Azimuth acoustic logging device and measurement method while drilling

Abstract

An azimuthal acoustic LWD apparatus is sequentially provided with a centralizer, a transmitting circuit, transmitting transducers, an acoustic insulator, a receiving transducer array, ultrasonic transducers and a receiving circuit on a drill collar. The azimuthal acoustic LWD apparatus is capable of operating in a dipole mode or a unipole mode, to cover all the sectors around a wellbore by adopting a fixed time interval measurement mode or an alternating time interval measurement mode according to a relationship of an interval between measurement times and a rotation speed of the apparatus, thereby achieving azimuthal acoustic LWD. This apparatus overcomes problems that the fixed time interval measurement mode may not cover all the sectors and further may not achieve azimuthal acoustic imaging in a case where the rotation speed and the interval between measurement times are under certain conditions.

Description

technical field [0001] The invention mainly belongs to the technical field of logging while drilling, and in particular relates to an azimuth acoustic logging device and a measurement method while drilling. Background technique [0002] Acoustic logging is one of the important measurement methods used to evaluate oil and gas reservoirs and guide the safe production of oil fields. For example, in rock mechanics analysis, acoustic data can provide pore pressure, rock strength, formation invasion, in-situ stress orientation and size, etc. Information; in petrophysical analysis, acoustic data can be used to evaluate formation lithology, porosity and identify pore fluid types. In recent years, the sonic logging while drilling technology measures the compressional wave and shear wave velocity of the formation while drilling, reduces the time occupied by the drilling machine at the well site, and judges the drilling efficiency and risk management in real time, which can meet the ne...

AI Technical Summary

Problems solved by technology

[0010] The present invention provides an azimuth acoustic logging device while drilling and its matching measuring method. The device can work in dipole mode or bias pole mode, solving the problem that the existing azimuth acoustic logging device adopts a single bias polar emission. The receiving structure has the problem of strong drill collar wave interference, and the sound system installed in the centralizer has a large drilling noise interference problem

Measurement method According to the relationship between the measurement time interval and the rotational speed of the azimuth acoustic logging device while drilling, the fixed time interval measurement mode or the alternating time interval measurement mode is adopted to cover all sectors around the wellbore to realize the azimuth acoustic wave measurement while drilling and solve the problem of fixed time interval measurement. In the time interval measurement mode, when there is a specific relationship between the measurement time interval and the rotational speed of the instrument, the technical problem that the azimuth measurement cannot be realized

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