Multiple parameters׳ estimation in horizontal well logging using a conductance-probe array

• We propose a multi-parameter estimation method based on the conductance-probe array.
• A step of threshold filtering is introduced to improve estimation accuracy.
• A new algorithm of data normalization is employed to widen estimation range.
• A matching algorithm based on data fusion is used to improve estimation reliability.
• The method newly proposed works with higher performance comparing to the previously proposed.

In this paper, a new method is proposed to simultaneously estimate three parameters in horizontal well logging with oil–water two-phase stratified flow by using a conductance-probe array. It is known that an ideal sensor׳s response is determined by the water level and the azimuth angle of the sensor in a horizontal well, and is proportional to the conductivity of the water phase. In terms of the sensor model, the three parameters are estimated simultaneously by using the conductance probe array by the aid of experimental calibration. Firstly, the sensor is calibrated by static experiments with water of known conductivity. For all possible combinations of water level and azimuth angle, the sensor responses are collected and stored in a sample set as the sample data. In actual use, the sensor is first transported to the desired position in the horizontal well underground and the sensor response is collected as the measured data. Then, through the steps of threshold filtering, data normalization and matching calculation, the sample data that best matches the measured data is searched from the sample set. Finally, the parameters are estimated by the aid of the matched sample. The experimental results show that the estimation errors of water level and azimuth angle are within ±2% and ±3°, respectively and the relative error of water conductivity is no more than ±2%. Moreover, comparing with the estimation method previously proposed by the authors, the new method is of higher reliability, higher accuracy and wider range for water level estimation.