Interwell sedimentary sequence research method based on Markov chain mathematic model

Abstract

The invention provides an interwell sedimentary sequence research method based on a Markov chain mathematic model. The method comprises: counting frequency number on each kind of lithofacies transferring to another kind of lithofacies, establishing an upward transfer frequency matrix N; transferring the upward transfer frequency matrix N to a random sequence transition probability matrix S, and transferring the upward transfer frequency matrix N to an upward transition probability matrix P; according to the random sequence transition probability matrix S and the upward transition probability matrix P, obtaining a single well state difference value matrix K; simplifying the upward transition probability matrix P, to obtained a simplified upward transition probability matrix P'; and establishing a sedimentary sequence mode through the simplified upward transition probability matrix P'. For a stratigraphic section which is complex in lithological changes but has certain deposition law, the interwell sedimentary sequence research method based on a Markov chain mathematic model can predict change rules of lithological characters on a vertical direction of adjacent domains of the well according to lithological changes of a drilled well.

Description

technical field [0001] The invention relates to the technical field of oilfield development, in particular to a method for studying interwell deposition sequences based on a Markov chain mathematical model. Background technique [0002] Markov chain is a Markov process that occurs in discrete time intervals and discrete state spaces. Its original model was proposed by A.A. Markov in 1907. This method is commonly used to model modeling in queuing theory and statistics, and can also be used as a signal model for entropy coding techniques, such as algorithmic coding. The most recent application of Markov chains is in geostatistics for stochastic simulations of two- to three-dimensional discrete variables based on observational data. [0003] In recent years, scholars at home and abroad are also exploring the use of Markov chain mathematics to analyze sedimentary facies. According to geological theory, the sedimentary lithology at a certain moment is only related to the lithol...

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Problems solved by technology

For complex stratigraphic sections with certain sedimentary rules, the vertical facies model of structural analysis is a random process, which conforms to the mathematical model of "Markov chain". For example, Wu Anbin et al. (1995) applied the Markov chain method to the West In the analysis of the Devonian sedimentary facies in the ore field, a simplified probabilistic structural section was established, and the sedimentary environment and facies were interpreted; However, in previous studies, only the Markov chain mathematical model was used to analyze the sedimentary facies types of continuous coring data, and no corresponding sedimentary sequence model was established.

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