Over-metal sleeve magnetosonic resistivity imaging logging method and device

Abstract

Provided is an over-metal sleeve magnetosonic resistivity imaging logging method and device. A magnetic body distributed in a well is used for generating magnetostatic fields on stratums at the periphery of the well, and an ultrasonic probe array launches ultrasonic waves to a certain area of the stratums at the periphery of the well. Ultrasound stimulation and the magnetostatic fields mutually affect to stimulate lorentz force and alternating voltage, an equivalent current source is formed in a target area, and further electromagnetic fields are generated on the stratums at the periphery of the well. Voltage signals and ultrasound echo signals are propagated to the well through the stratums after measurement, obtained information is processed based on an electromagnetism reciprocal theory, the resistivity of the target area is obtained, and resistivity image reconstruction of the periphery of the well is further achieved. By using device in the method, a magnetic body system, the ultrasonic probe array and a measurement coil serve as one portion of underground instruments to be arranged in a well cylinder. Radial movement and longitudinal movement of an ultrasound focal zone are achieved by using whole longitudinal extraction of the ultrasonic probe array, electronic control technology and instruments in the well cylinder, and stratum resistivity imaging of an over-metal sleeve is further achieved.

Description

technical field [0001] The invention relates to a method for measuring the resistivity distribution around a well in the field of petroleum exploration, in particular to an imaging logging method for formation resistivity around a metal casing well. technical background [0002] Oil exploration logging is called "the eyes of the petroleum industry". With the help of logging technology, petroleum geologists and petroleum development engineers can understand important information such as porosity, permeability, and oil and gas saturation of the formation around the wellbore. [0003] In order to achieve stable and high production in oilfields, each oilfield is faced with the difficult problem of effective remaining oil evaluation and fluid dynamic detection in metal casing wells. The resistivity of the metal casing is usually 10 times the resistivity of the tested formation. 7 ~10 10 times, the magnetic permeability is 10 to 200 times that of the tested formation, and the hu...

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Problems solved by technology

Since the weak formation electromagnetic signal will be shielded by the huge casing signal, this brings many difficulties to the realization of resistivity logging through metal casing, including the detection of nanovolt-level weak signals, and the interference of various interference signals on weak effective signals. influence, later data processing and interpretation difficulties, etc.

The above-mentioned difficulties lead to the unsatisfactory use effect of the existing metal casing resistivity logging tools, which are mainly reflected in the large measurement error, the limited effective measurement range of formation resistivity, and the measurement effect is seriously affected by the salinity of formation water ( It is not suitable for use when the salinity of formation water is lower than 5KPPM), the vertical resolution and measurement accuracy are not ideal, the cement sheath has a great influence on the formation resistivity measurement results, and the logging data interpretation method is not mature, etc.

[0005] Although the two types of logging technologies, electrical and acoustic, are very mature, electrical imaging or acoustic imaging alone cannot achieve resistivity imaging through metal casings well, and existing cased well remaining oil evaluation technologies cannot Meet the requirements of logging engineering and the actual needs of oilfield development

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