Novel shear wave velocity prediction method suitable for low-porosity sand shale stratum

Abstract

The invention discloses a novel shear wave velocity prediction method for a low-porosity sand shale stratum. The method includes the steps that firstly, logging parameters of a reservoir stratum section are input, and one-dimensional median filtering processing is conducted on actually measured longitudinal wave data; according to the size of porosity of a current depth point, the initial shear wave velocity of a small-porosity stratum section, the initial shear wave velocity of a large-porosity stratum section and the initial shear wave velocity of a middle-porosity stratum section are respectively calculated; according to the initial shear wave velocities, a firstly-predicted initial shear wave velocity is calculated through back calculation; the firstly-predicted initial shear wave velocity serves as initial shear wave velocities, the back calculation process is repeated so that back calculation accuracy is improved, and then the finally-predicted shear wave velocity is acquired and recorded; the predicted shear wave velocity of each logging depth point of the reservoir stratum section can be acquired until all the logging points are calculated. The method has the advantage that the shear wave velocity prediction effect of the small-porosity stratum section is good.

Description

technical field [0001] The invention belongs to the technical field of logging shear wave velocity inversion, and relates to a new method for predicting shear wave velocity suitable for low-porosity sand-shale formations. Background technique [0002] (1) Seismic shear wave: shear wave is a wave in which the forward direction of the seismic wave is perpendicular to the vibration direction of the particle. The shear wave has its inherent advantages in judging lithology, fractures and oil and gas. [0003] (2) Shear wave prediction: predict (or estimate) the shear wave data of the target well or other wells based on known logging data or other data of the target well or other wells. [0004] (3) Pore structure: refers to the geometric shape, size, distribution, connectivity and configuration relationship between pores and throats of rocks. [0005] (4) Logging curve: the formations around the wellbore are tested by various logging instruments, and the curves of parameters suc...

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Problems solved by technology

[0023] The purpose of the present invention is to provide a new method for predicting the shear wave velocity of low-porosity sand-mudstone formations, which solves the problem of the small-pore intervals in the three-low characteristic gas fields with low porosity, low permeability and low abundance in the prior art. For the problem that the prediction effect of shear wave in the small pore interval is poor

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