Coupled thermo-hydro analysis of steam flow in a horizontal wellbore in a heavy oil reservoir

A novel model for dynamic temperature distribution in heavy oil reservoirs is derived from the principle of energy conservation.A difference equation of the model is firstly separated into radial and axial difference equations and then integrated.Taking into account the coupling of temperature and pressure in the reservoir and wellbore,models for calculating distributions of the reservoir temperature,reservoir pressure,and water saturation are also developed.The steam injected into the wellbore has a more significant effect on reservoir pressure than on reservoir temperature.Calculation results indicate that the reservoir temperature and pressure decrease exponentially with increasing distance from the horizontal wellbore.The radial variation range of the pressure field induced by steam is twice as wide as that of the temperature field,and both variation ranges decrease from the wellbore heel to the toe.Variation of water saturation induced by steam is similar to the temperature and pressure fields.The radial variation ranges of the reservoir temperature and pressure increase with steam injection time,but rate of increase diminishes gradually.

Application of steam injection in iron ore sintering:fuel combustion efficiency and CO emissions

Improving the combustion efficiency of fuels is essential to reducing pollutant emissions in the iron ore sintering process.The sintering bed surface steam-injection technology has attracted significant research interest for its potential advantages in low-energy consumption and low emission.The effect of steam injection on fuel combustion efficiency and CO emission was studied by comparing the thermodynamic response from the sintering process before and after steam injection.The mechanism of improving combustion efficiency was also revealed.The results indicated that the sintering gas medium of H_(2)O-H_(2)-N_(2)-O_(2) with the blown steam improved the heat transfer conditions of fuel combustion and promoted the water gas reaction.The optimum state of steam injection was achieved at 15 min after ignition with 0.02 m^(3) min^(-1).The CO emission reduction is 10.91% compared with the base case.The combustion efficiency was 88.83%,6.15% higher than conventional sintering,and the solid fuel consumption was reduced by 1.15 kg t^(-1).It was indicated that steam injection would improve combustion efficiency and reduce solid fuel consumption.Meanwhile,the steam injection could improve the combustion kinetic conditions in the zone of unburned fuel and low oxygen partial pressure.It was conducive to the reaction of H_(2)O with C and CO to convert the CO of reducing atmosphere to CO_(2),which in turn realized the complete combustion of fuel and CO and improved the efficiency of fuel combustion.

Application of direct steam injection system to minimize browning of white radish(Raphanus sativus)broth during sterilization

Direct steam injection(DSI)was applied to minimize the quality changes of white radish(Raphanus sativus)broth during sterilization.This study compared the degree of browning of white radish broth from a retort sterilization system and a DSI system.The quality changes after thermal treatments,such as retorting and DSI,were evaluated by Lab color values,the browning index(BI)and sensory evaluation.As the volume of the retort pouch increased,the thermal processing time increased.Significant increases of a and b values,color difference and BI were observed.Unlike the retort sterilization,the DSI treatment showed no significant differences in color properties of the radish broth with a wide range of sterilization temperature.The highest sensory score among the DSI treated samples was observed at the lowest sterilization temperature(125℃).The results demonstrated that the DSI treatment showed a higher stability in the quality associated with the browning reaction,such as the color indices and BI because the DSI process rapidly increased the temperature of the radish broth by transferring the latent heat of steam to the fluid.

Thermal oil recovery factors from sandpacks of variable mineralogy

S Steam injection is commonly used for production of viscous crude oil.Reservoir rock often contains clay minerals.Reactive nature of steam and clay minerals may lead to formation damage.This work in-vestigates oil recovery and changes in petrophysical properties as a function of the mineralogy.Sand-packs with quartz,calcite,feldspar,kaolinite,smectite,and illite were prepared for steam injection experiments.Permeability of the steamed sandpacks was determined using coreflood experiments.Chemical composition of the produced aqueous samples was determined using ICP-OES(inductively coupled plasma-optical emission spectroscopy).Morphology of the rock samples was studied using SEM-EDs(scanning electron microscope-energy dispersive X-ray spectroscopy).Mineralogy and elemental content of the solid samples were determined using XRD(X-ray diffraction)analysis and XRF(X-ray fluorescence)respectively.It was found that aqueous phase samples produced from clay-rich sandpacks tend to have higher pH than samples produced from samples without clay minerals.Oil recovery factors for 100%quartz case was determined to be 65 wt%.Calcite-and feldspar-rich sandpacks produced 56 and 61 wt%of oil respectively.Sandpacks with clay fractions have shown the lowest oil recovery-39,29,and 28 wt%for kaolinite-,smectite-,and illite-rich samples respectively.Mineral dissolution and pre-cipitation were the dominant damaging mechanism for quartz and calcite cases.Feldspar-rich sandpack demonstrated signs of structural destruction of the mineral and fines release.Kaolinite's effect on oil recovery was found to be associated with fines migration.Smectite hydration and swelling in presence of steam was the dominant formation damage effect on the oil production.Steam interaction with illite-rich sandpack caused formation of amorphous silica.This paper presents oil recovery factors as a function of injected pore volume(PV)of steam for sandpacks of different mineralogy.Obtained results characterize petrophysical changes caused by steam interaction with minerals in presence of oil.This data provides insights into effects of steam on minerals with different structures and properties.

Design and application of a novel coal-fired drum boiler using saline water in heavy oil recovery

In this paper,the design and operation of a novel coal-fired circulating fluidized bed(CFB)drum boiler that can generate superheated steam using saline water were introduced.The natural circulation water dynamics with a drum was adopted instead of the traditional once-through steam generator(OTSG)design,so that superheated steam can be generated for the better performance of the steam assisted gravity drainage(SAGD)technology in heavy oil recovery.The optimized staged evaporation method was proposed to further decrease the salinity of water in the clean water section of the boiler.The evaporating pipes of the salted water section were rearranged in the back pass of the boiler,where the heat load is low,to further improve the heat transfer safety.A CFB combustion technology was used for coal firing to achieve a uniform heat transfer condition with low heat flux.Pollutant control technologies were adopted to reduce pollutant emissions.Based on the field test,the recommended water standard for the coal-fired CFB drum boilers was determined.With the present technology,the treated recovery wastewater can be reused in steam-injection boilers to generate superheated steam.The engineering applications show that the boiler efficiency is higher than 90%,the blowdown rate is limited within 5.5%,and the superheat of steam can reach up to 30 K.Besides,the heavy oil recovery efficiency is significantly improved.Moreover,the pollutant emissions of SO2,NOV and dust are controlled within the ranges of 20-90 mg/(N·m^(3)),30-90 mg/(N·m^(3))and 2-10 mg/(N·m^(3))respectively.