| The oil is the olefin-based in most oil fields of our country. Heating up technique of gas-buring is adopted widely when oil field was developed early for oil flow easily. That is mixing hot water into oil-gas-water pipelins or heat tranferring into oil-gas-water pipelines by goiing with heat water lines so that we can increases the temperature of oil-gas-water produced by oil well for oil-gas-gthering and dilivering safely.It consumes 15~30m3 natural-gas to transport per ton crude oil in our country. Take Daqing oil field for example, gathering one ton oil consumes 15~30m3 natural-gas, and 13×108m3natural gas annually, which occupy 78% of the total energy consuming in ground projects. With the deeply exploitation of oil field, majority of the eastern oil field have entered high water-cut developing bear stage. The water-cut of most oil wells exceeds by 85%, and some reach 95%. Because of the specific heat capacity per unite of mass of water is twice the crude oil's, the higher the water-cut is, the more the oil gathing and transfering energy consuming is. Because of oil fields entering supper high water-cut (exceeded by 85%), oil field is facing with the badly lack of energy, such as gas, electricity and water. This situation affects the development of the oil field seriously. And hence, the energy loss must be reduced immediately. UOGGT (unheated oil-gas gathering and transfering) is one of the main measures that reduce the energy consuming in domestic and overseas oil field. Some oil fields have done UOGGT technics experiment since 1970s, such as Shengli oil field, Zhongyuan oil field, Liaohe oil field, Changqing oil field, Fuyu oil field, Huabei oil field, Jiangsu oil field, Henan oil field and Daqing oil field etc. Until now, some UOGGT technics have been studied successfully, for example natural gathering and transferring without any orther helps, chemical assistant gathering and transferring, little balls cleaning olefin assistant gathering and transferring, and mixing normal temperature water into oil-gas pipes assistant gathering and transferring.And these techniques have been used in some oil field. But basic theory and influential factors of UOGGT haven't been perfect yet.The method to define limit and to do hydraulic/ thermodynamic calculation of oil-gas-water three-phase pipelines haven't been studied by the systemic experiment and theory research.The output of oil well produced liquid and the oil-gas-water tempareure of oil-well-head icrease continuously with supper high wather cut so that the oil-gas-water three phase flow pattern and hydro/ thermo speciality change greatly. In order to provide technic help for UOGGT and advance the total economic benefit of oil fields, it need urgently to reestablish new limits, study on hydraulic/ thermodynamic calculation method of oil-gas-water pipelines, and develep management software. We sdudy on the new technical limits and hydraulic/thermodynamic calculating method of oil-gas-water mixing pipelines for UOGGT system, and make assistant running management software in this paper. The research contents of this paper belong to complex multiphase flow problem that involves many subjects and realm, such as oil-gas gathering and transfering, engineering thermodynamics, heat transfer, multiphase hydrodynamics, computer technique etc. the followings are done. 1. The test methods of confirming the boundaries limits and sdudying hydraulic/ thermodynamic characteristic of oil-gas-wather pipes are given for gathering and transferring oil-gas without heating during the supper highly-watery stage. Two sets of experimental devices that use the oil-gas-water mixture produced by oil fields as the medium are developed. These devices are installed in two different districts of Daqing oil field separately. Cooperating with existing establishment of the oil well, oil gathering pipeline and measuring house, these devices can test some parameters of the oil-gas-water mixture, such as liquid production output, gas production output, water-cut, flow pattern, pressure, temperature in the oil gathering pipeline, etc. This method can reflect the actual situation of the oil-gas-water pipelines really with supper high water cut, and the result can be utilized widely in the oil fields. 2. Oil-gas-water flow pattern and oil-water state of oil gathering pipelines have been studied by experimental in Daqing oil field. Result indicates that the three-phase flow pattern of oil-gas-water is slug flow during highly-watery stage, and oil-water two phases pattern is stratified flow, oil-in-water emulsion, or the oil–in-water-in-oil emulsion-suspension liquid of water-continuous phase. The methods of confiming the temperature limit and safe value of pressure for UOGGT have been provided during producing oil of highly-watery stage. The experimental results indicate that the temperature limit can be 2-9℃lower than freezing point of crude oil in Daqing oil field. This conclusion breaks through the conventional conception that the temperature limits of unheated oil gathering should be higher than the freezing point for 3-high-type crude oil without any medicament. The new limit is more scientific and credible than the early limit provided by the run experience and indoor experiment because it is confirmed by the test result of flow pattern, temperature and pressure of oil-gas-water produced in the oil well. This limit can reflect the oil producing actual situation more exactly with supper high water-cut. The new limit confirmed in the paper has already been used in Daqing Lamadian oilfield, and economized 1×108 m3 natural gas annually. 3. In order to sdudy hydraulics/thermodynamics calculation method of oil-gas-water three-phase buried pipelines by testing datas, the pressure drop and temperature drop are tested under different temperature, water-cut, liquid production ouput and gas production output in oil gathering pipeline. 4. Several typical slug flow pressure drop models of gas-liquid two phases and oil-gas-water three-phase are introduced. The model error is gived out through the contrasting analysis between calculation result and testing result. The conclusion is that these models aren't suitable for the pressure drop calculation of oil-gas-water gathering-transporting pipeline with supper high water cut. We modified the Baker pressure drop model by the measured pressue drop in real oil gathering pipes.The hydraulic calculation method of oil-gas-water mixture transportation pipeline provided by this paper is suitable for normal well or the intermission more oil well extracting intermittently during supper highly-watery stage. 5. The exact soil heat physical characters are the base of calculating soil natural temperature field.The soil temperature field is the base of calculating axis temperature drop of oil-gas-water in three-phase flow pipeline. Twelve soil-samples were taken from everglade, infield and badlands in severe cold region. We measured their water-containing rate, dry density, thermal conductivity, temperature diffusivity and volumetric specific heat capacity with both states of frozen and thaw. Some temperature sensors are buried in soil in different depth ofhigh and low hypsography in severe chilliness region.The soil natural temperature field is measured. These temperature datas are base of verifying the calculation method of the soil natural temperature field. We analyzed the running method of oil-gas-water gathering pipes when atmosphere environment temperaure changed suddenly. The changes of soil's natural temperature have been sdudied with the changes of soil's heat physical characters. The soil natural temperature field is computed by the physical parameters tested in the severe cold region. The mathematics model of periodic non-steady soil temperature field is satisfied thought contrasting analysis between calculation result and experiment result. We draw a conclusion that the soil natural temperature changes very little with the frozen and thaw soil heat physical characters so that the change of the soil thermal physical characteristics can be neglected while computing the temperature drop of trthree-phase buried pipeline. 6. The temperature drop calculating mathematics model of oil-gas-water three-phase buried pipeline is established with the annual periodicity change of soil temperature field and time delay first time. The contrasting result indicates that the average relative error between the calculation well head temperature and test result is smaller than ±9%. So the thermodynamic calculation method is fit for the mixture transportation pipeline with supper high water cut. 7. Based on the research of the limit of oil-gas-water and hydraulic/ thermodynamic calculation method of oil-gas-water mixture transportation pipeline gathering and transferring without heating, the software named "Assistant operating software for the run and management of UOGGT during supper highly-watery stage" is developed. This software can calculate the temperature drop and pressure drop in transportation pipeline of the water-containing ascends 85% and simulate numerically the operating chart of the pressure on well head and the returning oil temperature in measuring space. The software also provides an advice for the whole year's operation of UOGGT for every well. The Operating management for UOGGT is scintific with this soft. The achievement of this paper is that provide academic reference and scientific means for the operating and management of the no heating oil-gas-water gatering and delivering with supper high water cut, the paper is helpful to the development of multiphase flow and its academic and applied value is momentous.
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