The Method Of Isotope Contamination Homing Calculation And Its Application

China is one of the earliest country which uses RI label injection profile logging. Early in the 50's of last century, Yumen Oilfield once proceeded to injection profile logging withГКgamma-ray logging tool of former Soviet Union and used 65Zn in RI label injection profile logging. Daqing oilfield surveyed injection profile with home-made gamma-ray tool , of which 65Zn,110Ag about 8 radioisotope tracer were used one after another. In 1984, Daqing oilfield cooperated with china atomic energy isotope institute and successfully developed 131Ba-GTP microballoons tracer(particle diameter is 100-300μm),which can solve the problem of RI"desorption"form carrier. In order to accommodate different porosity and fissure, Zhongyuan oilfield and isotope research institute of Henan academy of sciences coordinated together to develop 131Ba-GTP microballoons tracer whose microballoons tracer is 100-2500μm. Meanwhile, Daqing,Shenglli,Liaohe,Dagang oilfield and so on develop and expand downhole tracer releaser to remove the contamination caused by the release of borefild radioisotope tracer at well head. At present, this kind of construction artwork is still used in oilfield, but its development tendency will be multiparameter integration logging and integrated interpretation.Label injection profile logging means to inject radioisotope tracer into the well under the condition that downflow well is in the regular water injection. With the injected water flowing in, these tracers will filter and add up at the rock surface of borehole injection layer, and the label curve can be generated by means of using gamma-ray logging tool. The amount of each injection layer can be displayed by the divergence of radioactivity in the bore log. Intake capacity of each layer will be calculated in the way of comparing the gamma curve before and after injecting tracer.Label injection profile logging artwork presents great changes and developments in the past 50 years.In the 90's of last century, the 31Ba-GTP microballoons release artwork was widely used and spreaded. And logging process was also developed form discharging overflow to re-pressuring into blowout device, achieving no stopped injection,no blowout,no overflow hermetic logging, making the label curve well reflect the injection profile under the condition of regular water injection.Based on long-term field experience and data analysis, we can make out, instead of percolating to the formation surface with the flow, isotope gets scoring on the part of borehole caused by the reasons that 131Ba-GTP microballoons carrier surface activity is not good enough, a little bigger density, unpurified injection water and less bright and clean pipe wall, causing some false anomaly that have nothing to do with the injection water amount, which is also called"blemish". Blemish can be divided into adsorption Blemish and deposition Blemish based on the blemish formation mechanism. Annulus box coupling, bottom hole regulator, casing endophragm or oil tube ectooecium belong to adsorption Blemish, and excluder blemish together with bottom hole Blemish caused by 131Ba-GTP microballoons tracer's downwelling, belongs to the kind of deposition blemish. The relative intake capacity in label injection profile logging data interpretation is calculated with the area formed by folding gamma ray curve and isotope curve, of which blemish has a great impact on precision of measurement. So, according to the fact that blemish doesn't affect the interpretation result before the isotope is distributed in the downhole, I want to study blemish type and blemish correction coefficient. Because the blemish damages the direct ratio relationship among formation influx,amount of isotope filter and accumulation and radioactivity, the relative influx accuracy is impacted. I also studied the blemish area migration pattern and computational methods in many kind of injection allocation walls and commingled water injection well to calibrate blemish and make it used in the data interpretation.Main research content:RI label injection profile logging is the foremost way of surveying injection profile,playing a great part in oilfield development. So, we set up mathematical model and physical model to modify it based on the concept that blemish breaks the data accuracy of RI label injection profile logging, whose main contents as follows:1. Demonstrate the concept of label injection profile logging, and then derive that water injection rate of formation surface,filter and accumulation amount of isotope carrier and radioactivity are in direct proportion to each other.2.Study how to chose the isotope carrier and make its radioactivity parameters,adsorbability and so on meet the need of logging artwork and conditions for construction work..3. Research on construction artwork and control the blemish.4. Categorize based on blemish mechanism, meanwhile set up blemish area migration model and computational methods based on the injection allocation conditions of water wellResearch methods:1. Based on water well injection allocation situation, utilizing mathematical model to proceed to theory deduction, then to verify it by using analog well to get the concept of label injection profile logging.2. According to the construction artwork and conditions, analyzing the option condition of radioactive isotope and its carrier to look for applicable isotope and its carrier then to carry out the indoor and performance test.3. Identify and select correction coefficient of removing blemish, set up blemish area migration computational method to modify the interpretation result and to improve the datum accuracy.