The Analysis on Coal-Based Fluvial Facies Modelling by Using Sequential Indicator Algorithm and Object-Based Method for CBM Project in Australia

摘要

The coal-based fluvial facies modelling is used to descript to coal-swamp fluvial geological depositional system in three dimension(3D)space in order to capture the uncertainty for field development.More than 600 more wells with logs and lithology information are located in an area of 1,2000 km.Facies model of sequential indicator algorithm(SIS)and object-based calculation(OBS)were run to create multi-cases in between wells.However,the applicability and advantage/disadvantage of these two methods in coal bed methane(CBM)project have no knowledge,which hampers the numerical simulation modelling.This paper explored the capabilities of the standard SIS and object-based methods in order to generate and choose the proper model fit the purpose for CBM development in Australia.Fluvial frame facies concept was built based on basin geology setting,log information,core photo and lithology description.Six coal members and their sublayers in all wells have been defined and correlated according to sequence stratigraphy,which gave the solid basis for structure model construction.Two variogram-based geostatistical modelling were established by using pixel-based arithmetic(SIS)and object-based methods(OBS).Different ways to condition the models created multi-cases in each model for measure the uncertainty.Comparison of two model results can be drawn from modelling methods,facies shapes,condition parameters and other property parameters etc.Comparison results show that OBS resulting bodies looks better.But these two algorithms are not so perfect.SIS is easier to condition to well data but no facies relationship.While OBS resulting bodies are real-like zigzag-shape fluvial depositional models,which seems to be more complicated but honor data with more choices.OBS could be chosen to gain an updated model for field development plan in the future.And the multipoint facies simulation(MPFS)which could integrate with the merits of two models can be tried further tried.Two algorithm models have Integrated all known well data with geological facies concept resulting in different and thousands of realizations.These results reveal the uncertainty of this complex fluvial geological setting and give birth of a new suggestion for further optimization future CBM development in Australia.