A Simultaneous Realization Method of Seismic Lithofacies Identification and Quantitative Evaluation of Uncertainty

Abstract

The invention relates to a method for synchronous realization of seismic lithofacies identification and its uncertainty quantitative evaluation, including: determining the lithofacies type, carrying out logging lithofacies definition; establishing the petrophysical response relationship between logging physical property parameters and elasticity; establishing lithofacies Probabilistic and statistical relationship between facies and logging attributes; establish the probability and statistical relationship of well-seismic scale elastic parameters, construct the statistical relationship between lithofacies and seismic scale elastic parameters; invert the probability distribution information of the elastic parameters of the target layer; combine the inversion The probability information of the elastic parameters of the target layer and the statistical relationship between the lithofacies and the seismic scale elastic parameters are used to obtain the lithofacies probability information of the target layer, the maximum a posteriori probability solution of the lithofacies distribution is obtained according to the lithofacies probability information, and the final model parameters are output. This program quantitatively characterizes the uncertainty of each link of lithofacies identification and its propagation and accumulation characteristics in the lithofacies identification process. It can carry out uncertainty analysis on seismic lithofacies identification, reduce the risk of reservoir evaluation, and has a wide range of applications.

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 quantitative uncertainty evaluation thereof. Background technique [0002] Reservoir lithofacies identification is an important means of reservoir evaluation and characterization. The process of using seismic data to invert reservoir lithofacies distribution information is called seismic lithofacies identification. Seismic lithofacies identification is an effective method to obtain internal images of underground media and describe reservoir lithofacies distribution information, which 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 lithofacies are directly define...

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

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