Oil and gas well downhole casing string distributed optical cable whole process online stress detection device

Abstract

The invention relates to the technical field of stress detection devices for downhole casing strings in oil and gas wells, in particular to a whole-course online stress detection device for distributed optical fiber cables in downhole casing strings in oil and gas wells. The device comprises a Brillouin optical-time-domain analyzer, a coupled detection sub and at least four casings. The coupled detection sub is fixedly disposed between at least two pairs of adjacent casings. The remaining adjacent casings are fixedly installed together through couplings. During the process of stress testing for downhole casing strings, the device features capability of detecting deformation in the elasticity range, capability of online stress detection for normally serving casing strings, and capability of stress detection for downhole well-depth casing strings. Detection efficiency and detection range are increased greatly, so that technicians can be aided in optimizing practically required steel class and wall thickness of downhole casings in a certain section according to the obtained stress information, people can effectively judge safety of the downhole serving casing strings, and finally, comprehensive cost in oil and gas well development and production is lowered.

Description

technical field [0001] The invention relates to the technical field of an oil and gas well downhole casing string stress detection device, and relates to an oil and gas well downhole casing string distributed optical cable full-process online stress detection device. Background technique [0002] At present, the strain and stress detection technologies of downhole casing strings in oil and gas wells mainly include MFC multi-arm caliper detection technology, ultrasonic downhole imaging detection technology and magnetic detection technology. The plastic deformation is detected, but the deformation of the casing string in the elastic range cannot be detected, and it cannot be applied to the strain detection and stress detection of the casing string of oil and gas wells in normal service. At the same time, using the above detection technologies, instruments must be lowered into the oil and gas wellbore, thus interrupting the normal production of oil and gas wells. The traditiona...

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Problems solved by technology

[0003]The present invention provides a whole-process on-line stress detection device for distributed optical cables in downhole casing strings of oil and gas wells. In the actual use of the downhole casing string stress detection device of oil and gas wells, it is impossible to detect the deformation within the elastic range, the online stress detection of the casing string in normal service, and the stress on the casing string at the full depth of the downhole. The problem with testing

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