Carbonaceous nanomaterials have excellent electrical conductivity, which can be used as the conductive fillers to fill polymer matrix to prepare conductive polymer composites. The classification, conductive mechanism, electrical properties, and application fields of the carbonaceous nano conductive materials were discussed. Moreover, the recent progress in this filed had been briefly reviewed. Finally, the current problems and future development trend of conductive polymer composites filled by carbonaceous nanomaterials were presented.
Microchemical technology is a front technology of multi⁃disciplines in chemical engineering fields. The technology core is microscale transfer and chemical reaction in microchannel reactor. The application of microchemical technology can improve resource⁃utilization efficiency for energy saving and consumption reduction, enhance security, intensification and miniaturization of the chemical process, by decreasing dispersion scale, strengthening mixing and transfer, raising control and efficiency. The technology principle, characteristics, advantage and industrial application of microchemical technology were introduced, with the aim of deepening people's understanding of the microchemical technology, and then promoting the development and application of microchemical technology.
Five kinds of hydrophobic association hydrogel are synthesized with the method of free⁃radical solution polymerization, in which the hydrophilic monomer is acrylic amide (AM), hydrophobic monomers are octadecyl acrylate (C18) and dimethyacetamide(DMAC),the surfactants are lauryl sodium sulfate (SDS),tetrabutylammonium bromide (TBAB),cetyl trimethyl ammonium bromide (CTAB).The gas storage performance of CH4 and the water absorption capability for five hydrogels are measured. The experimental data has proven that the addition of TBAB or CTAB has a significant effect on the storage performance of hydrogels, and the best storage performance of CH4 is HC⁃SDS/TBAB. In addition,the addition of TBAB or CTAB has an obvious effect on the swelling ratio of hydrogel, and the swelling ratios of hydrogels with the addition of two kinds of surfactants are obviously lower than the one with the addition of a single surfactant (SDS).
Viscous solid tar residue was produced in the process of gasification and coking of coal, which is extremely difficult to deal with because because of the large amount of harmful substances such as pulverized coal coke powder and coal tar.To solve the problem of harmless treatment of tar residue, tar residue was mixed with compound additives to prepare solidified blocks, and then tar and solid residue were separated by pyrolysis of dry distillation. Through the study of the strength characteristics of the cured block, the optimum technological conditions were determined as the amount of binder 0.15, the ratio of agent to slag 1∶2 and the curing age 7 days. The compressive strength of the cured block can reach 2 MPa after 7 days, the drop strength can reach 94%, and the thermal stability can reach 98%. Tar and high calorific value gases were obtained from the solidified block by pyrolysis of dry distillation, and the tailings of dry distillation meet the requirement of pollutants in sludges (GB 4284—2018), which can be directly discharged as agricultural soil or building materials.
The permeability and absorption experiments of low permeability sandstone core under the actual formation temperature and pressure were carried out,which were used to analyze the waterflooding huff⁃puff 's oil recovery law of imbibition and compared with imbibition experiments of normal temperature⁃pressure.The experiments show that the imbibition efficiency of normal temperature⁃pressure is 18%~24%,with an average of 21%.The permeability rate of core in the first six hours is the fastest,which is 0.8~1.7 %/h.The imbibition efficiency of actual reservior's temperature and pressure conditions is 24%~31%,with an average of 27%;Imbibition rate is the fastest in the first round,which is 2.6~3.6 %/h.Compared with imbibition of normal temperature⁃pressure,the imbibition of actual reservior 's temperature and pressure conditions can promote the imbibition efficiency by 5% to 7%,and the imbibition rate is also significantly higher than the imbibition of normal temperature⁃pressure.The analysis believes that imbibition of actual reservior 's temperature and pressure conditions can increase the imbibition's power and reduce the imbibition's resistance,which is more conducive to oil⁃water displacement.Furthermore,the theoretical calculation model of the imbibition depth is established, and the cores' imbibition depth is about 0.25~0.63 cm.It is considered that the depth of the early rapid imbibition stage is in the centimeter range,and the imbibition depth increases with the imbibition efficiency.According to the comprehensive research,increasing the reservior's pressure and large⁃area fracturing can effectively improve the imbibition efficiency.
In the middle and late stage of development of offshore heavy oil field, strong injection and strong production are mainly adopted. Under this kind of large volume of liquid scouring, the microscopic pore structure of reservoir and the efficiency of water drive oil are changed, which brings difficulty to understanding the law of water drive development in high water cut stage of oilfield. Through simulating long⁃term water flooding and scouring physical experiments, the variation law of each characteristic parameter of reservoir during the long term water flooding scouring process is studied. The results show that for high porosity and high permeability reservoirs after long⁃term water flooding, the porosity change is not obvious, permeability is obviously increased, and invalid circulation channels are easily formed. The characteristics of pore microcosmic change are obvious, the radius of pore throat increases and the seepage ability increases. With the increase of displacement ratio, the isosmotic point shifts to the right. When the water saturation is the same, the oil phase permeability increases, the water phase permeability decreases, the residual oil saturation decreases, and the oil displacement efficiency increases by nearly 10%. The research results have been used in the field test of 2 000 m3/d liquid production per well in offshore sandstone reservoirs with high water cut, which provides theoretical support for the formulation of development strategy in high water cut period of offshore oil fields.
Aiming at W block in J Oilfield, combining screening criteria, theoretical calculation and numerical simulation method, while evaluating reservoir properties, remaining reserves and development status, a feasibility evaluation method of steam ensuing steam stimulation was established. Then the steam feasibility of target block was evaluated: It turns out that the geological characteristics of this block agreed well with the screening standard of steam flooding. Furthermore, the steam flooding generates a higher recoverable reserve than steam stimulation, the effective heat communication was formed between wells, and he degree of reservoir heated during stimulation stage can meet the needs of steam flooding. The project of converting to steam flooding after steam stimulation was optimized. It was determined that conducting the intermittent steam injection performed a better flooding effect when the recovery factor of steam stimulation reached 15.20%, in which steam injection time, interval time, steam injection rate, steam quality and production⁃injection ratio were 3 months, 1 month, 133.33 t/d, 0.60 and 1.3 respectively. The recovery factor was 42.3% when the oil⁃steam ratio reached 0.12, 29.6% higher than that of steam stimulation. This study contributed an evaluation method for steam flooding ensuing stimulation, and provided a good reference to similar reservoirs.
In order to screen out the best microemulsion flooding system, the influence of microemulsion performance on the remaining oil of the pores is selected as an index. Through the core oil⁃displacement test and pores of remaining oil experiment, we have proved the remarkable effect of the microemulsion flooding in enhancing the recovery factor from two aspects, macroscopic and microscopic. The results show that the particle size of the best microemulsion for 8 mL n⁃octane, 8 mL water,4.5 mass fraction of Carboxyl betaine,6 mass fraction of N⁃Butyl alcohol,5 mass fraction of NaCl has smaller particle size distribution, higher viscosity, stronger stability and smaller proportion of residual oil containing pores. To compare with the water flooding, the amplification of microemulsion flooding can achieve 10.8% and the final recovery is up to 49.7%.This result proves that microemulsion can remarkably improve recovery efficiency. The ratio of residual oil to pore decreases with the decrease of pore radius, which indicates that pore radius has a significant effect on remaining oil distribution. Compared with matrix core, the ratio of residual oil pore to fractured core is larger and oil displacement efficiency is relatively low.
he carbonate reservoir has tight lithology and is operated at high temperature in S block. In order to improve the oil recovery, it is necessary to carry on the acid fracturing treatment to the target reservoir. According to the characteristics of the target reservoir, the acid fluid for acid fracturing was optimized and evaluated. Through the porosity and permeability experiment, the porosity of S block was 0.1%~2.0%, and the permeability was below 0.01 mD, which belonged to ultra⁃low permeability reservoir. According to the uniaxial compression test, the compressive strength of the reservoir was high, ranging from 40 to 70 MPa. X⁃ray diffraction showed that dolomite and calcite were the main minerals in the reservoir ( 80%~90% in total), with a small amount of quartz and clay (mass fraction was about 10%). The main acid was 20% hydrochloric acid, the thickener was 0.3% xanthan gum, and the dissolution rate of rock powder was about 90% when hydrochloric acid acted alone, and the main acid solution was hydrochloric acid. Taking into account that the reservoir lithology of carbonate rock in S block was dense and the formation temperature was 100~140 ℃, the viscosity of modified xanthan gum was about 10 mPa·s at 140 ℃. The modified xanthan gum was selected as high temperature resistant thickener.
According to the characteristics of high water cut, serious water channeling and poor water drive development in a block of Daqing Oilfield, a new polymer composite nano⁃microsphere profile control and oil displacement agent NWQ⁃2 was developed by dispersion polymerization method, and its particle size distribution, water absorption and expansion performance, temperature and salt resistance performance, viscoelastic performance, profile control and plugging performance and oil displacement performance were evaluated in the laboratory. The results show that the average particle size of NWQ⁃2 is 512.6 nm, and the particle size distribution is uniform. The water absorption expansion ratio in distilled water for 20 h can be more than 10 times, and that in high temperature (120 ℃) and high salinity water (75 200 mg/L) for 20 h can still be more than 8 times, which shows that NWQ⁃2 has good water absorption expansion performance,temperature resistance and salt resistance. After water absorption and expansion, it has good viscoelasticity, good profile control and plugging effect for cores with different permeability, which can effectively block large channels, increase injection pressure, and make the subsequent injected fluid enter more micro channels. After injection of 0.5 PV composite nano microsphere NWQ⁃2 into heterogeneous core, the recovery of core after water flooding can be significantly increased by more than 20%, which has good oil displacement effect.
In order to investigate the phenomenon of gas⁃liquid bias in parallel separators in oil⁃gas gathering and transportation system, an experiment facility for gas⁃liquid two⁃phase splitting was designed, constructed and instrumented. Flow rates, pressure, pressure drop，liquid level and liquid holdup were measured and recorded by data⁃acquisition system. Gas⁃liquid splitting pipelines of two geometries (horizontal pipeline⁃T junction⁃ horizontal pipeline and horizontal pipeline⁃T junction⁃vertical pipeline) were constructed. Experiments on splitting of slug flow were carried out and splitting characteristics of gas⁃liquid were studied with symmetrical and asymmetrical pipeline conditions. When the pipeline conditions are symmetrical, the two phases of slug flow splitting into two separators are even for pipelines of two geometries. When the pipeline conditions at the outlets of separators are asymmetrical, mal⁃distribution of both two phases occurs and liquid tends to split more evenly than gas. Based on the calculation of pressure drop, a splitting model was established and the influence of gas⁃liquid velocity on the flow characteristics was explained simply.
The analytic hierarchy process is introduced to construct energy efficiency index system of gathering and transportation system, which provides a favorable means for energy efficiency evaluation of the system as a whole. Combining with the triangular fuzzy number in fuzzy theory, the judgment matrix construction and weight calculation of AHP are reformed. To some extent, it reduces the defects of hierarchical analysis, such as the strong subjective factors of legal person and the neglect of the model of people's cognition of objective things, and makes the evaluation results more accurate and comprehensiv. Taking a gathering and transportation block of oilfield as an example, the weakness of its energy consumption is found out, and the improvement suggestions are put forward.
Through the heat transfer analysis of the experimental loop of the insulated crude oil, the calculation model of the experimental loop temperature field of the insulated waxy crude oil was established.The internal temperature distribution of the pipeline and the variation of the temperature gradient of the inner wall of the pipeline were calculated.The effects of different ambient temperature,oil flow velocity and wax formation on the temperature field distribution of the pipeline were studied.The results showed that the greater the temperature difference between the oil temperature in the tube and the cooling water in the casing,the larger the average temperature gradient of the tube wall.The average temperature gradient of the pipe wall increased as the oil flow velocity increased,however,when the temperature gradient of the inner surface of the sediment deposit layer on the pipe wall was lower than the initial time, the magnitude of the decrease gradually decreased as the length from the inlet end increased.
ith the development and application of liquefied natural gas (LNG),the demand for spiral⁃wound LNG heat exchanger (SWHE) is increasing,and the performance of the SWHE will seriously affect the liquefaction process level.This paper built a two⁃phase convection heat transfer model and analyzed the influence of different structure parameters for SWHE.The study shows that the shell⁃side heat transfer coefficient of SWHE decreases with the increase of winding angle and longitudinal distance between tube, increases with the increase of outside tube diameter.
The high water cut sandstone oilfields in Kazakhstan involve the MMG project, the PK project and the related oilfields of the North Buzzaki project. After long⁃term water flooding, these oilfields have entered a stage of rapid decline, low⁃efficiency and high water cut. Taking the North Buzzaki oilfield as an example, this paper addresses the characteristics of remaining oil distribution by comprehensive analysis of material balance, log interpretation, performance, water channel and numerical simulation in order to improve remaining oil recovery in high water cut sandstone oilfield. The results show that, longitudinal distribution of remaining oil is affected by sedimentation rhythm and heterogeneity, differently enriched in layers and in⁃between layers, and laterally enriched in those sites of weak conformance as a result of sedimentary environment and petrophysical properties. Combined with the characteristics of water flooding and the characteristics of remaining oil enrichment, adjustment measures are formulated to maximize both recovery factor and economic benefits during the contract period.
Hydrate blocking phenomenon in subsea pipelines is becoming more and more serious due to the environmental characteristics of low temperature and high pressure in deep⁃water oil and gas fields. In response to the above problems of flow assurance in the deep sea oil and gas field, relying on the Zhuhai Gaolan terminal of CNOOC deepwater natural gas, a multi⁃phase hydrate experimental loop of large⁃scale subsea mixed transportation pipeline was established in the pilot evaluation base of offshore oil and gas field flow safety, which could break through the technical bottleneck of flow assurance that restricts the safe development and operation of offshore oil and gas fields, and provide technical means and support to ensure the safe operation of offshore oil and gas fields in China. The total length of this loop is 350 m, the inner diameter is about 150 mm, and the design pressure is 21 MPa. This device belongs to a high⁃pressure, large⁃caliber hydrate experimental system with crude oil as experimental medium. In this paper, this loop could be used for experimental study on the principle of oil⁃gas⁃water multiphase flow, hydrate formation and hydrate control technology under low temperature and high pressure conditions. It could also be used to screen and evaluate the performance of various hydrate inhibitors, related instruments and equipment.
