# A New Method of Geological Modeling for the Hydrocarbon Secondary Migration Research
## 3 A Novel Object Stochastic Modeling Method  
Stochastic reservoir modeling is an essential technique utilized to simulate the behavior of subsurface hydrocarbon reservoirs by incorporating random variations in geological properties [15]. This method involves generating multiple realizations of reservoir properties through statistical techniques like conditional simulation or geostatistics. Subsequently, numerical reservoir simulation models are employed to simulate fluid flow within the reservoir. The outcomes of these simulations enable the estimation of reserve uncertainty, the optimization of field development plans, and the assessment of exploration and production risks [63]. Geological data from diverse sources, including drill logs, geological maps, and geophysical data, are processed using geostatistical techniques to construct a comprehensive three-dimensional model of the subsurface. This model facilitates the visualization of the distribution of geological features and properties such as the lithology, porosity, and permeability [64].  
Traditional geological modeling methods often suffer from assigning facies types or physical properties randomly to gridded structural frameworks based on well and seismic data in pixels. This can result in over-characterization or fuzzy boundaries of reservoir heterogeneity [65]. Object-based modeling has emerged as a popular alternative, defining and modeling geological objects or entities, such as faults and lithological units, as discrete 3D volumes or objects [66]. However, this approach has limitations, particularly when dealing with more than two microfacies or object internal heterogeneity, due to the complexity of algorithms and implicitly generated fractions within pixel-based random modeling.  
To overcome these limitations, this study introduces a novel object geological modeling approach that enables a more detailed and accurate representation of reservoir architecture and heterogeneity, as well as the better integration of various types of geological data. This approach directly generates reservoir bodies with definitive geometry, including the length, width, thickness, and their quantitative relationships. By setting geometric parameters of modeling units and adhering to sedimentary laws, this method restores the understanding of geologists, allowing for the reconstruction of spatial geometric characteristics, internal property features, and the inter-relationships of geological elements, such as strata, facies, and structures, under geological sedimentary conditions to the greatest extent possible. To capture the heterogeneity within sand bodies, a new geological modeling method defines unit sand bodies for different sedimentary systems. Internal heterogeneity is identified and incorporated within each unit sand body, while their distribution in the strata reflects three-dimensional spatial heterogeneity. As a result, the heterogeneity at various levels of the migration system can be reasonably expressed.  
The development of a conceptual reservoir geological model involves establishing the primary framework for the distribution of reservoir sand bodies in three-dimensional space. This framework, also known as a skeleton model or sand body distribution model, forms the foundation for constructing the reservoir's physical property model or static model. The physical property model, encompassing parameters such as porosity and permeability, relies on the skeleton model as a starting point and incorporates rock physical property data to quantify the model and determine the spatial distribution of various reservoir physical property zones. This represents the crucial second step in the reservoir modeling process.