Method for predicting transverse wave time difference by using logging data

Abstract

The invention discloses a method for predicting the transverse wave time difference by using logging data, and belongs to the technical field of petroleum logging. According to the method, a transverse wave time difference curve is constructed by using longitudinal wave time difference and density in an oil layer and/or a water layer section, a natural gamma relative value is calculated out by using natural gamma logging, and then a relevant relationship between the natural gamma relative value and the transverse wave time difference is established. A formula for predicting the transverse wavetime difference is established by using conventional logging data, so that accurate acquisition of the transverse wave time difference in any stratum (including oil, gas and water layers) is realized, the transverse-to-longitudinal wave time difference ratio and the Poisson's ratio which reflect properties of a reservoir fluid and parameters such as the Young's modulus, the bulk modulus and the shear modulus which reflect mechanical properties of a reservoir rock are calculated by using the transverse wave time difference, and the purposes of effectively identifying the gas layer and quantitatively evaluating the mechanical properties of the reservoir rock are further achieved.

Description

technical field [0001] The invention belongs to the technical field of petroleum well logging, in particular to a method for predicting shear wave time difference by using well logging data. Background technique [0002] A transverse wave is a wave whose direction of propagation is perpendicular to the vibration direction of the particle. Shear wave time difference is an important parameter for reservoir lithology, fluid identification and calculation of rock mechanics parameters, especially in the division of gas and oil (water) layers and calculation of rock mechanics parameters, the role of compressional and shear wave time difference is particularly important . According to the P-wave and S-wave time differences, parameters such as the S-wave time difference ratio, Poisson's ratio, and volume compressibility coefficient reflecting the difference in reservoir fluid properties (mainly gas and oil (water)) can be calculated. At the same time, parameters such as Young's mo...

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Problems solved by technology

[0005] (1) Since the parameters that need to be input in the empirical formula method include density, P-wave transit time, resistivity, etc., it can only be applied in key wells

In most development wells or old wells, only compressional wave transit time and resistivity curves are measured, but density measurement is not performed, which makes it unable to be widely used

At the same time, in the gas layer section, since the compressional wave time difference and density are affected by the gas in the reservoir, the shear wave time difference predicted by using it is also affected by the gas layer, and the prediction results have large errors and cannot be used

[0006] (2) The Xu-White theoretical model method requires many input parameters, and most of the parameters are difficult to obtain directly, and need to be calculated from other data

It leads to a large amount of calculation, low calculation efficiency, and more calculation processes increase the multi-solution and error of the calculation results

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