Through-casing formation resistivity continuous measurement method

Abstract

The invention discloses a through-casing formation resistivity continuous measurement method. The through-casing formation resistivity continuous measurement method includes the steps that a ground instrument sends a control signal to a transmission circuit, the transmission circuit continuously motivates a transmission coil to generate electromagnetic induction responses, and a receiving coil receives the waveform of the responses; an artificial circuit and high-accuracy AD amplify the waveform of the responses, AD conversion is carried out after filtration, sampling sites are switched, dataof the original waveform of the responses is obtained, and after being encoded through telemetry cartridges, the data is transmitted to cables; the cables transmit the waveform data to the ground instrument and drive a downhole instrument to move at a constant speed, and then continuous measurement is conducted on the strata of different depths; the ground instrument converts encoding signals intolevel signals, and then the level signals are restored into data; a computer receives the restored data, and then the restored data is processed to obtain resistivity curve values of the strata. According to the through-casing formation resistivity continuous measurement method, a transient electromagnetic field is activated in a transient mode, electromagnetic induction signals generated by a transient vortex field are measured, continuous measurement of stratum resistivity is achieved through continuous transmission, and continuous stratum resistivity curves can be obtained.

Description

technical field [0001] The invention belongs to the technical field of special instruments for measuring physical parameters of casing well formations and evaluating lithology in petroleum engineering well logging construction, and more specifically relates to a method for continuously measuring resistivity of casing formations. Background technique [0002] In the process of petroleum development, the continuous measurement of formation resistivity is very important. People can analyze the electrical difference of the formation, the depositional environment and the relationship between oil and water through the continuous change of the logging curve. In open-hole wells, most of the logging curves are continuous, and the variation trends of the logging curves obtained by different logging methods are similar as a whole, but there are differences in subtle points or interfaces. The differences in the shape of these curves and the logging values ​​can be used to Evaluate the r...

AI Technical Summary

Problems solved by technology

However, the measurement of formation resistivity in a cased hole encounters the influence of the casing, because the conductivity and magnetic permeability of the casing are high, and the formation resistivity logging faces great difficulties. The existing through-casing formation resistivity measurement The direct current method is used in the well, the electrode is pushed against the inner wall of the casing, and the casing and the formation are powered through the electrode. After the current is stable, the current and voltage flowing through the formation are measured to obtain the resistivity of the formation. This method can only be used for fixed-point measurement. Logging The timeliness is low, the most important thing is that the continuous formation resistivity curve cannot be obtained

Images