| The flow of acid gas well is complex flow of gas and liquid, gas and solid, even gas, liquid and solid. There are difficulties in the model of flow, including parameter variations, heat transfer and chemical reaction and the solving of transient model. In the process of mining in sour gas well, as along with the reducing of temperature and pressure, the elemental sulfur will precipitate. When the flow rate of gas is less than the critical suspension speed, large amounts of elemental sulfur would attach to the well surface, then influent the normal production of gas well.There have been more acidic gas field in region of Sichuan-Chongqing, such as Luo Jiazhai and Puguang. However, the classic flow model of multi-phase in wellbore can not describe the complex flow characteristics and flow process in acidic gas well, so the prediction of temperature and pressure is not accurate. At last, according to the deviation betweens calculated position and amount of sulfur deposition and actual value.In view of the physical parameters of high sulfur gas, the deviation factor and viscosity calculation models are optimized. On the theory basis of heat transfer and flow of gas-solid, the gas-solid two phase temperature and pressure model is established. And the reliability of the model has been tested by data, which is provided by literature. This paper mainly completed the following contents.(1) Based on the literature experimental data, the methods are summarized and compared for deviation factor and viscosity calculation, including the DAK, PR, DPR, HY and SRK method for deviation factor calculation and the LG, Dempsey and LBC method for viscosity calculation. The results demonstrated that the DPR method combined with WA calibration and the Dempsey method combined with Standing calibration is more appropriate for the calculation of deviation factor and viscosity for high hydrogen sulfide content gas.(2) Using a large amount of heat capacity at constant pressure data(Cp), the empirical formula for calculation of Cp is established, and the relative error is less than4.2%.(3) The Cullender-Smith(C-S) and the average temperature deviation factor methods for calculation of the bottomhole flowing pressure are compared. The conclusions show that C-S method is more suitable for the calculation of high H2S content gas bottom-hole pressure through case calculation.(4) Based on the C-S model, considering the wellbore radial heat transfer, single gas phase temperature and pressure distribution model is established. Then Visual Basic6.0software is used to programming and to solve the model. Compared with the results with Pipesim software, the temperature relative error is0.57%, and the pressure relative error is2%. Thus, the model is reliable. The new model is also studied the effect on temperature and pressure by gas production, hydrogen sulfide content and tubing diameter. The results showed that the yield have a great impact on temperature and pressure, while the hydrogen sulfide content and tubing inner diameter changes have little effect on temperature, but have a certain effect on pressure. (5) On the basis of the above model, the model parameters (density, friction coefficient, Joule-Thomson coefficient) have been modified. Taking the impact of dynamics change of sulfur particles dissolution and precipitation on temperature and pressure into account, high sulfur gas well gas-solid two phases temperature and pressure Odistribution model is established. Then Visual Basic6.0software is used for programming and to solve the model. The results demonstrated that the changes of hydrogen sulfide content have a greater impact on pressure and the volume of precipitation solid sulfur particles. And the production has little impact on temperature and pressure, while the tubing inner diameter has little effect on temperature and pressure distribution and the volume of precipitation sulfur particle. |
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