Abstract:The effect of the key agents adding order about filtrate reducer, inhibitor and coating agent on the rheological property, filtration property and inhibition property of potassium-amine based polysulfonate drilling fluid was studied. The best adding order of drilling fluid agents for potassium-amine based polysulfonate drilling fluid was obtained as follows: filtrate reducer, 30% coating agent, inhibitor and 70% coating agent. The apparent viscosity (AV) of the drilling fluid was 41 mPa·s, the API filtration (FL(API)) was 3.7 mL, the ratio of shear force and plastic viscosity was 0.31, the roll recovery was 93.48% and the linear expansion rate was 14.3%. Active mechanism of the affection was analyzed by using laser scattering particle size analyzer. The results showed that the drilling fluid adding inhibitor firstly displayed low AV (25 mPa·s) and high FL(API) (6.4—7.0 mL), which was rich of large particle and not conducive to the formation of dense cake. So it showed a bad filtration property. The AV of the drilling fluid adding coating agent firstly was 36.0—39.5 mPa·s, and the FL(API) was 5.1—5.5 mL. Both larger and smaller particle size was less in the particle size distribution, so the drilling fluid showed a bad filtration property. The AV of the drilling fluid adding filtrate reducer firstly was 35.0—42.5 mPa·s, and the FL(API) was 3.6—4.2 mL. It had a wide particle size distribution, which was between a few microns to one thousand microns and presented a multi-peak distribution. The particle size distribution was beneficial to the accumulation of clay particles and would result in the formatin of a fine and close filter cake. The corresponding drilling fluid showed a good rheological property and filtration property.

Abstract:Ideal packing technology was a new reservoir protecting technology, which was based on d₉₀ (particle diameter with accumulation of 90% volume fraction on the size composition of accumulated distribution curve) rule. By considering the whole formation pore throat size, temporary plugging agent with suitable particle size could be optimized by this technology and achieve better reservoir protecting effect. Based on the characteristic of reservoirs of major blocks in Tuha oilfield, the ideal packing technology was applied to optimize temporary plugging projects of twelve blocks for protecting the reservoirs, including Qiuling, Wenmi, Shanshan and so on. Using a self-developed ideal packing temporary blocking software, a combination of three temporary plugging agents with 1000, 600 and 100 mesh in mass ratio 2:13:5 could make d₉₀ of the particle in drilling fluid (110.92 μm) larger than the maximum pore size of reservoir (d_max=80.33 μm), which could effectively plug pore throat with various sizes in reservoir. The experiment results showed that the optimized temporary plugging agent could improve the buildup of core permeability and reduce the filter loss without impacting the rheology of the drilling fluids. The appropriate amount of the compound temporary plugging agents was 3%. The reservoir permeability recovery value improved from 30% to more than 80%, which had a good reservoir protection effect. This technology was applied in 20 wells in Tuha oilfield, as a result, the daily fluid production of testing wells increased more than 45% than that of adjacent wells, and the average water content was 18%.

Abstract:The liquidity, API filtration and sedimentary stability of fibers with different length were tested and analyzed in this paper. The dispersion and dosage of fibers in cement slurry and the compressive strength, flexible strength, tensile strength and the microstructure of cement paste were also discussed. The results showed that the cement slurry with brucite fibers could significantly decrease the liquidity and 45%—50% of API filtration, and barely impacted the sedimentary stability. And the mechanical properties of cement paste were significantly developed for 16.2%, 48.8% and 41.4% by the dosage of 3% fibers for compressive strength, 5% fibers for flexible strength and 8% fibers for tensile strength, after curing in water-bath for 14 days. When using the dispersion means of mechanical shearing and ultrasonic processing, the brucite fibers were uniformly distributed in cement paste as a single filiform fiber that could develop the compactness and confine the micro-fracture of cement paste. The mechanical property gain ratio of cement paste was increased noteworthy by fibers. The tensile compressive strength ratio of 5% fiber reinforced cement improved 27.5%. So the fibers could reduce the brittleness of cement paste as well. However, the brucite fibers with exorbitant dosage would be entanglement and disperse difficultly in cement paste. So the fibers only had filling effect and the strength of cement paste still got a certain amount of increase.

Abstract:Viscosity change regularity of adding novel non-ionic surfactants (GS-1, GS-2 and GS-3) with different hydrophobic chain length to non-crosslinked associative structural fracturing fluid using hydrophobic associative polymer as thickener was investigated. The number of carbon atoms in hydrophobic tail of GS-1, GS-2 and GS-3 was 6, 10 and 14 respectively. GS-3 was selected as the optimal tackifying adjuvant for the fracturing fluid accordingly. The optimum concentration and application temperature range of GS-3 were obtained. And the influence of GS-3 on the viscosity and viscoelasticity of base fracturing fluid was also investigated. The results of experiments showed that the apparent viscosity of fracturing fluid could be greatly increased by adding traces GS-3 (0.03%—0.05%). The optimum concentration of GS-3 was the concentration corresponding to the peak apparent viscosity of complex system and its applicable temperature range was 30—90℃. Within the test concentration range, the apparent viscosity of system increased first and then decreased, the change trend accorded with Biggs’s 3 periods model. When the temperature increased from 30℃ to 120℃, the apparent viscosity of system also increased first and then decreased. The maximum tackifying rate was 168% at 63℃. The viscoelasticity of fracturing fluid was also enhanced simultaneously. The storage modulus could be increased 1—10 times according to the concentration of thickener. So the dosage of thickener could be greatly decreased by using GS-3 as tackifying adjuvant.

Abstract:The properties of a novel supramolecular complex fracturing fluid consisting of worm-like micelle and associative polyacrylamide copolymer were investigated. The studied properties included rheology, temperature stability, shear recovery, viscoelasticity, gel breaking，sand suspension and fluid conductivity. The results showed that the optimum formula of fracturing fluid was 1% viscoelastic surfactant VES-M and 0.15% copolymer VES-G. The viscosity of fracturing fluid was 60 mPa·s after shearing 120 min at a shear rate of 100 s^-1 and 90℃, indicating good rheology. The viscosity of fracturing fluid decreased rapidly with shear rate increasing from 40 s^-1 to 1000 s^-1, and then recovered instantly with shear rate decreasing from 1000 s^-1 to 40 s^-1. The dynamic properties of fluid showed that storage modulus was larger than loss modulus at 60℃ with frequency range 0.1—100 rad/s, indicating highly viscoelasticity. Gel could be broken with 0.3% oxidative agent in 30 min, the viscosity of fluid after breaking was 4 mPa·s and the surface tension was 27.6 mN/m, which contained 10 mg/L residue. The static sedimentation rate of proppant in fracturing fluid preparing with different field water was 0.038—0.054 mm/s at 80℃. The retained conductivity of this fluid was 90% which showed good fluid conductivity.

Abstract:Taking reservoir and fluid of SZ36-1 Oilfield in Bohai as research object, the property of the profile control agent, channel sealing agent and cold production agent was evaluated using the value of viscosity and oil recovery as indicators, as well as the flooding performance of the above system separately and jointly was carried out. Results showed that the channel sealing agent (modified starch, main agent concentration 80000 mg/L, auxiliaries concentration 2150 mg/L) possessed better anti-dilution and anti-shear than common profile control agent (Cr³⁺ polymer gel, polymer concentration 4000 mg/L, mass ratio of polymer and Cr³⁺ 180:1) did. When Mixed at oil-water volume ratio 1:5 with cold production agent water solution, the crude oil was turned to be an oil-in-water emulsion, as a result, the viscosity and seepage resistance decreased accordingly, the oil viscosity decreased from 540 mPa·s to 3.4 mPa·s. With the increase of core heterogeneity, the oil recovery of water flooding decreased, however, the increments of oil recovery of combined measures(“profile control + cold production” , “channel sealing + cold production” ) increased. The increase of difference between “profile control + cold production” and “channel sealing + cold production” suggested that the better ability to the control profile of channel sealing agent forced more cold production agent to lower permeability layers and then the oil viscosity reduction area could be extended, which prominently improved flooding effect. In heterogeneous core with layer permeabilities of 6000×10^-3μm2, 2000×10^-3μm2, 200×10^-3μm2, respectively, the increased recovery of profile control, channel sealing, cold production, and combined measures “profile control + cold production” and “channel sealing + cold production” was 25.5%, 33.9%, 6.1%, 30.4% and 39.9%, respectively, which suggested that the fluid profile control ability of “channel sealing + cold production” was better and had higher increased recovery.

Abstract:The plugging capacity of weak gel during its flowing process was one of the most important factors affecting the realization of in-depth profile control. In this paper, a long sand-packed model was used to conduct the evaluation experiments of weak gel plugging capacity, and the migration-plugging property of a class of weak gel (phenolic crosslinking partially hydrolyzed polyacrylamide system) was studied. The results showed that the residual resistance factor (F_rr) was the best index for the strong gel evaluation process, while for the weak gel permeability plugging rate (E) was the best choice. Dynamic gelation condition had little effect on the plugging capacity of weak gel. And to achieve the most in-depth profile control, the subsequent water flooding should be conducted continuously after the injection of gel solution rather than waiting for the gelation. By its flowing ability, weak gel could well plug the part without gel injection. When the gel injection depth was 4.2 m and the injection volume was 2.0 PV, the weak gel could strongly plug in 0—8.5 m section (E≥96.3%, F_rr=27.0—385.7) and partially plug in 8.5—25.8 m section (3.0%≤E≤76.7%, F_rr=1.0—4.3), and there was no plugging in 25.8—32.0 m section. Compared with the gel injection part, the plugging capacity of weak gel in the part without gel injection was much weaker. Shearing effect of porous media made the viscosity and particle size of weak gel decrease significantly, resulting in the obvious drop of its plugging capacity with increasing migration distance.

Abstract:High temperature-resistant polymer (HTP) was synthesized by in-situ cross-linking of interpenetrating reaction using H-2 monomer containing amide bond and H-1 molecule containing hydroxyl as raw materials. IR spectra result showed that there were characteristic functional groups of H-1 and H-2 cross bond at the same time, that was to say that H-1 cross-linking reaction and H-2 polymerization could simultaneously take place. The interpenetrating cross-linking structure, extension properties at room temperature and long-term heat resistance properties of the material were tested. The experiment results showed that in the whole range of observations, HTP material cross-links and interpenetrates uniformly. The SEM pictures confirmed the interpenetration structure of HTP material. After cross-linking and interpenetration, the scale of HTP structure became smaller than before. This material had tensile resistance, dispersion stability in water, volume expansion, and could reach the maximum swelling ratio of 1.69 within 1.5 hrs at room temperature. At 90℃, 120℃ and 140℃, after soaking 130 days in formation water, HTP volume reduction rate was 1.57%, 3.24% and 6.82%, respectively.

Abstract:The fractured low-permeability reservoirs are characteristic of numerous microcracks, serious heterogeneity and water channeling and the conventional flooding technology is difficult to play an effective role in the reservoir. In the paper, the superfine polymer microspheres were synthesized by inverse microemulsion polymerization, using Span80 and Tween80 as the emulsifiers, cyclohexane as the oil phase, ammonium persulfate as initiator, acrylamide and dimethyl acrylamide 2 sodium sulfonate as comonomers, N, N-methacrylamide as the chemical crosslinker and hectorite as the inorganic crosslinker. The static performance, plugging property and oil displacement efficiency were evaluated. The results showed that superfine polymer microspheres were a kind of spherical micron particles and the initial average particle size was 8.5μm. The superfine polymer microspheres had good swelling property and the particle size could reach 8 times of the initial size after 48 hours under the condition of simulated formation water at the temperature of 20℃. The superfine polymer microspheres also had good temperature-resistant, salt-resistant and shear-resistant properties. The plugging ratio was up to 88.39% and the enhancement of oil recovery reached up to 21.37%.The field experiments of the well S in Changqing Oilfeild H392 block indicated that the injection pressure rose after profile control and flooding, at the same time, the water content of well group fell from 93.5% to 74.2%, and daily fluid production rate increases by 125%.

Abstract:It was difficult to confirm the oil-water interface in thin-layered bottom-water reservoir. So a novel bottom water separator was built by gel foam to overcome the technical limitations of perforation completion method and solve serious water coning. Gel foam had dual function of gel and foam, whose selectivity and sealing capacity were good. Viscometric method and Ross-Miles method were used to optimize the composition of gel foam. The best formula of gel foam was obtained as follows: 0.2% polymer LA100, 0.4% organic chromium crosslinking agent FH-7, 0.25% surfactant SDS and N2. The performance evaluation results showed that system viscosity increased from 11.6 to 200.0 mPa·s within 24 hrs, which caused foam comprehensive value increased from 2838.0 to 11899.0 mL·min. Along with the gelling, the stability of gel foam gradually reinforced. The resistance coefficient was larger than 6.0, which resulted in a high injection pressure to supply the stratum energy. The plugging rate exceeded 93.8% for different permeability sand-filled pipes. Its selectivity was better than simple gel. Glass visual model result showed that gel foam priority accessed to water cone and bottom water in immediate vicinity of wellbore and formed a barrier to enhance the swept volume of bottom water, which caused oil recovery raising 32.6%.

Abstract:Comb polymer gel with 2300×10⁴ relative molecular mass and ordinary polymer gel with 2200×10⁴ relative molecular mass were prepared. The rheological parameter, gelling properties, microstructure and core displacement effect of two gels were compared. Experiment results showed that the gelling time of two gels was 24 hrs. The volumetric shrinkage rate of ordinary polymer gel and comb polymer gel was 1.2% and 0.9% after aging 30 d at 30℃, indicating good thermal stability. The pseudo plastic and thickening of comb polymer gel was slightly higher than that of ordinary polymer gel before gelling. After gelling, the elasticity of comb polymer gel was higher than that of ordinary polymer gel. And the microstructure of comb polymer gel was dense. Core displacement experiment showed that the enhanced oil recovery rate of water flooding increased 24.61% after comb polymer gel plugging while it only increased 21.64% after ordinary polymer gel plugging. Comb polymer gel had better control effect than ordinary polymer gel.

Abstract:The influence of bottom-hole filter cake on injection pressure and water injection in water injection wells was studied through the core flow experiments and theoretical calculation methods combining with actual production situation. The results showed that "the equivalent permeability" theory was applicable to calculate the formation damage degree of filter cake in different reservoir. The thickness of filter cake formed by 5% (120 mL) and 30% (150 mL) diatomite had reached to 0.35 and 2.51 cm, and the permeability of filter cake was 4.2×10^-3 and 0.3×10^-3 mm2. The filter cake had a smaller effect on the permeability of low permeability reservoir and a serious effect on the permeability of mid-high permeability and high permeability reservoir when the permeability of filter cake was 0.3×10^-3 mm2. Damage rate increased with increasing reservoir permeability. When the permeability of reservoir was 50×10^-3 and 100×10^-3 mm2, the damage rate of reservoir permeability was 29.0% and 45.3%. The filter cake had little effect on the permeability of different reservoir when cake permeability was 4.2×10^-3 mm2. The downhole filter cake of low permeability reservoir could result in the increase of water injection pressure. However, the water injection quantity of water injection well changed a little with increasing filter cake thickness.

Abstract:In order to evaluate the influence of supercritical CO₂ on the physical property of unconsolidated sandstone reservoir in Suizhong 36-1 oilfield, under the reservoir condition, the core porosity and permeability before and after gas injection were tested by using improved test device. The results showed that the porosity, gas permeability and liquid permeability of reservoir all decreased after contact reaction. The core porosity in average with 30% and 50% gas saturation decreased from 55.36% and 54.84% to 55.15% and 54.59%, the change rate was -0.4% and -0.5%, respectively. The core gas permeability of that decreased from 5.019 and 5.060 μm² to 4.925 and 4.952 μm², the change rate was -1.9% and -2.1%. The core liquid permeability of that decreased from 2.417 and 2.426 μm² to 2.289 and 2.291 μm², the change rate was -5.3% and -5.6%. Under the reservoir condition, corrosion products changed into the precipitation of carbonate because of the decrease of CO2 partial pressure. The larger initial porosity and permeability, the smaller decrease degree of reservoir physical properties was. Gas saturation had little effect on the change of reservoir physical properties.

Abstract:The static performances of foaming agent DLF, including foamability, stability, were tested and evaluated using the method of Waring Blender, and on this basis the dynamic plugging and profile control ability was studied through one-dimensional core flow experiments. The results showed that, the DLF system had great heat-resistant and aging-resistant performances, and the static foamability and dynamic plugging and profile control abilities of the whole system were best under 80℃, what’s more, the foam resistance factor of the DLF system was still about 18 when the temperature reached up to 180℃; at the same time, its static salt tolerance performance was also very good, and the DLF system was tolerant to Ca²⁺ and Mg²⁺ at certain concentration, correspondingly for the whole system，the sensitivity order from strong to weak was: Mg²⁺ (40 mg/L), Ca²⁺ (600 mg/L) and Na⁺ (28000 mg/L).

Abstract:Four kinds of polymer’s intrinsic viscosity [η] were measured and calculated by using Brookfield viscometer with type of ULA rotor under the condition of 77 r/min rotor speed and 30℃. The standard uncertainty of Brookfield method and Ubbelohde method was determined respectively. Compared with Ubbelohde method, Brookfield method was simpler, more time-saving and efficient which could enhance work efficiency 4 to 5 times and the measurement error was relatively small. The R2 standard deviation of Brookfield method and Ubbelohde method was 0.6261%—1.4750% and 3.3980%—4.9860%, while the [η] standard deviation was 23.2579%—27.6825% and 30.2660%—101.2736% respectively. Therefore, the [η] and the R² standard uncertainty in Brookfield method were lower than that in Ubbelohde method, and the R² standard uncertainty of their differed 1 magnitude. The measuring accuracy of Brookfield method was higher than that of Ubbelohde method, and the average determination precision achieved 0.8775%. Moreover, the Brookfield method could overcome the limitations of narrow measuring ranges and fewer types of appropriate polymer that the Ubbelohde method had. It was suitable for the intrinsic viscosity measurement of common polymers, salt resisting polymers and hydrophobic associating polymers with medium or high relative molecular mass. It was a new application approach to be promoted in oil industry.

Abstract:The influence of inorganic ions on the molecular size of hydrophobically associating polymer S308 was investigated by light scattering technology. The dependence of the molecular size on polymer concentration and salt content was also studied. Meanwhile, we also tested the rheological properties of S308 in salt solvent. The results showed the Rh of the S308 solutions prepared by NaCl、KCl、NH₄Cl solutions with the concentration of 1 mol/L and CaCl₂ solution with the concentiaon of 0.01 mol/L, respectively, was arranged as follows, R_h（Ca²⁺）< R_h（K⁺）≈ R_h（NH⁴⁺）< R_h（Na⁺）. In other words, the order of the influencing capacity of these cations was as follows, Ca²⁺>K⁺≈NH⁴⁺>Na⁺. When the Na⁺h of the polymer in the NaCl、Na₂CO₃ and Na₂SO₄ solutions was of 217 nm, 277 nm and 238 nm, respectively, indicating that polymer molecular size tended to be larger in solvent containing high valence anions than in solvent containing monovalent anions when the solvent contained the same kind and amount of cations. In different salt solvents, the apparent viscosity of the polymer solution basically increased with the increase of the molecular size. Besides, with the salt content increasing, the molecular size of S308 increased at first and then went down, and the ratio of gyration radius to the hydrodynamic radius (R_g/R_h) decreased gradually, indicating the polymer chain transformed from stretch to curl.

Abstract:Based on the reservoir and fluid in Gangxi Block3 area of Dagang oilfield，the effect of polymer concentration on solution seepage characteristics was carried out and the mechanism was analyzed. The results showed that resistance factors（FR）and residual resistance factors（FRR）decreased with increasing core permeability at same polymer concentration，while FR and FRR increased with increasing polymer concentration at same core permeability. The increment rate of FR and FRR reduced when the mass concentration of polymer increased from 400 to 1600 mg/L，and that increased with 1600—2500 mg/L，at last，reduced again after 2500 mg/L. So it was recommended that 2500 mg/L was the upper limit concentration of high concentration polymer flooding. Themolecule chains in polymer solution broke under the shearing action of core pore，and the network structure was destroyed，the parcel ability of water molecule decreased，which showed the increasing viscosity ability and percolation resistance of polymer solution decreased in macroscopic scale. Polymer molecular clew size increased first and then decreased when the concentration of polymer increased from 50 to 400 mg/L，and 245.3 nm was the lowest value at 200 mg/L. The distribution of molecular clew size had the trend of being divergent first and then concentrated.

Abstract:Emulsification tests and oil/water interfacial tension measurements were conducted to develop alkali/surfactant spontaneous emulsification system which was suitable to shengtuo high temperature and high salinity reservoir，and oil displacement efficiency of the spontaneous emulsification system were investigated by flooding test. The results showed that the interfacial tension of oil/water could be lowered to an ultralow level when adding 0.5 g/L of surfactant B4 to the 2 g/L NaOH+2 g/L Na2CO3 compound alkaline solution，leading to easy spontaneous emulsification of oil and forming emulsion under interfacial disturbance. Oil was emulsified by spontaneous emulsification system under the shearing action of porous media，the droplets might coalesce in the pore throat and generate strong jamin effect，and the mobility ratio of water to oil could be effectively reduced so as to increase the sweep efficiency and oil recovery. Droplets were ether entrained along with flowing aqueous phase to improve oil displacement efficiency. While emulsification and entrainment still leaded to the oil recovery enhance and pressure drop，it did not seem to be as effective as emulsification and entrapment. The optimal spontaneous emulsification formula was as follows: 2 g/L B4+2 g/L NaOH+2 g/L Na₂CO₃，and the oil recovery increased by 21.5% by spontaneous emulsification flooding and the oil recovery did not decrease with the increase of the sandpack length.

Abstract:Unsulphonated oil，separated from petroleum sulfonate products，was oxidized and saponified，as a result，the petroleum carboxylate was obtained and the productivity of surfactants was increased by more than 25%. The compounds of petroleum sulfonate with petroleum carboxylate could produce ultra-low interfacial tension with Daqing crude at the range of Na₂CO₃ 6—12 g/L and surfactant 1—3 g/L. Considering the fact that the activity of petroleum sulfonate products decreased after unsulphonated oil being separated，the sample containing unsulphonated oil was oxidized and saponified directly and the mixed products of petroleum carboxylate and petroleum sulfonate were obtained，resulting in the productivity of surfactants was increased by more than 8% and the unreacted oil content decreased by 10%. The interface activity remained or slightly improved. The alkaline/surfactant/polymer combined systems using the above oxidation product as surfactant had good long-term stability of interfacial activity and could keep the initial ultra-low interfacial tension of 10^-4 mN/m of orders of magnitude during the store-test period（six months）

Abstract:Surface multiplication experiment after MEOR was carried out using beneficial bacterial in produced water. The concentration of bacteria increased from 6.4 × 10⁵ cells/mL to 3.6 × 10⁸ cells/mL and that of the beneficial bacterium including hydrocarbon bacteria，fermentation bacteria and denitrifying bacteria increased 3—4 levels per milliliter after surface fermentation. And the same time，that of the baleful bacterium，sulfate reducing bacteria，decreased 1 level per milliliter. After nutrition and mixed oil were added to produced water after MEOR，the surface tension of oil-water emulsion decreased 35.4%，and the oil viscosity decreased 43.0%. When physical model experiment carried out ， the bacterial count in produced water reached to 10⁷ cells/mL，and the oil recovery increased 10.67 percent point on the basis of original microbial enhanced oil recovery method. In combination with the surface multiplication technology and oilfield sewage disposal system，and after the new microbial flooding was carried out，the whole bacteria concentration of reinjection produced fluid increased to 5.8×10⁸ cell/mL，and that of produced liquid increased to 3.0×10⁶ cell/mL，cumulative quantity of oil was 20050 tons，the ratio of input to output was 1∶3.2.

Abstract:Choosing the best reaction condition of Chengbei heavy oil in sub-critical water upgrading simulation experiment，analyzing hydrocarbon composition and structure of heavy oil upgrading，and comparing viscosity effect with three upgrading reaction，we got results that water in sub-critical condition had the nature of near-critical fluid，and the effect of solvent and catalytic for hydrogen. When oil-water mass ratio was 8∶2，reaction temperature was 260℃，pressure was 6 MPa and time was 24h，the viscosity reduction rate was 21.4%，the content of asphalt decreased 56.46%. The infra-red spectrum of crude and upgrading heavy oil presented obviously cleavage of C—S bond. Reducing the pressure to 3 MPa and in non-critical condition for general upgrading of heavy oil，the viscosity of heavy oil decreased 7.98%. Adding 0.1% catalyst，the viscosity of heavy oil decreased 51.27% by near-critical water catalytic upgrading. Three upgrading methods were arranged according to the effect of viscosity reduction in following order: sub-critical water catalytic upgrading>sub-critical water upgrading>general upgrading.

Abstract:In this study, simulated the reservoir conditions of Suizhong 36-1 offshore oilfield, the optimization experiments of injection timing and injection pattern of the binary composite flooding after polymer flooding were developed. After polymer flooding, the launching of binary composite system was studied at different injection timing, including direct injection, water content ratio of the lowest point, 70% and 95%. The results showed that the ultimate recovery rate was 75.36%, 73.32%, 71.22% and 68.61%. The oil recovery of binary composite flooding in directly conversion after polymer flooding was the highest (42.61%). At the same water flooding conditions, the effect of injection mode of binary composite system on oil displacement efficiency was compared. The result showed that the oil displacement efficiency of 0.3 PV binary composite system was better than that of 0.05 PV polymer+0.2 PV binary composite system+0.05 PV polymer and that of 0.1 PV polymer+0.2 PV binary composite system. But the effect of injection mode on the ultimate recovery rate was not big. Using polymer as protection slug was more advantageous to control the cost of industrialization. And the flooding effect of before and after protection polymer slug was better than that of single front slug if polymer dosage of the slug was same. Under the same economic condition, the oil recovery ratio of polymer+0.3 PV binary composite flooding increased 19.05%, which was higher than that of the equivalent 0.7 PV polymer flooding by 1.61%, maximizing the overall effectiveness of oilfield development.

Abstract:Aiming at the problem that heavy oil have high viscosity，while the pure polymer flooding has poor affinity with crude oil and the displacing efficiency and enhancement of oil recovery is low，the viscosity reduction experiments of the heavy oil in offshore S using a polymer emulsifier RH327 was carried out，and the emulsion type，the emulsion concentration，the aggregation morphology，the wetting ability，the stability and the static/dynamic adsorption capacity were evaluated under reservoir conditions. On the basis，the flooding performance of RH327 were evaluated through physical simulation，and novel polymeric emulsifier system that could enhance oil recovery substantially was established. The results showed that，at lower concentrations（1.2 g/L），the viscosity reducer RH327 had strong emulsifying activity under the reservoir environmental conditions，the viscosity of crude oil could reduced by 94.7% at oil-water ratio of 50∶50；at the same time，RH327 also had fast emulsification speed and strong emulsification stability，the emulsification rate being of 0.17 mL/min. The static adsorption of RH327 at higher concentrations of 2g/L in the oil sands was only 3.4 mg/g，the saturated adsorption of the artificial core with the permeability of 2756.15×10^-3 μm² could be attained after injecting 2.5 PV RH327 solution with the concentration of 1.6 g/L，the saturated adsorption capacity being of 160 ug/g. Physical simulation results showed that when main viscosity reducing agent slug was 0.3 PV and polymer protective slug（amphiphilic acrylamide polymer ICGN）with concentration of 1750 mg/L and slug size of 0.06 PV was conducted，the RH327 solution could enhance the oil recovery by 17.3% based on the water flooding（35.72%）

Abstract:Effect of three kinds of new corrosion inhibitors，including imidazoline（a），alcohol amine（b）and benzotriazole derivative（c），on the motion behavior of oil droplets in oil and water emulsions was analyzed by using Turbiscan Lab stability analyzer with multiple light scattering technique，and their change curves of transmitted and backscattered light intensities were obtained. The causes of their emulsification tendency were analyzed according to the micro and macro analysis and some other aspects. The results showed that compared with other samples，sample b separated the most water and emerged a clear oil and water boundary after setting for 10 and 60 minutes. The average rate of liquid droplets in the dispersion phase of sample a，b and c within 10 minutes was 130.055，1385.460 and 101.501 μm/min，and the average diameter of that was 39.3，128.0 and 34.7 μm， respectively. The stability index of sample a，b and c was 11.80，15.65 and 11.74 in 60 minutes that was calculated by Turbiscan Easysoft software. Sample c showed little water separation，low moving speed and small diameter for liquid droplets，tough coalescence between oil droplets and floating，good emulsion stability and the strongest emulsification tendency. Sample b showed the fastest rate and the biggest volume of water separation，a large amount backscattering change and the smallest emulsification tendency.

Abstract:Biofilm is a layer of microbial film，formed in a relatively closed water environment. In the paper ，the amount of bacteria，CODcr，sulphide content，Fe²⁺ contentand the suspended sediments content in Shishen 100 waste water during the formation of the biofilm were investigated，further，the effect of the formation of the biofilm on the water quality was probed. The results showed that with the extending of incubation time，the amount of bacteria in sewage，CODcr，sulphide content and the concentration of suspended sediments in water，ascended in first and descended at last，while the Fe²⁺ content in the water increased gradually， which indicated that the bacterial reproduction was the main reason of the corrosion and scale. The formation of biofilm leaded to the instability of the field waste water during injection，and also leaded to serious corrosion and scale.

Abstract:The corrosion of pipe network in oilfield water injection system was a problem which was difficult to solve effectively in oil production process. The corrosion was caused by many factors，including physical factors，chemical factors and biological factors. In order to reveal the correlation between corrosion factors and corrosion，the physical and chemical properties of sewage effluent of 55 different stations in Shengli oilfield were analyzed. The correlation between physical，chemical and biological factors in sewage and corrosion was analyzed by SPSS program. The results showed that the correlation index between salinity（﹤20 g/L）， dissolved oxygen，suspended solids and corrosion rate was 0.345，0.440，0.305，respectively，the probability（P）was 0.039，0.001，0.044，showing a significant positive to corrosion. The correlation index between pH value，temperature and corrosion rate was 0.127，0.185，respectively，the P was 0.356，0.177，showing a limited correlation to corrosion. The correlation index between oil content and corrosion rate was -0.295，the P was 0.029，showing a significantly negative correlation. The correlation between bacteria and corrosion rate was reduced for antiseptic injection.

Abstract:Complex solvents were used to extract the crud oil from oil-wet oil sands from Xinjiang. In this study，the n-hexane/ethyl acetate（H-EA）complex solvents were chosen based on the theory of solubility parameter to substitute toluene，and the effects of the experiment conditions，including the ratio of solvent volume to the oil sand mass，extraction time，operating temperature， and stirring velocity，on the oil recovery were discussed. The results showed that，as for the oil sands，the optimal extraction agent was H-EA complex solvent containing EA volume fraction of 12.5%. The extraction was most effective when the stirring velocity was of 500 r/min，the extracting time was of 30 min，the extraction temperature was of 50℃ and the ratio of solvent volume to oil sand mass was 2∶1（mL∶g）. Under the condition，the oil recovery of oil sands could reach up to 78%.

Abstract:The detection technology of effective components in crude oil demulsifier was studied. A generally used demulsifier A with an unknown component was an object. By means of column chromatography and extraction, the components of a demulsifier were separated. Its chemical structure was analyzed by the instrument analysis methods of IR, GC and GC-MS. With acidic methylene blue method, ammonium thiocyanate method and the cloud point method, the type of surfactant in demulsifier A was determined. Using ammonium thiocyanate spectrophotometry, the content of polyether in demulsifier A was quantitative determination. The results showed that the solvent in demulsifier A was xylene, the effective component was propylene glycol polyoxypropylene polyoxyethylene polyether, the effective content was 10.5% (with demulsifier A sample) and 21.8% (with drying demulsifier A) respectively. It contained a small amount of sodium dodecyl benzene sulfonate (0.47%). And the molar ratio of polyoxyethylene and polyoxypropylene segment in polyether was 1.13. In practical application in the oilfield, on the basis of qualitative analysis, the effective component content in a polyether demulsifier might be rapidly detected by ammonium thiocyanate photometric method.

Abstract:Domestic and foreign scholars carried out many researches on environmental protection of marine drilling fluid，cost reduction and recovery and reuse. In the paper，several system of marine drilling fluid were introduced，such as silicate based drilling fluid，formate drilling fluid，methylglucamine glycosides drilling fluid，synthetic based drilling fluid system，low-poison oil mud drilling fluid，polyols drilling fluid. In addition，the development of the marine drilling fluid in the future was put forward.

Abstract:The synthesis technology and industrialization conditions of N-alkyl acrylamides at home and abroad were briefly summarized. The research and applications of N-alkyl acrylamides on drilling fluid additives, cement slurry additives, fracturing fluid additives and tertiary oil recovery additives were reviewed. The development direction was proposed.

Abstract:Factors affecting enhanced oil recovery with surfactants in carbonate reservoirs were summarized. Anionic surfactant， cationic surfactant，nonionic surfactant and ampholytic surfactant used to increase the oil recovery of carbonate reservoir were extensively researched and the application progress was reviewed. Advantages，disadvantages and feasibility of every surfactant in EOR were pointed out. Abroad field tests were also introduced.

Abstract:In the process of oil production，storage and transportation，oil leakage accidents happened frequently. How to control the pollution of environment effectively had increased a lot of attentions. This article presented the situation of soil pollution by petroleum and some traditional remediation methods including physical，chemical and biological treatment methods. The classification and application of microbial remediation technology was introduced. The article pointed out that isolation， colonization of degrading bacteria and improving the biological availability of petroleum hydrocarbon were the key factors for bioremediation.

Abstract:In this paper, chemical desulfurizer in wet desulfurization was reviewed, including alkanolamine desulfurizer, hydroxide desulfurizer, formaldehyde desulfurizer, strong oxide desulfurizer and other new desulfurizer. Meanwhile, the compositions, effect and characteristics of each desulfurizer were analyzed. Finally, the development direction was proposed.