The mechanisms of thermal solidification agent promoting steam diversion in heavy oil reservoirs

At high cycles of steam huff&puff,oil distribution in reservoirs becomes stronger heterogeneity due to steam channeling.Thermal solidification agent can be used to solve this problem.Its solution is a lowviscosity liquid at normal temperature,but it can be solidified above 80℃.The plugging degree is up to 99%at 250℃.The sweep efficiency reaches 59.2%,which is 7.3%higher than pure steam injection.In addition,simultaneous injection of viscosity reducer and/or nitrogen foams can further enhance oil recovery.The mechanism of this technology depends on its strong plugging ability,which changes the flowing pattern of steam to effectively mobilize remaining oil.Viscosity reducer and nitrogen foams further expand the sweep range and extends the effective period.Therefore,thermal solidification agent can plug steam channeling paths and adjust steam flowing direction to significantly enhance oil recovery at high cycles of steam huff&puff.

Aquathermolysis of conventional heavy oil with superheated steam

This paper presents a new aquathermolysis study of conventional heavy oil in superheated steam. A new high temperature autoclave was designed, where volume and pressure could be adjusted. Aquathermolysis was studied on two different conventional heavy oil samples under different reaction times and temperatures. Experimental results show that aquathermolysis does take place for conventional heavy oil. As reaction time increases, the oil viscosity reduces. However, the reaction will reach equilibrium after a certain period of time and won＇t be sensitive to any further reaction time any more. Analysis shows that, while resin and asphaltenes decrease, saturated hydrocarbons and the H/C ratio increase after reaction. The main mechanism of aquathermolysis includes hydrogenization, desulfuration reaction of resin and asphaltenes, etc.

Comparison of Constituents and Insecticidal Activities of Essential Oil from Artemisia lavandulaefolia by Steam Distillation and Supercritical-CO_2 Fluid Extraction

Essential oil was extracted from Artemisia lavandulaefolia DC.by steam distillation（SD） and supercritical-CO2 fluid extraction（SFE）,respectively.The constituents of the essentil oils extracted with those two methods were analyzed by gas chromatography-mass spectrometry（GC-MS） and insecticidal activities of the essential oils were evaluated,then the results were compared to assess their biological activity.Thirty-one compounds were identified in the essential oil extracted by SD,and its main components were eucalyptol,α,α,4-trimethyl-3-cyclohexene-1-methanol and so on.Twenty-two compounds were identified for the essential oil extracted by SFE,and its main components were cyclodecene,n-hexadecanoic acid and so on.Six chemical compositions were all contained in the essential oils extracted by the two methods,i.e.,eucalyptol,α,α,4-trimethyl-3-cyclohexene-1-methanol,caryophyllene,[3aS-（3aα,3bβ,4β,7α,7aS）]-octahydro-7-methyl-3-methylene-4-（1-methylethyl）-1H-cyclopenta[1,3]cyclopropa-[1,2]benzene,nerolidol and（-）-Spathulenol.The fumigation toxicity of the essential oil obtained by means of SD to the adults of Sitophilus zeamais is significantly higher than that of the essential oil by means of SFE.The contact toxicity of the essential oil obtained by means of SFE to the adults of S.zeamais is higher than that of the essential oil obtained by means of SD,but the difference is not significant.

Steam Flooding after Steam Soak in Heavy Oil Reservoirs through Extended-reach Horizontal Wells

This paper presents a new development scheme of simultaneous injection and production in a single horizontal well drilled for developing small block reservoirs or offshore reservoirs. It is possible to set special packers within the long completion horizontal interval to establish an injection zone and a production zone. This method can also be used in steam flooding after steam soak through a horizontal well. Simulation results showed that it was desirable to start steam flooding after six steam soaking cycles and at this time the oil/steam ratio was 0.25 and oil recovery efficiency was 23.48%. Steam flooding performance was affected by separation interval and steam injection rate. Reservoir numerical simulation indicated that maximum oil recovery would be achieved at a separation section of 40-50 m at steam injection rate of 100-180 t/d; and the larger the steam injection rate, the greater the water cut and pressure difference between injection zone and production zone. A steam injection rate of 120 t/d was suitable for steam flooding under practical injection-production conditions. All the results could be useful for the guidance of steam flooding projects.

Study of steam heat transfer enhanced by CO_(2) and chemical agents: In heavy oil production

Steam flooding with the assistance of carbon dioxide (CO_(2)) and chemicals is an effective approach for enhancing super heavy oil recovery. However, the promotion and application of CO_(2) and chemical agent-assisted steam flooding technology have been restricted by the current lack of research on the synergistic effect of CO_(2) and chemical agents on enhanced steam flooding heat transfer. The novel experiments on CO_(2)–chemicals cooperate affected steam condensation and seepage were conducted by adding CO_(2) and two chemicals (sodium dodecyl sulfate (SDS) and the betaine temperature-salt resistant foaming agent ZK-05200).According to the experimental findings, a “film” formed on the heat-transfer medium surface following the co-injection of CO_(2) and the chemical to impede the steam heat transfer, reducing the heat transfer efficiency of steam, heat flux and condensation heat transfer coefficient. The steam seepage experiment revealed that the temperature at the back end of the sandpack model was dramatically raised by 3.5–12.8 °C by adding CO_(2) and chemical agents, achieving the goal of driving deep-formation heavy oil. The combined effect of CO_(2) and SDS was the most effective for improving steam heat transfer, the steam heat loss was reduced by 6.2%, the steam condensation cycle was prolonged by 1.3 times, the condensation heat transfer coefficient was decreased by 15.5%, and the heavy oil recovery was enhanced by 9.82%. Theoretical recommendations are offered in this study for improving the CO_(2)–chemical-assisted steam flooding technique.

STUDY ON MASS TRANSFER IN SEPARATION OF ESSENTIAL OILS FROM PLANT MATERIALS BY STEAM DISTILLATION

The mass transfer model describing the separation of essential oils from plant materials has been proposed and the mass transfer coefficient has been obtained by fitting the present model to the experimental data for three kinds of plant materials. The validity of the model has been verified. To im' prove the vapor-solid contact, a mechanical agitator has been installed in the steam distillator. The effect of agitating rate on mass transfer coefficient has also been examined.

CO2 assisted steam flooding in late steam flooding in heavy oil reservoirs

To improve the oil recovery and economic efficiency in heavy oil reservoirs in late steam flooding,taking J6 Block of Xinjiang Oilfield as the research object,3D physical modeling experiments of steam flooding,CO2-foam assisted steam flooding,and CO2 assisted steam flooding under different perforation conditions are conducted,and CO2-assisted steam flooding is proposed for reservoirs in the late stage of steam flooding.The experimental results show that after adjusting the perforation in late steam flooding,the CO2 assisted steam flooding formed a lateral expansion of the steam chamber in the middle and lower parts of the injection well and a development mode for the production of overriding gravity oil drainage in the top chamber of the production well;high temperature water,oil,and CO2 formed stable low-viscosity quasi-single-phase emulsified fluid;and CO2 acted as a thermal insulation in the steam chamber at the top,reduced the steam partial pressure inside the steam chamber,and effectively improved the heat efficiency of injected steam.Based on the three-dimensional physical experiments and the developed situation of the J6 block in Xinjiang Oilfield,the CO2 assisted steam flooding for the J6 block was designed.The application showed that the CO2 assisted steam flooding made the oil vapor ratio increase from 0.12 to 0.16 by 34.0%,the oil recovery increase from 16.1%to 21.5%,and the final oil recovery goes up to 66.5%compared to steam flooding after perforation adjustment.

The Description of Oil Displacement Mechanism in Steam Injection of Multi-Field Synergy with Exergy Transfer

Steam injection is a most effective way for improving heavy oil recovery efficiency, and it has academic and practical significance for the mechanism of multi-field synergy oil displacement. Mechanism of “diversified” oil displacement which is obtained by traditional study methods in the exploitation territory of oil and gas fields has both respective roles and mutual cross shortages. To describe and analyze the displacement process of multi-field coupling with exergy transfer can simplify this kind of problem by introducing a unified goal-driving exergy. It needs to use the method of theoretical modeling, numerical simulation and experimental validation to study the basic law of exergy transfer in the oil displacement process of multi-field synergy, make a thorough research for the flooding process of steam injection with exergy transfer theory and reveal the oil displacement mechanism in steam injection of multi-field synergy. Thus the theory instruction and technical support can be provided to improve reservoirs producing degree and extraction ratio.

Preparation of Hydrogen through Catalytic Steam Reforming of Bio-oil

Hydrogen was prepared via catalytic steam reforming of bio-oil which was obtained from fast pyrolysis of biomass in a fluidized bed reactor.Influential factors including temperature,weight hourly space velocity(WHSV) of bio-oil,mass ratio of steam to bio-oil(S/B) as well as catalyst type on hydrogen selectivity and other desirable gas products were investigated.Based on hydrogen in stoichiometric potential and carbon balance in gaseous phase and feed,hydrogen yield and carbon selectivity were examined.The experimental results show that higher temperature favors the hydrogen selectivity by H2 mole fraction in gaseous products stream and it plays an important role in hydrogen yield and carbon selectivity.Higher hydrogen selectivity and yield,and carbon selectivity were obtained at lower bio-oil WHSV.In catalytic steam reforming system a maximum steam concentration value exists,at which hydrogen selectivity and yield,and carbon selectivity keep constant.Through experiments,preferential operation conditions were obtained as follows:temperature 800～850℃,bio-oil WHSV below 3.0 h-1,and mass ratio of steam to bio-oil 10～12.The performance tests indicate that Ni-based catalysts are optional,especially Ni/α-Al2O3 effective in the steam reforming process.

Mechanism investigation of steam flooding heavy oil by comprehensive molecular characterization

Steam flooding is a widely used technique to enhance oil recovery of heavy oil.Thermal viscosity reduction and distillation effect are considered as two main displacement mechanisms in steam flooding process.However,the molecular composition understanding and contribution for oil production are still unclear.In this study,the composition analysis of the heavy oil was investigated in the core scale steam flooding process with the temperature from 120 to 280℃.The crude oil,produced oils and residual oils were characterized comprehensively by gas chromatography and high-resolution mass spectrometry.It is found that steam flooding preferentially extracts aromatics and remains more resins in the residual oil.Viscosity reduction is the dominant mechanism when steam is injected at a low temperature.Large molecular heteroatoms with high carbon number and high double bond equivalent(DBE)are eluted into the produced oil,while compounds with low carbon number and low DBE are remained in the residual oil.As the steam temperature rises,the increased distillation effect results in the extraction of light hydrocarbons from the residual oil to the produced oil.More small heteroatoms with low carbon number and low DBE enter into the produced oil,especially in the none water cut stage.The compositional difference of produced oils is characterized in DBE versus carbon number distribution of the N and O containing compound classes.This work uses a variety of composition analysis methods to clarify the steam flooding mechanism and provides a novel understanding of steam flooding mechanisms with various temperatures and production stages from the molecular perspective.

Monitoring of steam chamber in steam-assisted gravity drainage based on the temperature sensitivity of oil sand

Thermosensitivity experiments and simulation calculations were conducted on typical oil sand core samples from Kinosis,Canada to predict the steam chamber development with time-lapse seismic data during the steam-assisted gravity drain-age(SAGD).Using an ultrasonic base made of polyether ether ketone resin instead of titanium alloy can improve the signal en-ergy and signal-to-noise ratio and get clear first arrival;with the rise of temperature,heavy oil changes from glass state(at-34.4℃),to quasi-solid state,and to liquid state(at 49.0℃)gradually;the quasi-solid heavy oil has significant frequency dis-persion.For the sand sample with high oil saturation,its elastic property depends mainly on the nature of the heavy oil,while for the sand sample with low oil saturation,the elastic property depends on the stiffness of the rock matrix.The elastic property of the oil sand is sensitive to temperature noticeably,when the temperature increases from 10℃ to 175℃,the oil sand samples decrease in compressional and shear wave velocities significantly.Based on the experimental data,the quantita-tive relationship between the compressional wave impedance of the oil sand and temperature was worked out,and the tem-perature variation of the steam chamber in the study area was predicted by time-lapse seismic inversion.

The Calculation of Heating Radius and Determination of Parameters in Heavy Oil Steam Stimulation

在稠油吞吐过程中,加热半径是热采中的重要指标,对注汽参数和生产制度起到了指导性作用。运用能量守恒原理,从热量注入方面考虑了蒸汽相变释放的气化潜热,从热量损失方面考虑井筒热量损失和顶底盖层热量损失,最终得到了新的加热半径计算公式。计算结果表明,加热半径受注汽参数、焖井时间、储层参数等因素影响,并系统阐述了岩层各物性参数的计算及选择方法。最后通过实例验证了该方法的计算值和试井解释出的值较为相符,为现场实际应用提供了可靠的方法。

A New Heat-conduction Logging Technique and its Application

The results of a heat-conduction experiment with a central point source in a sand barrel shows that the temperature of the heat source increase much faster in sand saturated with oil and air （dry sand） than in water sand. During cooling the temperature of the central heat source goes down slower in oil- or air-saturated sands than in water sands. Based on the theory of heat-conduction in porous media and the experimental results, we developed a new heat-conduction logging technique which utilizes an artificial heat source （dynamite charge or electric heater） to heat up target forma- tions in the borehole and then measure the change of temperature at a later time. Post-frac oil production is shown to be directly proportional to the size of the temperature anomaly when other reservoir parameters are fairly consistent. The method is used to evaluate potential oil production for marginal reservoirs in the FY formation in Song-Liao basin of China.

Research on Mechanisms of Steam Breakthrough and Profile Control Design for Steam Soaking Well

Scaled physical model tests for steam breakthrough were conducted based on the analysis of mechanisms and influence factors of steam breakthrough. Physical simulation results showed that at the initial steam breakthrough, preferential flow channels were formed in narrow sand packs and most residual oil left in these channels was immobile. This shortened the steam breakthrough time of follow-up steam flooding and decreased the increment of oil recovery efficiency. Steam breakthrough occurred easily for a smaller producer-injector spacing, and a bigger difference in physical properties between fluids and rock. Steam breakthrough is more likely to occur at a larger formation permeability （k）, greater steam displacement velocity （u） and smaller producer-injector spacing （L）. Steam breakthrough time is a function of the parameter group （uk/L）, i.e. tb=3.2151 （uk/L）^-0.5142. A non piston-like displacement model was built based on steam breakthrough observation for a steam stimulated well in the Jinglou Oilfield, Henan Oilfield Company. The steam volume swept in different directions could be obtained from inter-well permeability capacity and breakthrough angle, and the steam swept pore volume （SSPV） was also determined. Numerical simulation showed that steam sweep efficiency reached its peak value when a slug of profile control agent （slug size 10%-15% SSPV） was set at one half of the inter-well spacing. Field test with 12.5% SSPV of profile control agents in the Jinglou Oilfield achieved success in sealing breakthrough channels and good production performance of adjacent producers.

Enhanced Oil Recovery by Using Solar Energy: Case Study

This study investigates the steam generating potential of a solar steam generation system and the potential for utility scale implementation in Libya oil for steam demanding enhanced oil recovery (EOR) methods. The proposed system uses parabolic troughs as solar collectors. The technology is proved to be technically feasible. Solar EOR should be seen as an add-on to existing plants due to the abundance of solar energy in Libya. The System Advisor Model (SAM) model system, developed by the National Office of Renewable Energy (NRE), was used to assess the plant’s active and economic performance.

A Comparative Study on Hemp(Cannabis sativa)Essential Oil Extraction Using Traditional and Advanced Techniques

A comparative study of Cannabis sativa(Hemp)essential constituents obtained by using Supercritical Fluid Extraction(SCFE),Steam Distillation(SD)and Hydrodistillation(HD)is presented here.The optimized extraction temperatures were 130,110and 50℃for hydrodistillation,steam distillation and supercritical fluid extraction respectively.The essential oil of C.sativa was analyzed by using Gas chromatography mass spectrometry(GC-MS).A total of 33,30and 31components have been identified in HD,SD and SCFE respectively.Yield of essential oil using SCFE(0.039%)was more than HD(0.025%)and SD(0.035%)extraction respectively.The main component of sesquiterpenes obtained by hydrodistillation at 130℃with their percentages included caryophyllene(40.58%),trans-α-bergamotene(5.41%),humulene(10.97%),cis-β-farnesene(8.53%)and monoterpenes includedα-pinene(2.13%),d-limonene(6.46%),p-cymol(0.65%)and cineole(2.58%)respectively.The main component of sesquiterpenes obtained by SD steam distillation at110℃including caryophyllene(38.60%)trans-α-bergamotene(4.22%),humulene(10.26%),cis-β-farnesene(6.67%)and monoterpenes includedα-pinene(3.21%),d-limonene(7.07%),p-cymol(2.59%)and cineole(3.88%)whereas the more percentages of major components were obtained by SCFE at 50℃included caryophyllene(44.31%),trans-α-bergamotene(6.79%),humulene(11.97%)cis-β-farnesene(9.71%)and monoterpenes includedα-pinene(0.45%),d-limonene(2.13%)p-cymol(0.19%)and cineole(1.38%)respectively.We found yield/efficiency,chemical composition,quality of the essential oils by supercritical fluid extraction superior in terms of modern,green,saving energy and a rapid approach as compared to traditional techniques.

Correlation Dimension in Fault Diagnosis of 600 MW Steam Turbine Generator

GP algorithm of correlation dimension computation is ameliorated which overcomes the shortage of traditional one. Improved process of GP algorithm takes the influence of temporal correlative pairs of points on correlation dimension into account and promotes the computational efficiency prominently. Iterative SVD method is applied to remove the influence of noise on the result of correlation dimension. The faults of steam flow turbulence and oil film disturbance which occur in 600 MW Steam Turbine Generator are analyzed and whose correlation dimensions are computed. More distinct quantitative index than FFT is gained to distinguish two faults and it’s of little importance to apply correlation dimension to study the influence of various factors on steam flow turbulence fault for nonexistence of convergent floor in correlation integral curve, which presents a new way to learn the operational function of large capacity steam turbine generator and carry out comprehensive condition monitoring.

Analyzing the effect of steam quality and injection temperature on the performance of steam flooding

The heavy oil reservoirs are currently mainly targeted by thermal enhanced oil recovery technologies,particularly,steam flooding.Steam flooding is carried out by introducing heat into the reservoir to unlock the recovery of heavy oil by reducing oil viscosity.Several investigations were carried out to improve oil recovery by steam flooding.Most recently,high steam flooding is reported as an effective approach to improve recovery in high pressure heavy oil reservoirs.The oil recovery from steam flooding is sub-stantially affected by the steam quality and injection temperature.In this study,an attempt was made to look into the integration of parameters,i.e.steam quality and injection temperature upon steam flooding on oil recovery by using a simulation approach via ECLIPSE.The results obtained indicated that high temperature along with the moderate value of steam quality gives the best result regarding oil recovery for steam flooding in an economical way.

Extraction Optimization and Composition Analysis of Volatile Oil from Fruit of Alpinia zerumbet

[Objectives] The aim was to determine the optimum process for the extraction of volatile oil from Alpinia zerumbet fruit.[Methods]Steam distillation was used to extract volatile oil from A. zerumbet fruit. Based on the single factor tests,an orthogonal test was designed to explore the effects of solid-liquid ratio,soaking time,extraction time and grinding degree of material on the extraction rate. The composition of volatile oil from A. zerumbet fruit was analyzed using gas chromatography-mass spectrometry( GC-MS),and the relative mass fraction of each component was determined by peak area normalization. [Results] With volatile oil yield as the index,the optimum extraction process was determined: solid to liquid ratio of 1∶ 10,soaking time of 0. 5 h,grinding degree of passing through 24-mesh sieve and extraction time of 5 h. A total of 29 compounds were isolated. Among them,the contents of α-terpinene( 24. 894%),1,8-terpadiene( 15. 527%) andα-pinene( 6. 982%) were relatively high. [Conclusions]The optimized extraction process for volatile oil from A. zerumbet fruit is stable and reasonable. Under the optimum extraction process,the extraction effect of volatile oil from A. zerumbet fruit was the best. The chemical components of volatile oil from A. zerumbet fruit were determined by GC-MS as α-terpinene( 24. 894%),1,8-terpadiene( 15. 527%) and α-pinene( 6. 982%).

Organic bases as additives for steam-assisted gravity drainage

Steam-assisted gravity drainage(SAGD)is a mature technology for bitumen recovery from oil sands.However,it is an energy-intensive process that requires large amounts of steam to heat and mobilize bitumen.The purpose of this work is to develop ways to enhance SAGD performance through the use of organic base additives.The research is approached from three focus areas that supplement and guide each other:characterization tests,sand-pack floods,and computational simulation.A number of key mechanisms for enhancing oil recovery were identified,high-temperature additive characterization tests were developed,and promising alkalis were tested in porous media.Simulation was employed to history-match sandpack flood production data,in order to demonstrate the effect of an additive on the oil–water relative permeability.Based on these results,it was concluded that oxygenated organic bases had the most potential for improving bitumen recovery through reducing the oil–water interfacial tension(IFT)by increasing the pH of the system.These organic bases favorably modify the interfacial energies between the immiscible oil–water phases and enable them to flow easily through the porous media during production.Sand-pack flood tests have successfully demonstrated a 10%–15%improvement in bitumen recovery,over baseline,in the presence of IFT-reducing additives.Simulation results further showed that an IFT reduction had a positive impact on SAGD performance.This work demonstrates the potential of organic bases to improve not only SAGD,but other steam injection processes.Furthermore,a number of experimental methods were developed,tried,and tested during the course of this work.