbibition,the hydration effect of fresh water is superior to that of slick water in promoting the fracture complexity of marine shale in the same hydration duration.Second,fresh water has greater surface tension and lower viscosity and its hydration effect can not only promote the propagation of original fractures but induce new micro-fractures or branches,while the hydration effect of slick water mainly promotes the propagation of original fractures.Third,due to hydration effect,marine shale is damaged and its tensile strength is reduced.After the hydration pretreatment by fresh water and slick water,the tensile strength of the shale specimens are reduced by 35.6%and 18.1%,respectively.Fourth,according to the propagation paths of main fractures,the Brazilian tensile failure modes of hydrated shale can be divided into four types(i.e.,step shaped,dog-leg shaped,branching shaped and arc shaped)or their combinations,while the tensile failure mode of unhydrated shale is only a straight line.Fifth,hydration effect can effectively increase the complexity of the hydraulic fractures in marine shale,so if the conditions permit,it is recommended to inject a certain amount of fresh water at a high pumping rate within the limited pressure after perforation and to shut in the well until the hydraulic fracturing operation.And in order to reduce the difficulties of pumping the proppant during the hydraulic fracturing operation,a pumping strategy of“low proppant concentration,large volume of slurries”can be adopted to reach the expected proppant volume.
文摘Through the study of the theory of oil spill model, a mathematical modeling of oil spill on the sea is developed which with the consideration of spread, diffusion, drifting and attenuation of oil slick is influenced by evaporation and emulsification factors. A model that under the effect of ocean dynamic condition of tide, wind and wave, using Monte Carlo method to simulate the movement of oil slick is established. The modeling is applied to calculate and predict pollution range of oil spill at oil quay and oil ship in Daya Bay. The prediction results have basically shown the pollution situation by emergency of oil spill on the sea.
基金supported by National Natural Science Foundation of China (Grant Nos. 40971186 and 41001196 )the Open Research Fund of Key Laboratory of Digital Earth,Center for Earth Observation and Digital Earth,Chinese Academy of Sciences (Grant No. 2010LDE007)
文摘Offshore oil slicks are significant for both the monitoring of marine spill accidents and the detection of marine oil resources.The use of remote sensing technology to detect the thickness of oil slicks is a major area of research.The reflected light from oil slicks changes with the thickness of the oil.This is the theoretical basis of research on optical remote sensing of offshore oil slicks.A two-beam interference model that considers the offshore oil slick as a flat plate has been developed in this study.A quantitative remote sensing model which describes a series of processes that use oil slick thickness and reflectance as variables is established.The use of the Fresnel equation to analyze parameters in the model indicated that the key property of the quantitative relationship between the oil slick thickness and reflectance was ultimately the disappearance or extinction of the oil slick.This model has been tested and verified by data from offshore oil slick spectral response experiments.Results showed that the oil slick thickness remote sensing model can be theoretically analyzed and is efficient.The research indicated that the major cause of variations in the spectral response as a function of oil slick thickness was the different light-scattering characteristics.These characteristics can be used in remote sensing applications to identify the different types of offshore oil slicks.The theoretical interpretation of each parameter in this model led to the development of a look-up table of the model parameters which will improve the efficiency of future offshore oil slick remote sensing.
基金supported by National Natural Science Foundation of China(Grant No.41001196)the Open Research Fund of Key Laboratory of Marine Spill Oil Identification and Damage Assessment Technology,SOA(Grant No.201212)the Open Research Fund of Key Laboratory of Digital Earth,Center for Earth Observation and Digital Earth,Chinese Academy of Sciences(Grant No.2010LDE007).
文摘Determining oil slick thickness plays an important role in assessing oil spill volume and its environmental impacts on the ocean.In this study,we used a Hyperion image of an oil spill accident area and seawater and fresh crude oil samples collected in the Bohai Sea of China.A well-controlled laboratory experiment was designed to simulate spectral responses to different oil slick thicknesses.Spectral resampling and normalization methods were used to reduce the differences in spectral reflectances between the experimental background seawater sample and real background seawater.Fitting the analysis with laboratory experimental data results showed a linear relationship between normalized oil slick reflectance and normalized oil slick thickness[20th band(R^(2)-0.92938,n=49,pB0.01),26th band(R^(2)=0.93806,n=49,pB0.01),29th band(R^(2)=0.93288,n=49,pB0.01)].By using these statistical models,we successfully determined the normalized oil slick thickness with the Hyperion image.Our results indicate that hyperspectral remote sensing technology is an effective method to monitor oil spills on water.The spectral ranges of visible green and red light were the optimal bands for estimating oil slick thickness in case 2 water.The high,stabilized spectral reflectance of background seawater will be helpful in oil slick thickness inversion.
