Abstract:In order to treat waste polysulfonated drilling fluid efficiently，on the basis of polysulfonated drilling fluid，composed of 3% bentonite + 3% SMP-2（high temperature resistance filtrate loss reducer）+ 3% SMC（high temperature resistance filtrate loss reducer ）+3% SPNH（filtrate loss reducer）+0.3%FA-367（coating agent）+0.2%XY-27（viscosity reducer）+3% sulfonated asphalt （inhibitor），the dispersion stability of polysulfonated drilling fluid system was measured by near infrared scanning dispersive stability analyzer，and the colloid stability of drilling fluid was quantitatively characterized by the value of turbiscan stability index（TSI） to study the effect of various treatment agents on the colloid stability of poly sulfonated drilling fluid. In addition，through the determination of apparent viscosity and Zeta potential of drilling fluid system， the influence mechanism of various treatment agents on the colloid stability of poly sulfonated drilling fluid was analyzed. The results showed that，the various treatment agents affected the stability of polysulfonated drilling fluid system. Compared to that of the complete system，the TSI of the system without inhibitor increased by 88.5%，the viscosity decreased by 74% and the absolute value of Zeta potential decreased by 9.2%；the TSI of system without amphoteric ion class coating agent and viscosity reducer decreased by 46.2%，viscosity decreased by 51.9% and the absolute value of Zeta potential increased by 16.1%；the TSI of system without high temperature resistance filtrate loss reducer SMP-2 and SMC decreased by 42.3%，viscosity increased by 10.4% and the absolute value of Zeta potential decreased by 33.3%； the TSI of system without filtrate loss reducer SPNH decreased by 19.2%，the viscosity decreased by 23.4% and the absolute value of Zeta potential decreased by 8%. It could be concluded that the sulfonated asphalt inhibitor affected the colloid stability of drilling fluid system by mainly changing viscosity，while the coating agent，viscosity reducer and diluent had an effect on the colloid stability of drilling fluid system mainly by changing Zeta potential，while the filtrate loss reducer affected the colloid stability by changing both viscosity and Zeta potential.

Abstract:Aimed at the problem of the ordinary gel’ s weak strength，uncontrollable gelling time with well completion control in shale gas，a new type of the double crosslinking system MEA/MEB was used and the starch grafting modification was realized by the reaction of acrylamide （AM） and sodium methacrylate （NaMAA） with starch. By employing the high-temperature and high-pressure thickener to simulating the application environment of the gel system，the effect of the acrylamide dosage，crosslinking agent MEA dosage，the viscosity controlling agent HXC dosage，and pH value，et al，on the performance of the gel was investigated，and the gel’ s basic formulation was obtained as follows，5% starch + 4% acrylamide + 2% sodium methacrylate+ 0.125% cross-linking agent MEA + 5% crosslinking agent MEB + 6.5% toughening agent SL-2 + 0.0025% initiator APS. The thickening properties and the breakable property of the gel system were probed and enhancing degree of the gel system by three commonly-used weighing materials was investigated as well. The results showed that the basic formula gel materials could withstand the strength of 25 N. Through adjusting the pH value of 7—13，the gelling time of the obtained pack material ranged from 1 to 3 hours. The density of the gel material could be increased to 1.4 g/m³ after adding iron ore fines with 1200 mushes，meanwhile，the strength of the gel could be increased by 24%. The gel with high strength could be broken effectively by self-made environment-friendly breaker after well-completion operation，whose viscosity was as low as 42 mPa·s，which ensured the gel-breaking fluid flowback and provided guarantees for convenience and security of the field application of the gel packer.

Abstract:Jidong Oilfield is located in an environmentally sensitive area，in order to reduce environmental risks and meet the needs of large displacement well drilling，through investigating the biological toxicity of the polyether polyol SYP-2 and polyol JLX，biodegradability of SYP-2 and JLX，the conventional system compatibility of the SYP-2 and JLX with the Jidong oilfield polymer drilling fluid and lubrication performance of the SYP-2 and JLX，a kind of environmental protection lubricant for large displacement well，composed of 0.2% SYP-2 and 0.2% JLX，was obtained，and lubrication performance of the obtained lubricant was compared with that of the lubricant in use currently. The results showed that the two kinds of treatment agent are nonpoisonous，because the concentration for 50% of maximal effect（EC₅₀）of SYP-2 and JLX was higher than 500， 000 mg/L. The BOD₅/COD_Cr value of SYP-2 and JLX was 15.59% and 29.2%，respectively，indicating that the SYP-2 and JLX were biodegradable materials.The environmental-friendly lubricant had good compatibility with the polymer drilling fluid system，the rheological properties of the polymer drilling fluid，after adding 0.2% SYP-2 and 0.2% JLX，was stable，the reduction rate of the lubricating coefficient was higher than 70%，and the shale recovery rate was 75%，which indicated that the addition of 0.2% SYP-2 and 0.2% JLX could not only meet the lubrication condition but also improve the inhibition performance of drilling fluid. The compressively performance of the obtained environmental-friendly lubricant was superior to that of the lubricant in use，hence，the lubricant could be used for drilling large displacement wells of Jidong oilfield.

Abstract:In order to relieve the contamination of drilling mud in ultra-low permeability reservoir of carbonate rock，the corrosion effect of compound acid components on mud cake and core was evaluated by response surface regression analysis of the difference between dissolution rate of mud cake and core. The appropriate formula of plugging removal agent was determined. The plugging effect of compound acid on core was investigated and the plugging mechanism was analyzed. The results showed that four components were arranged according to their influence on dissolution efficiency of mud cake in following order: H₂O₂>HCl>HF>HAc，and that on dissolution efficiency of carbonate rock in following order: HCl>HAc>HF>H₂O₂. When the formula of plugging agent was 9.2% HCl+1.3% HF+5% H₂O₂+15% HAc，the recovery rate of core permeability after plugging removal was up to 130%.The compound acid had retarding property，and the damage of core could be reduced to minimum when the plug was removed. The stratum structure could be effectively protected so as to achieve the purpose of deep acidification.

Abstract:In order to obtain fracturing fluid with high temperature resistance，a gemini surfactant was synthesized with stearic acid，oxalic acid，N， N-dimethylbenzene-1， 4-diamine，N， N'-（ethane-1， 2-diyl） diethane-1， 2-diamine and 1， 3-dichloro-2-propanol as the materials. Using this gemini surfactant as viscosifier，a cleaning fracturing fluid was prepared by mixing ammonium chloride solution and gemini surfactant. The performance of cleaning fracturing fluid（3% gemini surfactant+1% NH₄C1），such as heat and shear resistance，sand-carrying property，gel-breaking property and so on，was investigated. The results showed that comparing with guargum fracturing fluid，this cleaning fracturing fluid was thermally stable and had good temperature and shear resistance. The viscosity of cleaning fracturing fluid was 88 mPa·s at 120℃，which could meet the requirement of high temperature oil and gas field. The sedimentation rate of seed in cleaning fracturing fluid was 0.79 mm/s at 120℃ ，which indicated that the cleaning fracturing fluid had a good sand-carrying performance. The compatibility between cleaning fracturing fluid and formation fluid was good. The cleaning fracturing fluids would break automatically when it encountered lamp kerosene，without adding gel breaker， which was very convenient to use.

Abstract:In order to establish reuse technology of fracturing folwback fluid，a new recyclable polymer farcturing fluid system including polymer thicker （partially hydrolyzed polyacrylamide），clean up agent （fluorocarbon surfactant），clay stabilizer（cationic polymer with low molecular weight） and organo-metallic crosslinker was studied in laboratory. The properties of fracturing fluid made by fresh water and gel breaking liquid（field simulation of fracturing fluid）were compared. The results showed that polymer thicker dissolved faster which could meet the requirements of online mixing. The fracturing fluid made by fresh water had good temperature（105℃）and shear resistance，good shear recovery and viscoelasticity. The viscosity loss ratio of fracturing fluid was 57% at room temperature. The fraction reduction ratio of fracturing fluid was more than 40% comparing with water under the same conditions. The fracturing fluid could be completely broken at 95℃，the viscosity of gel breaking liquid was less than 5 mPa·s，the residue was 11.7 mg/L，and the damage rate of core permeability was 10.94%. The gel breaking liquid could be reused after adding 0.12% stabilizer. The performance of farcturing fluid system made by gel breaking liquid was similar to that by fresh water，which could met the requirement of oilfield operation.

Abstract:In order to improve the utilization efficiency of water in Sulige gas field of Ordos basin，a recyclable fracturing fluid（RFF）was prepared using a the muti-functional polyacrylamide thickening agent CJ3-1 as main ingredient，the reinforcement agent ZJ（an anionic surfacant）and clean up additive TGF （a fluoronates surfactant）as adjuvents，which was composed of 0.4% CJ3-1+0.4% ZJ+0.5% TGF. The properties of carrying proppant performance，temperature resistance and salt tolerance，viscoelastic，drag reduction and the recycled use of the RFF was investigated. The evaluation experiments indicated that the recyclable fracturing fluid had a good resistance to temperature and shear，after being sheared for 60 min at the temperature of 90℃ and at the shearing rate of 170 s^-1 ， the viscosity of the RFF maintained around 60 mPa·s，at the same time，the viscosity decreased rapidly and recovered quickly when the shear rate was increased from 170 s^-1 to 1700 s^-1and then to 170 s^-1. The RFF had little residues，and exhibited excellent carrying proppant performance and flowback performance，the flow capacity retention being of 92%. The recycle fluid had been applied successfully in 300 wells in Sulige gas field，the total volume was about 1000000 m³ and more than 400000 m³ of flowback fluid was recycled. The flowback fluid could be reused after simple settlement treatment，which could relieve the difficulties caused by the rapid increase of water consumption in Sulige gas field.

Abstract:The silica nanoparticles used as depressurizing and injection-augmenting agent was mostly dispersed in the medium with aggregate structure，which resulted in it was difficult to be injected into the small pores and even leaded to blockage of the pores. In this paper，a kind of water-based nano-silica with in-situ surface modification was dispersed in water with the action of dispersant， and was characterized by transmission electron microscopy and dynamic light scattering. Their phase dispersion and separation behavior as well as adsorption measurement were studied. Meanwhile，the depressurizing and injection-augmenting ability of the silica nanoparticles dispersion was investigated through field tests. The results indicated that the as-prepared water-based silica nanoparticles exhibited super hydrophobicity and was able to disperse in water as monodisperse particle with a grain size of about 7 nm， as a result，the transmittance of the silica nanoparticles dispersion was greater than 99% and the Zeta potential was -43.1 mV. Besides，the as-prepared super-hydrophobic nano-silica could be well separated from the dispersion system and adsorbed on porous core of wells，which could make the hydrophilicity of the cores transform into hydrophobicity. The as-prepared water-based silica nanoparticle as a depressurizing and injection-augmenting agent could reduce the pressure and increase the injection rate of the reservoir by 26.4% and 106.7%，respectively，and the period of validity was more than 10 months.

Abstract:In order to evaluate the gelling effect of cross-linked polymer solution in reservoir pores objectively and effectively，the viscosity，molecular size and aggregation，permeability limit and static gelling effect of amphion polymer solution（AIPS）and amphion cross-linked polymer solution（AICPS）were studied by using Bush viscometer，dynamic/static laser light scattering，atomic force microscope and core flow experiment. The results showed that AICPS had a good delay gelling characteristics. The molecular aggregated in AIPS showed a sparse network structure，while the molecular size increased significantly in AICPS，and the network structure of AICPS became dense and robust. With the increase of polymer concentration，the permeability limit of AIPS and AICPS increased. In the following water flooding stage，the injection pressure of AIPS flooding dropped，while that of AICPS flooding rose first and then smooth，showing unique characteristics of seepage flow. The greater core permeability and polymer concentration，the better gelling effect of AICPS was. When the concentration of polymer was 800，1500，2500 and 4000 mg/L and corresponding reservoir permeability was greater than 400×10^-3，800×10^-3，1700×10^-3 and 3500×10^-3μm²，AICPS could obtain good static gelling effect.

Abstract:In order to obtain good water plugging effect in high temperature horizontal well with long perforation section and high permeability channel，a depth cross-linking thermosetting phenolic plugging agent was prepared. The gelling，plugging and flood flushing performance of plugging agent at formation temperature（110℃）were studied，and pilot test was carried out at Chu 28-P1 well. The experiment results showed that the plugging agent was homogeneous transparent and low viscous solution，and kept stable at the temperature lower than 80℃ . The effect of formation shearing，adsorption or chromatographic separation on the composition and gelling performance of plugging agent could be ignored. The delayed gelling time was shortened with the increase of temperature，which could be controlled between 12 to 48 h when the temperature was higher than 85℃ . Heated sand pack experiment indicated that the blocking ratio of cured agent kept stable to 96% even after flushed with large amount and high pressure of injected water，showing strong blocking strength and bearing hydraulic push. The gel properties kept stable after aging one year at 110℃ . Field test illustrated the technical advantages of plugging agent，such as being injected selectively to high permeability channel，balancing the formation pressure difference higher than 8 MPa at 110℃，bearing fluid pushing force and suction force generated by negative pressure operation near well.

Abstract:In order to reduce the toxicity of polymer gel plugging agent，organic plugging agent BHW-101 was prepared by 0.15%—0.30% main agent hydroxy alkane，0.15%—0.40% additive methenamine and 0.15%—0.5% polymer. The gelling effect of pH value and salinity on BHW-101 was studied. The stability，sealing，dynamic gelation and toxicity of BHW-101 were also investigated. Finally，BHW-101 was applied in Bohai oilfield. The results showed that BHW-101 could form gel at pH value of 5—8，and the effect of salinity on gelling strength and sealing performance of BHW-101 was less. The long-term stability of BHW-101 was nice，whose viscosity decreased by less than 15% after storing for 90 d at 85℃. The stemming ratio of BHW-101 to single sand filling tube was about 94% which showing good sealing performance，and BHW-101 could selectively plug high permeability layer.BHW-101 could also form gell under shock condition，but the gelling time prolonged. BHW-101 was non-toxic and environmental friendly which could replace current crosslinking agent，such as heavy metal chromium ion and high toxic phenol or aldehyde. After BHW-101 was used in A31 well of Bohai oilfield，the effect of increasing oil and decreasing water was obvious，which was suitable for water shut off or well profile control operation in high water cut or extra high water cut stage.

Abstract:In order to reveal the relationship between the molecular composition of oil fractions and interfacial properties，emulsifying properties and clarify the mechanisms of oil-water interfacial properties change and crude oil emulsification，Bohai heavy oil was separated into asphaltene，resin and remaining fraction according to polarity difference，mass percents of three fractions being of 5.45%，26.5% and 57.13%，respectively. Molecular composition of three fractions was investigated by infrared spectrum，element analysis and high-resolution mass spectrometry. Moreover，interfacial tensiometer and interfacial viscoelastic instrument were used to study the interfacial properties. The results demonstrated that the asphaltene and resin was rich in acidic compounds. Moreover，the relative molecular weight，the degree of condensation and the content of heteroatom of acidic compounds in asphaltene were higher than that of resin. The interfacial tensions between model formation water and model oil of 0.55% asphaltene，5% resin，5% remaining oil，was 11.5 mN/m，20 mN/m，28 mN/m，respectively，which indicated that the acidic compounds in crude oil were the main interfacial active materials，which with heteroatoms exhibited stronger interfacial activity. The interfacial shearing viscosity of three fractions model oils decreased with increasing shear rate，meantime，at shear range of 0.02—0.4 rad·s^-1，three fractions was arranged according to the interfacial shearing viscosity as follows：asphaltene>resin > remaining fraction，which indicated that the interfacial film formed had obvious structure，especially for asphaltene. The W/O emulsion formed by crude oil and ethanolamine solution presented high stability for more than a week. The stability decreased obviously by removing the asphaltene in crude oil，and the oil-water separated completely after 11 h；while，the emulsification did not appear as both of asphaltene and resin were removed，which suggested that the asphaltene and resin were the main active components for emulsification of Bohai heavy oil.

Abstract:To determine the pressure interval and realization conditions of impure CO₂ near-miscible flooding，from the perspective of physiochemical and engineering，slim tube test and slim tube simulation were conducted comprehensively to establish the defining method based on the displacement efficiency and interfacial tension（IFT）under different pressures，respectively. A near-miscible region（NMR）was divided from the vicinity of conventional minimum miscible pressure（MMP） . It was shown that the displacement efficiency and IFT of the NMR was 85%—95% and 0.001—0.05 mN/m，respectively. Taken the 1st section of the well QHD 29-2E-5 as an example，the pressure intervals of the NMR was 26.52—32.9 MPa，which was 0.8—1 times MMP；and the lower limit of CO₂ content was 64% obtained

Abstract:Due to the characteristics of great burial depth，high viscosity and high formation pressure with Wutong formation heavy oil reservoir in the east of Lukeqin oilfield，the conventional steam boiler had low efficiency because of difficult injection. In view of the outstanding production contradiction，supercritical steam soaking technology was put forward to increase production. The characteristics of supercritical steam were studied by physical simulation and numerical simulation，and the mechanism of enhanced recovery of crude oil by supercritical steam was analyzed. Through the establishment of supercritical steam injection parameter calculation model，the injection parameters were optimized and the parameters along flow was simulated. Finally，a pilot test in Lukeqin oilfield was carried out. The results showed that supercritical steam had the features of high solubility，high diffusivity and high reaction. The enhancement effect produced in the development of deep heavy oil was different from that of ordinary hot fluid. Under the condition of 35 MPa，400℃ and 3.5 PV injection volume，the displacement efficiency of supercritical steam was above 90%. The optimum injection parameters of supercritical steam were obtained by calculation：>375℃ steam injection temperature， 5.4—9 t/h steam injection capacity，3600 t steam injection scale in the early three rounds，27 MPa steam injection pressure at wellhead and 3—4 days soak time. By introducing a 35 MPa supercritical pressure steam boiler and wellhead equipment，3 wells in 9 rounds of steam soaking tests were successfully implemented with 4000 tons cumulative oil，showing obvious oil increment. The supercritical steam soaking technology could be used for the development of deep ultra heavy oil in the east of Lukeqin oilfield.

Abstract:In order to control the gas channeling in the later stage of steam soaking for improving the utilization rate of steam，the three-phase foam system was prepared by adding solid particles with polymer and modified starch gel as suspension agent respectively. The foaming ability and stability，sand suspension performance，sealing property，erosion resistance and displacement effect of permeable three-phase foam system were studied by static evaluation method and physical simulation test. The experimental results showed that the greater dosage of consolidation agent（cement，fly ash，self-assembly particles or cement， self-assembly particles），the lower foaming capacity of three-phase foam system，and the stronger stability and performance of suspended sand were. The stability of three-phase foam with approximately 10% of consolidation agent was more ideal，and as much as 30% of consolidation agent content of polymer and modified starch gel system separately had good capability of suspending sand. Three-phase foam system with starch gel and polymer as suspending agent could make the seal ratio reach 90%— 95% and 80%—90% by adjusting the dosage of consolidation agent. Two three-phase foam systems could withstand continuous flushing of 200℃ steam. The three-phase foam system with starch gel had better oil displacement effect on heterogeneous core model，and the enhanced oil recovery rate of 5 times and 10 times difference model was 28.8% and 26.4%， respectively.

Abstract:In order to discover mechanism of the low-temperature oxidation（LTO）reaction of the heavy oil and their effect on the oil composition and property，taken Liaohe oilfield block Qi40 heavy oil as experimental sample，the low temperature oxidation mechanism and the effect of temperature and catalyst on LTO was studied in laboratory high temperature and high pressure reactor. The results showed that the system pressure decreased，oxygen content decreased and carbon hydrocarbon increased after LTO reaction. The oxygen consumption were 43.87%，58.46%，52.53% and 62.89%，respectively，after LTO reaction under 120℃， LTO reaction under 180℃，LTO reaction under 120℃ with catalyst and LTO reaction under 180℃ with catalyst，respectively.During LTO process，both bond breaking reaction of macromolecule and condensation reaction of micromolecule occurred in crude oil，which resulted in the crude oil contents of saturated hydrocarbon，aromatic hydrocarbon and asphaltene increased，while the gum decrease. The viscosity of crude oil was increased by 17.63%，34.00%，18.22% and 38.50%，respectively，after LTO reaction under 120℃，LTO reaction under 180℃，LTO reaction under 120℃ with catalyst and LTO reaction under 180℃ with catalyst， respectively. which was relative to the increase of the content of asphaltene. The LTO reaction rate and oxygen consumption was affected by reaction temperature and catalyst. The higher the reaction temperature，the faster the reaction，and the higher the oxygen consumption. Moreover，the addition of cobalt naphthenate and manganese naphthenate catalyst could enhance the LTO reactivity and increase reaction rate and oxygen consumption.

Abstract:In order to improve the persistence of high temperature oxidation during fire flooding，obtain the oxidation reaction mechanism of heavy oil，and ensure the smooth start of combustion，a series of static experiments of low temperature oxidation were carried out on heavy oil sample from a fire flooding test area of Liaohe oilfield. The effect of oil composition，temperature， pressure and water saturation on low temperature oxidation reaction were studied. The grey correlation method was used to evaluate the influence factors of oxidation. The results showed that high content of saturated and aromatic hydrocarbons in crude oil was contribute to the low temperature oxidation of crude oil. The low-temperature oxidation rate increased with increasing temperature. Especially after 170℃ ，the rate of growth increased significantly. High oxygen partial pressure promoted the reaction of low-temperature oxidation，because oxygen concentration increased on the same interface. As the water saturation increased，the degree of oxidation reaction showed a downward trend. Finally，the influence factors of low temperature oxidation were sorted by Gray correlation method. And temperature was the primary influenced factor of low temperature oxidation reaction.

Abstract:Aiming at the problem that gas channeling affected the efficiency of fire flooding on heavy crude oil reservoir exploitation，a laboratory experiment of high temperature profile plugging agent was carried out based on the principle of high temperature salting out. The effect of the influence factors，such as the concentration and injection volume of NaCl and Na₂ SiO₃ ， temperature，curing time，permeability and heterogeneity of sand filling tube on plugging was studied. The results showed that with increasing concentration of plugging agent，the plugging rate significantly increased which reached the highest in saturation concentration. The sealing effect of two plugging agent enhanced with increasing injection volume. As the temperature rose，the plugging rate of NaCl increased and tended to stability，while that of Na₂ SiO₃ gradually decreased. Time was needed for salting out when the formation temperature was lower than 300℃ ，which could effectively improve the plugging effect of profile control system. However if the temperature was above 300℃，the time was no need to be considered. The higher permeability of sand filling tube，the better profile control effect and blocking effect of plugging agent on high permeability layer were，which was suitable for the heterogeneous formation.

Abstract:In order to improve the stability of polymer flooding in high temperature reservoir of Shuanghe oilfield，ordinary partially hydrolyzed polyacrylamide（HPAM）mixed with oilfield produced water were chosen to study the influence of thermal oxidation degradation and hydrolysis on the viscosity of HPAM solution at 95℃. The main mechanism of polymer degradation in high temperature reservoir of Shuanghe oilfield was analyzed and several methods to improve HPAM thermal stability were discussed. The results showed that the existence of dissolved oxygen would sharply lower the viscosity of HPAM solution. When the oxygen content increased from 0.5 to 3.0 mg/L，the viscosity retention rate of HPAM solution decreased from 100% to 27.5% after aging 180 d at 95℃. The hydrolysis rate of HPAM was very fast at high temperature. While the viscosity of HPAM solution was not significantly decreased when the degree of hydrolysis was 40%—60% and the oxygen content was less than 0.3 mg/L. The free radical degradation was the main mechanism of polymer degradation in high temperature reservoir of Shuanghe oilfield. Controlling oxygen content and inhibiting free radical degradation of HPAM were the key technology to enhance the stability of HPAM at high temperature. When the polymer was applied in reservoir with 80—95℃ ，taking oxygen control technology at the process of polymer preparation and new type of polymer flooding technology，or adding a small amount of cross-linking agent in HPAM solution to form low crosslinked polymer solution could significantly improve the heat resistance of polymer，which obtained good oil displacement results in field application.

Abstract:In order to obtain hydrophobically both end-capped polyacrylamide with good hydrophobic association，the precursor of hydrophobically end-capped polyacrylamide was obtained through reversible addition-fragmentation chain transfer （RAFT）polymerization of acrylamide （AM） in dimethyl sulfoxide （DMSO） by 2,2'-azobis （2-methylpropiondodecylamidine）dihydrochloride（AIBL）as initiator agent，the dithioester as chain transfer agent by bis（thiobenzoyl）disulfide（BTBDS）reacting with AIBL in situ . Then the precursor reacted with a combination of lauroyl peroxide（LPO）and AIBL to prepare hydrophobically both end-capped polyacrylamide by radical-addition-fragmentation-coupling process. The structure of hydrophobically both end-capped polyacrylamide was confirmed by ¹H-NMR spectra and UV spectra. The conversion rate of acrylamide was calculated from 1H-NMR spectra. The molecular weight and molecular weight distribution were determined by gel permeation chromatography （GPC）. The properties of hydrophobically modified polyacrylamide were studied with fluorescence probe and surface tension meter. The results showed that the conversion rate and polymerization rate of AM could be controlled by adjusting AIBL content and polymerization time. Telechelic hydrophobically modified polyacrylamide could be analyzed more accurately by GPC with mixtures containing 35% of acetonitrile as eluent. When polyacrylamide was polymerized by RAFT under a certain conversion，the conversion rate and polymerization rate of AM increased linearly along with polymerization time and the polydispersity index （PDI） of polyacrylamide was about 2.0，showing a certain degree of controllability of the preparation method. Compared with hydrophobically end-capped polyacrylamide，the molecular weight of hydrophobically both end-capped polyacrylamide increased slightly， molecular weight distribution had little change， intramolecular association strengthened， the critical aggregation concentration（c_CAC=2 g/L）increased，and hydrophobic association improved when the concentration of polymer was bigger than c_CAC.

Abstract:In order to improve the stability of crude oil emulsion，the dispersion stabilities of hydrophilic and hydrophobic alumina nanoparticles in anionic surfactant sodium dodecyl benzene sulfonate （SDBS），cationic surfactant cetyltrimethyl ammonium bromide（CTAB）and nonionic surfactant alkylphenol ployoxethylene ether（OP-10）were studied. O/W emulsion was prepared by alumina nanofluids，liquid paraffin and OP-10. The effects of hydrophilic and hydrophobic nanoparticles and OP-10 on emulsion stability were investigated. The results showed that the surfactant type and concentration had great influence on the dispersion of alumina nanoparticles，and the dispersibility of OP-10 was better. The stability of O/W emulsion was closely related to nanoparticle and surfactant. On a certain concentration，with increaseing concentration of nanoparticle and surfactant，the interfacial tension between oil and water decreased as well as the stability of emulsion enhanced. High concentration of nanoparticle and surfactant could increase the interfacial tension and water separation rate and decrease the stability. The emulsion composed of 0.3% OP-10 and 0.2% hydrophobic alumina nanoparticle had good stability. Compared with hydrophilic alumina nanofluids，hydrophobic alumina nanofluids exhibited higher dispersion stability and stronger ability to stabilize O/W emulsion.

Abstract:In order to make sure the interfacial activity of different components of petroleum sulfonates，component H，C and B with different polarity were separated from purified KPS，which was used in Xinjiang oilfield. The molecular structure，weight distribution of KPS and components were analyzed by 1H-NMR and MS，and the interfacial activities of KPS and components in different concentration of surfactant，alkali and salt were investigated. The results showed that the H component consisted essentially of molecules with low nuclear ratios and the molecular structure was dominated by aromatics. The B component consisted essentially of molecules with high nuclear ratios and the molecular structure was dominated by straight chain alkanes. The C component consisted essentially of molecules with high nuclear ratios and low nuclear ratios and the molecular structure was dominated by branched alkanes. The C component had the best surface activity at different surfactant concentrations of 0.1%—0.5% and the weak alkali concentrations of 0.2%—2.0%. The interfacial tension between the ASP system，composed of 1.2% weak alkali，0.3% C component and 0.18% polymer，and the crude oil could reach 10^-4 mN/m. In addition，the C component had better interfacial ability at the concentration of salt concentrations of 0.2%—2.0%. The interfacial tension could reach 10^-3mN/m.

Abstract:To clear the emulsification properties of ASP system on the crude oil of the Jing 11 block and improve the demulsification and dehydration treatment effect of the produced fluid of after ASP flooding，through the indoor experiment，the influence of rotation rate，single oil displacement agent（polymer，surfactant，alkaline）and ternary compound system on the emulsion stability on the formed oil-water emulsion was probed. The results indicated that，the rotation rate had great influence on the formation of emulsion. The bigger the rotation rate，the smaller the diameter of emulsion drops and the more stable the emulsion. At the rotation rate of 4000 r/min and the stirring time of 20 minutes，as the polymer concentration rose，the emulsion became stable，and when the polymer concentration was greater than 300 mg/L，the dehydration rate（＜5%）of the emulsion changed little. When the surfactant concentration was higher than 500 mg/L，the emulsion stability was strengthened obviously. Weak alkaline concentration was set 0.1% as the turning point，with the increase of weak base concentration，the emulsion stability enhanced firstly and then weakened. The components of the ternary compound system was arranged according to the influence of their on the emulsion stability，polymer concentration＞surfactant concentration＞weak alkaline concentration.

Abstract:In order to obtain the oil field water treatment agent suitable for the Yanchang oilfield with good compatibility，the corrosion performance and bactericidal performance of corrosion inhibitor，fungicide after being compounded with scale inhibitor，flocculant and demulsifier were investigated，and the compatibility of the treatment agents were studied. The results showed that the compatibility of phosphine imidazoline inhibitor SW-629 with inorganic flocculants including poly aluminum chloride（PAC）and polyferric sulfate（PFS），scale inhibitors including amino trimethylene phosphonic acid ATMP and copolymer HQ-1，polyether SW-101 demulsifier was poor；the compatibility of the cationic imidazoline inhibitor SW-639 with the fungicides including isothiomer SW-906 and quaternary ammonium salt 1227， flocculant including PFS， anionic polyacrylamide XN-2， bis hexamethylene triamine penta （methylene phosphonic acid） BH-1 and barium strontium scale inhibitor HQ-2，and polyester SW-102 demulsifier was not well；the compatibility of the double imidazoline inhibitor SW-649 with chlorine dioxide fungicide，flocculants including PAC and PFS，scale inhibitors including ATMP and HQ-2，polyester SW-102 demulsifier was poor；the compatibility of the isothiomers SW-906 fungicide with flocculants including PFS and anionic polyacrylamide XN-2，double imidazoline inhibitor SW-649 was bad. There was the better compatibility between phosphine imidazoline inhibitor SW-629，phosphonate scale inhibitors including bis hexamethylene triamine penta（methylene phosphonic acid）BH-1 and ethylene diamine tetra（methylene phosphonic acid）sodium EDTMPS，and isothiomer SW-906 fungicide，which could be generalized to use in Yanchang oilfied.

Abstract:The introduction of alkali component in alkaline/surfactant/polymer（ASP）system led to the formation of a large number of silicon scale in oilfield injection-production system，and the silicon scale was difficult to remove when it once formed. To solve the severe problem of silicon scale in injection-production equipment，a new copolymer scale inhibitor for silicon scale called ACAA was synthesized by using aconitic acid（AA），citric acid（CA），acrylic acid（AC）and 2-acrylamide-2-methyl propane sulfonic acid （AMPS） as monomers，ammonium persulfate as initiator. The influence of synthetic process conditions on the anti-scaling property of products was examined，the properties and influencing factors of silica scaling prevention of ACAA were studied，and the scale inhibition mechanism was analyzed. The results showed that the optimum synthesis condition of ACAA was obtained as follows：70℃ polymerization temperature，3 h polymerization time，15% initiator dosage and 2.0∶1.5∶1.0∶0.8 monomer molar ratio of AA∶CA∶AC∶AMPS. The anti-scaling effect of ACAA was affected by temperature，pH value and ACAA dosage. The rate of silica scaling prevention of ACAA increased first and then decreased with increasing temperature，decreased gradually with increasing pH value，and increased with increasing dosage of ACAA. On the condition of pH=8，55℃ and 80 mg/L ACAA，the average prevention rate of silica scale was 76.23%. The main scale inhibition mechanism of ACAA to silicon scale was preliminarily considered as the adsorption and dispersion effect.

Abstract:In order to solve the serious CaCO₃ scale problem in Jing11 faulted block in Huabei oilfield，the inhibition performances of sodium of polyaspartic acid（PASP），polyacrylic acid（PAA），diethylenetriamine penta（methylene phosphonic acid）（DTPMP）and 1-hydroxyethylidene-1，1-diphosphonic acid（HEDP）under the alkalescent combination flooding environment were investigated by the static scale inhibition evaluation experiment，and the microscopic scale inhibiton mechanism was analyzed by molecular dynamics simulation of the interaction between the inhibitor and CaCO₃ surface. The results showed that the scale inhibition effect of four kinds of scale inhibitors on calcium carbonate scale was as follows，HEDP> DTPMP> PAA> PASP. The inhibition performance was tightly related to the interaction energy between the scale inhibitor and the CaCO₃ surface. The larger the interaction energy of the sacle inhibitor on the CaCO₃ surface was，the better the scale inhibition performance would be. The sequence of the interaction energies was consistent with that of the inhibition performance. The deformation energies of scale inhibitors on the CaCO₃ surface were much smaller than the interaction energies. Strong nonbonded interactions existed between the scale inhibitors and the calcium and carbonate ions. The adsorption of scale inhibitors on the CaCO₃ surface will be more stable with stronger non-bonded interactions.

Abstract:In order to improve the efficiency of chemical treatment of fracturing flowback fluids，and reduce the load of subsequent treatment process，the poly-silicic-cation coagulant（PSiC）was prepared to treat fracturing flowback fluids. Through Box-Behnken experiment design and response surface analysis，optimization grouping of Si concentration，polymerization pH，Si/（Al+Fe）molar ratio was realized，a quadratic response surface model and optimum level values were obtained. The experimental data were multivariable regression fitting by the statistical software Design Expert. Three-dimensional images were used to reveal interaction between three factors. The results showed that coagulation performances and stability were significantly influenced by the Si/（Fe+Al）molar ratio. It was found that the optimization grouping of the main influence factors for coagulation were as following：Si concentration，pH value and Si/（Al+Fe）molar ratio being of 3.39%，1.3 and 1.8，respectively，and the removal rate of turbidity and COD were 88.52% and 70.35% ，respectively，with the active ingredient （Fe + Al） dosage of 130 mg/L. The quadratic polynomial regression equation model of Si concentration，polymerization pH，Si/（Al+Fe）molar ratio and treatment effect was significant and reliable. The interaction between Si concentration and Si/（Al+Fe）molar ratio was not significant，and there was some kind of interaction between Si concentration and pH，while the interaction between Si/（Al + Fe）molar ratio and pH was significant.

Abstract:In order to reduce the damages from conventional water-based workover fluids，such as water，formation water，water based foam in Kalaza group reservoir of Shengbei oil and gas field，Tuha basin，a kind of solid-free and low-density oil-based foam workover fluid was developed. The properties of workover fluid were analyzed and the workover fluid was applied on 5 wells in Kalaza group reservoir. The results showed that the density of solid-free and low-density oil-based foam workover fluid composed of 30% formation water，70% crude oil，0.25% oil-based foaming converting agent DRzh-3，0.20% oil-based foam stabilizer DRxc-2，0.45% oil-based foaming agent DRfoam-2，was 0.34—0.90 g/cm3. The foam of workover fluid had high intensity，over 24 hrs stable time and strong anti-leakage blocking ability. The permeability recovery ratio of core after polluted by workover fluid was greater than 94%. The workover fluid had good resistance of high temperature（120℃）and compressive strength（10—11MPa）. According to the characteristics of oil-based foam fluid，the complete set of workover technology measure was improved.After this technology applied in 5 Wells on site，the effective rate was 100%，and the average recovery time of each well shortened 3 days. The pollution to reservoir damage was reduced，the leakage was less，and the performance of workover fluid was stable. Furthermore，the construction on site was convenient with low cost. It could effectively solve the water sensitivity and water locking during workover operations in low pressure reservoirs.

Abstract:Capillary action exists in the whole process of low permeability development，and the ability of altering capillary action can directly influence the EOR. Based on the pore size of low permeability reservoirs，this paper developed a capillary action analysis system cored with capillary tube/bundle，micro metering and visual evaluation，simulating the migration of flood fluids in the porous media as in the capillary tube/bundle，and evaluating the capillary resistance of flood fluids，reflecting the injection ability and enlarging sweep volume ability of different flood fluids. Five oil displacing agents including water，betai surfactant and nano SiO₂ oil-displacing agents，were selected as the objectives and their absorption ability and capillary resistance in capillaries with different diameter of 0.3—10 μm was evaluated. The results showed that，No matter hydrophilic capillary or hydrophobic capillary，the ability of nano SiO₂ oil-displacing agents for decreasing the capillary resistance was higher than that of water and common betai surfactant，weakly hydrophilic modified nano SiO₂ was the best in lowering the capillary resistance. Moreover，the smaller the diameter of capillary tube was，the injection ability of the hydrophilic modified nano SiO₂ was better，indicating that these nano-materials could decrease the "threshold" permeability of flooding fluids，thus increase the sweeping volume which can not be swept by conventional water flooding，and improve the injection ability of low permeability reservoirs.

Abstract:In order to reduce the drag and torque of deep horizontal well，large amount of crude oil was added in the water-based drilling fluid. However，crude oil not only bring harm to fluorescent logging，but also cause serious environmental pollution.Therefore，it is important to develop novel environmental-friendly lubricant that can take the place of crude oil. In this review，the research progress of lubricant in water-based drilling fluid in recent years was elaborated，and the development of water-based drilling fluid lubricants was prospected through comparing the advantages and disadvantages of different kinds of lubricants.

Abstract:With drilling efforts of extended reach well，horizontal well，deep well and ultra-deep well strengthened continuously， the problem between lubrication and downhole safety became more and more prominent. In the process of drilling，it is one of the main technical measures to prevent and solve drilling safety problem by adding lubricant into drilling fluid for reducing downhole friction. The type and mechanism of drilling fluid lubricant was introduced in this article，the development and research status of drilling fluid lubricant were reviewed and its development direction in the future was suggested，hoping it contributed to the development and application of drilling fluid lubricant.

Abstract:The relevant test methods of biodegradation and biological toxicity evaluation were firstly introduced in this article. The recent research and application of environmental lubricants，environmental fluid loss reducing agents，environmental anti-sloughing additives and environmental viscosity reducing treatments were focused on. In addition，the development suggestions of environmental drilling fluid additives were also proposed.

Abstract:White oil-based drilling fluids can avoid the problem of borehole sloughing. The application of white oil-based drilling fluid when drilling in horizontal wells，high temperature deep wells，and large displacement directional well，deep water well and the complex formation was summarized. In addition，the problem and relevant suggestions on future research about the white oil-based drilling fluids were put forward.

Abstract:Due to high injectivity，various injection mode and low cost，foam system had been paid more and more attention on the application of profile control in low permeability oilfield. However，foams were vulnerable to high temperature，high salt，high pressure and other environmental impacts in the practical application，which could reduce the foam stability. The current research progress and application of nanoparticle stabilized foam system was summarized in this paper，and the mechanism of nanoparticle in stabilizing foam was analyzed. It was suggested that a integrated foaming and stabilizing agent could be obtained by changing the surface property of nanoparticle. This kind of integrated foaming and stabilizing system，with high stability and mechanical strength，and generating in formation，would have an important influence on foam profile control technology in low permeability oilfield.

Abstract:At present，the research on the performance improvement method of CO₂ foam system is mainly focused on the following aspects：①Optimization of the surfactant molecular structure，including the strengthening of the hydrophilic group，the optimization of the hydrophobic group and the introduction of the pro-CO₂ group；②Combination of surfactant，including anionic/ nonionic surfactants，anionic/amphiprotic surfactants and nonionic/amphiprotic surfactants；③Improving the viscosity of the base fluid and the viscoelasticity of liquid film by polymer；④Using the nanoparticles to improve the gas/liquid interface properties of the foam. In this paper，the progress of research，the mechanism and the existing problems was introduced，and the research direction in the future was looked forward.

Abstract:The effect of water flooding development in low permeability oilfield depends on whether the water is "evenly" displacing the whole reservoir. In view of the three problems of water injection development in low permeability oilfield，such as"no injection，no production and no blockage"，the essential causes of water injection，crude oil production and water plugging were analyzed. Two suggestions were put forward：（1）according to the specific circumstances of permeability and crack，design of swellable particle（microspheres）combined with flexible particles，formation of intelligent dynamic displacement control slug along fracture path，suppression of crossflow，greatly expand the swept volume；（2）by means of modification of nano materials，the particles were functionalized to weaken water molecular interaction，realizing the inject and recovery，greatly expanding the low permeability area swept volume，where conventional water flooding can not reach.