Research On Bottom Hole Pressure Response Calculation And Productivity Prediction System Of Single Geothermal Well

With the traditional energy sources depletion such as crude oil and coal and the improvement of environmental protection awareness, the geothermal resource has received more and more attention. Well test analysis can invert formation flow model with the unchanged date of well bottom. Use the formation flow model, we can get the production prediction of different conditions. The correlation algorithm is already mature and can be used to well test analysis of geothermal well. But geothermal well usually get the wellhead pressure by open flow test and the data is time-varying, the data does not suited to common method. Aiming at present problem that there is no analysis method suited to the data of geothermal well open flow test, unable to obtain the flow characteristics of the formation and productivity prediction, this thesis presented one method that can calculate pressure response according to the data of geothermal well open flow test and designed and implemented productivity prediction system based on the method.First, the method was introduced in detail, the method falls into two parts, part one is to calculate the well bottom hole pressure accurately according to wellhead pressure based on pressure drop within the wellbore, part two is to calculate pressure response with the well bottom hole pressure which was calculated by part one. Because of well bore temperature and pressure is rather changeable, part one considered the coupled heat of fluid, cement sheath and formation and present one method to calculate the distribution of wellbore temperature, pressure and density. Besides, the method accounts for well bore friction and against gravity; part two accounts for uncertainties not only include true error but also pressure drop which caused by the temperature, pressure and density distribution, it used deconvolution, variable projection algorithm, SVD and DFP method to get the optimal solution.Second, the thesis designed and implemented productivity prediction system based on the method. The system concentrates on computational analysis of single well, can obtain the flow characteristics of the formation, productivity prediction and provide analysis tool for geothermal development.Last, one geothermal well open test data has been treated by the method and system, the thesis provided the productivity that used processed data, the result verified the correctness and practicability of this method and system.