Due to high depletion of classical reservoirs of oil and gas fields, there is an increasing need to study and model reservoirs with a complex mineralogical and structural composition, as well as marginal areas with deteriorated reservoir porosity and permeability. The methods of attribute analysis and rock physics modeling are widely used to predict lithology and reservoir properties for such reservoirs.
A common approach to rock physics modeling is to build a fluid-mineral model and then build a rock physics model based on the fluid-mineral model. This is due to the fact that the fluid-mineral and rock physics models are usually built by different specialists, and the tools for solving these problems in commercial software are separated. When building a fluid-mineral model for a complex section, there is often not enough well logging data to determine the main mineral composition. To obtain a solution, the total number of mineral components should not exceed the number of equations. In this case, simple equations based on acoustic logging data such as mean time are used. Rock physics modeling is based on complex theoretical models for elastic moduli, i.e. there is a contradiction with the equations used to build the mineral model using acoustic logging.
In order to maintain a more detailed mineral component composition and have self-consistent mineral and rock physics models, a joint solution approach has been implemented. Moreover, due to the limited number of logs, the components of the mineral composition are combined, which requires fine-tuning of the tabular constants. Therefore, a mechanism for automatic adjustment of model parameters and fine-tuning (under constraints) of tabular petrophysical constants is implemented in the joint mineral-rock physics modeling.
References
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