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In this paper, an integrated calibration method for position sensitive detector (PSD) of moving support mechanism in vacuum plasma environment is proposed. That is, the PSD is used to track the laser spot to restore the coordinate information of the signal. Firstly, a PSD integrated calibration principle is proposed to reduce the position error of the signaler by tracking laser points with PSD. Then on this basis, due to the spatial declination angle in the PSD imaging model, a spatial declination correction model was established to compensate the spatial declination error. Finally, there are errors occurred in the measurement because of the nonlinearity of PSD, and the improved backpropagation (BP) neural network calibration algorithm is adopted to further correct the errors through the Fletcher–Reeves linear search method to obtain the accurate coordinate information of the annunciator. MATLAB is used to verify the convergence of the calibration algorithm error. Simulation results show that 951 epochs need to be trained by using the traditional BP algorithm to make the position error converge to 0.001 mm. But when using the improved BP algorithm, only 44 epochs are needed.

This paper proposes a spherical gear pair with three degrees of freedom based on meshing transmission principle. The kinematic meshing relationship between the spherical gear pair is illustrated with its pitch spheres and pitch cones. This determines that the spherical gear surface is completed with two tooth surfaces of ring-involute spherical gear and a semi-spherical bevel gear. Mathematical models and numerical results of the two tooth surfaces are presented for obtaining geometry model of the spherical gear pair with the CAD three-dimensional molding technique. This study provides the basis for future studies to design and analyze a novel spherical gear.

Overview The rheology of polyacrylamide solutions and the effect of viscous-elastic fluids upon production equipment are described. Methods to solve the negative effects of viscous-elastic fluids on equipment are also introduced. The results of the modification(s) on the system and equipment show that the service life of equipment more than doubled, mechanical degradation of polymer decreased more than 50%, and energy consumption decreased markedly. Summary Most flow systems and equipment for the injection, production, and gathering of large amounts of fluid are designed for Newtonian fluids. Now, an increasing number of oil fields are on viscous-elastic flooding. After flooding by polyacrylamide (PAM) fluids, it was seen that the flow of this type of fluid in production and surface systems and equipment has its special characteristics, which in turn require special designs for the equipment and flow process. This paper introduces the actual performance of the production and surface flow systems and equipment, and points out the influence that the special rheologic characteristics, especially the viscous-elastic nature of the fluid, has on the system and the modification made. For example, there is a normal force acting on the beam pump sucker rods that causes pronounced eccentric mechanical wear on one side of the sucker rods and thereby very short service life for beam-pump wells. This normal force significantly lowers the efficiency of centrifugal pumps, increases the vibration and mechanical degradation in triplex pumps and the whole system, lowers the efficiency of maturing tanks and static mixers, etc. The modifications on the system and equipment and their results are shown. For example, the service life of beam pumps more than doubled; mechanical degradation of polymer in the system and triplex pumps decreased more than 50 and 70%, respectively; and the energy consumption of mixing equipment decreased 80%, among other results.

An investigation into the feasibility of using biosurfactant-rhamnolipid-fermentation liquor (RH) as a sacrificial agent was conducted in the laboratory and alkaline-surfactant-polymer (ASP)-flooding pilot test. The interfacial tensions (IFTs) between solutions containing biosurfactant or mixture of biosurfactant and alkylbenzene sulfonate (ORS) at different ratios and crude oil were studied at a constant NaOH concentration. The results show interfacial characteristics (IFT, interfacial viscosity and adsorption) of RH and significant synergic effect between RH and ORS. Adsorption isotherms of RH and ORS were determined to assess the effect of RH on reducing the adsorption of ORS on sandstone. Static adsorption experiments indicate that adsorption loss of ORS can be reduced by 25–30% when RH is mixed with ORS or pre-adsorbed on sandstone. The core-flooding tests show that the enhanced oil recovery with the formulation of ASP of 0.2 wt.% RH and 0.15 wt.% ORS (system 1) is 7% more than that with the formulation of ASP of only 0.15 wt.% ORS, and is equal to that with the formulation of ASP of 0.3 wt.% ORS. This indicates that using RH can reduce the cost of ASP flooding. The ASP-flooding pilot test was conducted with system 1 and resulted in 16.6%(OOIP) of the enhanced oil recovery in the whole test area.

After the success of polymer flooding in Daqing, two alkaline-surfactant-polymer (ASP) floods have been conducted to (1) increase oil recovery further (2) study the feasibility of ASP flooding (3) provide technical and practical experience for expanding the ASP pilots. Inverted five spot pattern is adopted in both pilots. Pilot 1 (PO) is located in the West Central area of Daqing Oil Field and consists of 4 injectors and 9 producers. Pilot 2 (XF) is located in the South area of Daqing Oil Field and has 1 injector and 4 producers. The crude oil of both pilots have high paraffin content and low acid value. Compared to PO, XF has characteristics of lower heterogeneity, lighter oil and higher recovery by water flooding. For each pilot, after extensive screening, an ASP system has been determined. The ASP systems all feature very low surfactant concentration and wide range of ultra low interfacial tension with change of concentration of any of the three components. Core flooding and numerical simulation show more than 20% OOIP incremental recovery by ASP over water flooding for both pilots. By the end of May, 1995, 100% of ASP slug and 100% of the polymer buffer have been injected inmore » the pilots. Production wells showed good responses in terms of large decrease in water cut and increase in oil production. The performance of each pilot has followed the numerical simulation predication very well, or even a bit better. Emulsions showed up in producers, but the emulsions are easy to be broken by a special de-emulsifier. No formation damage and scaling have been detected. The ASP flood pilot tests are technically successful and, based on the preliminary evaluation, economically feasible. Therefore, in the near future, much larger scale ASP flood field tests are going to be performed at several districts in Daqing Oil Field.« less

Daqing Oil Field is the largest oil field in China and one of the largest oil fields in the world. Development began 35 years ago. By cyclic identification and comparison of continental heterogeneous sandstones, studies on sedimentation models and sand body types, a better understanding of the development stage, water flood characteristics and residual oil distribution of different types of sandstones was obtained. A whole set of technologies (including geology, reservoir engineering, drilling, production, open hole logging and production logging) were developed to increase the recoverable reserves of different zones. As a result, at each stage of development the recoverable reserves of the oil field were increased. It is estimated that after drilling the third round of infill wells and after polymer flooding, the recoverable reserves will be 118 to 133% higher than 1978. Daqing was brought on production in 1960. The present water cut is around 80%. Production reached 50 × 106t in 1976 and in 1995 reached a record high of 56 × 106. Production has been stable for 20 years and is estimated to be stable for another long period of time. Excellent development results have been obtained and are better than planned.

This paper introduces a method to fracture more than 30 zones in a single well per day and also how to fracture low permeability zones when the impermeable barrier(s) to high permeability and high water cut zones are only about 0.5 m thick and not create channels in the cement sheathe. The above methods are used in a large scale in Daqing Oil Field (about 1,000 wells per year since 1980). The results are quite good, cumulative incremental oil production by these fracturing methods is about 60 million tons; the fracturing costs per ton of incremental oil is about $ 6.

Studying zones, geological sediments, oil and water, etc. of different characteristics, suitable ASP systems mainly with alkylbenzene sulfonate, bio-surfactant, NaOH, Na2CO3 and polymer were screened. After getting good results in laboratory studies, five ASP pilot tests have been conducted with different well spacings, zones and at different locations etc. Our aim was to study: 1) the injectivity and productivity of ASP systems; 2) the damage to the reservoir with different kinds of alkaline; 3) the method of lift and how to increase very low productivity; 4) Chromatographic separation with different well spacing; 5) the effect of this EOR method and its potential; 6) its technical and economical benefits. Both laboratory and pilots studies showed that different zones, oil and water, and different surfactant components all require different ASP systems; bio-surfactant is compatible with alkylbenzene sulfonate; and no matter what kind of alkaline where selected in the pilot, theoretically, there is some damage to the zone, but the damage to the reservoir was not significant in the pilots, the same for chromatographic separation. Numerical simulation and pilot results both showed that more than 20% OOIP oil recovery were obtained over that of water flooding. The actual production data was better than numerical simulation. Even in a reservoir with long-term 100% water cut, the chemical cost per ton of incremental oil is around 30$ to 40$. Especially in a very low oil price situation in the world today, this method can obtain good benefits both technically and economically. Over all, the success of these ASP flooding pilots in Daqing Oil Field are good examples on enhanced oil recovery with similar types of reservoir sediment as Daqing, and also provides a new method to achieve sustained development of resource developing companies.

After studying zones, geological sediments, oil and water, etc. of different characteristics, an Alkaline-Surfactant-Polymer flooding formulation mainly with alkylbenzene sulfonate was screened. Pilot investigation with this formulation has been conducted with different alkali and different zones, good results have been achieved both technically and economically.[1,2] Based on former study results,[3,4] screening of ASP formulations to further reduce the usage of surfactants and get better technical and economical results were performed. The interfacial tension behavior between oil and bio-surfactant ASP systems, emulsion characteristics, adsorption, core flooding, as well as numerical simulation, etc. were studied. After success in the laboratory study, the first Alkaline Bio-Surfactant Polymer Flooding Pilot was conducted in the north of the oil field. Both laboratory and pilot studies showed that the Alkaline Bio-Surfactant Polymer Flooding system not only can further reduce the usage of surfactant and dynamic adsorption, but also can further reduce the ultra-low interfacial tension, extend the ultra-low interfacial tension area. Its emulsion phenomenon and chromatographic separation was not significant. After the implementation of the Alkaline Bio-Surfactant Polymer Flooding pilot, good results in terms of daily water cut decrease and incremental oil of the central well were obtained, the actual production data was better than the numerical simulation prediction. Now, the oil recovery of the central area is 21.5% OOIP over that of water flooding, preliminary economic analyses show that the chemical cost per ton of incremental oil is less than 30$. This should be a good bio-chemical flooding method.

Abstract Daqing Oil Field has already successfully implemented two alkaline/surfactant/polymer (ASP) floods with dense well spacing. To further confirm the feasibility of ASP flooding at industrial well spacing, confirm "absolute incremental oil" (incremental oil after the pay zone reaches 100% water cut by water flooding, and not incremental oil over 98% water cut as is normally calculated in China) and to further confirm the magnitude of chromatographic separation of the injected chemicals on condition of large well spacing, two ASP field tests with a larger well spacing (200m to 250m) are in progress in Daqing now, the results of one of the field tests in a more advanced stage (i.e. a larger portion of chemicals have been injected) is presented in the this paper. This larger well spacing field test consists of 4 injectors and 9 producers forming 4 inverted five spot patterns. The distance between producers (or injectors) is 28Om and between producer and injector 200m. By the end of 1995, 7 new wells were drilled. The data from these wells showed that, on the average, 92.5% of the pay zone (PI33) were already water flooded. In these 7 new wells, 5 producers (including the center well) had a water cut of 100% for 9 months from the start of production to the time the ASP flood lowered the water cut. The average water cut of the 9 producers was 98.4%. Single well tracer logging at the center well obtained a residual oil saturation of 18+3%. By numerical simulation, the water flood recovery was already 67.2% before the ASP flood. Core tests were performed to optimize the sequence and quantity of chemicals to be injected. The results showed that, on condition of constant quantity of polymer and surfactant injected, injecting a polymer slug before the ASP slug and injecting a tapered ASP slug can increase the recovery of the flood; increasing the viscosity of the ASP slug can offset the effect of the heterogeneity of the pay zone. The injection scheme was optimized according to the above tests, the characteristics of the pilot area and by numerical simulation. According to the optimized program, it was predicted that the ultimate recovery of the ASP field test would be 77.2% OOIP, about 10% higher than the 100% water cut recovery and 25% OOIP higher than the 98% water cut recovery. The polymer slug was injected during the period Sept. 18 to Nov. 2, 1996. After that, the ASP slug started to be injected. After injecting 0.09 PV of ASP, the surrounding wells started to respond by lower water cuts. The water cut of the center well dropped from 100% to 46.9%. now the cumulative incremental oil production of the center well is 7,494 t, equivalent to 12.8% OOIP increase in recovery, much better than that predicted. It is estimated that the ultimate incremental recovery will be 16 to 17% OOIP over that of 100% water cut by water flooding. Preliminary economic analyses show the chemical cost per barrel of incremental oil is around $6.5 When the water cut dropped to 50%, the produced fluid was completely emulsified, this condition was maintained for a long period of time (0.123 PV). At reservoir temperature, the viscosity of the emulsion was 140 mPa S, and it could further emulsify oil and water. The emulsion was very stable, but it could be broken easily by a de-emulsifier developed in Daqing. The field test shows that by optimized designing, ASP flooding of ultra-high pay zones can obtain very good technical and economical results. Large amount of emulsified fluids is an important factor for good results of ASP flooding. The results of this field test should be of important reference for ASP flooding of 100% water cut pay zones. P. 305

Abstract Several papers on polymer flooding pilot test in Daqing have been published previously, they stress on enhancing oil recovery by polymer flooding in thick pay zone of major reservoirs with high permeability and heterogeneity. This paper presents the polymer flooding pilot test results in thin layers of non-essential reservoirs with medium-low permeability and heterogeneity. The purpose is to:study the feasibility of polymer flooding in such thin pay zones;test separate injection techniques;provide data for further extending polymer flooding potentials. The pilot has 4 injectors and 9 producers in inverted five spot patterns. The polymer flooding through Putaohua P I 1–3 formation had been finished in this pilot in 1990, then S II 10–16 was plugged and S II 10–16 was perforated to perform polymer flooding by dual-pipe separate injection. S II 10–16 formation includes 5 sedimentary time units and has complex geometry of sandbody and some layers pinch out in a few wells in the pilot. Its microstructure relief is large, the deference in depth of the formation is 3 7 meters. The net thickness of a single layer is 0.4 to 4.0 meters. Its average permeability is 0.342 m2 and Dykstra-Parson coefficient is 0.6. Polymer injection started in December of 1993 and 0.35 PV of polymer solution has been injected by the end of 1995. When 0.025 PV polymer solution was injected, the producers responded one after another. The average water cut of the pilot decreased from 94.5% to 80.1% and daily oil production increased from 37 tons to 95 tons maximum. The water cut of the central well decreased from 95.1% to 63.1%, daily oil production increased from 8 tons to 33 tons. Up to now the oil recovery for the central well has increased 10.84% OOIP over water flooding with the polymer flooding efficiency of 151 tons of oil per ton of polymer. The measurements of injection and production profile showed that the heterogeneity of the reservoir is adjusted and that separate injection technique by dual-pipe is feasible. P. 431

In the last few years horizontal wells are becoming increasly important. This paper presents a hydrodynamic method for solving the flow problem of areal water–flooding systems of combinations of vertical and hprizontal wells( 5–spot well pattern and 7–spot well pattern). The potential function, production rate, breakthrough time, areal sweep efficiency and stream functions are derived respectively. Also, the flow resistance method is used for getting the equations of horizontal well production for all the areal floods. Finally, the equations of oil productions derived by the two methods are compared.

The thick targets of Ti, Fe, Ni and Zn have been bombarded with 3 to 7MeV nickel ions. The x-ray spectra of the projectiles and targets showed a significant difference in the intensity of the x-ray radiation for several targets. The explanation of this phenomenon by quasimolecular orbital energy level correlation diagrams and the possible application of Ni ion induced x-ray emission were discussed.