Research On Downhole Throttling Technology For Xushen Gasfield In Daqing

Hydrate freezing in gas wells and ground multiple throttling process caused high costs of well construction and complicated ground process. In view of this situation, this dissertation studies the adaptability of downhole throttling technology in the Daqing Oilfield and developed a set of downhole throttling process which is suitable for Daqing Xushen Gas field through theoretical and experimental verification. Reasonable results are achieved in the field test, which might provide solid foundation for further large scale application.The project mainly focus on following aspects:1. The basic principle and the global and domestic application status of downhole throttling technique are described. And the necessity of the research and significance application of the technology in Daqing Oilfield are further explained.2. The downhole throttling technique suitable for the geological condition of Daqing Oilfield has been studied. The model parameters are verified through large amount of lab experiments, so that the software to determine the parameters has been programmed.3. As that the CO2corrosion on natural gas wells commonly exists in Daqing Oilfield, the study about the optimal anti-corrosion metal and elastic sealing element materials selection is carried out.4. Two kinds of downhole throttle structures, pre-and post-positioned,-are developed to meet different requirements. The finite element method is used for strength analysis and structure optimization of the vital parts such as choking and sealing elements.5. The salvage technique for both pre-and post-positioning downhole throttles are studied via in door and field mimicking experiments. The reliability are demonstrated.6. The feasibility of the downhole throttling process is validated via the field experiments, in which the favorable effects are achieved.