Measurement of the water-to-liquid ratio of oil-water two-phase flow for low flow rates and high water content

Oil-water two-phase flow is widely present in the petroleum industry, and the vast majority of oilfields have entered the period of exploitation under high water content. Accurate measurement of water-to-liquid ratio (WLR) is crucial to oil production. Currently, there are fewer works related to the WLR measurement at high water content and low flow rates. In order to get a complete picture of WLR measurement in this context by electrical resistance tomography (ERT) sensors, dynamic experiments with a total flow rate not exceeding 4m3h-1 were conducted. These dynamic experiments considered the influence of the direction of the test pipelines, the inner diameter of the ERT sensor and the conductivity of the water. According to the relative positions of the measurement and excitation electrode pairs of the ERT sensor, different strategies for WLR calculation were established. This paper presents all results of the experiments of the WLR measurement. Especially, image reconstruction at different flow rates was conducted, as a way to qualitatively reflect the mixing of oil and water, thus helping to understand the WLR measurements. The whole work reveals the regularities of the WLR measurement by ERT, and provides a reference for subsequent work to realize the WLR accurate measurement in oil-water two-phase flow at high water content and low flow rates.