A dual-parameter measuring method for wet steam based on the characteristics of differential pressure under phase-isolation state

Abstract

To achieve accurate measurement of steam injection volume in the process of steam-driving heavy oil, a low-cost online metering device for wet steam flows is urgently needed. Primarily, the traditional Venturi device has a relative error due to the wet steam flow patterns. Therefore, a new physical model for wet steam measurement composed of a swirler and a Venturi was designed, based on the phase-isolation technology for multi-phase flow measurement. A theoretical explanation of the differential pressures was then proposed. Numerical simulations were conducted to investigate wet steam measurement, specifically under the condition of 10∼20 MPa. A new correlation for the steam quality and mass flow rate with the pressure drop was developed by the multiphase flow model via Eulerian. A novel wet steam dual-differential pressure measurement model was established by considering the effects of temperature and pressure, which predicts the wet steam overall mass flow rate and steam quality of the measurement device. Block P601 and Block P6 of the oilfield located in eastern China were selected as the development test area, and the differential pressure prediction was carried out for 68 different working conditions of two Wells based on the dual-parameter measurement model, which was then calibrated. The experimental fieldwork on Block P601 demonstrated that the feasibility of the dual-parameter measuring method was verified, with relative deviations of ±7% between the predicted and experimental values of differential pressure. After calibration of the measurement model, the predicted values were compared with the experimental values, yielding relative deviations of ±3.5% and ±5% for mass flow rate and steam mass measured online for wet steam, with Mean Absolute Percentage Errors (MAPE) of 1.73% and 2.21%. Thus, the dual-parameter measuring method has a certain engineering significance for the steam injection technology of heavy oil in oilfields.