Abstract:A novel cement retar der HL-1 was synthesized by copolymerization of acrylic acid （AA）, maleic acid （MA）, sodium p-styrenesulfonate（SSS）and the hydrophilic long-chain alkene monomers （LN）. The optimized synthesis conditions had been determined by single factor method and the structure of the HL- 1 obtained at the optimal synthetic conditions was characterized with infrared spectrum （IR）and nuclear magnetic resonance hydrogen spectrum （H¹-NMR ）.The influence of the HL- 1, obtained atoptimal synthetic conditions, on the retarding propertiesand rheological properties of the slurry （oil well cement G + 3.0% silicon micro +30% sand + 1.5% filtrate reducer SZ1-2 + 0.8% dispersant SXY, water cement ratio W/S =0.44）and on the compressive strength of cement stone was investigated. The optimized synthesis conditions were as follows: the mole ratio of AA, MA, SSS, LN was 0.06∶1∶0.54∶0.1, the monomer mass fraction was of 30%, the reaction temperature was60℃, the dosage of initiator was 5%,and the pH value of 5. The IR and H¹-NMR results confirmed that, the structure of HL-1 was consistent with the molecular design. It turned out that the HL- 1 had good thermal stability and could be used below 260℃.The evaluation results showed that HL- 1 had good high temperature retarding performance and the thickening time of the cement slurry containing 1.0%HL-1 reached 380 min at the temperature of 150℃and at the pressure of 80MPa. HL-1 had good dispersion effect on the slurry, which could effectively improve the liquidity of the slurry and had little influence on the strength of cement stone.

Abstract:Calcium carbonate whisker（CCW）was used to modify the properties of the oil cement system, and the influence of CCW on both cementing slurry and cement paste was preliminary tested. The results showed that, at water cement ratio of 0.44, the fluidity of the slurry containing CCW decreased, thus, the slurry dispersing agent should be added and optimized, and the water cement ratio and the dosage of the CCW also should be controlled. Compared to the blank slurry the initial consistency of the slurry containing 10% CCW increased from 16.4 bc to34.6 bc and the thickening time （70bc ）decreased from 311 min to 160 min, the API filtrate loss also decreased significantly. The thickening time of the cement slurry could be well controlled by using0.5% retarder HN- 22. The compressing strength, flexure strength and splitting tensile strength of the cement paste with 10% CCW increased by 10%,54% and28% ,respectively, compared to that of the blank sample, which indicating that the cement paste with the CCW had the strong toughing effect. In addition, the enhancement mechanism of the cement pastes with CCW was analyzed by the means of establishing a surface physical model and XRD measurements.

Abstract:The reaction kinetic experiments between a surface cross-linked acid and Syria limestone were conducted by using a rotating disc at temperatures of 60℃，90℃，120℃and 150℃. Reaction kinetic equations were deduced to demonstrate the reaction characteristics of surface cross-link acid and limestone from target layer of Syria at corresponding temperatures. The results indicated that experiment temperature was an important influence factor on the reaction rate. The higher temperature ，the faster reaction was. Corresponding reacting rate constant of the acid and limestone were 5.68× 10^-8（mol/L）-1.51/（cm²·s）、1.94× 10^-7（mol/L）^-1.03/（cm²·s）、2.76× 10^-7（mol/L）^-0.72/（cm²·s）和1.62× 10^-6（mol/L）^-0.42/（cm²·s），and the reacting orders were 1.51，1.03，0.72 and 0.42respectively at above temperatures. The reacting rate constant of surface cross-link acid was smaller about 1 order of magnitude than that of conventional gelling acid at60℃，and 2 order of magnitude at120℃compared with earlier experiment results ，which showed the better retarding performance. Therefore ，the surface cross-linked acid possessed the advantages of acid fracturing stimulation in high temperature deep well of carbonate reservoirs in aspect of increasing the effective acid-etched distance.

Abstract:A kind of synthetic polymer-based fracturing fluid system was introduced ，which was composed of0.40% thickener XJJ- 4，0.25% cross-linker J-1，0.015% pH regulator W-1 and 0.2% cleanup agent. The performance of heat resistant，shear resistant，viscoelasticity ，rheological property and gel-broken fluid was studied. The last viscosity of the fracturing fluid was about 120 mPa·s after shearing 2 hrs at 150℃and 170 s^-1. The fracturing fluid system was resilient to heat and shear. In the linear viscoelastic region ，the storage modulus G' was greater than loss modulusG' '，and it was a typical viscoelastic fluid. The consistency coefficient（2.141 mPa·s^0.476）was large ，and the index of rheological behavior（0.476）was small，indicating obviousnon-Newtonian fluid behavior. With adding 0.01% breaker APS，the gel was broken after 3 hrs at 150℃. The viscosity，residue content ，surface tension and interfacial tension of the gel-broken fluid was 1.38mPa·s，15mg/L，26.24mN/m and1.83mN/m respectively ，which would decrease the damage to formation and flow back easily.

Abstract:A water-soluble polymer thickener BCG-1 was synthesized by using acrylic acid，acrylamide，cationic unsaturated monomer and anionic unsaturated monomer as mainly polymeric monomers，sodium dodecyl benzene sulfonate as emulsifier and ammonium persulfate-sodium bisulfite as initiator system. BCG-1 could be able to swell in seawater ，and the apparent viscosity of seawater solution with BCG-1 dosage of 0.6% was greater than80mPa·s. The seawater-based fracturing fluid was prepared by using the thickener and other related additives ，the formula was obtained as follows: 0.6% BCG-l+0.4% metal ions chelating agent BCG-5 + 0.3% viscosity synergist B-55+ 0.1% temperature stabilizer B-13+ 0.02%～0.05% capsule gel-breaker BCG-10. The fracturing fluid had no precipitation and the apparent viscosity changed little after being laid up for a week at 30℃，indicating a good stability at normal temperature. The viscosity of the fracturing fluid remained at 46.9 mPa·s after shearing at 170 s^-1and 140℃for 60minutes，showing good temperature and shearing tolerance. The falling ball viscosity was 4534.7 mPa·s，showing goodcarrying capacity. And it could be completely gelout，the content of residue was less than 5 mg/L. The surface tension of broken gel liquid was less than 26mN/m. The damage of broken gel liquid on flow conductivity of support crack diversion was below8% ，which completely possessed the performance characteristics of clean fracturing fluid.

Abstract:Aimed at the defects of the cationic viscoelastic fracturing floodings, a zwitterionic/anionic mixed sufactant clean fracuring flooding was prepared and the relative properties were characterized. The viscoelastic surfactant fracturing fluid was made of 2.24% zwitterionic surfactant betaine，0.9% anionic surfactant SDS，6.2% KCl and deionized water. The result of performance evaluation indicated that the viscosity of fracturing fluid increased firstly and then decreased with increasing concentration of KCl，and that increased with increasing dosage of SDS. The apparent viscosity of fracturing fluid was about 59.5 mPa·s at 65℃and 170s^-1 after shearing 40minutes，indicating good temperature resistance and shear resistance performance. The sedimentation rate of sands in fracturing fluid was 0.02，0.14and 0.51mm/s at room temperature，55℃and 65℃respectively ，indicating good sand-carrying performance. The viscosity of fracturing fluid decreased to 2.15mPa·s quickly when the dosage of kerosene was 2% ，the surface and interfacial tension of the breaker fluid was 26.542 and 0.8562mN/m respectively ，and there was no residue. The leak-off coefficient of fracturing fluid in natural core was 5.6 × 10^-4m/min^1/2 ，exhibiting a good filtration property. The damage rate ofbreaker fluid to the core permeability was19.1% ，and the fracturing fluid was suitable for the fracturing operation in the reservoirwithin 65℃.

Abstract:According to the characteristics that the reservoir bed of Liu 62block in Huabei oilfield was deeply buried at high temperature ，the formula of movable gel system with good temperature performance was optimized ，which consisted of 1500mg/L polyacrylamide，2000 mg/L resinous cross-linking agent，1000 mg/L hexamine cross-promoting agent and50 mg/L thermal stabilizing agent. Combined with the hierarchical flooding process ，the shear effect of eccentric water distributor and blanking plug on the crosslinking performance of movable gel solution was studied through model experiment in laboratory. The results showed that the viscosity-retention rate of gel solution was 97.76% after passing through the eccentric water distributor，and that was 98.64% after cross-linking. The eccentric water distributor shear had little effect on the properties of movable gel. But the blanking plug shear had great influence on the performance of movable gel. The smaller opening degree of plug device，the bigger throttle pressure difference was while the movable gel passed，the more serious shear on the movable gel was ，which even affected the crosslinking of movable gel. Therefore ，in the use of tubing string of movable gel flooding ，it was suggested to fish up the blanking plugs in control-drive objective layers. The field trials in Liu 62-72wells revealed that the movable gel after control-driving had no influence on the tripping and allocation in separate injection and the control-driving effect was preferable.

Abstract:Com pared with traditional foams ，low tension foam has better profile-controlling ，oil-washing ，and temperature and salinity resisting abilities. Based on its characteristics and the model of foam resistance factor，influencing factors including the concentration of foaming agent solution，gas injection velocity and oil saturation were studied through core-flow experiments. In combination with the experiments and sensitivity analysis ，parameters influencing numerical simulation of low tension foam flooding such as es ，ev and eo were calculated with LSM method. Moreover ，the accuracy of the model parameters was verified through oil displacement experiment with low tension foam. The results showed that the modified model could exactly simulate the displacement mechanism of low tension foam flooding，and the values of the parameters es ，ev and eo were 1.37，0.49and 1.585，respectively.

Abstract:In order to better understand the interaction between crude oil and foam，the influence factors of foam-oil interaction stability were researched，including oil type ，oil phase content，surfactant concentration ，surfactant type，salinity ，alkyl chain length and polymer content. Under different experiment conditions ，the half-time of foam drainage in the absence and presence of oil was measured. The result showed that different crude oil had different effect on foam stability and TK 729 oil exhibited the strongest stability to foam. Light oil and heavy oil both improved foam stability within a certain range of oil content. Different surfactant systems exhibited different degrees of sensitivity to oil ，and anionic surfactant AS showed the best foam stability to oil.After adding20% TK729 oil to amphoteric surfactants MZ and AS compounded system （mass ratio1∶2），oil destabilized foam with surfactant concentration less than 0.05% while stabilized foam with concentration more than0.075%. The increase of salinity had an inverse effect on foam stability to oil. Oil stabilized foam when the salinity was less than 5 × 10⁴mg/L while destabilized foam when the salinity was larger than10× 10⁴mg/L. Additionally，the shorter the alkane chain length ，the higher the tendency of alkane to destabilize foam was. Long-chain alkane with more than 16carbon number showed stability to foam. Adding polymer to the aqueous phase improved the foam performance in the presence of oil，and the more dosage of polymer the better foam stability to oil was.

Abstract:Comprehensive properties of core flow, oil displacement efficiency and anti-ageing of the synthesized partially crosslinkedpolyacrylamide （B-PPG ）were investigated through a comparison with conventional partially hydrolyzed polyacrylamide （HPAM）. The research results showed that, the steady-state pressure and the capacity of transfer pressure in the core flow experiment of B-PPG were significantly improved compared with that of HPAM. Meanwhile, a phenomenon of“fluid diversion ” could be observed in double tube core flow experiments, which indicated that B-PPG exhibited profile control ability in non-homogeneous porous media. Furthermore, micro-visualization displacement experiments proved that B-PPG could displace much residual oil after HPAM solution flooding. The ageing experiment demonstrated that B-PPG possessed excellent anti-ageing capability, ensuring that the system could keep excellent viscoelasticity and core flowing property during a long time under the condition of 85℃via a course of the polymer evolution from elastic to viscous.

Abstract:Te rpolymers ZS- 1，ZS-2，ZS-3 were synthesized using acrylamide，acrylic and 1% ，2% ，3% 2-acrylamide hexadecyl sulfonate （NaAMC16S） respectively. The composition of terpolymer was determined by elemental analyzer. The relative molecular mass，viscosity ，salt resistance ，shear resistance and injectivity were tested. The results showed that the relative molecular mass of ZS-1，ZS-2 and ZS-3 was 1661× 10⁴，921 × 10⁴and 523 × 10⁴respectively. Elemental analysis results indicated that ZS- 1，ZS-2 and ZS-3 contained 0.998% ，1.488% ，1.973% NaAMC16S separately ，according to the content of element S. With increasing content of NaAMC16S，the relative molecular mass of terpolymer decreased ，viscosity increased ，salt resistance and shear resistance enhanced. After capillary shearing at room temperature，the viscosity retention rate of ZS- 1，ZS-2 and ZS-3 was 84.1% ，87.6% and 89.4% . Core flooding tests results showed that the injectivity of ZS- 3 was good. Comparing to 1.8 g/L partially hydrolyzed polyacrylamide solution with relative molecular mass 1600× 10⁴，0.9 g/L ZS-3 displacing fluid could get similar recovery ratio（22.48%），which could reduce the cost of polymer flooding.

Abstract:In order to study the viscosity reducing effect of the polymer solution in Daqing oilfield，the totally ion analysis of the polymer solution from the wellhead of the injection well was conducted ，the effect of reducing substances ，Fe^{2 +}and S^{2 -}，on the properties of polymer solution was researched. The results showed that the concentration of Fe^{2 +}and S^{2 -}ions had little effects on the properties of the polymer solution under anaerobic conditions ，while the viscosity of the polymer solution droped sharply with increase of the concentration of Fe^{2 +} and S^{2 -}ions under the condition of oxygen exposure. The viscosity of the polymer solution with 1.18mg/L Fe^{2 +} ions dropped by 42.49% ，while the viscosity of the polymer solution with 2.49mg/L S^{2 -}dropped by 49.42%. With the increase of concentration of Fe^{2 +}and S^{2 -}，the polymer molecules line size also sharply reduced ，the thixotropy of the polymer solution degraded. Fe^{2 +}and S^{2 -}ions made HPAM degradation，which was the main cause of HPAM solution viscosity decreased. In the field ，several measurements were proposed in order to reduce the effects of reducing substances on the polymer solution.

Abstract:An anionic gemini surfactantGMAS-14was synthesized via series of reactions, such as nucleophilic substitution, ring opening and netrualization reaction by using ethylenediamine, 1-bromotetradecane and maleic anhydride as raw materials. The structure of N, N' -（2-tetradecyl）-ethylenediamine and GMAS-14was characterized by infrared spectroscopy（IR）, and the surface activity and foaming properties of GMAS-14were tested. The results of IR showed that，the structure of the intermediate and final products were consistent with the design, and it was determined that the substances were the target products. The performance test of GMAS-14 indicated that, at the temperature of 25℃, the critical micelle concentration （c cmc）of the GMAS- 14was of 0.048 mmol/L and the surface tension（γ cmc）of the GMAS- 14was of 27.5 mN/m. At the critical micelle concentration, the maximum foam volume ofGMAS-14solution of 10mL was of23mL, and the half-life period of the foam was 590 s, presenting good foaming properties.

Abstract:The optimum mass ratio 3∶7 of branched alkylbenzbene sulfonate sodium （BABS）and cocoamido propyl hydroxy sulfobetaine （CHSB）was obtained based on the critical micelle concentration （ccmc）and equilibrium surface tension （γ）of BABS and CHSB binary mixture ，and the ccmc of compound system was 0.0513g/L and the γcmc was 26.4 mN/m. Three phase behaviors of the mixed system，with BABS and CHSB binary mixture as surfactant，different chain length alcohols as co-surfactant，NaCl as salt component，simulation oil containing 2% crude oil as oil phase，were studied by Winsor diagram and conductivity scanning method to explore the effects of NaCl，n-butyl alcohol and surfactant concentration on the phase behavior of the system. The results showed that the system experienced microemulsion change from Winsor I to Winsor III and then Winsor II with increasing NaCl concentration，that from Winsor III to Winsor II with increasing n-butanol concentration，that from Winsor III to Winsor I with increasing surfactant concentration. The optimum formation condition of middle phase microemulsion was obtained as follows: 0.5～1.5 mol/L NaCl ，0 ～2.2% n-butyl alcohol and 0.5% ～8% surfactant. Under this condition，the interfacial tension betweencrude oil and water could achieve 10^-3mN/m magnitude in a short time，which satisfied the requirement of oil displacement agent.

Abstract:Aimed at the difficulty of heavy oil development and the process of emulsification and viscosity reduction ，theself-emulsifying system with polymer nonionic block polyurethane surfactants as the main agent was developed. The polymer nonionic block polyurethane surfactant （DBPS）was synthesized，and the critical micelle concentration was2.71× 10^-6mol/L. The effect of initiator （Na₂CO₃）dosage and different emulsifier and auxiliary surfactant on the emulsification and viscosity reduction of heavy oil was studied. The optimum formula was obtained by orthogonal test: 0.5% Na₂CO₃，0.5% DBPS，0.5% Tween-80and 0.6% polyethylene glycol. After self-emulsifying system and heavy oil was mixed ，dispersed oil-in-water emulsified oil droplets was developed. The emulsification viscosity reduction rate was above98% ，the dehydration rate reached 73% after2.5 h sedimentation at 80℃，the surface tension of self-emulsifying solution was 27.02mN/m at 70℃，and the interfacial tension between self-emulsifying system and heavy oil reduced to0.0057mN/m

Abstract:ANDES oilfield belonged to high temperature（96℃）and high salinity（71.5 g/L）reservoir. Under this condition，four kinds of surfactants were combined with an ideal AP-P5 polymer with a high temperature and high salinity resistant. It was found that the interfacial tension of binary combination system formed by 0.3% sulfonate（MJ2）or Daqing petroleum sulfonate（DQ）and 2500 mg/L AP-P5 could reach 10^-3 mN/m magnitude. The effects of temperature and salinity on the viscosity of two kinds of binary combination system were examined. The results showed that the viscosity of two kinds of binary combination system decreased with increasing temperature and salinity. At 96℃ and salinity of 70 g/L，the viscosity of binary combination system with 3000 mg/L AP-P5，0.3% MJ2 and sulfocarbamide stabilizer was 99.4 mPa·s which satisfied the field requirement. And in this situation，the viscosity of this binary combination system tended to be stable after two months and there was small fluctuation of interfacial tension. During indoor physical simulation flooding experiment，the enhanced oil recovery rate reached the largest value（24.5%） when the injection volume of binary combination system was 0.65 PV. The displacement project of early water flooding（until 85% water content）+ 0.65 PV（3000 mg/L AP-P5 + 0.3% MJ2）+ late water flooding （until 98% water content） was the best oil displacement plan.

Abstract:Simulated polymer/surfactant produced water was prepared according to the practical component of produced water from the polymer/surfactant flooding process in Xinjiang oilfield. Effects of each component including solid particle，polymer（HPAM） and surfactant on emulsion stability of the binary produced water were investigated. Results showed that the surfactant had a significant impact on the emulsion stability，and there were some minor influences for solid particle and polymer. Montmorillonite particle had a clear influence on the emulsion stability over kaolin and vermiculite particles. At montmorillonite dosage of 200 mg/L，the maximum oil content and turbidity of produced water were obtained at 807 mg/L and 1984 NTU，respectively. When the montmorillonite concentration was over 200 mg/L，the oil content and turbidity of produced water were decreased，but the droplet Zeta potential in produced water was high. HPAM（M=10×10⁶）could directly affect the bulk viscosity and also destroy the emulsion stability due to its strong flocculation capacity，especially at its high concentration by enhancing the flocculation with oil droplets in simulated produced water. Surfactant could significantly increase the emulsion stability due to its strong interfacial property for changing the Zeta potential of oil droplets and the process of oil droplets collision and coalescence. The surfactants were arranged according to their influence on the emulsion stability of simulated polymer/surfactant produced water in following order: sodium dodecyl benzene sulfonate（DBS）>Tween-80>Span-80>benzalkonium chloride.

Abstract:Comparison of micro-model experiments among Polymer, Polymer-Surfactant and Alkali-Surfactant-Polymer flooding were conducted on anisotropic micro-model, modeling oilfield production from different chemical flooding. Via micro-model flooding, the oil drop shape change-transfer-redistribute was observed. Furthermore, through calculating and counting, the oil recovery of these three ways were obtained, being of 43%, 59% and 92% , respectively, for Polymer, Polymer-Surfactant and Alkali-Surfactant-Polymer flooding, respectively. The phenomenon of profile control, emulsification, ultralow interfacial tension, and wettability reversal was specifically described. In the end, the conclusion was drawn that alkali-surfactant-polymer flooding still would be the major component of chemical flooding.

Abstract:Box-Behnken and response surface methodology were used to research and probe the best level and mutual effect of cysteine concentration，pH value and Na₂SO₄ concentration that affected the growth of sulfate-reducing bacteria（SRB）. The data was analyzed by Design-Expert.8.05B software. The results showed that three factors were arranged according to their influence on anti-vulcanization rate of SRB in following order: cysteine concentration，medium pH and sodium sulfate concentration. And the interaction between two factors in fitted regression model had insignificant effect on anti-vulcanization rate of SRB. The optimum culture condition was obtained as follows: 0.01% cysteine mass fraction，8.0 pH value and 2.0 g/L sodium sulfate concentration. Under this condition，the average anti-vulcanization rate of SRB was 10.642%，which was close to the predicted value（10.097%）. Therefore，it was feasible for the established model due to the consistent result between prediction and experiment.

Abstract:Aimed at Lengyilian crude oil in Liaohe oilfield, Polyorganosiloxane demulsifier FW-135 was prepared through the reaction of hydrogen-containing silicone oil with acrylic acid（MA）, methacrylic acid（MAA）, methy methacrylate（MMA）and n-butyl acrylate（BA）, using sulfoacid resin as the catalyst. On basis of the single factor test, the effect of the reaction temperature, reaction time, catalyst usage and BPO usage on the reaction conversion were examined. The optimal reaction conditions were determined as follows: the reaction temperature was 80℃, reaction time was 5 h, catalyst dosage was 21% of the mixed acid, and the 1.0% benzoyl peroxide （BPO） dosage was 1% of the reactant. The structure of the polysiloxane demulsifier FW-135 was characterized by FT-IR and the dehydration effect on crude oil was studied. The FT-IR analysis showed that the objective polymer was obtained through the reaction. The dehydration rate of the crude oil treated by polyorganosiloxane demulsifier FW-135 was up to 90.65% after treated at the temperature of 60℃and at the FW-135 dosage of 80 mg/L for 120 min, and two-phase separation was visible with clear interface.

Abstract:The inhibition actions of 1-phenylaminomethyl-benzimidazole（BMP）on the corrosion of N80 steel in HCl was studied by means of weight loss and electrochemical test. The results showed BMP could inhibit the corrosion of N80 steel in 5 mol/L HCl solution at the BMP concentration of 2 mmol/L, and the inhibition efficiency was more than 88% at the temperature of 333K. Active energies on the corrosion reaction increased with the increase of inhibitor concentration. The adsorption of BMP on the surface of N80 steel obeyed Langmuir isotherm, and adsorption energies were less than -35 kJ/mol in the temperature range of 303～333 K. In addition, the inhibition performance of BMP was investigated by molecular dynamics simulation method.

Abstract:In order to study the influence of the combined action of multiple factors on the barium sulfate scale inhibition，through the chemical inhibition method，orthogonal experiments on the barium sulfate scale inhibition of screened barium/strontium scale inhibitor TH-1 with the concentration of 80 mg/L were conducted. The single influence on the scale inhibition of Ba²⁺ concentration， SO₄^2- concentration，pH，temperature and salinity was studied，and especially focused on the combined action of five factors. The results showed that the three kinds of scale inhibitors ZX-101，TH-1 and TH-607B all showed a good scale inhibition performance. The scale inhibition rate of the three scale inhibitors all showed the trend of first increase and then decrease with the increase of inhibitor concentration，and correspondingly，the scale inhibition rate of TH-1 was stable. With the increase of Ba²⁺ concentration， the scale inhibition rate decreased. With the increase of SO₄^2- concentration，the scale inhibition rate decreased slightly. With the increase of temperature，the scale inhibition rate obviously increased at first and then decreased slowly. An excessive high pH or low pH all reduced the scale inhibition rate，and when the pH value was 7，the scale inhibition rate was the maximum. With the increase of salinity，the scale inhibition rate increased at first and then decreased a little. The orthogonal experiment results showed that under the conditions of Ba²⁺ concentration at 800 mg/L，the SO₄^2- concentration at 1600 mg/L，the temperature at 75℃ and the salinity at 65 g/L，the scale inhibition rate was the maximum，the scale inhibition rate was the highest. The sequence of the influence on the barium sulfate scale inhibition effect among the five factors was as follows，Ba²⁺ concentration > pH > salinity > SO₄^2- concentration > temperature.

Abstract:Adopting diethylenetriaminepentaacetic acid（DTPA）as main agent，the effects of different conversion and surfactant agent on the dissolution rate of BaSO₄ scale by DTPA were investigated. The experiment results showed that descaling effect would enhance when the concentration of DTPA increased. The compounds whose molecular contained conjugated double bond could significantly increase the dissolution rate of BaSO₄ scale，especially with the synergistic effect of cinnamic acid. In addition， appropriate amount of nonionic surfactant could enhance the descaling effect. Through orthogonal test，the descaling rate could reach 89.01% when the optimum concentration of DTPA，cinnamic acid and alcohol ethoxylate（PPJ）was 0.075，0.075 and 0.02 mol/L，under the condition of 25℃，12 pH value and 10 hrs reaction time. And the core permeability recovery rate could reach 94.67% by adopting oilfield produced water as the solution at the present ratio in core scale dissolution experiment.

Abstract:For the purpose of sulfur recovery, the high sulfur gas-field water was treated by air catalytic oxidation with the oxidized object of HS^-. Kinetics of sulfur removal, sulfur yield and the effects of different process parameters on removal had been studied． Results indicated that the production of high valence state sulfur could be avoided by controlling the oxidized object and reaction conditions reasonably. When the dosage of catalyst C (a polymer complex) was of 50 mg/L at the air flow rate of 150 L/h and at neutral condition a higher sulfur removal efficiency of 92.13% and preferable sulfur yield of 16.45% was obtained. The sulfide removal kinetics for the first-order kinetic equation could be described by ln[S^2-]= 6.186-0.019t, the correlation coefficient was of 0.972, and the apparent reaction rate constant was of 0.317 × 10^-3 s^-1; the dynamics equations of elemental sulfur production process was as follows, [S] = 22.95 lnt+23.51, the timely separation of new ecological sulfur and the inhibition of S₂O₃^2- production could obtain higher yield of elemental sulfur.

Abstract:The environmentally friendly drilling fluid can protect the reservoir stratum，and prevent environment from being destructed. In the paper，the current status and progress of the environmentally friendly drilling fluid at home and abroad，including methyl glucoside drilling fluid system，polyamines drilling fluid system，synthetic-based drilling fluid system，organic salt drilling fluid system，were mainly introduced. The drilling fluid system were evaluated and compared，and some suggestions were provided for the relevant developments，which were expected in the future.

Abstract:silicon-based plugging agent has a broad prospect in high temperature and high salinity reservoirs. inorganic silicon-based plugging agent，organic silicon-based plugging agent and organic-inorganic silicon compound plugging agent were summarized. The characteristics，mechanism and research progress were briefed. Besides，some development tendency were proposed，such as developing organic-inorganic silicon combined system，using silicon nanomaterials selectively，strengthening the study on micromechanism of silicon-based plugging agent.

Abstract:This paper analyzed the main components of fracturing flowback fluid，introduced the research and application progress on mainstream treatment technology of fracturing flowback fluid at home and abroad，which included physical method，chemical method，physical-chemical method and biological method. Through summarizing the problems in indoor research and field application，the important development tendency of fracturing flowback fluid processing technology was advised.

Abstract:Aiming at the problem of sand production in oil well，the research progress and application status of four kinds of chemical sand control agents in domestic and foreign were introduced. The chemical sand control agents included resin chemical and control agents，silicate chemical sand control agents，oligomers of chemical sand control agents and composite chemical sand control agents. The paper put forward some suggestions on research and development direction of sand control agent in the future.

Abstract:Asphaltene precipitation mechanism, experimental method, predicting model, influential factors and suppression method were studied, and the conditions of asphaltene precipitation were analyzed, and their advantages and disadvantages of the method predicting asphaltene precipitation were compared, further, modern research status and future development of asphaltene was pointed out.

Abstract:Thermal methods have been successfully applied in many heavy oil fields，however，the reservoirs at great depth or thin pay zones are not suitable candidates for thermal methods. In recent years，the development of horizontal well provides a significant foundation for the application of chemical flooding，especially for polymer flooding for heavy oils. Polymer flooding in combination with horizontal wells has become a promising technology for enhanced heavy oil recovery. Many oil companies in Canada have used this technology to improve waterflooding of heavy oils，and the field results are promising. In this paper，the advancement in laboratory research and field application of polymer flooding for heavy oil recovery in Canada was reviewed from the aspects of laboratory study，exploration of mechanism and field application. It is expected to provide a prospect of applying polymer flooding for heavy oil recovery in China.

Abstract:Methods for characterizing the wettability and types of wetting agents were briefly described in this paper. From multiple angles including the charged type，location and quantity of the hydrophilic group as well as the chain length，the structure of the hydrophobic group and whether there is a benzene ring or not，the rules and mechanism for wettability alteration of oil-wet solid surface by different surfactants including Gemini surfactant in aspects of EOR were overviewed in detail.