## Quantitative prediction of reservoir characteristics based on inverse modeling theory

**LIU Qian;YIN Xing-Yao;LI Chao;School of Geosciences,China University of Petroleum(Huadong);CNOOC Research Institute;**

Reservoir parameters are used to describe the reservoir characteristics quantitatively.It′s important to predict reservoir parameters in reservoir characterizations.This paper proposes a method to predict reservoir parameters based on inverse modeling theory.In the framework of rock physics theory,this paper focuses on parameter prediction with inverse modeling in the reservoir parameter domain.First of all,an accurate rock physics model was established according to the characteristic of the target reservoir.Then,in the reservoir parameter domain,elastic parameters at every point were calculated to form elastic data cubes.Isosurfaces of the elastic data cubes can be calculated with the Marching Cubes algorithm.The reservoir parameter prediction was implemented by the isosurface intersection of three different elastic parameters in the same domain.Based on these,an extended inverse modeling method has also been proposed.It contains two main parts-inverse modelings in two different reservoir parameter domains and the domain transformations of the inverse modeling results.Different kinds of elastic parameters make different contributions to the accuracy of inverse modeling.An applicability evaluation method was proposed for the choice of elastic parameters as input data.A model data and a real example have been chosen to test the inverse modeling method.In the model test,there are 54 points with different reservoir properties in the original model.A rock physics model was established and several elastic parameters were calculated.The prediction result was consistent with the original model data.In the real example,the proposed method was applied to a set of data from Eastern China.A site-specific rock physics model was built according to the well data.The inverse modeling method was first validated by the application on the well data.Inverted elastic parameters were also taken as the input data of inverse modeling.The accuracy of the inverse modeling with inverted elastic data was also high enough.Based on the theory of rock physics modeling,an extended inverse modeling method in reservoir parameter domain has been proposed to predict reservoir parameters quantitatively in this paper.The accuracy of the rock physics model is the foundation of the inverse modeling.The choice of input data is very important to the stability of the inverse modeling results.So the applicability of the input data should be evaluated before the inverse modeling.Tests on model data and real data have proved the rationality and applicability of this method in the prediction of reservoir parameters.

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