Experimental study on wax deposition of highly paraffinic oil in intermittent gas-oil flow in pipelines

Oil-gas two phase wax deposition is a fairly common and open-ended question in flow assurance of multiphase transportation pipelines.This paper investigated the two main aspects of oil-gas two phase wax deposition layer:apparent thickness and crystal structure characteristics.A typical highly paraffinic oil in Bohai Sea,China,was used as the experimental material to investigate the wax deposition thickness in oil-gas two phase under the influence of different oil temperatures,superficial gas/liquid phase velocities and gas-oil ratios by using multiphase flow loop experimental device.Just as in the classical theory of wax molecular diffusion,it showed that wax deposition thickness of oil-gas two phase increased with increasing oil temperature.Analysis of the impact of different superficial phase velocities found that the actual liquid flow heat transfer and shear stripping was the gas phase dominant mechanisms determining wax deposit thickness.In addition,the crystal structure of the wax deposition layer was characterized with the help of small-angle X-ray scattering(SAXS)for different circumferential positions,flow rates and gas-oil ratios.The bottom deposition layer had a complex crystal structure and high hardness,which were subject to change over flow rate variations.Furthermore,the SAXS results provided evidence that the indirect effect of the actual liquid velocity modified by the gas phase was the main mechanism.Our study of the effect of gas phase on the wax deposition of oil-gas two phase will help shed light onto the mechanism by which this important process occurs.Our findings address a very urgent need in the field of wax deposition of highly paraffinic oil to understand the flow security of oilgas two phase that occurs easily in multiphase field pipelines.

A salt-induced tackifying polymer for enhancing oil recovery in highsalinity reservoirs:Synthesis,evaluation,and mechanism

Polymerflooding is an effective method widely applied for enhancing oil recovery(EOR)by reducing the mobility ratio between theinjected water and crude oil.However,traditional polymers encounter challenges in high salinity reservoirs due to their salt sensitivity.Toovercome this challenge,we synthesized a zwitterion polymer(PAMNS)with salt-induced tackifying property through copolymerization ofacrylamide and a zwitterion monomer,methylacrylamide propyl-N,N-dimethylbutylsulfonate(NS).NS monomer is obtained from thereaction between 1,4-butanesultone and dimethylamino propyl methylacrylamide.In this study,the rheological properties,salt responsiveness,and EOR efficiency of PAMNS were evaluated.Results demonstrate that PAMNS exhibits desirable salt-induced tackifyingcharacteristics,with viscosity increasing up to 2.4 times as the NaCl concentration reaches a salinity of 30×10^(4)mg L^(-1).Furthermore,highvalence ions possess a much stronger effect on enhancing viscosity,manifested as Mg^(2+)>Ca^(2+)>Na^(+).Molecular dynamics simulations(MD)andfluid dynamics experiment results demonstrate that PAMNS molecules exhibit a more stretched state and enhanced intermolecularassociations in high-salinity environments.It is because of the salt-induced tackifying,PAMNS demonstrates superior performance inpolymerflooding experiments under salinity ranges from 5×10^(4)mg L^(-1)to 20×10^(4)mg L^(-1),leading to 10.38–19.83%higher EOR thantraditional polymers.

Effect of high-multiple water injection on rock pore structure and oil displacement efficiency

Experimental methods,including mercury pressure,nuclear magnetic resonance(NMR)and core(wateroil)displacement,are used to examine the effects of high-multiple water injection(i.e.water injection with high injected pore volume)on rock properties,pore structure and oil displacement efficiency of an oilfield in the western South China Sea.The results show an increase in the permeability of rocks along with particle migration,an increase in the pore volume and the average pore throat radius,and enhanced heterogeneity after high-multiple water injection.Compared with normal water injection methods,a high-multiple water injection is more effective in improving the oil displacement efficiency.The degree of recovery increases faster in the early stage due to the expansion of the swept area,and the transition from oil-wet to water-wet.The degree of recovery increases less in the late stage due to various factors,including the enhancement of heterogeneity in the rocks.Considering both the economic aspect and the production limit of water flooding,it is recommended to adopt other technologies to further enhance oil recovery after 300 PV water injection.

Remaining oil distribution characteristics in an oil reservoir with ultra-high water-cut

An accurate mapping and understanding of remaining oil distribution is very important for water control and stabilize oil production of mature oilfields in ultra-high water-cut stage.Currently,the Tuo-21 Fault Block of the Shengtuo Oilfield has entered the stage of ultra-high water cut(97.2%).Poor adaptability of the well pattern,ineffective water injection cycle and low efficiency of engineering measures(such as workover,re-perforation and utilization of high-capacity pumps)are the significant problems in the ultra-high water-cut reservoir.In order to accurately describe the oil and water flow characteristics,relative permeability curves at high water injection multiple(injected pore volume)and a semiquantitative method is applied to perform fine reservoir simulation of the Sand group 3e7 in the Block.An accurate reservoir model is built and history matching is performed.The distribution characteristics of remaining oil in lateral and vertical directions are quantitatively simulated and analyzed.The results show that the numerical simulation considering relative permeability at high injection multiple can reflect truly the remaining oil distribution characteristics after water flooding in an ultrahigh water-cut stage.The distribution of remaining oil saturation can be mapped more accurately and quantitatively by using the‘four-points and five-types’classification method,providing a basis for potential tapping of various remaining oil types of oil reservoirs in late-stage of development with high water-cut.

Experimental investigation on using CO_(2)/H_(2)O emulsion with high water cut in enhanced oil recovery

CO_(2) emulsions used for EOR have received a lot of interest because of its good performance on CO_(2)mobility reduction.However,most of them have been focusing on the high quality CO_(2) emulsion(high CO_(2) fraction),while CO_(2) emulsion with high water cut has been rarely researched.In this paper,we carried out a comprehensive experimental study of using high water cut CO_(2)/H_(2)O emulsion for enhancing oil recovery.Firstly,a nonionic surfactant,alkyl glycosides(APG),was selected to stabilize CO_(2)/H_(2)O emulsion,and the corresponding morphology and stability were evaluated with a transparent PVT cell.Subsequently,plugging capacity and apparent viscosity of CO_(2)/H_(2)O emulsion were measured systematically by a sand pack displacement apparatus connected with a 1.95-m long capillary tube.Furthermore,a high water cut(40 vol%) CO_(2)/H_(2)O emulsion was selected for flooding experiments in a long sand pack and a core sample,and the oil recovery,the rate of oil recovery,and the pressure gradients were analyzed.The results indicated that APG had a good performance on emulsifying and stabilizing CO_(2) emulsion.An inversion from H_(2)O/CO_(2) emulsion to CO_(2)/H_(2)O emulsion with the increase in water cut was confirmed.CO_(2)/H_(2)O emulsions with lower water cuts presented higher apparent viscosity,while the optimal plugging capacity of CO_(2)/H_(2)O emulsion occurred at a certain water cut.Eventually,the displacement using CO_(2)/H_(2)O emulsion provided 18.98% and 13.36% additional oil recovery than that using pure CO_(2) in long sand pack and core tests,respectively.This work may provide guidelines for EOR using CO_(2) emulsions with high water cut.

Optimization of the Plugging Agent Dosage for High Temperature Salt Profile Control in Heavy Oil Reservoirs

After steam discharge in heavy oil reservoirs,the distribution of temperature,pressure,and permeability in different wells becomes irregular.Flow channels can easily be produced,which affect the sweep efficiency of the oil displacement.Previous studies have shown that the salting-out plugging method can effectively block these channels in high-temperature reservoirs,improve the suction profile,and increase oil production.In the present study,the optimal dosage of the plugging agent is determined taking into account connection transmissibility and inter-well volumes.Together with the connectivity model,a water flooding simulation model is introduced.Moreover,a non-gradient stochastic disturbance algorithm is used to obtain the optimal plugging agent dosage,which provides the basis for the high-temperature salting-out plugging agent adjustment in the field.

Mechanical characteristics and reservoir stimulation mechanisms of the Gulong shale oil reservoirs, the northern Songliao Basin

Shale oil of the Qingshankou Formation of the Gulong Sag,the northern Songliao Basin,represents the first attempt at large-scale development of pure-shale-type shale oil in China.By integrating the multiscale refined reservoir characterization with macro-micro-scale mechanical testing,it is clarified that the Gulong shale is characterized by high clay mineral content,high rock plasticity,highly-developed bedding,and prominent mechanical anisotropy.A three-dimensional(3D)fracture propagation model of hydraulic fracturing was built for the Gulong shale,which fully captures the hydraulic fracture distribution pattern affected by the high bedding density,in-situ stress,and fracturing treatment parameters.Our research showed that due to influences of bedding,hydraulic fracturing in the Gulong shale forms a complex fracture morphology featuring the main fracture with multiple perpendicular branches that have different lengths(like the outdoor directional TV antenna);however,the vertical propagation of fractures is inhibited,and the fracture height is commonly less than 10 m.The limited stimulated reservoir volume(SRV)is the main problem facing the fracturing stimulation of the Gulong shale oil.Bedding density has vital effects on fracture morphology,so case-specific fracturing designs shall be developed for shale intervals with different bedding development degrees.For reservoirs with welldeveloped bedding,it is suggested to properly increase the perforation cluster spacing and raise the volume and proportions of viscous fluids of the pad,so as to effectively promote vertical fracture propagation and improve reservoir stimulation performance.This study integrates multi-scale fine reservoir characterization and macro-micro-scale mechanical testing,as well as the construction and numerical simulation of hydraulic fracturing models for high-density layered shale reservoirs,providing a new approach and methodological framework for the fracturing research of high-density layered shale reservoirs.

Shale oil development techniques and application based on ternary-element storage and flow concept in Jiyang Depression,Bohai Bay Basin,East China

The ternary-element storage and flow concept for shale oil reservoirs in Jiyang Depression of Bohai Bay Basin,East China,was proposed based on the data of more than 10000 m cores and the production of more than 60 horizontal wells.The synergy of three elements(storage,fracture and pressure)contributes to the enrichment and high production of shale oil in Jiyang Depression.The storage element controls the enrichment of shale oil;specifically,the presence of inorganic pores and fractures,as well as laminae of lime-mud rocks,in the saline lake basin,is conducive to the storage of shale oil,and the high hydrocarbon generating capacity and free hydrocarbon content are the material basis for high production.The fracture element controls the shale oil flow;specifically,natural fractures act as flow channels for shale oil to migrate and accumulate,and induced fractures communicate natural fractures to form complex fracture network,which is fundamental to high production.The pressure element controls the high and stable production of shale oil;specifically,the high formation pressure provides the drive force for the migration and accumulation of hydrocarbons,and fracturing stimulation significantly increases the elastic energy of rock and fluid,improves the imbibition replacement of oil in the pores/fractures,and reduces the stress sensitivity,guaranteeing the stable production of shale oil for a long time.Based on the ternary-element storage and flow concept,a 3D development technology was formed,with the core techniques of 3D well pattern optimization,3D balanced fracturing,and full-cycle optimization of adjustment and control.This technology effectively guides the production and provides a support to the large-scale beneficial development of shale oil in Jiyang Depression.

Breeding of Brassica napus Cultivar Shuangyou 092 with High Oil Content and Its Fine-quality and High-yield Cultural Techniques

Shuangyou 092, a Brassica napus cultivar with high oil content, high quality and high yield, was bred by Institute of Industrial Crops of Henan Academy of Agricultural Sciences with Zhongshuang 9 as female parent, and the cytoplasmic male sterility maintainer line 32B as male parent. It was registered and released in 2014. The average yield was 2 858.5 kg/hm^2 in Henan province regional test of high quality, 12.43% higher than the check variety Fengyou 9 in 2010-2011 and 2011-2012. Its yield was 3 478.8 kg/ha in Henan Province productive test of high quality,9.52% higher than the check variety Fengyou 9 in 2012-2013. According to the test results in 2011-2012 and 2012-2013, the seeds quality of Shuangyou 092 was very good with near zero erucic acid （0.0%, 0.1%） in fat acid, 17.19 μmol/g and 19.78 μmol/g glucosinolates in its meal, the oil content of 46.60% and 45.76%. The cultivar was resistant （tolerant） to Sclerotinia, virus diseases, cold, and lodging. Its high yield and high quality can be obtained by planting in large scale, sowing at right time, rational close planting, balancing fertilizer and harvesting at right time.

The Breeding of Hybrid Rape Variety Youyan 924 with Strong Heterosis and High Oil

The rape project of ＂Development and Application of Cabbage Type Rape Hybrids with Strong Heterosis＂ which belongs to National 863 Program aimed to breed the rape variety whose rapeseed yield or oil yield increased more than 10% compared with check （CK） variety, or oil yield increased more than 3 percentage points compared with CK. In the regional trial in the middle react,es of the Yangtze River for two years, the average rapeseed yield and oil yield of Youyan 924 which is a hybrid rape variety respectively reached 2 695.95 and 1 264.35 kg/hm2, which respectively increased by 5.22% and 13.4% compared with those of the other test- ing varieties in the same group, and respectively increased by 10.06% and 23.68% compared with those of Zhongyouza 2 which belongs to CK, thus reaching the standard of hybrid rape variety with strong heterosis; the average oil percentage of the variety in the two years was 46.63%,which increased by 3.44 percentage points compared with that of all the other testing varieties in the same group, and in- creased by 5.14 percentage points compared with that of Zhongyouza 2, and the oil percentage of it in the production testing reached 49.21%. Thus Youyan 924 is a variety with strong heterosis and high oil, moreover, its contents of erucic acid and glucosinolate are 0,25% and 20.27 μmol/g, respectively. From the data aggregation of national regional trial, it has the advantages of high oil yield, high yielding ability, reaching the standards of low erucic acid and low glucosinolate, strong lodging re- sistance, good disease resistance aqd moderate mature period.

Origin and accumulation of high-maturity oil and gas in deep parts of the Baxian Depression, Bohai Bay Basin, China

Great quantities of light oil and gas are produced from deep buried hill reservoirs at depths of 5,641 m to 6,027 m and 190 ℃ to 201 ℃ in the Niudong-1 Well, representing the deepest and hottest commercial hydrocarbons discovered in the Bohai Bay Basin in eastern China. This discovery suggests favorable exploration prospects for the deep parts of the basin. However, the discovery raises questions regarding the genesis and accumulation of hydrocarbons in deep reservoirs. Based on the geochemical features of the hydrocarbons and characteristics of the source rocks as well as thermal simulation experiments of hydrocarbon generation, we conclude that the oil and gas were generated from the highly mature Sha-4 Member （Es4） source rocks instead of thermal cracking of crude oils in earlier accumulations. The source kitchen with abnormal pressures and karsted carbonate reservoirs control the formation of high-maturity hydrocarbon accumulations in the buried hills （i.e., Niudong-1） in conjunction with several structural-lithologic traps in the ES4 reservoirs since the deposition of the upper Minghuazhen Formation. This means the oil and gas exploration potential in the deep parts of the Baxian Depression is probably high.

Biodegraded Oil and Its High Molecular Weight (C_(35+)) n-alkanes in the Qianmiqiao Region in the Bohai Bay Basin, Northern China

With a production of 208.2 m3/d, heavy oil was produced by drill stem test (DST) from three shallow reservoirs in Sand Group Nos. Ⅰ and Ⅲ of the Neogene Guantao Formation (NgⅠ and NgⅢ) and the Eogene Dongying Formation (Ed) in an exploratory well Ban-14-1 within the Qianmiqiao region, Bohai Bay Basin, northern China. Based on the GC and GC-MS data of the NgⅠ and NgⅢ heavy oil samples, all n-alkanes and most isoprenoid hydrocarbons are lost and the GC baseline appears as an evident 'hump', implying a large quantity of unresolved complex mixture (UCM), which typically revealed a result of heavy biodegradation. However, there still is a complete series of C14-C73 n-alkanes in the high-temperature gas chromatograms (HTGC) of the heavy oil, among which, the abundance of C30- n-alkanes are drastically reduced. The C35-C55 high molecular weight (HMW) n-alkanes are at high abundance and show a normal distribution pattern with major peak at C43 and an obvious odd-carbon-number predominance with CPI37-55 and OEP45-49 values of 1.17 and 1.16-1.20, respectively. According to GC-MS analysis, the heavy oil is characterized by dual source inputs of aquatic microbes and terrestrial higher plants. Various steranes and tricyclic terpanes indicate an algal origin, and hopane-type triterpanes, C24 tetracyclic terpane and drimane series show the bacterial contribution. With the odd-carbon-number preference, HMW n-alkanes provide significant information not only on higher plant source input and immaturity, but also on the strong resistibility to biodegradation.

High performance electrocoagulation process in treating palm oil mill effluent using high current intensity application

Electrocoagulation process using high current intensity to treat palm oil mill effluent(POME) was investigated in this study.Various operating parameters such as electrolysis time, inter-electrode distance and initial pH were carried out to determine the efficient process condition on the removal of chemical oxygen demand(COD),biological oxygen demand(BOD) and suspended solids(SS).The highest treatment was achieved at 50 min with the removal efficiencies for COD, BOD and SS obtained as 85%, 83%, and 84%, respectively.More than 50 min treatment showed the fluctuated trends of removal efficiencies which can be considered insignificant.The application of higher current resulted in higher removals of organics while the gas bubbles also assisted in removing the pollutant particles by floatation.In an inter-electrode distance study, the removal efficiency decreased when inter-electrode distance was either higher or lower than 10 mm due to the increase of solution resistance and the decrease of anode active surface area.In initial pH study, it was found that high removal efficiencies were achieved in slightly acidic POME sample rather than in neutral or basic condition.An electrocoagulation process by using the optimum operating parameters was able to remove COD, BOD and SS up to 95%, 94% and 96% respectively.The experimental results confirm that application of high current intensity in electrocoagulation provided high treatment efficiency at a reduced reaction time.

Wear behavior of high velocity arc sprayed 3Cr13 steel coating in oil containing sand

To improve the wear resistance of the machine components serving in desert areas, the 3Cr13 stainless steel coating was produced by the high velocity arc spraying technique. The microstructure and phase constitute of the coating were analyzed by SEM and XRD. The effects of sand content on the friction and wear behaviors of the coating under the lubrication of oil containing sand were investigated on a ball-on-disk tester. SEM was used to reveal the wear mechanisms of the coating. The results show that the wear volume increases with increasing the sand content in the oil, and the sprayed coating exhibits better triobological properties compared with the 1045 steel. The predominant wear mechanisms of the sprayed coating are micro-cutting, brittle fracture and delamination.

Formulation development and preparation of fish oil liposome by using high pressure homogenizer for food supplement product

It is known that “Fish Oil” is the raw material that has lot of benefits for health, because fish oil consists of several necessary unsaturated fatty acids, particularly Omega-3 and Docosahexanoic acid (DHA). Omega-3 can decrease triglyceride level, and then it can increase HDL cholesterol level. In addition, DHA can support brain cell synthesis and also nervous system for human.

Biogas Production from Anaerobic Digestion of High Oil Waste

The possibility of anaerobic digestion of high oil waste at high temperatures was explored,and the effects of fat concentration on biogas production via anaerobic digestion were analyzed by batch and continuous experiments successively. Besides,the response and recovery of the digestion system to the shock of high concentrations of oil were studied. The results showed that the anaerobic digestion of high oil waste could be carried out,and fat concentration had a significant effect on the anaerobic digestion. In the batch experiments,the process of anaerobic digestion could carry out only when fat concentration was 0-1. 68%,and the average methane content was 46. 42%; with the increase of fat concentration,both methane content and production rate decreased significantly,and the digestion period was extended obviously. When fat concentration exceeded 2. 52%,the anaerobic digestion failed to start,and methane could not be detected in the produced biogas. In the continuous experiments,the system could withstand a certain concentration of fat( 6 g/L),and anaerobic digestion process would be inhibited when it experienced the impact of a high oil load( 26. 7 g/L). Nevertheless,this process could recover quickly after the removal of the impact,and the system could withstand a higher fat concentration( 13 g/L) than before. Furthermore,the volume production rate of biogas was approximately 1 L/( L·d),and methane content was about 55%.

Effects of oil contamination and bioremediation on geotechnical properties of highly plastic clayey soil

Leakage of oil and its derivatives into the soil can change the engineering behavior of soil as well as cause environmental disasters.Also,recovering the contaminated sites into their natural condition and making contaminated materials as both environmentally and geotechnically suitable construction materials need the employment of remediation techniques.Bioremediation,as an efficient,low cost and environmentalfriendly approach,was used in the case of highly plastic clayey soils.To better understand the change in geotechnical properties of highly plastic fine-grained soil due to crude oil contamination and bioremediation,Atterberg limits,compaction,unconfined compression,direct shear,and consolidation tests were conducted on natural,contaminated,and bioremediated soil samples to investigate the effects of contamination and remediation on fine-grained soil properties.Oil contamination reduced maximum dry density(MDD),optimum moisture content(OMC),unconfined compressive strength(UCS),shear strength,swelling pressure,and coefficient of consolidation of soil.In addition,contamination increased the compression and swelling indices and compressibility of soil.Bioremediation reduced soil contamination by about 50%.Moreover,in comparison with contaminated soil,bioremediation reduced the MDD,UCS,swelling index,free swelling and swelling pressure of soil,and also increased OMC,shear strength,cohesion,internal friction angle,failure strain,porosity,compression index,and settlement.Microstructural analyses showed that oil contamination does not alter the soil structure in terms of chemical compounds,elements,and constituent minerals.While it decreased the specific surface area of the soil,and the bioremediation significantly increased the mentioned parameters.Bioremediation resulted in the formation of quasi-fibrous textures and porous and agglomerated structures.As a result,oil contamination affected the mechanical properties of soil negatively,but bioremediation improved these properties.

High temperature tribological behaviors of nano-diamond as oil additive

The tribological behaviors of the nano-diamond particles including the nano- diamond and the nano-diamond modified were studied at high temperature using SRV multifunctional test system. The worn steel surfaces were analyzed by means of X-ray photoelectron spectroscopy (XPS). The results show that nano-diamond particles can obviously improve the antiwear and friction reducing properties of the base oil at high temperature and the high load. The friction coefficient of the nano-diamond is very low at 200 ℃ when the test load is not more than 20 N. This tribological behaviors should attributed to the similarly to “ball bearing” lubrication action of the nano-diamond particles, so the movement between tribological pairs become sliding/rolling. The nano-diamond modified by dimer ester possesses excellent antiwear and friction reducing performance at 500 ℃ and load 500 N. The tribochemical reaction film between the nano-diamond particles and the renascent wear surface plays dominating lubrication role and the presence of the dimer ester on the rubbing surface can be propitious to form lubrication film containing nano- diamond on the worn surface at high temperature and high load.

Development of peanut varieties with high oil content by in vitro mutagenesis and screening

Peanut (Arachis hypogaea L.) is an important oil crop globally and high oil content is one of the major targets in peanut breeding programs. Previous studies indicated that the osmotic pressure (OP) of the leaves of peanut plants subjected to drought stress was negatively correlated with kernel oil content. Based on this knowledge, we established a practical and reliable method for creating new peanut varieties with high oil content using in vitro mutagenesis and directional OP-based selection. Using embryonic leaflets of peanut variety Huayu 20 as explants, pingyangmycin (PYM) as the mutagen, and hydroxyproline (HYP) as the OP regulator, we developed 15 HYP-tolerant regenerated plants. For each regenerated plant, we selected offspring with oil content>55% (relative to 49.5% for Huayu 20). We developed and released three new peanut varieties with high yield and high oil content from the offspring of the HYP-tolerant regenerated plants. The three new varieties were named as Yuhua 4, Yuhua 9 and Yuhua 14 and their oil contents were 57.7, 61.1 and 59.3%, respectively. The results indicate that in vitro mutagenesis with PYM followed by directed screening with HYP is a useful approach for breeding peanut varieties with high oil contents.

A New Method for Predicting Wall Sticking Occurrence Temperature of High Water Cut Crude Oil

In crude oil transportation, adhesion of oil on pipe wall can cause partial or total blockage of the pipe. This process is significantly affected by wall sticking occurrence temperature(WSOT). In this work, an efficient approach for estimating WSOT of high water-cut oil, which can agree well with the actual environment of multiphase transportation pipeline, is proposed. Based on the energy dissipation theory, it is possible to make comparison of average shear rates between the stirred vessel and the flow loop. The impacts of water content and shear rate on WSOT are investigated using the stirred vessel and the flow loop. Good agreement has been observed between the stirred vessel and the flow loop results with the maximum and the average absolute deviations equating to 3.30 °C and 2.18 °C, respectively. The development of gathering scheme can enjoy some benefits from this method.