Calculation model for on-way parameters of horizontal wellbore in the superheated steam injection

摘要

Due to superheated steam as a pure gas, the ordinary steam model for the calculation of horizontal well-bore parameters based on two phases flow theory isn't applicable to the superheated steam injection process. According to the conservation of mass, conservation of momentum and conservation of energy, a calculation model for on-way parameters of horizontal well-bore in the superheated steam injection considering the steam phase changing is set up. The on-way parameters of temperature, pressure and dryness of a horizontal well injected superheated steam from Kazakhstan Kumsai oilfield is calculated using the model, and the calculation result of the new model is in good agreement with that of the field data, which verifies the effectiveness of the model. Sensitivity analysis indicates that the length to the heel of horizontal well undergoing the steam phase state changing increases as the injection rate or the degree of superheat increases, but the increase extent is not significant when the injection rate is larger than 8 t/h or the degree of superheat is larger than 80 °C. In the permeability distribution pattern that the permeability increases along the horizontal well-bore, steam temperature is decreased at the lowest rate and the length to the heel of horizontal well undergoing the steam phase changing is the longest.