Method for synchronously realizing seismic lithofacies identification and quantitative assessment of uncertainty of seismic lithofacies identification

Abstract

The invention relates to a method for synchronously realizing seismic lithofacies identification and quantitative assessment of uncertainty of the seismic lithofacies identification. The method comprises the steps of determining the type of the lithofacies and performing logging lithofacies definition, establishing a rock physical response relation between logging physical parameters and elasticity, establishing a probability statistical relation between the lithofacies and logging attributes, establishing the probability statistical relation of well-seismic scale elasticity parameters and constructing the statistical relation of the lithofacies and the seismic scale elasticity parameters, inverting the information of the probability distribution of the elasticity parameters of a target layer, obtaining the lithofacies probability information of the target layer by combining the inverted probability information of the elasticity parameters of the target layer and the statistical relation of the lithofacies and the seismic scale elasticity parameters, obtaining the maximum posterior probability solution of the lithofacies distribution according to the probability information of the lithofacies and outputting final model parameters. The method is capable of quantitatively characterizing the uncertainty of each link of lithofacies identification and the propagation and accumulation characteristics of the uncertainty in the lithofacies identification process, and also capable of performing uncertainty analysis on the seismic lithofacies identification; as a result, the reservoir evaluation risk is reduced; in short, the method is wide in application range.

Description

Technical field [0001] The invention relates to the field of seismic exploration of oil and gas fields and shale gas, in particular to a method for simultaneously realizing seismic lithofacies identification and its uncertainty quantitative evaluation. Background technique [0002] Reservoir lithofacies identification is an important method for reservoir evaluation and characterization. The process of using seismic data to invert reservoir lithofacies distribution information is called seismic lithofacies identification. Seismic lithofacies recognition is an effective method to obtain internal images of underground media and describe the distribution information of reservoir lithofacies, and can provide basic constraint information for reservoir geostatistical modeling. The main steps of seismic lithofacies identification include seismic data rebound, well seismic scale matching, petrophysical modeling and logging lithofacies definition. When the lithofacies are directly defined...

AI Technical Summary

Problems solved by technology

The traditional method of reservoir lithofacies identification can only obtain uniquely determined lithofacies distribution information, ignoring the influence of uncertainty factors in each link in lithofacies identification on the final result, and unable to evaluate the uncertainty of its inversion information, which increases the Risks of late stage reservoir characterization

[0003] In short, the main problems in the current traditional seismic lithofacies research are: 1. The traditional method uses the elastic parameters of seismic inversion to directly predict lithofacies information, and cannot consider the influence of seismic inversion uncertainty on lithofacies identification

2. It is necessary to integrate logging and seismic information in seismic lithofacies identification, but the difference in the observation scale of the two data will inevitably introduce errors

Traditional methods cannot consider the impact of its errors on lithofacies identification

3. The traditional method establishes the petrophysical relationship of reservoir physical properties and elastic parameters directly through the petrophysical model, ignoring the influence of uncertain factors such as rock heterogeneity and mathematical approximation of the petrophysical model

4. In the definition of lithofacies in well logging, the traditional method directly establishes the deterministic relationship between lithofacies and physical parameters or elastic parameters based on logging data, and cannot characterize the corresponding relationship between lithofacies and various parameter combinations in the definition of lithofacies. Uncertainty

5. The traditional method obtains the only determined reservoir lithofacies distribution information, and its inversion results cannot be used as constraint information to serve subsequent reservoir geostatistical modeling

The traditional method only transmits the optimal inversion solution of the upstream link, but cannot quantitatively transmit the uncertainty information of the inversion result of the upstream link, which ultimately makes the uncertainty of the inversion result unable to be evaluated, increasing the risk of reservoir evaluation

Images