Research On The Restoration Of The Ordovician Paleo-geomorphology And Its Influence On The Reservoir In The Central Area Of ??Sulige Gas Field

The Sulige Gas Field in Ordos Basin mainly develops at the top of the Ordovician weathering crust.In this paper,regarding the middle of Sulige region Majiagou formation palaeogeomorphology recovery as the research object,it makes full use of the present materials that concerning to drilling data,logging data,analytical experiments and gas testing,and then carried out stratigraphic classification and correlation.This article combined the impression method and the residual thickness method to restore the study area palaeogeomorphology.Detailed alysis of the reservoir features and reservoir controlling factors of the study area and then further explored the paleogeomorphological and its controlling effects on reservoirs.Several conclusions can be drawn as follows:1.The preservation of the fifth member of Majiagou formation varies a little from place to place.In general,the layers in north and west part of Sulige region have been subjected an intensive erosion,the layer exposed more older,and the southeastern parts relatively intact.That the overall geomorphic characteristics of the study area is high in the east low in the west,the uneven distribution of stratigraphic thickness.2.The main lithology of reservoir in the study area contains anhydrite tuberculosis and pore or residual solvent mould powder crystal dolomite,and pure powder crystal dolomite.Reservoir space types are mainly residual pore and intergranular pore that after being half a pack of anhydrite TB dissolve die.The best Reservoir property is Ma513,following good is,Ma5a1,Ma522.3.Comparing the pros and cons of the methods of paleogeomorphological recovery,then this study mainly uses the impression method and the residual thickness method to recovery the palaeogeomorphology of study area.It all locals on the Karst Highland,based on the thickness of Benxi and Carboniferous formation,the Karst Highland can be subdivided on the high.platform and the depression;according to the Benxi and Carboniferous formation thickness,the Karst Highland can be subdivided on the highland,platform and the depression;then on the basis of the Benxi restore formation thickness,each three geomorphic units further subdivided into micro-highland,micro-platform,micro-depressions.4.The karst palaeogeomorphology of study area controls the karst reservoir development and distribution of natural gas production,it's the main control factor of reservoir in May1-4.Adjacent to the erosion of hollow micro-platform area is a favorable area of the karst reservoir development,because the dolomite and gypsodolomite subjected to weathering and leaching is easy to form the good solution porosity reservoir.According to the sedimentary characteristics,palaeogeomorphology characteristics,reservoir characteristics and controlling factors Majiagou formation in the middle of Sulige region,find out the geological factors which are suitable for the weathering crust reservoir:palaeogeomorphology is the main factor of M51-4 reservoir and then putting forward the reservoir favorable zone is mainly annular discontinuous distribution in M512 strata exposed region and adjacent to M513 or M511 strata exposed region.