The Influence Of Middle Carboniferous Paleostructural And Paleogeomorphic Features On The Reservoirs Of The Ma 5 Sub-member _1-4 In The Eastern Sulige Area

The east of Sulige Gas Field in Ordos Basin mainly develops at the top of the Ordovician weathering crust.The middle carboniferous,as an important period for the end of Supergene weathering denudation,karstification and tectonic deformation,also for the beginning of the coal source strata's deposition.Focus on the middle carboniferous9 paleostructure-paleolandform of Mawu1-4 sub-segment and it's effect on reservoir,makes full use of the present basic geological data and gas testing,then carried out stratigraphic and sedimentary micro facies' classification and correlation,and uses the impression method to restore the study area's palaeogeomorphology,paleolandform.Detailed analysis the paleostructure's influence on reservoir,then further explored the paleostructure-paleolandform's controlling effects on Mawu1-5 reservoirs.Several conclusions can be drawn as follows:1.It's not a suitable way to choose the residual thickness method to recovery the palaeogeolandform of study area with the nose-like paleostructure characteristics,and chooses the impression method with 9#coal seam as the time-maker strata is not only unaffected by the ancient structure,but also can achieve better effect.2.In order to have a better understanding of the influence of karst landform on reservoir,then on the basis of the Benxi restore formation thickness,each three geomorphic units further subdivided into micro-highland,micro-platform,micro-depressions,and found that they are associated with the advantages and disadvantages of natural gas' distribution3.The stratigraphic framework and formation thickness of Mawu1-4 remains stable in historical evolution,and it will reflects the paleostructure characteristics when uses the impression recovery thickness plus Mawu1-4 formation's thickness.The study fouded that the ancient folding is useful to avoid weathering erosion and preserved as a whole,it also can assist in the development and extension of the ancient groove,besides,it restricts the selection of paleogeomorphological restoration methods.4.The paleostructure-paleolandform affects the upper Paleozoic coal measure source focal thickness,conducting migration conditions and karst conditions in the study area.For well studying the influence of two factors on reservoir physical properties,then matching the four geomorphic and the paleostructural units into four types as follows:?micro-highland+inherited-highland,?micro-depressions+inherited depression,?micro-platform+inherited deflection,?micro-depressions erosion,among them,type ?has a poor karst condition,which is not conducive to the migration and accumulation of natural gas,type?and type.has a similar karstic condition on the micro-depressions'same side,and The reservoir phy-sical properties either good or bad on the same side in the transition zone(type?).At last,Quantificating the Mawu1-4 favorable area into three part,according to the preservation condition,the micro platform which adjacent to the micro-depression area can be divided into the first and the second class,and the place of poor preservation without micro-depression is the third class.In this pape,the study of paleostructure-paleolandform and the spatial configuration can help for the predicting.