Method for evaluating stratum permeability by acoustic logging while drilling

Abstract

The invention discloses a method for evaluating stratum permeability by acoustic logging while drilling. The method comprises: conducting monopole acoustic logging while drilling in a depth interval;establishing a simplified Biot-Rosenbaum while-drilling model considering an equivalent instrument; selecting a non-permeable layer, and calibrating an equivalent instrument modulus; carrying out wavefield separation to obtain a direct stoneley wave form, and simulating a theoretical direct stoneley wave form without permeability influence; calculating frequency shift and time lag of theory and actual measurement respectively, and solving an objective function to obtain a permeability value of the depth point; repeating the above steps until the whole depth interval is processed, and obtaining a stratum permeability curve in the processing depth interval. According to the method, due to the real-time performance of measurement while drilling, the impedance effect of a mud cake does not need to be considered. Compared with wireline logging, the sensitivity of the stoneley wave phase velocity to the permeability in the while-drilling environment is higher, so that the inversion result is more real and accurate. By adopting the simplified Biot-Rosenbaum while-drilling model, the inversion efficiency is greatly improved, and the method has an important practical application value forfield data processing.

Description

technical field [0001] The invention belongs to the field of applied geophysical acoustic logging, and in particular relates to a method for evaluating formation permeability by using monopole Stoneley wave logging while drilling. Background technique [0002] Permeability is one of the important parameters to characterize reservoir properties. The evaluation of reservoir permeability is of great significance to correctly understand reservoirs and guide oil and gas exploration and development. However, the existing permeability evaluation methods are restricted to varying degrees in production and application. So far, no method can completely replace other methods. In practical applications, the permeability results obtained by various methods are generally compared and verified. In order to get more accurate formation permeability. Therefore, it is still necessary to propose an accurate and effective new method for permeability evaluation. [0003] As for the most direct ...

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Problems solved by technology

However, the impedance value of the mud cake is an unknown quantity, and it is difficult to determine the accurate impedance value during actual measurement

[0006] How to evaluate the permeability accurately and effectively has attracted more and more people's attention, but the current permeability evaluation methods are difficult to meet people's needs

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