Abstract:In order to reduce the effect of fluid loss reducer on the viscosity of drilling fluid，polymer fluid loss reducer GZ-1 was synthesized by four kinds of monomer，including acrylamide （AM），N-vinyl pyrrolidone （NVP），2-acrylamido-2-methyl propanesulfonic acid（AMPS）and allyl polyethylene glycol（APEG）. The molecular structure of GZ-1 was detected by infrared spectroscopy. The effect of GZ-1 on the rheological and filtration properties of drilling fluid was studied，and that on the microstructure of mud filter cake was analyzed by environmental scanning electron microscope. The results showed that the product accorded with the design. The viscosity-average molecular weight of GZ-1 was about 2.29×10⁵，and the viscosity was only 7 mPa·s when the concentration of GZ-1 was 1.6% in aqueous solution. With increasing concentration of GZ-1，the filtration loss of polymer drilling fluid decreased，the apparent viscosity（AV）and plastic viscosity（PV）increased modestly. When 1.6% GZ-1 was added in base mud，the AV and PV increased by 1.7 and 1.5 times as original mud，while AV and PV increased by 1.1 and 2.7 times after aging 16 h at 180℃. Even after the addition of barite to raise density，the viscosity of drilling fluid did not appear sharp increase. GZ-1 could make the mud filter cake more compact and inhibit coalescence of clay particle. GZ-1 had good resistance of high temperature（180℃）and had little effect on the viscosity of drilling fluid. The viscosity increasing effect of GZ-1 was less than that of common fluid loss reducer JT888 and SY-3.

Abstract:In order to solve the problem of poor temperature resistance of hydroxypropyl starch （HPS） ，a type of environmental-friendly filtrate reducer ，HPS was prepared by the reaction of corn starch and propylene oxide in alkaline solution， the optimal reaction was probed and the relation between molar substitution degree（MS）and filtrate reducing performance of HPS was studied，and the performance of the complex system composed of HPS and several viscosity reducers was investigated. The optimum reaction conditions were as follows：reaction temperature was 60℃ ，reaction time was 20 h，the amount of propylene oxide was 26%（based on the starch mass），the amount of sodium hydroxide was 0.7%（based on the starch mass），and the starch slurry mass fraction was 45%. The filtrate reducing performance of HPS was the best when MS was 0.23. HPPS was obtained through mixing silicon-fluorine type viscosity reducer GE with HPS at mass ratio of 0.5∶1，and HPPS could resist high temperature up to 150℃ in 4% NaCl salt water muds，whose viscosity was 16 mPa·s at room temperature. Compared with HPS，at the temperature of 140℃，HPPS could resist salt，Ca2+ and Mg2+ was up to 15%，900 mg/L and 360 mg/L，respectively.

Abstract:In order to maintain the fluid loss additive properties and the solubility at the same time，allyl methacrylate，acrylic acid， butyl acrylate were introduced during the vinyl acetate copolymerization process，a lightly branched polyvinyl alcohol（B-PVA）was prepared. The structure of B-PVA was characterized by FTIR，1H-NMR and DSC，and the solubility and the filtration-reducing ability of the B-PBA were investigated. FTIR and 1H-NMR spectra analysis proved that the structure of B-PVA was in accord with that of the object product，and the DSC results showed that the melting point of B-PVA was lower than that of PVA 1799，because the introduction of copolymerization units prevented the hydrogen interaction between hydroxyl groups in some extent. The B-PVA had the same solubility as PVA 1799；however，the B-PVA had a better filtration-reducing property compared to that of PVA 1799. Under the same condition，when the temperature raised up from 70℃ to 90℃，the filtrate loss of the slurry with PVA 1799 increased dramatically from 30 mL to 400 mL；However，the filtrate loss of the slurry with B-PVA only increased from 36 mL to 70 mL. The polymer B-PVA has potential use in oil exploitation.

Abstract:In order to keep the excellent anti-collapse properties of silicate，and reduce or eliminate the effects of silicate on the rheology of drilling fluid system，hybrid silicon anti-sloughing agent was synthesized by surface modification with C₂H₃OSiCl₃ and then hybridization reaction with sorbitol. The rheological and anti-sloughing properties of drilling fluid prepared by hybrid silicon anti-sloughing agent and common agents were studied. The results showed that the optimum surface modified condition of silicon oxide was obtained as follows：room temperature，pH=8，2 mol/L tetraethylorthosilicate concentration and 25% C₂H₃OSiCl₃ volume fraction，2 h gel time. Hybrid silicon anti-sloughing agent had organic/inorganic hybrid structure. The rheology of hybrid silicon anti-sloughing drilling fluid was good，the effect of preventing pressure transmission was obvious，and the resistance temperature was 150℃. The collapse prevention effect of hybrid silicon anti-sloughing drilling fluid was better than that of zwitterionic polymer drilling fluid and potassium polyacrylate drilling fluid.

Abstract:In order to solve the problem of cement slurry unstable problem of anionic styrene-butadiene latex happened when directly added into to oil well，the suitable stabilizers were optimized by different experiments. The styrene-butadiene latex was composed of 70% of styrene butadiene latex puree，2% of the non ion surface active agent FB-1，1% of non ion surface active agent FB-2，0.4% of the anion surface active agent YB-1，0.25% of the anion surface active agent YB-2 as well as a certain amount of preservatives and deionized water，denoted as BZT-L1. It was studied on the latex cement slurry properties of mechanical stability， salt resistance and temperature resistance. At the temperature of 50—150℃ and the pressure of 25—75 MPa，latex cement slurry systems containing 6% of BZT-L1 exhibited excellent stability，and the thickening curve of cement slurry showed right angle thickening. Besides，the BZT-L1 cement slurry exhibited excellent half-saturation salt resistance properties，and thickening curve of cement slurry showed right angle thickening. The conventional density slurry containing BZT-L1 not only reduced the fluid loss （less than 50 mL）but also exhibited excellent combination properties，such as good rheological properties，low fluid loss，zero free liquid，and cement slurry density almost zero，etc. Moreover，the cement compressive strength was more than 14 MPa after curing 24 h.

Abstract:In order to reduce the corrosion of the high-density and solid-free well killing fluid made by the waste acidic brine，a high temperature corrosion inhibitor WX1A was synthesized using diethanolamine，formaldehyde and acetophenone as the raw materials and with the orthogonal experiment method. The performance of the inhibitor WX1A was researched by utilizing weight loss method，electrochemical method and SEM method for the N80 and P110 steel in the well killing fluid（acid high-density and solid-free well killing fluid with pH of 3 made by the ordinary calcium old water）. The results showed that when the molar ratio of the reactant mole ratio of diethanolamine，formaldehyde and acetophenone was 1.2∶2∶1.2，the reaction temperature was 110℃ ， reaction time was 10 h and the reaction pH was 1，the obtained corrosion inhibitor WX1A had the best inhibiting effect. When the temperature rose from 60℃ to 80℃ at the best WX1A concentration of 80 mg/L，the inhibition efficiency of WX1A on the N80 and P110 steel increased from 87.07% and 88.05% to 93.12% and 92.62%，respectively. The inhibition efficiency of WX1A on the N80 and P110 steel could reach above 90%，respectively，in the well killing fluid with the density of 1.6，1.7 and 1.8 g/cm³ at the WX1A concentration of 80 mg/L. Furtherly，the inhibition efficiency of WX1A on N80 and P110 steel in the well killing fluid with the density of 1.6 g/cm³ was above 94%，respectively，at the high temperature and pressure of 120℃，2 MPa and 150℃，4 MPa. A complete protection film formed on the surface of a metal matrix when the inhibitor WX1A was added in the well killing fluid，and the corrosion electric current reduced from 10^-4A/cm² to 10^-5A/cm²，as a result，the corrosion of ordinary steel reduced in the well killing fluid.

Abstract:PEO gemini surfactant fracturing fluid was developed using propylene-bis［（octadecyl polyoxyethylene）ammonium chloride］（ HY for short ）as thickening agent and sodium salicylate（NaSal）as counter-ion salt，and its performances such as viscoelasticity，deformation recovery，suspending proppant capability，heat and shear resistance and gel-breaking were systematically investigated. The viscosity of the fracturing fluid increased with increasing HY content at 60℃，and the viscosity was the highest at the NaSal dosage of 1%，the optimal formulation of the fracturing fluid was 3% HY +1% NaSal. the thickening agent HY could form into a uniform three-dimensional network structure under the action of counter ion salt. HY fracturing fluid had good deformation recovery performance，and its viscosity decreased rapidly at high shear rate and was nearly superimposed in rate-decreasing direction. The storage modulus G' of the HY fracturing fluid was greater than loss modulus G" in the angular frequency region 0.03～100 rad/s，exhibiting a very strong viscoelastic characteristic. Meanwhile，HY fracturing fluid had good heat and shear resistant property. The viscosity of the HY fracturing fluid was always higher than 50 mPa·s after sheared for 90 minutes at the temperature of 90℃ and at the shear rate of 170 s^-1，which indicated that the HY fracturing fluid had good heat-resistance and shear-tolerance. The fracturing fluid had a better sand-carrying performance，and the settlement velocities of the sands（30%，v/v）in the fracturing fluid were 0.075 mm/min，15.25 mm/min at 25℃ and 90℃，respectively. The viscosity of the HY fracturing fluid decreased below 5 mPa·s within 210 mins when mixing the HY fracturing fluid and the kerosene at volume ratio of 5∶1，and the surface tension of the breaker fluid was 22.92 mN/m while the interfacial tension between the breaker fluid and the kerosene was of 0.55 mN/m，and the residue content was of only 56 mg/L，indicating that HY fracturing fluid could meet the requirements of field operation.

Abstract:In order to increase the viscosity of guar gum fracturing fluid formulated by oilfield produced water，the produced water was pretreated by self-made polysilicate flocculant and then modified by chelating agent OM-002，iodine-containing stabilizer P-104 and heavy-metal zirconium compound HZR-02. The influence of OM-002，P-104 and HZR-02 on the viscosity of guar gum fracturing fluid formulated by the modified water was investigated. The study results showed that the dynamic viscosity of fracturing fluid formulated by pretreated produced water decreased significantly in comparison to fresh water，while that increased by modifying oilfield produced water. The produced water modified by three additives（OM-002、P-104 and HZR-02）at the same time had more significant thickening effect than single additive. On the condition of 65℃ and a combination of OM-002，P-104 and HZR-02 in mass ratio 10∶2∶5，the dynamic viscosity of fracturing fluid increased from 74 mPa·s to 306 mPa·s after the fluid formulated by modified produced water，and the temperature and shearing resistance of fracturing fluid were augmented.

Abstract:Aiming at the current problem that the slippery water fracturing fluid（SWFF）does great harm to the formation large and has poor salt resistance，etc，a water in water friction reducer FR-4 was synthesized，and using FR-4 as main agent，the FR-4 SWFF was prepared，composed of 0.10% friction reducer FR-4，0.11% composite synergist ZX-1 and 0.50% clay stabilizer NW-2. Furthermore，the property of the FR-4 SWFF was studied，including drag-reducing property，salt resistance，the damage of FR-4 SWFF to flow conductivity of propping agent and to core，etc. The results showed that at the shear rate of 10000 s^-1 and in the line of 1/8 "diameter caliber，the drag reduction rate of the FR-4 SWFF was 72.1% and 71.4%，respectively，at the room temperature of 25℃ and the temperature of 70℃，respectively，indicating that the FR-4 SWFF had excellent drag reduction performance and FR-4 had good temperature resistance；the drag reduction rate of different FR-4 SWFF prepared with salt water，return drainage and simulated seawater，respectively，was more than 70%，which indicated that the FR-4 had good salt resistance. Under the condition of the sand（50/70 mesh ceramide proppant）concentration of 10 kg/m² and the pressure range of 10—70 MPa，after injecting the FR-4 SWFF，the flow capacity damage rate of proppant filling was less than 10%，which indicated that the FR-4 SWFF belonged to the low damage SWFF. After injecting the FR-4 SWFF into the low permeable core with the permeability of 1.92×10^-3—3.52×10^-3μm² for 24 h，the core damage was low，being of 5.62%. The apparent viscosity of the FR-4 SWFF was of 1.203 mPa·s at the temperature of 30℃ and at the rotational speed of 100 r/min，the surface tension was of 24.96 mN/m at the temperature of 25℃， and the volume expansion was of 2.88 mL，the FR-4 SWFF had a good surface activity and the anti-swelling performance，which are conducive to protection of the reservoir and fracturing fluid flowback after fracturing. The dispersion time of the FR-4 was less than 5 s，and FR-4 was non-toxic and environmental friendly. What is more，the FR-4 SWFF had excellent drag reduction performance during the construction process，which could meet the online mixing technological requirements，

Abstract:The offshore oilfield in China always had the problem of high permeability，strong heterogeneity，inefficient water flooding et al. To improve this situation，modified starch gel and foam composite oil displacement technology was studied by physical simulation experiment. The flooding effect of the combination system in heterogeneous cores and the effect of different gel location on the combination flooding consequence were investigated. The results showed that modified starch gel prefered to enter high permeable zone which oil saturation was low，compelled foam into the middle and low permeable zone which oil saturation was high. In that case，the recovery degree of this combination flooding could be 24.63% higher than that of first water flooding，the moisture content of core outlet port reduced from 98% to 45.3%. The oil displacement effect of combination system was better than that of starch gel or foam alone. When starch gel located in deep core and trimline，foam channeling problem could be solved，and the sweeping volume of foam flooding could be enlarged，the residual oil in low permeability layer could be displaced. The recovery ratio increased 28.97% in foam flooding stage，the ultimate recovery ratio could reach 63.11%.

Abstract:For organic chromium/HPAM weak gels，salinity（＜5000 mg/L）of NaHCO3 type oilfield wastewater has a huge impact on its gelation time and strength. The effect of salinity on the performance of organic chromium/HPAM weak gels，such as gelation time，gel strength，shear properties and viscoelastic were investigated by brookfield viscometer and RS150 rheology instrument. The experimental results showed that under the identical gelation condition，the gelation time shortened and the viscosity of weak gels raised as salinity increased. Salinity ranging from 2371.14 mg/L to 3084.60 mg/L had a significant delay effect on gelation， while the acceleration arose when salinity was beyond 3449.44 mg/L. Damage of shear on weak gel was not reversible. The weak gel with high salinity had higher viscosity at a low shear rate，while the viscosity with different salinity was similar at a high shear rate（≥21 s^-1）. Storage modulus G' and loss modulus G'' of the weak gels increased with the increase of salinity. Elastic of weak gel were dominant at high salinity，while viscous became dominant at low salinity.

Abstract:In order to reduce the water content of oil well and improve the development effect of water flooding in Haiwaihe oilfield， chromium organic cross-linked polymer weak gel was prepared by partially hydrolyzed polyacrylamide（HPAM）and organic chrome crosslinking agent based on reservoir condition. The temperature resistance，salt tolerance，shearing resistance，injectivity， plugging property and injection profile improvement ability of weak gel were studied. The results showed that the gelling time was three days and the gel strength was C grade when the temperature was 70℃ and the formula of weak gel flooding system was 2000 mg/L HPAM+ 100 mg/L organic chrome crosslinking agent. The weak gel had good temperature resistance，salt tolerance and shearing resistance，the temperature-resistance capacity was up to 90℃，and salt resisting concentration was 3621.2 mg/L. Core flow experiment results showed that the weak gel had good injectivity，plugging property and injection profile improvement ability with 10.4%—12.7% enhanced oil recovery rate and above 90% profile improvement rate to heterogeneous cores.

Abstract:In order to solve the problem of increased injection pressure and declined injection volume during late injection period of main slug of some alkali-surfactant-polymer（ASP）flooding injection wells in Daqing oilfield，a compound plug removal agent composed of inorganic ammonium degradation agent and compound acid was prepared. The plug removal effect on the plug from ASP injection well was studied in lab and blocking test was applied on the injection wells of Daqing oilfield. The results showed that this compound plug remover agent had good dissolve effect on the plug of injection wells with more than 98% dissolving rate. When the plug removal agent was applied on site，the degradation agent was injected first which used to degrade the clumps blocking of polymer，then the compound acid was injected which used to treat the residual scale and mechanical impurity. After the plug of 14 wells with ASP injection was removed，the average pressure of the wells in early days decreased 2.2 MPa，the average daily injection increased 12.5 m³，and the average period of validity reached to 183 days. The compound plug removal agent had a better decompression and augmented injection effect to ASP flooding injection wells which injectability declined because of plug in late injection period of main slug and side slug.

Abstract:In order to slow down the rising velocity of water content in production liquid during unconsolidated sandstone reservoirs development and improve the effect of tip screen out fracturing sand control，octadecyltrichlorosilane（OTS）was used to the treatment of hydrophobic modification on the surface of propping agent（quartz sand）by self-assembly method. The effect of OTS solution concentration，soaking time and air drying time on the broken rate，acid solubility and fluid resistance ratio（NFRR value） of OTS self-assembled hydrophobic quartz sand was studied. The condition of modification treatment on the surface of quartz sand was optimized by orthogonal test，the flushing resistance was determined，and the self-assembled monolayer formation mechanism and the hydrophobic mechanism were introduced. The results showed that the OTS solution concentration had the greatest influence on the broken rate while the soaking time had the greatest influence on the acid solubility and NFRR value. The NFRR value of quartz sand after soaked one hour by 10 mmol/L OTS solution and air dried 84 hrs got peak point 2.531 with the best hydrophobic result. OTS self-assembled hydrophobic quartz sand had an excellent hydrophobic performance and the water permeability of core could keep stable after 5 days scoured by deionized water. OTS self-assembled hydrophobic quartz sand had a stable surface property and it could satisfy the need of tip screen out fracturing sand control.

Abstract:In order to reveal the effect of xanthan gum on the performance of colloidal gas aphron（CGA）and blocking behavior characteristics of CGA，the CGA was prepared by betaine surfactant and xanthan gum solution under the condition of high speed stirring. The effect of xanthan gum concentration on the foaming ability，viscosity and bubble size was studied，the plugging effect of CGA was investigated by homogeneous and heterogeneous sandpacks. The experiment results showed that with the increase of xanthan gum concentration，the viscosity of awaiting foaming solution，low shear rate viscosity of CGA and drainage half-life increased，and foaming volume decreased. The drainage half-life and foaming volume of CGA was 46 hrs and 345 mL respectively， and its low shear rate viscosity was greater than 40 Pa·s when xanthan gum concentration was 6 g/L and surfactant concentration was 4 g/L. When xanthan gum concentration was the same，the average diameter of CGA increased with the extension of standing time. When standing time was the same，the average diameter of CGA decreased with increasing xanthan gum concentration. Diameter swelling rate of CGA slowed down with the increase of xanthan gum concentration. Micrographs showed that CGA owned a unique thick aqueous protective shell，bubbles existed in separate spheres and there was no plateau boundary around bubbles which stability was higher. CGA had a strong plugging effect toward homogeneous and heterogeneous model. The maximum displacement pressure of homogeneous and heterogeneous model reached 7.52 and 7.89 MPa respectively. CGA could remarkably improved heterogeneity of reservoir and showed a better profile control ability.

Abstract:In view of the heavy oil reservoir，amphiphilic polymer（ICJN）oil displacement agent system，which was suitable for heavy oil exploitation，was designed and synthesized. By scanning electron microscopy（SEM），fluorescence microscope，spinning drop interfacial tensiometer，contact angle meter，quartz crystal micro balances and micro displacement model，aggregation structure of ICJN in solution and the effect of ICJN on the heavy oil emulsification，dispersion ability and the viscosity reduction and oil displacement properties were studied. The results showed that the ICJN solution with the concentration of 1000 mg/L could reduce the oil-water interfacial tension to the magnitude order of 10^-1 mN/m. The viscosity increasing ability of ICJN was higher than that of the common HPAM with hydrolysis degree of 25% and the viscosity-average molecular weight of 1800×10⁴. When the volume ratio of the crude oil and water was 1∶1，1200 mg/L ICJN solutions could make the viscosity of the mixed oil and water system drop to below 100 mPa·s，meaning that the viscosity reduction rate was more than 95%. Using asphaltene to simulate the heavy components of crude oil and 1200 mg/L ICJN solution as mobile phase，the asphaltene adsorption in the surface of SiO₂ chip，decreased from 489.2 ng/cm² to 207.4 ng/cm² and the adsorption layer thickness deceased from 4.7 nm to 3.1 nm after desorption for 40 min，which indicated that ICJN had strong oil sweep ability. ICJN solution displaced the crude oil not only through expanding the sweep volume displacement，but also by emulsifying dispersion crude oil due to low oil-water interfacial tension. Experimental results of microdisplacement showed that the oil displacement effect of 1000 mg/L ICJN system was significantly better than that of 1000 mg/L HPAM system and that of 1000 mg/L HPAM+3000 mg/LAOS system.

Abstract:An amphoteric hydrophobic quadripolymer（PAADC）was synthesized by free radical solution polymerization using acrylamide（AM），2-Acrylamide-2-methylpro panesulfonic acid（AMPS），N，N-dimethyl acrylamide（DMAM）and cetyl dimethyl allyl ammonium chloride（CDAAC）as monomers. The elastic and viscous moduli vary with reaction time in the polymerization process was investigated. The rheokinetics equation was established for the first time to well describe the changes of elastic modulus in the process of polymerization. The results of rheological studies showed that，the critical association concentration of PAADC was about 2.5 g/L，and at the same concentration of 6 g/L the viscosity of PAADC solution was 3 times more than that of PAAD solution at the temperature of 30℃ and at the sheer rate of 170 s^-1. PAADC solution possessed better characteristics of heat resistance，shear resistance，much more significant viscoelasticity and thixotropy compared with that of PAAD solution. The flow curves of these two polymer solutions could be described by co-rotational Jeffreys model.

Abstract:To understand the oil incremental mechanism of hydrophobic associating polymer flooding further，the influence of polymer concentration，polymer type，conditioning agent concentration and sand grain size on adsorption and desorption was studied with oil sand grains of SZ36-1 reservoir formation，injected water and hydrophobic associating polymer as the research object. Results showed that the static adsorption and desorption of hydrophobic associating polymer was closely related with intermolecular association degree，adsorption mode and sand grains specific surface area. When the AP-P4 concentration was at the range of 500— 2500 mg/L，the range of the adsorption quantity and the desorption quantity was 0.758—1.278 mg/g and 0.122—0.653 mg/g， respectively. When the polymer concentration was higher than 1200 mg/L，the proportion of the multilayer adsorption increased. Compared with monolayer adsorption，when multilayer adsorption happened，the binding force between polymer molecular aggregate and sand grains surface was weaker，and adsorption stability was worse，hence，the polymer molecule was easier to be desorbed. The addition of the β-cyclodextrin could inhibit the association action happened among the hydrophobic groups，as a result，the polymer aggregate size became smaller. When polymer aggregate size and sand grains got smaller，the adsorption of polymer molecule increased，at the same time，the amount of polymer molecules attached to sand grains surface by means of monolayer adsorption increased，and the adsorption stability enhanced.

Abstract:In process of polymer flooding，the phenomenon of profile reversal has bad influence on enhancement of oil recovery. In order to further improve effect of polymer flooding，we make some researches on the effect of polymer flooding，the reversal time of polymer profile and its influencing factors through the methods of theoretical analysis and laboratory test. Results showed that with the increase of the core permeability，reversal time of polymer flooding profile would delay and the delay degree would increase. When the concentration of polymer solution was 1600 mg/L，permeability differential was 4 and the core permeability was more than 1200×10^-3μm²，this phenomenon became especially obvious. With the increase of permeability differential and thickness ratio of divided layer （high permeability layer /low permeability layer），that was to say，with the increase of formation coefficient differential，the reversal time of polymer flooding profile was advanced. When the concentration of polymer solution was 1600 mg/L，average core permeability was 300×10^-3 μm² and formation coefficient was 10，the reversal time of polymer flooding profile was advanced to 0.06—0.07 PV. With the increase of core permeability and formation capacity differential，the enhancement of oil recovery increased at first and then decreased. The reversal time of polymer flooding T_p and formation capacity differential D_j satisfy the equation T_p=a（D_j-1）^-1( here，a was the reversal coefficient），With the increase of the polymer solution concentration，the reversal coefficient decreased，profile reversal time was advanced. Using this equation，the relationship between profile reversal time and formation coefficient differential could be quantitative described，and the injection parameters could be adjusted timely and the effect of polymer flooding could be improved.

Abstract:In order to improve the solubility of Betaine surfactant in the high-temperature and high-salinity reservoir conditions of Shengli oilfield，the hydroxyl groups were introduced onto the molecular chains of sulfobetaine surfactant，a novel alkyl-hydroxyl-sulfobetaine surfactant MBS16 was synthesized by two-step method. The structure of the surfactant MBS16 was characterized by infrared spectrum （IR） and nuclear magnetic resonance （NMR）. The oil/water interfacial activity and foam properties were investigated using spinning-drop interfacial tensiometer and Ross-Miles meter；and the oil displacement experiment was conducted in a sandpacked core with the permeability of 1500 ×10^-3 μm². The results showed that interfacial tension（IFT） between 0.3% modified betaine surfactant solutions and Shengli crude oil from various blocks could reach ultralow，implying that the surfactant was temperature-resistant and salt-tolerant. Compared with single HPAM system（0.15% HPAM），the viscosity of the compound system（0.3% MBS16 + 0.15% HPAM）increased slightly. The oil displacement experiment results indicated that the compound system（surfactant/polymer）increased oil recovery by 9.4% than single HPAM system did. Moreover，the foaming ability of the modified betaine was strong and the foam stability of the modified betaine compounded with anionic-nonionic surfactant B4 was good.

Abstract:In order to obtain polymer/surfactant compound flooding system with good performance，the amphoteric surfactant was synthesized by cardanol，epichlorohydrin and catalyst tetrabutyl ammonium bromide. The structure of the product was characterized by infrared spectrometer. The effect of the dosage of polyacrylamide and surfactant on the oil-water interfacial tension and emulsifying property was studied. Experimental results showed that the product had the structural characteristics of cardanol betaine surfactant. The oil-water interfacial tension was 10^-4—10^-3 mN/m when the concentration of surfactant was low（0.5—3.0 g/L）. The equilibrium interfacial tension of flooding system increased with increasing concentration of polymer，and the amount of surfactant had little influence on equilibrium interfacial tension. When the mass concentration of surfactant was 0.3—0.8 g/L and that of polymer was 0.5 g/L，the equilibrium interfacial tension of binary system could achieve 10^-6—10^-5 mN/m. The emulsification property of polymer/surfactant compound flooding system was good. With the increase of surfactant concentration，the time for removing moisture of binary system extended（200—1000 s）. Compounding surfactant with polymer could lower the oil-water interfacial tension and improve the emulsion stability.

Abstract:In order to further improve oil recovery of maturing oilfield by water flooding，the flow characteristics and oil displacement characteristics of the formation water and hexadecyl hydroxypropyl sulfo betaine（HHSB）solution with different salinity in low permeability porous media were analyzed by indoor physical simulation experiments. The experimental results showed that the surface action of low salinity formation water（or surfactant solution）and rock was stronger than that of high salinity and the flow resistance of low salinity formation water and surfactant solution in low permeability porous media was smaller than that of high salinity formation water and surfactant solution. The wetting contact angles of low salinity（4700 mg/L）formation water on the surface of the rock was 83°，and that of high salinity（47000 mg/L）formation water on the surface of the rock was 84.5°. At the condition of low salinity，the adsorption loss of HHSB with 3000 mg/L mass concentration on the rocks surface was 23.33%，while at the condition of high salinity，it was 16.73%. After adsorption on the rock surface，the interfacial tensions between low salinity HHSB solution and crude oil was 0.0045 mN/m，and that of high salinity HHSB solution and crude oil was 0.008 mN/m. Besides，the EOR experimental results showed that high salinity water flooding recovery and low salinity water-flooding recovery was 32.5% and 33.8%，respectively. After high salinity water flooding，the subsequent low salinity water flooding，high salinity HHSB solution flooding，and low salinity HHSB solution flooding could make oil recovery increased by 1.3%，6.2%，and 8.2%， respectively. After low salinity water flooding（oil recovery being of 33.8%），the subsequent low salinity HHSB solution flooding could make oil recovery increased by 7.3%（total oil recovery being of 41.1%）. It was known that low salinity water flooding and the subsequent low salinity surfactant solution flooding could improve oil recovery to the best.

Abstract:In order to study the interaction between polymer with ultrahigh molecular weight and surfactant，the effect of partially hydrolyzed polyacrylamide（HPAM）with ultrahigh molecular weight on the interfacial tension（IFT）between anionic surfactant （alkylbenzene sulfonate）or anionic-nonionic surfactant（polyoxyethylene ether carboxylate）and normal alkanes was studied. The results showed that the IFT between single long chain alkylbenzene sulfonate and nonane decreased initially，then increased，and finally stabilized with the increase of HPAM concentration，while the IFT between double long chain alkylbenzene sulfonate or polyoxyethylene ether carboxylate and nonane increased rapidly and then stabilized. The ability to reduce IFT of surfactant was influenced by HPAM mainly through changing the interfacial film arrangement of alkylbenzene sulfonate and polyoxyethylene ether carboxylate. Besides，good water-solubility of HPAM led to the distribution capacity of surfactant in oil phase and aqueous phase. IFT between surfactant and normal alkane increased with increasing hydrophilicity of surfactant under low carbon number of alkyl chain. HPAM had no influence to IFT under high carbon number of alkyl chain. There was competition between two influences. When the interface activity of surfactant was strong，the influence of HPAM on IFT was achieved mainly by changing the interfacial film arrangement structure.

Abstract:For improving the flow-turning ability of hydrophobically associating polymer/surfactant binary combination and getting a good effect of enhancing oil recovery in Dagang oilfield，the effect of polymer and surfactant concentration，core permeability and injection water descaling on the viscosity and seepage characteristics of hydrophobically associating polymer and binary combination system was studied. The results showed that the viscosity of polymer solution and binary combination system increased with the increase of polymer concentration. The critical association concentration of hydrophobically associating polymer was 1—2 g/L. A small amount of surfactant could enhance the association of hydrophobic associated polymer and improve the viscosity and seepage resistance of binary combination system. The higher permeability of core，the lower resistance coefficient and residual resistance coefficient of binary system was. The polymer and binary combination system configured by descaling softened water had the biggest viscosity. Besides，the smaller polymer concentration，the more obvious thickening effect of softening water was. The polymer and binary combination system configured by softened water with scale had the biggest resistance coefficient and residual resistance coefficient，the highest injection pressure and the best flow-turning ability.

Abstract:As for alkali-surfactant-polymer system，the problem of the chemical flooding agent retention in reservoir and the resulting chromatographic separation phenomenon，is the hot-button issue among petroleum science and technology personnel. According to field actual demand，the oil displacement agent properties and its variation regulation in reservoir was researched during the course of alkali-surfactant-polymer flooding with strong base at artificial core containing natural sands with the length of 18 m，based on the geological and fluid characteristics in reservoir of Daqing Lamadian oilfield. The results showed that，comparing with polymer，the relative molecular mass of surfactant and alkali is smaller，so the inaccessible pore volume was smaller，their swept volume was larger，their liquid retention was larger and their breakthrough time was later，which led to chromatographic fractionation phenomenon among the three parts，and weakened their synergistic effect in oil displacement process. During the injection process of alkali-surfactant-polymer composite system，when the injected slug size was up to 0.482—0.543 PV，the interfacial tension could reach to a magnitude of 10^-2 mN/m within the whole length of the core and reach to a magnitude of 10^-3 mN/m in the local area. During the transmission and migration process of alkali-surfactant-polymer composite system in the artificial core，the polymer molecular coil dimension decreased due to the pore shear effect，the viscosity of the system gradually reduced from injection side to produced end，as a result，the viscosity loss rate of produced end was as high as 69%. At the end of succeeding water flooding，the residual oil saturation and the retention of surface active agent in the core gradually reduced from injection side to produced end，and the residual oil saturation was of 58% and the retention of surface active agent was of 0.6462 mg/g at the produced end.

Abstract:based on the reservoir condition of the second plant of DaQing oilfield after waterflooding，microbial enhanced oil recovery experiment was developed，and the Indigenous microbial strains Rhodococcus rubber（Rr）with better emulsification was selected，and its physiology and biochemistry characteristic were studied，the saturated hydrocarbon compositions of the crude oil before and after biochemical reaction were analyzed，and the changes of the indigenous microorganism and metabolites were measured with the physical model；the microbial flooding experiments were conducted. The results showed that Rr had better emulsification to oil and paraffin，the emulsification activity of oil-water interface was higher than 60%；the saturated hydrocarbon concentration of nC₁₁—nC₁₇ decreased after microbial reaction；no Rr was checked from the liquid of physical models during incubation；acetic acid，propionic acid，propanedioic acid，citric acid，succinic acid，etc，were evaluated with liquid chromatography， and the concentration of acetic acid was up to 166.19 mg/L. The results of microbial displacement experiment showed the air injection could not enhance oil recovery effectively，the injection of excessive Rr could disturb the Microorganisms' ecological equilibrium，and the simple injection of mineral medium could activate the Microorganisms well and obtain higher enhancement of oil recovery（8.51%）. Accordingly，indigenous microbial flooding after water flooding was suggested in the second plant of Daqing oilfield.

Abstract:In order to study the effects of the hydrogen agent and metal catalysts on in-situ combustion development，effect of the formic acid，ferrous（nickel）-base ions solution on improving the oxygen utilization rate and combustion efficiency was investigated during heavy oil flooding；effect of adding the ferrous ion solution on thin oil combustion stability was also probed . Experimental results showed that，compared to the basic heavy oil fire flooding experiment，after adding 0.3% formic acid and 0.05% ferrous ion solution into the simulated oil sand，the combustion stability was enhanced and the CO₂，CO content in the exhausted gas increased while the O₂ content decreased significantly，the O2 utilization ratio increased by 8.27%，the combustion front was increased by 27℃ and the oil recovery was enhanced by 7.33%. Compared to the thin oil fire flooding base experiment，the addition of 0.05% ferrous ion solution made fuel concentration increased，which ensured the sustainable combustion on the thin oil fire flooding experiment.

Abstract:In order to analyze the molecular structure of sub-fractions of the ultra heavy oil and further investigate the high viscosity mechanism of the ultra heavy oil，Xinjiang block nine 7 ultra heavy oil was separated into different fractions which were saturate，aromatic，resin，and n-C 7 insoluble asphaltene．The fundamental properties of each fraction were measured by VPO and elemental analyzer，and the average structural parameters of different fractions were analyzed based on ¹H-NMR determination using B-L method. Model molecular structure of different fractions was obtained based on average structural parameters. The structure of the model molecular was represented by aromatic ring connected with aliphatic ring along with alkyl side chains and hetero-atom. The model molecular showed that the structure of asphaltene and heavy glial was complex，while the structure of other fractions was relatively simple. Moreover，the simulation value and experimental value of molecular weight was close and the relative error was less than 3%，which indicated that the model molecular structure constructed by B-L method was reasonable. There was strong association action between resin，asphaltene and aromatic，resulting in forming Macromolecular aggregation structure，and achieving the high viscosity characreristic of the Xinjiang block nine 7 ultra heavy oil .

Abstract:In order to effectively improve the liquidity of the high viscosity and low mobility oil，the performances of the amphoteric viscosity reducer AVR with intellectual property were studied systematically，and the influences of alkalis and polymers were investigated. Experimental results indicated that the viscosity reduction efficiency was more than 82%，and the system could change the wettability of oil-wet surface，and had good ability of stripping oil film within 41 seconds，and could achieve lower interfacial tension（IFT）1.8×10^-2 mN/m. Alkali could help to enhance the performances of the amphoteric viscosity reducer AVR. Especially for adding Na₂CO₃ system，the viscosity reduction efficiency increased to more than 85%，the stripping film time shortened to 10 seconds，and ultra-low IFT（less than 1.0×10^-2mN/m）could achieve within 15 minutes rapidly，and IFT still showed a downward trend with the extension of time. When the polymer concentration was in the range of 100—500 mg/L，the viscosity reduction efficiency of the AVR systems was more than 80%，and the systems could still reach ultra-low IFT. The molecules of the viscosity reducer AVR could form three-dimensional network structure through the association，so that the solution had certain viscosity to improve the role of the swept volume. The AVR solution had good shear resistance capacity，and the viscosity retention rate was 86% after high speed shear（5000 r/min）in 60 seconds；the AVR solutions could pass through the nuclear pore membrane（more than 0.2 μm）and viscosity retention rate was more than 90%，which indicated that the AVR solution had good injectivity.

Abstract:In order to reveal the effect of water-soluble viscosity reducer and oil-soluble viscosity reducer on the demulsification and dehydration of heavy oil produced fluid，the effects of polyoxyethylene ether water-soluble viscosity reducer（SH）and unsaturated ester polymer oil-soluble viscosity reducer（SL）on the demulsification of Chenzhuang heavy oil produced fluid in Shengli oilfield were investigated. The influence mechanism of SH and SL on the stability of heavy oil produced fluid were studied through interfacial films by interfacial dilational rheology method and scanning electron microscope. The results showed that when the concentration of SH increased from 0 to 3 g/L，the oil-water interfacial dilational modulus reduced from 20.09 mN/m to 3.02 mN/m， the dehydration rate increased from 47.62% to 66.67%，interfacial viscous modulus and elastic modulus decreased simultaneously， and the phase angle increased from 18.43o to 29.43o. SH molecules could increase the distance between asphaltenes and between colloid and asphaltene，and reduce the intensity of interfacial film. When the concentration of SL increased from 0 to 3 g/L，the interfacial dilational modulus increased from 20.09 mN/m to 34.76 mN/m，the dehydration rate decreased from 47.62% to 6.08%， interfacial viscous modulus decreased while elastic modulus increased，and the phase angle decreased from 18.43o to 9.83o. SL could enhance the interaction between asphaltene molecules which led to bituminous surface render a rule configuration with shape of “scales”，structure compact and interfacial film strength enhance. SH was good for heavy oil demulsification dehydration，on the contraty，SL was bad for heavy oil demulsification dehydration.

Abstract:In order to obtain a demulsifier suitable for heavy oil produced fluid by polymer flooding in Bohai oilfield，demulsifier DW03 with comb-like structure was developed by the polymerization of acrylic modified polyether，methylacrylic acid and butyl acrylate in aqueous. The demulsifying performance of DW03 which was synthesized in lab was studied by bottle test. The bottle test in situ and the pilot test of DW03 which was produced in plant were conducted in Bohai oilfield. The results showed that the dehydration ratio of DW03 which was synthesized in lab was greater than 80% for crude oil emulsion in 60 min. Compared with demulsifier XC33 which was used in oilfield，the average water content in oil and the average oil content in produced water decreased 5.5% and 995 mg/L respectively after emulsion breaking of produced fluid by DW03 in bottle test in situ. During the pilot test，the appropriate concentration of DW03 ranged from 90 to 120 mg/L，and the optimum concentration of DW03 was 100 mg/L. The dosage of DW03 reduced by 23%，water content in oil after thermo-chemical treatment reduced by 26%，and oil content in produced water reduced by 66% compared with the result of the same process by XC33. DW03 had advantages including low dosage，high dehydration rate，clear dehydrated water，and good demulsification effect than XC33.

Abstract:In order to overcome the shortcomings of existing sulfate scale detergent and increase scale removal rate by enhancing the synergistic effect between chelating agent and additives，a kind of chelating agent-based alkaline detergent named as SA-209 was developed. The effects of SA-209 concentration，descaling time，pH value，temperature，and salt concentration on the scale removal rate for barium and strontium sulfate scale were evaluated. The results showed that with the increase of SA-209 concentration， descaling time and temperature，the scale removal rate of SA-209 to barium and strontium sulfate scale increased first and then gradually stabilized；with the increase of pH value，the scale removal rate increased first and then decreased；and with the increase of KCl concentration in the solution，the scale removal rate decreased slowly. The optimum descaling condition of SA-209 to barium and strontium sulfate scale was obtained as follows：4%—12% SA-209 dosage，4—12 h descaling time，11—12 pH value，80—120℃ descaling temperature. The scale removal rate of SA-209 to barium and strontium sulfate was about 55% and 65% respectively，and to scale sample in offshore oilfield with barium sulfate as the main component was 72.4%. The corrosion rate of 4% and 12% SA-209 on N-80 steel sheet was 0.2022 and 0.4412 g/（m2·h）respectively，which was significantly lower than that in industry standard. SA-209 had high scale removal rate and low corrosion to equipment or tubing which was suitable for the scale undissolved by acid.

Abstract:In order to improve the determination accuracy of partially hydrolyzed polyacrylamide（HPAM）in produced liquid by liquid chromatography，the effect of HPAM relative molecular weight，molecular weight distribution，hydrolysis degree，solution salinity and other factors on the determination results was studied，and the problems existing in the determination of HPAM concentration in produced fluid on site was analyzed. The results showed that the polymer relative molecular weight，molecular weight distribution and solution salinity had no significant impact on the concentration determination，while the hydrolysis degree was the restriction factor of polymer concentration determination in produced fluid by liquid chromatography. The slope of work curve increased with increasing hydrolysis degree of HPAM. When the hydrolysis degree of standard sample was lower than that of the sample to be tested，the measured result was lower than the true one，on the contrary，that was higher. After tested sample on site was pretreated by microporous membrane with suitable pore size and dilution method with distilled water，the interference effect of the oil in produced fluid sample，organic impurities and higher chromaticity could be eliminated. Because the polymer dry powder sample for injection as standard sample on site measurement，the measured result of polymer concentration was lower than the actual value.

Abstract:Sulfonated phenolic resin（SMP）played an important role in deep well drilling. In order to prepare more high-temperature resistant and salt-tolerant drilling fluid additive on the basis of SMP，the domestic research progress of sulfonated phenolic resin was reviewed in terms of mechanism，research of modification，production process，field application and quality control. The suggestion of modification research of sulfonated phenolic resin in the future was proposed.

Abstract:Nanomaterials could improve the performance of water plugging and profile control agent，and became more and more important in the field of water plugging and profile control. The structure and performance characteristic of nanomaterials was briefly introduced. The research and application progress of nanomaterials in water plugging and profile control were reviewed， especially on the functions of nanomaterials in adjusting gelling time，improving the stability and mechanical performance of water plugging and profile control agent，as well as enhancing the stability of emulsion and foam. Furthermore，the application prospect of nanocomposites in the technique of water plugging and profile control in high temperature deep well reservoir，super high permeability and large pore reservoir and low permeability reservoirs was proposed.

Abstract:The latest research progresses of polyacrylamide biodegradation in recent years were reviewed. The composition and performance of the aerobic and anaerobic degrading microorganisms were introduced. The mechanisms and ways of polyacrylamide biodegradation were summarized. The thermodynamics parameters of Gibbs free energy during the polyacrylamide biodegradation were calculated and the dynamics property was discussed. The future research directions of polyacrylamide biodegradation was proposed.

Abstract:Recently, the switchable surfactant has drawn researchers’attention and it has a wide application prospect. The progress on synthesis and applications of CO₂ switchable surfactants were detailly summarized in this article, including the structures, interaction mechanisms, synthetic methods and potential application fields. Besides, the existing problems, the improvement measures and the development prospect of such switchable surfactants were outlooked.