Abstract:In order to discover the effect and action mechanism of salt water on performance of organic salt drilling fluid（OSDF)，and to regulate and stabilize the performance of the OSDF, indoor experiments were made to test the influence of salt water intrusion on the performance and stability of OSDF，and the mechanism of salt water intrusion was analyzed. The results showed that the main effect of salt water on the OSDF system was dilution ，which leaded to a decrease in viscosity and shear stress greatly，mud cake thickening and poor settlement stability. when the 40% salt water intrusion，apparent viscosity decreased from 103 mPa·s to 18.5 mPa·s， API and HTHP filitration increased from 1 mL to 2.7 mL and 7 mL to 28.1 mL，respectively；The filter cake thickness of API and HTHP increased from 2 mm and 0.5 mm to 1 mm and 7 mm，respectively；the density difference of the drilling fluid at the temperature of 20℃ and 150℃ increased from 0 g/cm³ and 0.18 g/cm³ to 0.08 g/cm³ and 0.32 g/cm³，respectively. These changes would undoubtedly increase the frequency of underground complex situation.

Abstract:Based on molecular structure design to strengthen the bonding strength between amine inhibitor molecules and clay particles， choosing silane coupling agent KH-570 as key monomer， DMAA and DMDAAC as functional monomers， organosilicon-amine inhibitor called PKDAS with high temperature was synthesized by radical copolymerization. The heat resistance，adsorption property on clays and inhibition property to bentonite and mud shale were studied. The results showed that PKDAS was resistant to high temperature of 220℃. The adsorption capacity of PKDAS was stronger than that of inhibitor NH-1 and FA-367，the adsorption of PKDAS，NH-1 and FA-367 before aging on clay particles was 27.3，10.2 and 12.6 mg/g， respectively，while the relative parameters after aging for 16 hours at the temperature of 220℃ ，was 6.8，1.9 and 2.0 mg/g， respectively. The inhibiting property of PKDAS to bentonite and mud shale was excellent，which was superior than that of NH-1 and FA-367 at the high temperature. The extreme anti-pollution of bentonite in the 1% PKDAS solution，was 40% and 30%， respectively，before and after aging for 16 hours at the temperature of 220℃.Expansion height of mud shale in 2.0% PKDAS solution for 16 h after aging at the temperature of 220℃ was 0.57 mm，which was ， lower than that in NH-1 or FA-367 solution， being of 1.07 and 1.05 mm，respectively. The rolling recovery of the mud shale in the PKDAS ，NH-1 and FA-367 solutions after aging for 16 h at the temperature of 220℃ was 86.67%， 38.29% and 38.07%.

Abstract:Aiming at the fractured leakage reservoirs，a new kind of shearing-resistant pre-formed gel microsphere plugging agent WQ-5 was synthesized by inverse suspension polymerization，using Span80 as the emulsifiers，potassium persulfate as initiator， acrylamide，as comonomer，JL-2 as the chemical crosslinker and hectorite as the inorganic crosslinker. The particle size distributions of WQ-5 before and after swelling were evaluated by use of laser particle size analyzer. The effects of swelling property and shearing-resistant were also evaluated. The plugging property of WQ-5 was also evaluated by HTHP Dynamic Filtration Press plugging experiment. The results showed that the initial average particle size of synthesized pre-formed gel microsphere plugging agent was of 184.5 μm. The average particle size after swelling was of 450.5 μm in 1%NaCl solution at the temperature of 20℃. The expansion ratio of WQ-5 was related to temperature，salinity and pH value，the lower sanity and the higher temperature and pH value，the better swelling property of plugging agent. The plugging agent had good plugging and bearing ability.

Abstract:In order to solve the problem of nano-SiO₂ aggregation and the bad stability of organic silicone defoamer with easy layering， polydimethylsiloxane（PDMS）was used to modify the surface of nano-SiO₂. The influence of reaction temperature on the grafting rate and hydrophobicity of nanoparticle was investigated. The effect of the hydrophobicity and dosage of nanoparticle on the defoaming and inhibiting foam performance of defoamer， and the stability of defoamer were studied. The results showed that the zeta potential， hydrophobicity and grafting rate of modified nano-SiO₂ increased with increasing reaction temperature. When the reaction temperature was 65℃， the zeta potential（-4 mV）and contact angle（166.4°）of nanoparticle reached their highest value. The defoaming and inhibiting property of deformer increased with increasing hydrophobicity of nano-SiO₂. With increasing dosage of nano-SiO₂， the defoaming time of defoamer decreased first and increased later， and the inhibiting foam time of defoamer increased first and decreased later. When the amount of nano-SiO₂ was 7% and the contact angle of nanoparticle tablet was 166.4°， the defoaming and inhibiting foam effect was the best with 16 s defoaming time and 88 s inhibiting foam time. The defoamer which used modified nano-SiO₂ as the main body had good stability， could dispersed in deionized water quickly and the liquid level was oil free. The emulsion which was diluted with deionized water didn’ t layered after 60 min centrifugation at 3000 r/min. Its ability was better than that of commercially available silicone emulsion defoamer.

Abstract:It is difficult to shut off the useless water production from horizontal wells because of the big number of water points. To solve this problem， a kind of annular chemical packing martial （MMH/MT/AM system） was developed using 4% aluminum-magnesium layered hydroxide/sodium soil（MMH/MT）and 4% acrylamide（AM） . Effects of the influencing factors on rheological properties of the MMH/MT/AM system were explored. Results showed that when the MMH/MT concentration increased from 1% to 4% and the temperature rose from 30℃ to 70℃，both the recovery rate and the recovery strength of the system were obviously enhanced. With the increase of the shear rate from 1000 s^-1 to 7000 s^-1，the damage degree of the system structure was sharply intensified，but the elasticity modulus after system ecovered was similar to that of system before shearing. Moreover，a particle-coating with a three-dimensional network structure was formed after the addition of the accelerating agent. With the increase of the accelerating agent concentration，the consolidation time of the system was rapidly shortened and the strength of the consolidated system was obviously improved. The elasticity modulus after the system recovered exceeded 38 kPa when the concentration of the accelerating agent was only 60 mg/L. The plugging strength of the system in the annular space was 8.3 MPa/m when the annular space was packed with sand. Results of the scanning electron microscope tests indicateed that the particles inside the system were dispersed after the shearing action；with the extension of the recovery time，dispersed particles gradually aggregated and associated in layers and a obvious layered network structure was constructed after the recovery time exceeded 60 seconds.

Abstract:In order to improve the performance of hydrophobically associating polyacrylamide，hydrophobically associating fluorinated polyacrylamide（FAPAM）was prepared with 1H， 1H， 2H， 2H-heptadeca fluorodecyl acrylate（HFA），acrylamide （AM）and acrylic acid（AA）through radical micellar polymerization. The molecular structure of the terpolymer was confirmed by infrared spectrometer. The effects of the dosage of AA and HFA on the apparent viscosity and relative molecular mass of FAPAM were studied，and the temperature tolerance，salt resistance，shearing resistance and cross-linking behavior of FAPAM were investigated. The results showed that the FAPAM was a terpolymer which consist of AM，AA and HFA. The largest apparent viscosity of FAPAM was 3376.7 mPa·s when the dosage of HFA and AA was 0.5% and 30%—40% in terms of total monomer mass respectively. The apparent viscosity of FAPAM was still higher than 100 mPa·s placing 60 min at 110℃，and that higher than 500 mPa·s shearing 48 h at 300 r/min，showing good temperature tolerance and shearing resistance. The apparent viscosity of FAPAM was higher than 50 mPa·s when the concentration of Na⁺ or Ca²⁺ was 0.5 g/L respectively. The salt resistance of FAPAM was better than that of PAM（without HFA） . The FAPAM showed better crosslinking behavior at 30℃ with chromium-organic as the crosslink agent. The temperature tolerance，salt resistance and shearing resistance of FAPAM were better than that of PAM，which might ensure FAPAM to be the potential candidate as thickener for fracturing fluid.

Abstract:With the needs of the development of deep and ultra-deep carbonate reservoirs，the conventional acid liquid system couldn’ t meet the demands of acid fracturing in deep carbonate reservoirs with high temperature. In order to obtain the acid liquid system with good anti-temperature performance，an anti-temperature cross-linking agent of organic zirconium ECA-1 was synthesized when zirconium oxychloride， water， isopropyl alcohol， lactic acid and xylitol was mixed at the mass ratio of 12∶15∶30∶15∶0.125 and reacted for 3—4 h at 50—55℃ . Meanwhile，EVA-180 was selected as the thickening agents used under high temperature. The formula of the cross-linked acid（CLA）system was finally settled as： 20%HCl+0.8%—1.2% EVA-180+3.0%—5.0% ECA-1+0.03%EBA， the gelling strength of the CLA system was higher than 0.06 MPa. The high temperature rheological， retarding and viscosity-breaking property of the system were evaluated，and micro-structure was also studied by electronic microscope scanning. The results showed the viscosity of the CLA system was about 100 mPa·s after sheared for 1 h at the temperature of 140℃ and at the shear rate of 170 s^-1， which indicated the CLA system had good temperature and shear tolerance. The CLA system had good retarding property， the dissolution rate of marble was of 60% after dissolution reaction for 10 h， which ensured that the CLA system could flow into the deep layer. In addition， the system could break thoroughly， the viscosity of the breaking fluid was merely 3 mPa·s， which guaranteed the CLA system could flow-back easily. As a result， the CLA system could perfectly meet the basic needs of acid fracturing under high temperature. Microstructure analysis showed that the cross-linking reaction occurred after adding the organic zirconium into the gelled acid， and a complex and dense mesh structure of the CLA system was formed， which improved the shear resistance of heat-resistant and retarding property of the CLA system.

Abstract:In order to reduce the product cost as much as possible，the effect of the agent's four ingredients--perfluorononyl alkenyloxy benzene sulfonate（OBS），octyl phenol polyoxyethylene ether-10（OP-10），calcium chloride，methyl alcohol，on the surface（interfacial）tension of the clean-up additive YMZP-2 was researched，on this basis，the formulation of clean-up additive was optimized by orthogonal experiment，a new clean-up additive YMZP-3 was obtained，and the properties of YMZP-3 Investigated was investigated. The experimental results showed that，OBS was the dominant factor to affect the surface tension， while OP-10 was the dominant factor to affect the interfacial tension. OBS and OP-10 had a good synergistic effect in the water solution. When the OBS and OP-10 concentration was 100 mg/L，respectively，the surface tension was 27.4 and 32.9 mN/m， respectively；and the interfacial tension between the OBS solution（OP-10 solution）and the kerosene was 5.6（5.1）mN/m. However，the surface tension of the complex system，composed of 50 mg/L OBS and 50 mg/L OP-10，was only 21.4 mN/m，and the interfacial tension between the complex system and the kerosene was only 2.3 mN/m. The optimal recipe of clean-up additive YMZP-3 was as follows，1.2% OBS，1.2% OP-10，1.8% calcium chloride and 25% methyl alcohol，which could meet the requirements of the indexes of the superficial（interfacial）tension，and the cost of the YMZP-3 was lower than that of YMZP-2 by 40%.

Abstract:In order to solve the problem of low efficiency of enzyme breaker in fracturing fluid gel breaking，especially the problem that enzyme breaker was difficult to meet the needs of low temperature field gel breaking，the composition，the compatibility with fracturing fluid and the gel breaking performance of the low-temperature-tolerant complex enzyme MEMA10 from Enterobacter sp. N18 were studied. The effect of pH value，temperature and concentration of salt on enzyme activity was studied as well. The experiment results indicated that β-mannanase was the main ingredient in MEMA10，which contained cellulase and lipopeptide as well. The complex enzyme could be used as gel breaker in fracturing fluid which used gum as thickening agent. MEMA10 showed good compatibility with the additives of fracturing fluid. When the pH value was in the range of 3.0—8.0，the activity of MEMA10 retained over 75%. The viscosity of guar gum solution reduced to less than 5 mPa·s by MEMA10 at 20—60℃ within 3 h. The enzyme showed more than 80% of enzyme activity after incubating for a long time in the presence of 1 mol/L and 2 mol/L of NaCl. Meanwhile，the surface tension，interfacial tension and the amount of residues of fracturing liquid after a thorough gel breaking by MEMA10 at 40—60℃ all met the industry standard. MEMA10 met the needs of medium and low temperature gel breaking due to its low using concentration，broad working pH range，salt tolerance，strong activity at low temperature and low residues.

Abstract:During the fracturing process，encapsulated gel breaker with an inert capsule was placed inside a high pressure liquid with several tens megapascal. The release of capsule after the break of rubber was closed through the crack closure in traditional conception，and the effect of liquid column pressure，pump pressure and formation pressure was neglected in fracturing process. In order to reveal the effect of wellbore pressure on the release time of encapsulated gel breaker，the influence of pressure and pressure time on release rate of potassium persulfate encapsulated gel breaker was studied，the situation of clothing package of encapsulated gel breaker before and after compression was compared，the influence of capsule release on the viscosity of fracturing fluid was investigated. The results showed that the capsule package of gel breaker gradually brake and peeled under pressure，the release rate of encapsulated gel breaker increased with increasing pressure and pressure time. The release rate was 62% when the pressure was 35 MPa and the time was 40 min. When the temperature belowed 50℃，the release of encapsulated gel breaker in a short period of time had little effect on the viscosity of fracturing fluid，while that at high temperature would make the viscosity of fracturing fluid decreased rapidly until gel breaking， which effected the sand-carrying of fracturing fluid.

Abstract:In order to resolve the fracturing fluid flow-back water treatment problems，the feasibility that the flow-back water of clean fracturing fluid was used as oil displacement agent for enhanced oil recovery was evaluated according to the surfactant fluid flooding technique. The properties of interfacial tension，wettability reversion，adsorption and EOR of the broken fluid of the clean fracturing fluid were studied. The interfacial tension between the broken fluid with mass fraction of 0.001%—0.03% and crude oil was about 10^-3—10^-2 mN/m，and the interfacial tension between the broken fluid with mass fraction of 0.006% and the crude oil was 10^-3 mN/m ultra-low magnitude at the temperature rang from 60 to 90℃. The broken fluid had good emulsifying ability，the water separating proportion of the emulsion，prepared by mixing the broken fluid with mass fraction 0.004%—0.008% and the crude oil at volume ratio of 1∶1，was less than 60%，moreover，the broken fluid possessed good wettability alteration ability，which could change both the oil-wet and water-wet quartz surface to weak water-wet. The enhanced oil recovery was up to 10.04% based on water flooding，when 0.3 PV of 0.006% broken fluid was injected into core in laboratory. The purpose of environment protection and flow-back water reuse were realized，and the oil displacement agent system based on the clean fracturing fluid flow-back water gives a technical support for the further development of low permeability reservoirs.

Abstract:When researching plugging and fluid diversion in fractured reservoir by conventional method，pore structures and fluid flow characteristics could not be observe. the artificial fracture was plugged by modified starch gel and the plugging and fluid iversion in fractured reservoir was investigated on basis of computed tomography（CT）scanning technology and laboratory experiment. CT images presented the characteristic of core pores，oil and water distribution，and the process of improving swept volume after fracture was plugged. Experiment results showed that the artificial fracture run through the whole core，with uniform pore distribution and an average porosity of 22.7%. Serious water channeling in artificial fractures resulted in the displacing pressure could not be built up effectively and swept volume in matrix was low. The oil recovery of water flooding was only 10.6%. When the fracture was plugged by the modified starch gel system，the subsequent water was compelled to fluid diversion and started core matrix. Swept volume of subsequent water was more than 2/3 of matrix volume approximately，the total oil recovery was of 46.1%，enhanced by 35.5%. CT scanning technology provided a visual method for mechanism study of plugging fractured reservoir.

Abstract:In view of the strong heterogeneity in Mid-East 7 Badaowan conglomerate reservoir of Xinjiang oilfield， a strong gel profile control agent called LT-1 which was mainly composed of modified starch and acrylamide was developed. The shearing resistance， injectivity and sealing property of LT-1 were investigated， and a pilot test in two wells located in the target reservoir was tested. The results showed that the optimum formula of LT-1 was obtained as follows：2% —4% modified starch， 5% —6% acrylamide monomer， 0.01%—0.03% crosslinking agent and 0.6% gelling agent. The static gelling time of LT-1 was about 8 hrs at 30℃. The strength retention of LT-1 was as high as 95.5% after high speed shearing. The injectivity and sealing property of LT-1 in artificially conglomerate core were good. Field application results showed that the injection profile of water well was dramatically improved， water injection pressure increased， and the corresponding oil well had significant effect with 1790 t cumulative oil increment of two well groups， which indicated that LT-1 could effectively block dominant water channel and had a good application prospect on deep profile control of conglomerate reservoir.

Abstract:Influenced by the polymerization process， amphiphilic polymer（AP）has a wide distribution range of the molecular weight， and components with different molecular weight possess various structures and properties. In order to discover the effect of the components with different structures on the property of AP， fractions of AP with a series of molecular weight were obtained by means of double-gradient elution， and the result of separation was discussed. The elution device was optimized and improved， and recipitation-dissolve systems were compared and screened. AP fractions of different molecular weight are analyzed by FT-IR spectrum，and thickening and rheology properties were studied systematically. The experimental results showed that the precipitation-dissolve system of ethanol-water could classify the portion of the smaller molecule of AP effectively，while the precipitation-dissolve system of acetone-water had a good performance on the portion of the bigger molecule of AP. Different elution fractions had the similar molecular structure with the original sample， and the differences lied in the size of molecular weight and the content of hydrophobic groups per mass. The viscosity-increasing ability and rheological properties of the bigger molecule and the smaller molecule components were lower than those before separation. There was synergistic effect between the smaller molecules and the bigger molecules in the solution， which endowed the original amphiphilic polymer better thickening and rheology properties.

Abstract:In order to obtain the plugging slurry and plugging technology suitable for the old well in Hutubi gas storage，composite superfine cement slurry system and G level micro expansion fiber cement slurry system were used to plug the production layer and wellbore of old well separately. The performances of two plugging system were evaluated and the sectional extrusion and successive pressure test plugging technology of old well was put forward. The results showed that the composite superfine cement slurry system had good stability and injection ability，and the compressive strength reached 16.6 MPa，fully meeting the requirements of plugging production layer in field application. The G level micro expansion fiber cement slurry system had good fluid barrier property and mechanical deformation capacity. The cement stone had lower permeability，higher saturated kerosene breakthrough pressure and higher wall cementation intensity. The flexural strength of cement stone reached 12.0 MPa，meeting the requirements of plugging wellbore in field application. Two typical wells had been successfully plugged with the developed cement slurries and technology，demonstrating the feasibility of this technology.

Abstract:According to the characteristic of high temperature and high salinity and 80% of the horizontal wells completed with screen pipes in Zhongyuan oilfield， a heat resistance and salt tolerance system， composed of 5000 mg/L permeability regulator agent cationic ternary polymer RPM，6000 mg/L cross-linking agent PFR and 300 mg/L stabilizer JN，was developed，and the heat-resistance， salt-tolerance， thermo-stability and plugging property of the system were evaluated. The result showed that the heat resistance of the system was up to 90℃， the salt tolerance of the system was of 25 × 10⁴ mg/L（among which， Ca²⁺ and Mg²⁺ concentration was of 5000 mg/L）， the gel strength was above 5×10⁴ mPa·s and the thermo-stability was more than 90 days. The system had good selectivity and the water plugging efficiency reached up to 89% while the oil plugging rate was only 17%. The system could plug water in horizontal wells without oil well operation， especially suitable for water plugging in horizontal wells completed with slotted screen without packers and in open hole mode.

Abstract:In order to obtain the sand-control agent used in high-temperature steam stimulation well，compound resin of phenolic epoxy resin F-51 and pouring bisphenol A epoxy resin E-39D in mass ratio 1∶3 reacted with curing agent（4-methyl imidazole）， silane coupling agent and epoxy active toughening agent to produce composite resin sand-control agent. The solidified formula of composite resin sand-control agent was optimized by measuring the compressive strength of consolidated core，and the temperature resistance，acid and alkali resistance，and permeability of consolidated core were studied. The results showed that the optimum formula of composite resin sand-control agent was obtained as follows: 10% composite resin，1.0% 4-methyl imidazole，0.25% coupling agent and 2.5% toughening agent based on the mass of quartz. The compressive strength of consolidated core according to the optimum formula curing 2 days at 60℃ was about 13 MPa. The compressive strength of consolidated core placing 7 days at 260℃ was 11.99 MPa，showing good high-temperature resistance. The compressive strength of consolidated core was more than 3.5 MPa，when the core was soaked in 5% acid or alkali solution，saturated NaCl solution and diesel for 7 days，which satisfied the strength requirement of normal steam stimulation and oil production. Moreover，the permeability of consolidated core was good with 70.21 μm²， which met the requirement of heavy oil exploitation in high-temperature steam stimulation well.

Abstract:Aiming at the problems of poor stability and worse profile control effect of regular foam in strong heterogeneous formation，a microfoam with tiny diameter and high stability was prepared by a sandpack filled with glass beads with co-flowing nitrogen and foaming solution（xanthan gum and betaine surfactant） . The difference of stability between xanthan gum-stabilized microfoam and common microfoam was compared by parameters such as bubble shape，the average bubble diameter and bubble density，and the effectiveness in improving profile control capacity of two kinds of microfoam at micromodel and pore media was evaluated by micromodel tests and double-core experiments. The results showed that with increasing xanthan gum concentration， the thickness and viscoelasticity of liquid film of microfoam were increased，the average bubble diameter of microfoam decreased and bubble density increased，the variation rate of microfoam average bubble diameter and bubble density decreased which contributed to improve the stability. The swept volume of xanthan gum-stabilized microfoam in low permeability zone reached up to 90%，far higher than that of common microfoam. The result of double-core experiment showed that the microfoam had excellent profile control capacity in strong heterogeneous formation when the permeability grade reached to 10. The increase in profile control effects had a good correspondence with the increase of xanthan gum concentration in foaming solution.

Abstract:There are many differences between physical and chemical parameters of polymer flooding in formation and laboratory experiment results. If the experiment results are applied to the numerical simulation directly，the randomness will be large and the reliability of simulation results will not be guaranteed. Aim at this problem，taking Daqing refining polymer （HPAM）as an example，the viscosity loss of polymer was determined by simulating shear action of the hole and the near well bore area，the adsorbance of polymer flooding was measured by using the material balance method，and the relative permeability curve and the residual resistance coefficient of polymer flooding after shearing was determined. Through the history matching of small scale numerical simulation，the sensitivity of the above physicochemical parameters was analyzed. The study results showed that the measured data of relationship between polymer viscosity and concentration，adsorption capacity and relative permeability could reflect the actual situation in the reservoir，however，the difference between residual resistance coefficient and the actual situation was relatively large. Though revising the residual resistance coefficient，the small scale numerical simulation was in a good coincidence，which can be applied to the numerical simulation of field polymer flooding.

Abstract:In order to discover the relationship between structure and performance of hydrophobically associating polymer, the effect of the length of the micro block length（N_H） on the rheological properties of the hydrophobically associating polymer，a acrylamide-sodium acrylate-N-Dodecylacrylamide copolymer, containing 0.2 mol% N-Dodecylacrylamide hydrophobic monomer chain，was studied by using the method of steady state stress，shear rate and frequency scanning. The results showed that，with the increase of micro-block length，the associative effect of the polymer enhanced and the polymer solution was easier to form a space network structure，and the critical association concentration（CAC） decreased and thickening performance and viscoelastic properties were greatly improved .When N_H increased from 3.3 to 12.5，CAC decreased from 1684 mg/L to 846 mg/L，and zero shear viscosity increased from 204.73 mPa·s to 65833.19 mPa·s，and relaxation time increased from 0.07 s to 12.64 s. The rheological experiments confirmed that the association and disassociation of hydrophobically associating polymer was a reversible dynamic process，the longer the micro block length，the slower the recovery rate of structural viscosity after shear damage，but the higher viscosity after the recovery. Under the same conditions，increasing the temperature and the ionic strength of the solution was beneficial to enhance the association effect within certain range，which resulted in enhancing the resistance to temperature and salt performance of associative polymer to a higher level.

Abstract:To choose the KY series of polymers suitable for Zhen 35 fault block reservoirs from Jiangsu oilfield, the gas logging permeability and liquid (H_g) permeability, porosity, and the hydrodynamic radius of the KY series polymer under formation conditions of hen 35-6 well was measured and the relationship of the gas logging permeability (K_g) with the average pore throat radius(R-), and the relationship of the relative molecular mass (M-) of KY polymer and the molecular hydrodynamic radius (R_h) in the formation water of the Zhen 35 fault block reservoirs was created, furtherly, according to the theory of 1/3 bridging action, the relationship between K_g of the cores and M- of KY polymers was created. The results showed that there was a linear correlation between K_g and R- of the cores: R-=0.0026 Kg+0.2071,and the R_h of the KY polymer in the formation water of the Zhen 35 fault block reservoirs had a logarithm correlation with its M-：Rh=0.1212lnM- -0.6831. According to the stable plugging mechanism of the polymer to the pore throat that when the condition is R_h≥0.46R-, a stable plugging will be formed, the matching formula between Kg of the cores from Zhen 35 fault block reservoir and M- of KY polymers was obtained synthetically as follows, M-<615e^{0.01K_g，in other words, the M- of KY polymers should be lower than the upper limit, so that it is possible to avoid the blockage problem of the reservoir due to choosing the polymer with excessively high relative molecular mass.}

Abstract:In order to expand the application of crosslinked polymer system in high temperature and high salinity reservoirs，the long term stability of the crosslinked polymer system，composed of organic aldehyde crosslinker（GWG）and common polymer（KYPAM and KYPAN-6）or hydrophyobically associating polymer（AM-NVP and AM-DMDA）or salt resistant polymer（HPAM3 and NY-1），was studied. The gelling system with polymer HPAM3 was selected and the influences of oxygen content，salinity， divalent ion and temperature on long term stability were studied under condition of temperature of 100℃ and oxygen content less than 0.1 mg/L. the results showed that only crosslinked system composed of 1000 mg/L salt resistant polymer HPAM3 and 50 mg/L GWG had good stability，the viscosity was of 62.6 mPa·s after aged for 150 days，while the crosslinked system containing KYPAM， KYPAM-6，AM-NVP and AM-DMDA was broken after aged for 30 days. When the oxygen content was controlled less than 0.1 mg/L，the crosslinked system composed of 500—1800 mg/L HPAM3 and 35—80 mg/L GWG had good crosslinking ability and stability after aged for 90 days at the high temperature of 100℃. As oxygen content was less than 0.5 mg/L，the crosslinked system composed of 500 mg/L HPAM3，50 mg/L crosslinker and 200 mg/L thiourea could endure temperature of 105℃ and salinity of 200000 mg/L（including 500 mg/L Ca²⁺），and the viscosity of the system remained at 124 mPa·s after aged for 90 days at the temperature of 100℃，which was higher than that of polymer HPAM3 solution with the concentration of 2500 mg/L（42.7 mPa·s）.

Abstract:Aimed at the characteristics of strong heterogeneity in offshore oil field，in order to strengthen the application of polymer flooding in offshore oil field，The crosslinked polymer microsphere（CPM）was prepared by inverse suspension polymerization using acrylamide，2-acrylamido-2-methylpropane sulfonic acid and 2-acryloxyethyl trimethyl ammonium as main raw materials， and the shape in the dispersions system and plugging performance of CPM was investigated，furtherly，the oil displacement performance of the complex system，composed of 0.145% HAP and 0.03%CPM，was probed. The results showed that after the CPM was swelled for 10 days in the simulated water，the size was about 27～37 μm. The CPM had good plugging effect，when the 3 PV CPM system with the mass fraction of 0.04% was injected into the sand filling tube with permeability of 1.064 μm2 and the size of ? 2.5 cm×60 cm，the front pressure increased from 7.9 kPa to 190 kPa，at the same time，the middle and end pressure increased to some degree. Parallel cores oil displacement experiment showed that 20% of fluid flowed into low permeability cores. The enhanced oil recovery of the complex system was also higher than that of the pure polymer flooding by 10%. Heterogeneous core displacement experiment also showed that the enhanced oil recovery of complex system was higher than that of the pure polymer flooding by 6%. In a word，the CPM could improve greatly the effect of polymer flooding.

Abstract:For figuring out the effects of different assistants on petroleum sulfonate and optimizing the performance of DPS surfactant，GDPS surfactant were obtained through the process of separation of DPS surfactant（petroleum sulfonate）and remixing with different kind of alkali，inorganic salt and alcohols in a range of concentrations. The interfacial tension between the mixed solution and crude oil were measured to probe the effects of different assistants on petroleum sulfonate. The more effective formulation of GDPS surfactant and its difference with original DPS surfactant was given. The experiment results showed that the oil-water interfacial tension could be decreased to 10^-3，10^-2 and 10^-1mN/m after adding alkali，inorganic salt and alcohols in a certain concentration into the petroleum sulfonate solution，respectively. The better assistants for GDPS surfactant were sodium carbonate， sodium chloride and n-octyl alcohol with the optimum mass fraction of 0.8%，8% and 0.2%，respectively. Compared with original DPS surfactant，the optimized GDPS surfactant could make the interfacial tension decrease by one order of magnitude. The minimum concentration of GDPS surfactant reached the lowest interfacial tension value reduced in the fraction of 20%.

Abstract:In order to determine the effect of lower interfacial tension and wettability alteration upon tight oil cores imbibition，and obtain favorable condition of surfactant imbibitions，the effects of three kinds of surfactants，including heavy alkylbenzene petroleum sulfonate（ZPS），dodecyl benzene sulfonate（SDBS）and sulphobetaine（SB），on the imbibition efficiency of tight cores and the mechanism of spontaneous imbibition were studied by measuring the contact angle of cores and the interfacial tension between oil and surfactant solution. The results showed that the three kinds of surfactants solution improved oil recovery in some degrees contrasted with injected water solution. Two anionic surfactants（ZPS，SDBS）had the effect of wettability alteration， nonionic surfactant（SB）reduced the contact angle，but was not able to make the core water-wet. Oil-wet core did not occurred imbibition in water solution，while it realized imbibition when the wettability alteration caused by surfactant. The original wettability of cores affected the imbibition efficiency. Three cores were arranged according to their effect on the increase of imbibition efficiency in following order: water-wet core>neutral-wet core>oil-wet core. Three kinds of surfactant could lower the interfacial tension to the best range of interfacial tension of imbibitions which was 10^-1—10^-2 mN/m. The decrease of oil-water interfacial tension was beneficial to the increase of spontaneous imbibition efficiency.

Abstract:In order to discover the interfacial properties between alkali-free binary compound system and crude oil，sulfobetaine BS and polymer KYPAM-2 was used to prepare the binary compound system and the interfacial tension between the system and crude oil from East District 7（1）in Karamay oilfield was studied. The results showed that interfacial tension between binary compound system and crude oil from 6 oil wells in this district was all below 3.0×10^-2 mN/m，so the binary compound system had strong adaptability in this district ；the interfacial tension between the binary compound system and crude oil could maintain at range of 4.1×10^-2 —5.5×10^-3 mN/mwhen the concentration of BS was between 0.5—5.0 g/L，so the low interfacial tension window was very wide. The anti-salt，anti-calcium and anti-thinning properties of oil well produced water of BS was excellent. The concentrations of polymer had a certain impact on reducing the interfacial tension between binary compound system and crude oil，however，the concentration of the polymer being higher than 1.2 g/L had less impact on the interfacial tension. Drawing the interface activity map of binary compound system provided a theoretical guidance for formula design of binary compound system.

Abstract:The performance of alkylbenzene sulfonate surfactant effected recovery efficiency of alkali/surfactant/polymer (ASP) flooding directly. The quantitative matching relation between crude oil molecular weight and surfactant equivalent was formed by studying the influences of oil component and sand adsorption on surfactant concentration and interfacial tension of alkali ASP system. The results showed that the appropriate surfactant based on the matching relation of quantitative selection guaranteed ultra-low interfacial tension between different oil in Daqing oilfield and ASP system, and improved the adaptability of ASP system. Distribution proportion of surfactant in oil and water was affected by oil component. The higher concentration of asphaltene in crude oil, the lower concentration of surfactant in aqueous phase was. Surfactant equivalent changed slightly with oil content. Sand adsorption reduced the concentration and changed the equivalent and distribution of surfactant, and increased the interfacial tension of ASP system. Surfactant equivalent could be adjusted by adding the content of high carbon which would expand the range of ultra-low interfacial tension during the movement of ASP system in reservoir.

Abstract:The seepage characteristic of alkaline/surfactant/polymer（ASP）system in actual reservoir couldn’t be simulated through cores because of its limited length. To solve the problem，ASP seepage experiment in sand-filled pipes with the length of 30，100 and 240 cm was carried out. The effect of core length on chromatographic separation and damage for detention of ASP system was studied，and the concentration and viscosity change of every component in seepage front was analyzed. Experiment results showed that the effect of core length on chromatographic separation of ASP system during seepage press was obvious. Three components were arranged according to their production time in following order: polymer，alkali and surfactant，and according to the concentration stabilization time in following order: alkaili，polymer and surfactant. When core length increased from 30 to 240 cm， the production time of three components was postponed about 0.3 PV. Meanwhile，the concentration stabilization time of alkali and polymer was postponed 0.2 PV and 0.4 PV approximately，while that of surfactant was 0.5 PV in advance. The effect of core length on the retention loss rate of alkali and surfactant was little，but the retention loss rate of polymer increased from 23.29% to 55.74% with core length growing from 30 to 240 cm. With the ASP system seepage front extending forward，the concentration and viscosity of upstream region increased and became stable，while that of seepage front reduced. Three components were arranged according to their relative concentration on the same station in upstream region in following order: alkali，surfactant and polymer.

Abstract:In order to effectively develop heavy oil reservoir whose formation oil viscosity exceeded 200 mPa·s，the oil displacement performance and viscosity-reducing effect of heavy oil activator with amphiphilic polymer were studied. The results showed that the viscosity of activator solution increased with increasing concentration，and the viscosity of activator solution with 1500 mg/L was 39.1 mPa·s. The activator had a strong polar action with asphalt，so that the asphalt could easily fall off from the rock surface. The activator had a good effect on the emulsion dispersion of crude oil. The viscosity of crude oil and oil-water interfacial tension decreased with increasing activator dosage. When the mass ratio of activator and crude oil was 1∶1，the viscosity of crude oil fell below 100 mPa·s，and the oil-water interfacial tension was 2.6 mN/m with 1500 mg/L activator. Oil displacement experiment results showed that the recovery ratio of activator flooding was 54.45% ，better than that of partially hydrolyzed polyacrylamide with same concentration（32.73%）. The activator could effectively block high permeable layer and improve water injection profile，just because of the activator aggregates and the emulsified droplets produced by heavy oil emulsifying. After emulsification，the residual resistance coefficient in rock increased from 100 to about 200.

Abstract:Strain BC1 with excellent performance of biosurfactant production was isolated from the wastewater of Karamay oilfield in order to improve the microbial enhanced oil recovery process. According to the physiological and biochemical indexes and 16S rDNA sequences analysis，the strain BC1 was classified. The biosurfactant produced by strain BC1 was identified by using thin-layer chromatography （TLC） ， Fourier transform infrared spectrum （FT-IR） and high performance liquid chromatography-mass spectrometry（HPLC-MS）analysis. The effect of fermentation conditions on the biosurfactant produce of strain BC1 was studied by single-factor shaking-flask culture experiment，and the performance of biosurfactant was researched. The results showed that strain BC1 belonged to Pseudomonas aeruginosa，and the key component of biosurfactant produced by strain BC1 was mono-rhamnolipid RhC₁₀C₁₀. The RLs yield was 0.788 g/L determined by acid precipitation method，under the condition of fermentation: 37℃ culture temperature，8 initial pH value，5 g/L glucose concentration，96 h fermentation time. The biosurfactant production of strain BC1 could dramatically reduce the broth surface tension from 72 to 28.6 mN/m，and show high emulsification index against motor oil of 93%. In the oil stripping test，more than 74% of crude oil could be effectively stripped from the artificial oil sands by using the fermentation broth，fermentation supernatant and solution of crude rhamnolipid. The biosurfactant produced by strain P.aeruginosa BC1 had good application potential in microbial enhanced oil recovery and other aspects.

Abstract:In order to reveal the relationship between microbial functional gene numbers and oil production performance during an indigenous microbial enhanced oil recovery（IMEOR）field trial that was performed in district Min-7 of Karamay oilfield，the numbers of the functional genes，including alkB of hydrocarbon oxidizing bacteria（HOB），napA of nitrate reducing bacteria（NRB），and dsrB of sulfate reducing bacteria，were quantified by real-time fluorescent quantitative PCR method. The relationships between the changes of microbial functional gene abundances and oil production performance（liquid production，oil production， and water content）were comparatively analyzed during the IMEOR process. The results showed that the abundance of HOB and NRB increased，while that of SRB decreased，suggesting that the changes of microbial functional gene abundances had a positive correlation with the oil increment. Molecular quantification of microbial functional genes by real-time fluorescent quantitative PCR method could replace the test bottle that based on most probable number（MPN）method，and monitor microbial dynamics during IMEOR process in shorter period of time.

Abstract:In order to study the effect of microbial flooding after polymer flooding in Shengli oilfield，the pilot microbial flooding was conducted in Ng3 block of Gudao reservior. The high molecular polysaccharide activator system was injected，so that the microorganism in deep reservoir could be activated，and then the residual oil could be displaced. The filed test results indicated that the low-molecular-weight acids were an important indicator of the microbial metabolic activity. The concentration of the low-molecular-weight acids reached up to the peak value after 30 days after injection，moreover the concentration increased by 5—8 times compared to that before trial. The biological monitoring results indicated that the microbe were activated，the density was up to 105cell/mL，meanwhile，the time of the microbe increased lagged to that of low-molecular-weight acids，and the concentration of the low-molecular-weight acids began to decrease when the microbial density rose， which demonstrated that the low-molecular-weight acids was consumed by the anaerobic bacteria，in addition，the analysis indicated that the species of microorganism in the recovery were reduced by the molecular biology，and more important functional microorganisms were becoming dominant species. The well dynamical analysis indicated that the center well had the desired effect after 50 days，and the water cut decreased by 2%，the oil increased by 6 t/day，and the effects lasted more than 5 months. the oil of the center well 7XNB11 increased from 1.1 t/day to 4.5 t/day，the water ratio decreased over 6%.

Abstract:In order to solve the problem of scale formation in oil well after three compound flooding，the mechanism of scale formation and the composition of the scale were analyzed. Anti-fouling agent was synthesized with hydroxy five methyl phosphonic acid，scale inhibitor co-hypophosphite polymaleic anhydride，C₁₂—C₁₈ fatty alcohol polyoxyethylene （10） ether，USP2 alkyl fifteen，urotropine，sodium selenate and other raw materials. The influence of detergent concentration on the cleaning and anti-scale effect was studied，and anti-fouling agent was applied in hundreds of oil wells in Huabei oilfield. The results showed that the scale in oil wells was a complex of carbonate scale and silicon scale. When the amount of anti-fouling agent was 20—30 mg/L，the scale cleaning rate was greater than 60%，and the anti-scaling rate was greater than 95%. The practical results showed that anti-fouling agent not only solved the scaling problem of pump and pipe or rod in shaft，but also saved the energy consumption of oil well. The average pump cycle of oil well extended from about 70 d to about 600 d and the energy consumption of single well decreased by 23.19 percentage points，meeting the normal operation and energy saving requirements.

Abstract:The tracking，monitoring and evaluation of flooding performance in microbial enhanced oil recovery process was particularly important，so rapid quantitative analysis of biological surfactant became an important technical support. In order to rapid quantitative determination of rhamnolipid with low concentration，standard curve of rhamnolipid was obtained by optimized phenol-sulfuric acid method，oil spreading method and high performance liquid chromatography-electrospray mass spectrometry（HPLC-MS）. The results showed that the optimum acidification condition of phenol-sulfuric acid method was obtained as follows: 1 h acidification time and 80℃ acidification temperature. The phenol-sulfuric acid method could quickly quantitative measure 100—1000 mg/L rhamnolipid. The relationship of absorbance（A）and rhamnolipid concentration（c）was A=7.465×10^-4 c+0.047，with 0.9939 R²，showing good linear relationship. Rhamnolipid with concentration of 20—500 mg/L could be quickly approximate quantification by oil spreading method. The R² of rhamnolipid concentration and oil zone diameter standard curve was less than 0.95，showing large error. Rhamnolipid with concentration of 1—150 mg/L could be determined accurately by HPLC-MS. The relationship between the absorption peak area S and c was S=3085.4c-2201.4，with 0.9993 R²，showing good linear relationship. Phenol-sulfuric acid method，oil spreading method could be used to fast quantitative analysis of rhamnolipid on site，while HPLC-MS could be used to accurate quantitative analysis indoors.

Abstract:The mechanism of the formation and stability of non-aqueous foam，especially the crude oil foam，was analyzed，the main factors influencing the formation and stability of the crude oil foams were discussed，and the experimental methods to research the crude oil foams were introduced. In addtion，the research prospect of crude oil foams，which is useful for the further study of crude oil foaming and defoaming，was proposed.

Abstract:In order to promote the development of microfoam enhanced oil recovery technology，the structure，properties and plugging mechanism of microfoam system was reviewed，the main preparation methods for microfoam，such as high speed mixer process and microfluidic process，was summarized，and research progress of microfoam system used in flooding and profile control was overviewed. Finally，the problems and developmental tendency of microfoam microbubble system was pointed out.

Abstract:Polyoxyethylene ether surfactant exhibited good temperature resistant，salt tolerant as well as oil displacement effect， which played an important role in tertiary oil recovery. The research progresses of polyoxyethylene ether surfactant for oil displacement，including nonionic surfactant and anionic-nonionic surfactant，in the last five years were reviewed. The performance and oil displacement efficiency of the mixture of polyoxyethylene ether surfactant，polymer and alkali，or other surfactants were summarized. The research suggestions were proposed for the problems existed in polyoxyethylene ether surfactant used in tertiary oil recovery.