Method of Measuring the Range from the UWB Borehole Logging Tool to the Oil-water Contact

摘要

In this paper, a method was worked out to determine the distance from the borehole, horizontally drilled through oil stratum, to the oil-water contact (OWC), using the mathematical model [1] for an ultra-wideband electromagnetic pulse borehole radar (BHR). We simulated pulse shape voltages at the outputs of receiving antennas spaced along the borehole to determined their specific delay times relative to the pulse driver of the transmitting antenna. There was proposed the simple formula to calculate the distance from BHR to the OWC using this delay times. This formula was tasted with the use of the delay times simulated and measured. For simulation, the values of complex dielectric permittivity of the oil saturated rock and water saturated rock were assigned the refractive mixing dielectric model substantiated in [2]. The proposed method was experimentally tested using a laboratory prototype model of the BHR with the pulse duration 2 ns and a specific laboratory set up to physically simulate the oil-water contact environment. Having not used any a priori information about permittivity values for both the oil and water saturated rocks, the error of the distance determined proved to be of 2.3%.