Induced polarization frequency sweeping logging instrument in deep, middle and shallow small-power well

Abstract

The invention discloses an induced polarization frequency sweeping logging instrument in deep, middle and shallow small-power wells. A probe short joint, a direct-current power source short joint, a measuring control short joint, a communication short joint, a first emitting electrode, a second emitting electrode and a ground control unit are included; the probe short joint, the direct-current power source short joint, the measuring control short joint and the communication short joint are sequentially connected from bottom to top; the lower end of the probe short joint is connected with the first emitting electrode; the upper end of the communication short joint is connected with the second emitting electrode; the first emitting electrode and the second emitting electrode are forward andreverse direction emitting electrodes; the probe short joint comprises a first measuring electrode, a second measuring electrode and a third measuring electrode which are sequentially arranged from bottom to top; and the ground control unit is connected with the second emitting electrode through a cable. An electrode system of redundant measuring parameters of a probe part of an induced polarization logging instrument in the original logging field is simplified, a deep, middle and shallow measuring electrode system is increased, and induced polarization measuring in different deep, middle andshallow investigation depths achieved.

Description

technical field [0001] The invention belongs to the field of well logging instruments, and relates to an induced polarization scanning frequency well logging instrument in deep, medium and shallow low-power wells. Background technique [0002] In the field of petroleum logging tools, there are two main branches of induced polarization tools, constant pressure induced polarization logging tools and constant current induced polarization logging tools. The emission voltage of the constant-voltage induced polarization logging tool is a constant voltage. Considering the influence of the wellbore and the influence of mud resistivity and temperature, it is difficult for the acquisition end circuit to accurately acquire current signals, so the constant-current excitation pole is adopted. Chemical logging tools are more practical. The induced polarization logging tools in the petroleum field all use fixed charging and discharging time to measure the induced polarization potential. ...

AI Technical Summary

Problems solved by technology

The advantage of this is that continuous constant-speed measurement can be realized. The problem is that for different formations and lithologies, the induced polarization time is not consistent, and it cannot reflect the influence of different frequency resolutions on induced polarization logging.

In order to realize the large-scale exploration function in this field, the transmission power of well-ground induced polarization and ground-well induced polarization can reach 10KW~20KW, or even higher power. To be placed on the ground, just lead the emitter electrode to the downhole through the cable. The single-core current of the imported seven-core cable in the existing petroleum logging field is about 1.5A at most, and the impedance is 30Ω / km. To achieve 15A ~ 20A The current is transmitted to the downhole, and the electromagnetic coupling interference is strong

Images