Abstract:In order to reveal the effect of cationic monomer and crosslinker concentration on the shear and viscoelasticity of cationic polyacrylamide microsphere aqueous solution，the microspheres with cationic degree of 2%—20%，crosslinking degree of 0，and cationic degree of 10%，crosslinking degree of 0.05%—0.2% were prepared by inverse emulsion polymerization，taking acrylamide （AM），methacryloyloxyethyl trimethyl ammonium chloride（DMC）and N，N'-methylene bisacrylamide（MBA）as raw materials. The high temperature and high pressure rheometer was used to test and evaluate the temperature and shear resistance，shear recovery and viscoelasticity of cationic polyacrylamide microsphere solution. The results showed that the viscosity of polymer microsphere solution could be maintained above 150 mPa·s after shearing for two hours at 80°C and 170 s-1，indicating excellent temperature and shear resistance. With increasing cationicity，the shear resistance and shear recovery of microsphere solution enhanced，and the retention of viscosity increased from 30.79% to 68.56%. When the crosslinking agent was added，the stability of microspheres solution enhanced，and the viscosity retention rate was as high as 85.38%，but the overall viscosity of microspheres solution decreased. In the frequency range of 0.01—10 Hz，the elastic modulus of polymer microsphere solution was always greater than the viscous modulus，showing good elasticity. And as the cationic degree increased，the viscoelastic modulus of microspheres solution tended to increase. With the increase of crosslinking degree，the viscoelastic modulus of microspheres solution increased first and then decreased.

Abstract:In order to reveal the performance characteristics of polymer microsphere used in the drilling fluid and prepare fluid loss additive possessing the excellent property of high temperature tolerance and salt resistance，using polyethylene glycol aqueous solution as the dispersion medium，acrylamide（AM），acrylic acid（AA）and multifunctional acrylate as main monomers， polyacrylic acid as the dispersant，and using redox initiator as initiating system，a kind of micrometer scale hydrophilic anion cross-linked polymer microsphere was synthesized by the aqueous dispersion polymerization. The particle size and morphology of polymer microsphere was characterized by particle size analysis and scanning electron microscopy（SEM）. The results showed that the average particle size of the prepared polymer microsphere was less than 10 μm. The polymer microsphere could effectively reduce the volume of drilling fluid filtration and had little influence on the rheological property of drilling fluid. Polymer microsphere possessed excellent property of high temperature tolerance，whose initial decomposition temperature was 290.3℃. The filtration of the drilling fluid containing 4% bentonite and 3% polymer microsphere could be controlled within 10.5 mL after ageing treatment for 16 h at 200℃. The fluid loss additive possessed excellent property of resistance to sodium and calcium. The apparent viscosity，plastic viscosity and dynamic shear force of the drilling fluid containing 4% bentonite and 3% polymer microsphere had little changed after adding NaCl and CaCl2. The filtration was 11.0 mL when the content of NaCl was 2% and the filtration was 14.0 mL when the content of CaCl2 was 1%，which showed good resistance to sodium and calcium pollution.

Abstract:When seawater is used to prepare fracturing fluid，its high salinity and high content of calcium and magnesium ions will affect the swelling，crosslinking and gel breaking of fracturing fluid. In order to reduce the influence of seawater on fracturing fluid，the organophosphonic acid chelating agent SW-CA was prepared from formaldehyde，phosphorous acid and polyvinyl polyamine. The influencing factors of the chelation effect were studied. Crystal morphology was observed by scanning electron microscopy. The mechanism of action was analyzed，and the effect of SW-CA on the crosslinking performance and gel breaking of fracturing fluid was further evaluated. The results showed that the chelating value of SW-CA to Ca2+ and Mg2+ was 276 mg/g and 218 mg/g，respectively. The chelating effect increased with the increase of SW-CA dosage，and decreased with the increase of salinity， temperature and pH value. The precipitated crystal particles became loose and dispersed after adding chelating agent. The mechanism of action was mainly chelating and lattice distortion. The addition of 1% chelating agent SW-CA in seawater could improve the cross-linking performance，viscosity，temperature resistance and shear resistance of base fluid. The fracturing fluid adding 1% SW-CA had controllable gel breaking time and good gel breaking performance. The residual content was 113 mg/L. After soaking ceramsite in fracturing fluid gel breaking liquid with chelating agent for 4 h，only a small amount of guanidine gum residue was adsorbed on the surface of ceramsite，which prevented the precipitation of inorganic salts and reduced the influence on the conductivity of proppant. The chelating agent SW-CA had good compatibility with fracturing fluid，meeting the requirements of on-site construction.

Abstract:In order to obtain fracturing fluid with excellent performance，a new type of quaternary polymer thickener was prepared by aqueous solution polymerization using α-methacrylic acid（MAA），2-acrylamide-2-methylpro panesulfonic acid（AMPS），N， N-dimethyl acrylamide（DMAM），N-vinylcaprolactam（NVCL）as raw materials. The rheological properties of solutions at different mass concentrations were also studied. The polymer fracturing liquid gel system was prepared by using the organic zirconium cross-linked quaternary polymer. The effects of cross-linking ratio，shear rate and temperature on the cross-linking process were investigated. The result showed that the polymer had a strong viscosity-increasing ability with obvious shear thinning， the viscosity of 0.6% polymer solution was 100 mPa·s at the temperature of 25℃ and at the sheer rate of 170 s-1 . The flow curve could be well fitted with the Cross model. The crosslinked gel synthesized by 0.6% thickener solution and crosslinker at a crosslinking ratio of 100∶0.6 had stronger viscoelastic properties. Moreover，the polymer cross-linking process could be well simulated by the four-parameter cross-linking rheokinetics equation，which provided a rheological research basis for the application of polymer fracturing fluid.

Abstract:In order to improve the thermal endurance and shearing resistance of conventional thickener，a hydrophobic associating crosslinking acid thickener AAG4 was synthesized by using acrylamide（AM），dimethyldiallyl ammonium chloride（DMDAAC）， acrylic acid（AA），2-acrylamido-2-methylpropanesulfonic acid（AMPS）and hydrophobic monomer YD-D10 as raw materials through radical aqueous solution polymerization process. The synthesis process of AAG4 was optimized，the structure was characterized，and the properties of crosslinked acid prepared with AAG4 was investigated. The results showed that the optimum preparation condition of AAG4 was obtained as follows：0.01% initiator azodiisobutyl hydrochloride（V040），0.04% ammonium sulfate and sodium bisulfite in mass ratio 1∶1，0.42% YD-D10，35℃ reaction temperature，6 hours reaction time. AAG4 had good thermal stability. When the dosage of hydrochloric acid was 20%，AAG4 had good crosslinked property with organic zirconium cross-linking agent and the crosslinked solution possessed excellent temperature and shearing resistance. The viscosity of acid was 82 mPa·s after shearing for 1 h at 120℃ and 170 s-1 . The reaction rate of crosslinked acid with natural core was much lower than that of hydrochloric acid at 90℃，and the retarding rate of crosslinked acid was 97.3%，indicating good retardative property. The final dissolution rate of natural core by crosslinked acid was equivalent to that by 20% hydrochloric acid at 30℃. The acid pressure construction effect on site was good，which could realize the depth transformation of carbonate reservoir at high temperature.

Abstract:Aiming at the difficulty in repeated liquid dispensing with fracturing flowback fluids in present，the composition of the fracturing flowback fluids in different blocks of Sulige gasfield were systematically analyzed. At the same time，the single factor and orthogonal test were used to study the factors affecting the performance of fracturing fluid flowback. The results showed that great quantity of metal cations was carried out from the formation during the process of fracturing fluid flowback，which had a significant effect on the performance of repeated liquid dispensing. Eespecially，Ca2+，Mg2+ and Fe2+ had the greatest influence on the performance of liquid dispensing. For the 0.4% EM50 and guar colloid system，the upper limit values of the three ions satisfying the repeated liquid dispensing were 250，150，150 mg/L，and 275，250 and 200 mg/L，respectively. In addition，the high concentrarion of Cl- and salinity in the flowback fluids also affect the performance of the liquid dispensing. By adding a certain concentration of complexing agent or precipitating agent to the flowback fluids and then diluting with clear water，the problem of repeated liquid dispensing caused by metal ions or high salinity of the flowback fluids can be effectively solved.

Abstract:Aiming at improving the plane and micro heterogeneity characteristics of water drive heavy oil field in Bohai，and in order to realize the technical requirement of liquid flow diversion in reservoir，the geological characteristics and fluid properties of LD5-2 reservoir in Bohai were taken as simulation object. The hydration expansion，seepage characteristic and fluid flow diversion effect of microheterogeneous regulators including polymer microsphere and gel dispersion were studied. The results showed that the polymer microsphere had poor light transmittance and the appearance was spherical. While the gel dispersion had good light transmittance and the appearance was irregular slice. The initial median particle diameter of polymer microsphere was 8.7—9.2 μm. The microsphere swelled in injection water. The particle size was basically stable after immersing 7 days and the maximum expansion ratio was 2.5—3.0. Polymer microsphere and gel dispersion had strong injection ability and weak liquid flow diversion ability，which were suitable for micro-liquid flow diversion in low and medium permeability layers. Compared with polymer microsphere，the abilities of water absorption，retention in porous media during migration and liquid flow diversion of gel dispersion were poor. The reservoir with high average permeability and high heterogeneity should be combined with macro and micro fluid diversion measures. That was to say，the combination of strong gel and particles could increase the expand sweep volume and enhance oil recovery greatly.

Abstract:Bohai LD5-2 oilfield reservoir has the characteristics of large thickness， high average permeability， strong heterogeneity，large injection-production well spacing，high single-well injection-production intensity and high crude oil viscosity. Long-term water flooding development has further aggravated the heterogeneity of the reservoir，and the phenomenon of invalid cycles of water flooding development has become increasingly serious. In order to improve the effect of oilfield development，the effect of plugging/modulation/displacement combination and well pattern type on the effect of profile control and flooding was carried out. The results showed that the maximum viscosity of profile control agent composed of partially hydrolyzed polyacrylamide solution and organic chromium crosslinking agent reached 105 mPa·s after standing for 12 hours. It could still maintain high strength after 30 days. The initial particle size of displacement control agent，namely polymer microsphere was 8.7— 9.2 μm，and the expansion ratio was 3.7—4.1. The interfacial tension between surfactant solution and crude oil could reach 10-2 mN/ m. The viscosity reduction rate of heavy oil emulsification exceeded 80% when the water content of emulsion was greater than 40%. Compared with the combination of profile control agent，displacement control agent and surfactant，the combination of profile control agent and displacement control agent lacked the emulsification and viscosity reduction and oil washing effects of surfactants，the enhanced oil recovery rate reduced 8.9%. The macroscopic flow diversion effect of the combination of displacement control agent and surfactant was poor，the emulsification and viscosity reduction effect of the surfactant was not fully exerted，so that the enhanced oil recovery rate only reached 10.8%. The four well pattern types were arranged according to the development effects in following order：1 horizontal well（injection）+ 1 horizontal well（production），1 horizontal well + 2 vertical wells，1 vertical well + 1 horizontal well，and 1 vertical well + 2 vertical wells. When the average permeability of reservoir was high and the heterogeneity was strong，the treatment measures of large pores or ultra-high permeability strips could ensure that the subsequent microspheres performed microscopic liquid flow diversion，and the surfactants played the role of emulsification，viscosity reduction and oil washing.

Abstract:In order to achieve high efficiency and low cost development of offshore oilfield with high salinity，and meet the needs of deep liquid diversion technology，the transport capacity of the inorganic gel in 18 m super-long core was studied in this paper. The results showed that the contents of Ca2+ and Mg2+ in the injected water of target reservoir are 0.569 g/L and 0.229 g/L， respectively，and the two are not enough to react with the main agent Na2SiO3 solution to produce a large amount of inorganic gels， hence，additional CaCl2 solution is needed as additives. The concentrations of main agent and auxiliary agent were 3.7 g/L， respectively. When the injection course of "softened water + sodium silicate solution + softened water + calcium chloride solution" increased，the pressure gradient in each length of the core increased gradually. After alternating injection courses of intra layer precipitate，the inorganic gel reached 86.7% of the total core length，the ratio of pressure gradient in two adjacent length intervals of the core was 3.85，2.03，1.16，1.19 and 1.24，respectively，the pressure gradient ratio difference in each length interval was not significant，which indicating that the profile control agent of inorganic gel had good transport capacity and deep liquid diversion ability. Moreover，at the end of the following water flooding，the plugging rate of cores in each length interval was about 19.97%— 72.26%，which indicated that inorganic gel in the layer had strong scour resistance and durable deep liquid diversion capability.

Abstract:In order to block the straight-through water channeling fractures of Honghe Chang 8 reservoir，gels with different gelling time and strength were prepared by using partially hydrolyzed polyacrylamide G3515 as gelling agent，water-soluble phenolic resin as cross-linking agent，and ammonium chloride as catalyst. The stability，injection and plugging capacity of gel was evaluated. The results showed that the stability of the gel was good. The elastic modulus of the gel prepared by 0.5% G3515，0.5% water-soluble phenolic resin，0.2% catalyst and 0.3% nanoparticle QC-W after placing 180 days at 70℃ was greater than 10 Pa. The injection of jelly was good，and the viscosity of the gel-forming solution at 70℃ was less than 500 mPa·s. The blocking ability of the gel was good. The breakthrough pressure gradient of the strong gel containing 0.8% G3515 in a thin tube with a diameter of 0.7—1.8 mm was above 4 MPa/m，and that of the weak gel containing 0.3% G3515 in a thin tube with a diameter of 0.7—1.5 mm was above 1 MPa/m，which met the requirement of large dose injection in Honghe oilfield.

Abstract:In order to study and accurately predict the curing process and curing behavior of thermosetting epoxy resin plugging agent，the non-isothermal differential thermal scanning calorimetry was used to study the curing reaction kinetics of epoxy resin plugging agent system. The Kissinger equation and two-parameter（m，n）autocatalytic model were used to fit the curing kinetics of the system and calculate the curing kinetic parameters. The results showed that the curing process of the plugging agent system consisting of epoxy resin and triethanolamine was two-stage curing，which was a gelation stage and a curing stage. The apparent activation energy of the two stages obtained through fitting was 63.489 and 123.56 kJ/mol respectively. The activation energy in curing stage was twice bigger than that in gelation stage. The autocatalytic kinetic equation obtained from the two-stage curing process and the experimental data had a good degree of fit，which was instructive for the application of epoxy resin plugging agent system.

Abstract:According to the characteristic of high salinity of formation water，high concentration of Ca2 +，Mg2 +，Ba2 +，Sr2 +，and easy corrosion of reservoir rock demonstrated in CO2 pilot test in Changqing oilfield，a study of the interactions of CO2-formation water and CO2-rock-formation water，as well as simulation experiments to present the effects of CO2 flooding on reservoir rock were carried out. The results showed that the change of pH value，pressure and temperature had little influence on the concentration of cations in formation water and did not lead to the formation of inorganic scale in the process of CO2 flooding. In the near-well zone of gas injection well，with the increase of injection pressure，the dissolved CO2 in formation water increased，and the pH value of solution decreased，resulting in the dissolution of reservoir rock. The core piece became more hydrophilic after interacting with CO2，which was conducive to improving physical property of reservoir and enhancing oil recovery. In near wellbore area of production well，due to the reduced pressure，a lot of CO2 dissolved in the formation water was escaped. The hydrogencarbonate minerals in formation water became insoluble carbonate precipitation，which led to the reducing of reservoir permeability， decreasing of porosity，and the damage of reservoir. It was not conducive to the oil recovery of long 8 low permeability reservoir.

Abstract:Diffusion of supercritical CO2（scCO2）in crude oil determines the enhanced oil recovery efficiency of huff-puff method， especially in tight and shale unconventional oil reservoirs. In this work，an experimental device was setup to determine the diffusion coefficient of scCO2 in crude oil based on pressure drop method. The influences of initial gas injection pressure，temperature and crude oil viscosity on the diffusion coefficient of scCO2 were investigated. Furthermore，a method of predicting the concentration field and diffusion front of scCO2 in crude oil was established. The results showed that the diffusion coefficient of scCO2 in crude oil was in the order of 10-8 m2 /s and increased with increasing initial pressure and finally reached a plateaued value. The increase of temperature accelerated the molecular diffusion and the greatest diffusion coefficient occurred near the critical temperature of CO2. The diffusion coefficient was found to rapidly decline with the increase of the oil viscosity. After 0.4 h，the diffusion front of scCO2 reached the bottom of bulk crude oil phase，and completely filled the bulk phase after 10 h. In the later stage of diffusion，the concentration gradient of CO2 became low leading to gradual decrease in diffusion.

Abstract:The stability as well as the interfacial activity of nanoparticle/surfactant dispersion system should be analyzed for its application in enhanced oil recovery processes. The influence of ion composition，nano-SiO2 content and pH value on the stability of nano-SiO2/SDS systems were analyzed by sedimentation，nephelometry and Zeta potential measurements. The effects of nano-SiO2 on the capability of SDS to reduce interfacial tension were also studied under the same conditions. The experimental results suggested that in NaCl brine，the nano-SiO2/SDS systems had good stability，and the addition of nano-SiO2 could enhance the ability of SDS to reduce interfacial tension. In simulated formation water，the increase of nano-SiO2 content and the presence of divalent Ca2+ and Mg2+ ions tended to destabilize the system，the ability of SDS to reduce interfacial tension first increased and then decreased with the increase of nano-SiO2 content，the interfacial tension reached a minimum at 0.5% nano-SiO2. In acidic medium， the enhanced intergranular hydration force and the presence of H+ protective layer around nano-SiO2 could improve the stability of the system in the formation water. And when the mass fraction of nano-SiO2 was more than 0.5%，the lower pH value was beneficial to improve the ability of the system to reduce the interfacial tension.

Abstract:In order to improve the stability of Guantao and Gudao heavy oil，the improvement effect of dispersant NA1，AA，oleic acid，lauric acid and palmitic acid on asphaltene solubility was investigated，and the dispersant NA1 and AA were chosed due to the stable dispersion to the two asphaltenes. The effect of treatment temperature on the improvement effect of the dispersant and the interaction mode between the dispersant and the asphaltene were further investigated. It was found that the polyol nonionic dispersant NA1 could significantly increase the concentration of asphaltenes in the solution at low temperature；when the temperature was raised to 80°C，the concentration dropped sharply，which was still much higher than the asphaltene concentration without added NA1. The improvement effect of the sulfonic acid group-containing ionic dispersant AA was less affected by the treatment temperature. In addition，it was obtained by infrared spectroscopy that the sulfonic acid group of AA could form a red-shift hydrogen bond with the N—H bond and the O—H bond in the asphaltene. A functional group such as the hydroxyl group O—H，ether bond or ester group in NA1 could form a blue-shift hydrogen bond with the hetero atom such as N，O or S in the asphaltene molecule and the aromatic ring system conjugated π bond. Both dispersants interact with asphaltenes by adsorbing on the surface of asphaltene molecules and forming hydrogen bonds.

Abstract:In order to reveal the mechanism of remaining oil displaced by in-situ emulsification，the effects of salinity，oil-water ratio and surfactant concentration on emulsion type and stability of oil/water/anionic surfactant petroleum sulfonate（KPS-202） system under quasi-stable state were investigated through phase behavior test and microscopic images of emulsion. In-situ emulsification of surfactant on oil recovery was studied through microfluidic technique. The results showed that with the increment of salinity，the emulsion type changed from oil-in-water to bicontinuous phase and finally to water-in-oil. When the mass concentration of sodium chloride was 7.5—15 g/L，the bicontinuous phase emulsion formed with ultra-low interfacial tension. The volume of bicontinuous phase increased with the decrement of oil-water ratio. The syneresis rate of emulsion decreased with the increment of oil-water ratio，which indicated the stability of emulsion improving. The increasing of surfactant concentration benefited the formation of bicontinuous phase and the stability of emulsion. In-situ emulsification of KPS-202/polymer solution and crude oil could significantly displace the remaining oil of film，corner and column. The ultimate recovery factor of in-situ emulsion system was 11.4% ，which was higher than that of betaine surfactant AF-16/polymer solution with same IFT and viscosity but without emulsification. The emulsification was helpful to the dispersion and migration of the remaining oil，which could significantly improve oil recovery.

Abstract:With weak ASP flooding scale expanding unceasingly，the treatment problem of the weak ASP flooding produced fluid highlighted increasingly. In order to study feasibility of Diluting weak ASP system with weak ASP wastewater，the ASP system was diluted with different wastewater，and the viscosity characteristics，interface activity and oil displacement ability was evaluated， and the further validation was carried out through field test. The results showed that the lower limit of permeability of weak ASP wastewater injection reservoir with suspended substance content of 100 mg/L and oil content of 50 mg/L was 100×10-3 μm2，and when the permeability increased up to 300×10-3 μm2，the weak ASP wastewater could be injected smoothly. Compared with the weak ASP system diluted with deeply treated wastewater，the weak ASP system diluted with weak ASP wastewater had the following characteristics，slightly lower viscosity，better stability，better shear resistance，smaller molecular diagram size and slightly lower viscoelasticity. The interfacial activity and adsorption resistance of two kinds of systems was the same，and the interfacial activity stability and the emulsification performance of the latter was better. The results of laboratory and field experiments showed that the injection capacity of the latter was better and the decrease of water cut was larger. In a word，it is technically and economically feasible diluting weak ASP system with weak ASP wastewater and reinjecting the II oil layer in Daqing oilfield.

Abstract:In order to improve the problem of oil-water separation of conventional heavy oil emulsifier at the gathering end，a pH-responsive heavy oil emulsifier was prepared by N，N-diethylaminoethyl methacrylate（DEAEMA）functional monomer， acrylamide（AM），and azodiisobutyramidine hydrochloride（V-50）. The effect of monomer ratio on the surface activity of emulsifier was studied， and the effects of emulsifier concentration， oil-water ratio， temperature and salinity on the viscosity-reducing property of emulsifier and the stability of heavy oil emulsion were investigated. The pH response mechanism of heavy oil emulsifier was analyzed. The results showed that the surface activity of emulsifier was the best when the mass ratio of DEAEMA to AM monomer was 7∶3. As the emulsifier concentration increased，the oil-water ratio decreased，the temperature increased，and the viscosity reduction rate of emulsion gradually increased. However，when the oil-water ratio was too low，the stability of heavy oil emulsion decreased. The emulsifier had a significant pH response characteristic that presented uniform microsphere in alkaline condition with good surface activity，while presented a transparent polymer solution in acidic condition without surface activity. The viscosity of heavy oil emulsion decreased with the increase of emulsifier addition，the viscosity reduction was about 99%，and the temperature and salt resistance was good. DEAEMA could be protonated or deprotonated by adjusting the pH value，thus making the surface activity of emulsifier controllable and achieving controlled emulsification_x0002_demulsification of heavy oil emulsion.

Abstract:A new polyether demulsifier P-51T was synthesized to solve the difficulties in heavy oil demulsification，poor adaptability of conventional demulsifiers and high dehydration temperature. The effects of the mass ratio of ethylene oxide to propylene oxide and the adjuvant types on the demulsification and dehydration performance of the demulsifier were studied. Field tests were carried out at Guwu united station of Shengli oilfield. Researches showed that the optimal synthesis conditions of P-51T demulsifier was as follows，the mass ratio of initiator to ethylene oxide was 1∶19，the mass ratio of ethylene oxide to propylene oxide was 1：3，and the mass ratio of polyether to alkylbenzene sulfonic acid monoethanolamine was 5∶1. Compared with the demulsifiers commonly used in oilfields，P-51T had the advantages of faster dehydration speed and better demulsification effect. At a lower temperature， superiorities of P-51T were more obvious. In field tests，when the dehydration temperature was reduced from 73—80 °C to 65°C， after the demulsifier treatment，the water content of the transported oil was less than 0.8%，and met the standards stably（＜2%）. The application of demulsifier P-51T can reduce heating energy consumption，decrease production costs，and has a broad application prospect.

Abstract:In order to improve high temperature resistance and dehydration performance of demulsifier for oilsand emulsion treatment，phenol-amine resin containing dinaphthol structure was synthesized using 6，6-isopropylidenebisnaphthol，ethanediamine and methanol as the raw materials. Then multibranched high temperature resistant demulsifier was further synthesized using the phenol-amine resin as the initiator，KOH as the catalyst，through addition reaction with epoxyethane and epoxypropane respectively. High temperature resistance was studied by thermogravimetric analysis and hydroxyl value，dehydration performance was evaluated by high-temperature dehydration bottle tests. The results showed that the demulsifier had good temperature resistance with little mass loss below 350℃ and the stable hydroxyl value when temperature was at the range of 100—300℃，indicating that the demulsifier could be used to treat oilsand emulsion in the high temperature environment. For the oilsand emulsion from oilfield in Alberta，Canada，the dehydration rate reached up to 90% within 8 hours at the demulsifier dosage of 400 mg/L and at the temperature of 130℃ ，which was higher than that of the incumbent demulsifier. The obtained demusifier have excellent demulsification and dehydration performance for the oilsand emulsion.

Abstract:In order to analyze the influence mechanism of natural gas on oil dehydration，the natural gas was injected into the inlet oil of the first stage separator，the second stage separator and the electronic dehydrator which already had water base demulsifier in Bohai oilfield through gas-oil mixture equipment. The effect of gas dosage and time on the diameter of waterdrop in roily oil was studied，the effect of gas flow rate on oil dehydration was studied，the field trial of organic silicon defoamer was carried out and the influence of defoamer on oil dehydration was analyzed. The results showed that the waterdrop diameter and the dehydration rate of roily oil in the inlet of the first stage separator changed slightly as increasing flow rate of natural gas. While the waterdrop diameter increased and the dehydration rate accelerated in the inlet of the second stage separator and electronic dehydrator. When the flow rate of natural gas was 3 L/min，the balanced diameter of waterdrop reduced and the dehydration rate decreased. After the defoamer was injected into the inlet of the second stage separator and electronic dehydrator，the dehydration and degassing effects improved with increasing concentration of defoamer. The defoamer accelerated the degas rate of natural gas in the oil. The emulsifying waterdrop motion was accelerated when the gas bubble floated upward，which increased the coalescence rate of the small emulsifying waterdrop into the big one and finally improved the dehydration of oil.

Abstract:At present，there is no specific inhibitor for inhibiting the corrosion of wastewater containing high dissolved oxygen in Shengli oilfield，which results in large amount of reagent and poor corrosion inhibition efficiency. Considering the synergistic corrosion effects of dissolved oxygen，oxidizing substances and HCO3- ，a highly effective inhibitor，glucose thiocarbamate， containing multiple adsorption centers such as hydroxyl， N—C=S and O=C—N， was synthesized， and using glucose thiocarbamate as the main agent，organic carboxylate，thiourea and organic phosphonic acid（ATMP）as adjuvant，through orthogonal experiment，the formula of the compound inhibitor PTT-20 was obtained as follows，60% glucose thiocarbamate + 6% thiourea + 4% carboxylate + 10% ATMP. The corrosion rate of the steel test pieces in the sewage（oxygen concentration 8.0 mg/L） with 30 mg/L PTT-20 was 0.0405 mm/a at the temperature of 60℃ and the experiment time of 72 h. In the field application where the dissolved oxygen content was 0.6—1.4 mg/L，the corrosion inhibition rate of 30 mg/L PTT-20 could reach more than 90%，and the corrosion inhibition effect was significantly better than that of the current conventional corrosion inhibitors. PTT-20 could form multi-point adsorption and firmly adsorb on the metal surface，reducing oxygen adsorption. Carbon-sulfur groups and hydroxyl groups could also absorb dissolved oxygen in water and slow down oxygen corrosion. The compound components had a synergistic effect and further improve the corrosion inhibition efficiency.

Abstract:Tahe oilfield has a condition of high temperature，high oxygen and high salinity. The corrosion phenomenon of water injection pipeline and water injection well is serious. In order to effectively alleviate the serious corrosion situation of Tahe oilfield， Mannich base was synthesized by using acetic acid，benzylamine and acetophenone as raw materials，and then mixing it with surfactant（fatty alcohol polyoxyethylene ether，fatty alcohol polyoxyethylene ether phosphate），etc. to prepare Mannich base corrosion inhibitor. On the condition of high temperature and high pressure，the effect of dissolved oxygen and oxygen content on the corrosion of steel was investigated. The performance of inhibitor was evaluated by weight loss method and electrochemical test method. The results showed that the dissolved oxygen could increase the corrosion of pipeline. The corrosion rate increased with increasing oxygen concentration. The amino group and benzene ring in the Mannich base corrosion inhibitor formed an electron-rich conjugated system，which had a strong adsorption capacity. The inhibition rate could reach 92.57%，and the corrosion inhibition performance was good. Mannich base corrosion inhibitor was a mixed inhibition type corrosion inhibitor mainly for inhibiting anode reaction，which could effectively inhibit the corrosion under high temperature and high oxygen conditions.

Abstract:Firstly，polymerizable surfactants DC12MAAC with long hydrophobic chains were synthesized，and their structures were confirmed by IR and 1 H NMR analysis. Next，the copolymer P［DPM/DC12MAAC］was synthesized by copolymerization of dimethylaminopropyl methacrylamide（DPM）with the DC12MAAC. Using weight increment of iron sheet per unit surface area and turbidity reduction rate as evaluation indexes，the reaction conditions of copolymerization were optimized by single factor method. The optimum reaction conditions were obtained as follows，the monomer concentration was 50%，the monomer ratio of DPM to DC12MAAC was 100∶2，initiator concentration was 0.8% ，the reaction time was 6 h and the reaction temperature 60℃ . The evaluation of flocculation effect of P［DPM/C12DMAAC］showed that the highest turbidity reduction rate was 99.53%，the lowest weight gain of iron sheet per unit surface area was 43.02 g/m2，which could reduce flocs by 74.90%，composed of the result of flocculant treatment in oilfield，being of 171.39 g/m2. P［DPM/DC12MAAC］had good surface and interface activity. It was speculated that the principle of clean water was to destroy the diffusion double electron layer of oil droplets through electrostatic adsorption to neutralize the negative surface charge.

Abstract:After washing and sanding the chemical flooding injection wells in the YX block，a large number of highly viscous oil-containing colloids were found to be difficult to handle. The compatibility of the oil-containing colloid and the formation was analyzed by measuring the viscosity，pH value，water content，oil content and other components of the oil-containing colloid. The oily colloid was directly deoiled with chloroform to remove the crude oil on the surface and inside of the oily colloid，and then the colloid was dried and broken into a powder. The feasibility of reusing oil-containing colloid was analyzed by measuring the viscosity of the flooding system with different amounts of oil-containing colloid powder. The results showed that the colloids containing oil contained 80.47% water，7.16% polyacrylamide，6.49% crude oil，and a small amount of silicate and organic matter. The treated colloidal powder could be used in the preparation of oil displacement agent. In addition，through simple filtration，the oil colloid could be directly injected into the reservoir and used to block the superior channel or large pore channel，so as to achieve the purpose of oil colloid reuse.

Abstract:In the technologies of supercritical CO2 flooding enhanced oil recovery，the development of assistant which can effectively reduce minimum miscibility pressure（MMP）is significantly important. In order to shorten development period and raise efficiency remarkably，a convenient and visualized method to measure MMP，namely rising height test，was introduced. A high pressure cell with transparent windows was set up and by transforming volume expansion of oil phase into height data，a miscible-ratio curve against equilibrium pressure would be obtained after data processing. The whole process could be visualized. The measurement results by this method were compared to those by slim tube test to verify test accuracy. An experiment method which utilized simulation oil samples consisted of different ingredients was introduced for assistant screening. The results showed that the MMP measured by this method was accurate and the relative error was less than 5% compared with that of slim tube test. With this estimation method，an effective octaester assistant was screened out，which was able to reduce the MMP of crude-oil samples from Changqing，Xinjiang and Jilin oilfield under the temperature of 50—80℃ and dosage of 1% —3% . The biggest decline was up to 20%. The MMP could be determined accurately by rising height test and the effect of miscible flooding assistant could be estimated.

Abstract:为定量分析神木气田气井采出流体乳化物成分、确定影响气田乳化的主要因素，基于核磁共振技术，计算 了生产过程中采出水（PQ-8型泡排剂、凝析油、EM50压裂液、UT-6型泡排剂）与采出流体乳化物核磁共振T2谱叠 合区面积，定量评价了各采出水与乳化物的相似程度，并通过传统的傅立叶红外光谱仪对核磁共振技术分析乳 化物成分的可靠性进行了验证。结果表明，气井采出水中PQ-8型泡排剂与不同时间采出流体乳化物核磁共振 T2谱叠合区面积最大（2831.65~ 4235.80），其是造成神木气田处理厂采出水乳化的主要因素；UT-6型泡排剂与不 同时间采出流体乳化物核磁共振T2谱叠合区面积最小（87.61~ 394.20），其对采出水乳化几乎不造成影响。PQ-8 型泡排剂与凝析油和不同乳化物样品的核磁共振T2谱叠合区面积差异较大，说明二者在不同乳化物样品中的含 量存在较大差异，对后期的破乳剂配方确定及破乳带来一定难度。基于核磁共振技术对气井采出流体中乳化物 成分的分析结果与用傅立叶红外光谱仪测得的结果一致。图5表2参20

Abstract:Asphaltene precipitation is a common problem in the process of CO2 enhanced oil recovery project，which usually causes the pore throat plugging and wettability change of the reservoir. The formation damage and wettability change due to asphaltene precipitation was quantitatively evaluated under different CO2 injection pressures through core flooding test and NMR technique. The Experiment results showed that the viscosity and asphaltene content of the produced oil decreased and the asphaltene content of the residual oil increased with increasing injection pressure of CO2. When the injection pressure of CO2 was 9.1，16.2 and 24.1 MPa，the permeability reduction of core was 2.40%，7.41% and 8.32%，the mixed wettability index decreased 0.04，0.12 and 0.14，and the apparent contact angle increased 5°，12° and 19°，respectively. The higher injection pressure of CO2，the more serious asphaltene precipitation was，which would result in greater damage to the porosity and permeability of low permeability reservoir.

Abstract:In the field of microbial enhanced oil recovery（MEOR）research，anaerobic biological wastewater treatment and biogas fermentation，the amount of methane-producing bacteria（MPB）was determined by the complicated Hungate roller culture method. In order to measure the amount of MPB more easily and accurately，it was recommended to use a MPB-specific test bottle containing carbon source，nitrogen source，phosphorus source and chemical deoxidizer. The results showed that the water sample was infused into the test bottle and was diluted step by step，the culture solution became cloudy and bubbles appeared after culturing for 14 days at 30℃ or on-site temperature ± 5℃，indicating the growth of MPB. The MPB count was performed according to the conventional bacterial bottle method. The amounts of MPB in oilfield production fluid，microbial enhanced oil recovery agents and sewage treatment plant anaerobic digestion tank were determined by the bacterial bottle method，and the results were basically the same as those by the Hungate roller culture method. Compared with the Hungate roller culture method，the bacterial bottle method had the advantages of obvious growth indication，simple operation and high work efficiency.

Abstract:Slick-water is widely used in water-based fracturing for unconventional oil and gas exploitation，which can reduce the friction resistance. As the core of the slick-water fracturing fluid，the friction reducer determine the fluid’s performances. Combining with the related literature at home and abroad，this paper analyzes the mechanism of friction reducer，introduces the research and application progress of natural polysaccharide，surfactant and polyacrylamide. It is considered that both the instant powder polymer and W/W dispersion polymer have great application potential. The friction reducer with high-efficiency sand-carrying and salt resistance is the focus of future research.

Abstract:Zhongyuan oilfield，located in Dongpu Depression，is a complex fault-block reservoir with high temperature and high salt. After more than 30 years of exploration and development，it is in the stage of development with medium and high water cut. The development of tertiary oil recovery technologies in Zhongyuan oilfield in recent ten years was summarized in this paper， including gas flooding and chemical flooding. The research achievements and practices of various technologies in different reservoirs were introduced，and the understanding and development direction of EOR in Zhongyuan oilfield was pointed out. It provided reference for the development of EOR technologies in high temperature and high salt reservoirs at home and abroad.

Abstract:Viscosity reduction and mobility improvement are very crucial in heavy oil recovery. The mechanism，development and application of main viscosity reduction methods at home and abroad were discussed and compared，including thermal treatment based on steam injection，fire flooding，emusification，catalytic reaction，solvent dilution and microbial viscosity reduction. The characteristics and disadvantages of these methods were summarized. Finally，the development directions of heavy oil viscosity reduction technology were proposed.

Abstract:The traditional effective development technology of heavy oil resources is facing increasingly severe challenges of safety，environmental protection and economy. As a green solvent for heavy oil recovery at room temperature，ionic liquid has great potential. The concept and physicochemical properties of ionic liquids are described. The development of ionic liquids is reviewed. This paper summarizes the research progress and understanding of ionic liquid as viscosity reducer，dispersant，in-situ modification and displacement experiment. In view of the existing problems in the current research and the actual situation of the oil field，the application target of ionic liquid is the resources that can't be economically and effectively exploited by the existing thermal recovery technology and the heavy oil reservoir that needs to be enhanced recovery after steam injection development. As a new generation of in-situ modification and viscosity reduction technology for heavy oil，ionic liquid has great application potential. It should be used as an advanced reserve technology to speed up research and development.