Study On Reservoir Characteristics And Main Controlling Factors Of Dengying Formation In Northern Hebei Province

This dissertation focuses on the Dengying formation reservoirs in northern Yunnan and Guizhou provinces,researches on sedimentary facies characteristics,reservoir rock characteristics,reservoir physical characteristics and diagenesis,established diagenetic sequence,and unraveled the formation and conservation-mechanism of the reservoir in Dengying Formation in northern Yunnan and Guizhou provinces.Through these processes,the paper finally gets some significant results below:Analyzed sedimentary phases of Dengying Formation in northern Yunnan and Guizhou provinces.It is characterized with the restricted platform facies in deposit of the Sinian Dengying dolomite,it divided into two sub-phase:localized tidal flat,restricted lagoon.according to the advance and retreat of sea water,it could be divided into some micro facies:algal grain bank,algal flat,lagoon,grain bank,Hybrid Ping.In particular,the development range of tidal phase intertidal algae dolomite and tidal grains dolomite is the most widely used;the development range of the lagoon,beach and tide are also very well,especially in the late regression,the development of tidal is very well,evaporation platform facies is develop in local.The rock types of Dengying Formation are complex and diverse:algal-crumbs dolomite,algae lumps dolomite,the crystalline dolomite,fine crystalline dolomite,argillaceous dolomicrite,arenaceous dolomite,siliceous dolomite.In particular,algal-laminated dolomite is the important types,and crystalline grain dolomite?grain crumbs dolomite are followed it.Algal dolomite?grain crumbs dolomite mainly developed in Dengying 4.Dengying 2,crystalline grain dolomite are widely developed in Dengying formation.The main types of reservoir space of Dengying Formation are:?primary porosity,inter-crystal pores,inter-particle pores,residual inter-crystal pores.residual inter-particle pores;?secondary pores,inter-crystal dissolution pores,inter-particle dissolution pores,great dissolution pores;?fissures,structural fissure,diagenetic pressolution fissure,corroded fissure.Reservoir properties are very poor,porosity and permeability is low of the Dengying Fomation;the porosity of Deng 2 is better than Deng 4,it mainly caused by dissolution pores?cavities of algal dolomite in Deng 2,the permeability of Deng 4 is better than Deng 2.The types of capillary pressure curves shapes mainly include IV,the pore structures are based on fine pores and medium-sized roared,they are bad pore structure.According to the results of log interpretation,the reservoirs of-ZZdy3 is not developed,the reservoirs of Z2dy2 is well developed,the reservoirs of Z2dy4?Z2dy1 is general developed in the study area.The reservoirs of Z2dy2 is well developed,the overall thickness is very large,rnnainly distributed in the between 50-120m,shaped distribution as the long axis from northeast to-southwest.The Diagenesis of Dengying Formation are very complex and diverse,the main types of diagenesis include:?Constructive diagenesis,dolomization,denudation,recrystallization,fracturing;? destructive diagenesis,cementation,compaction and pressure solution,recrystallization,filling,silication.When the deposits of carbonate rocks were sedimentary in the Dengying,the reservoir develops lots of' inter-crystal pores,inter-particle pores,algal bonding grid pores,the primary porosities are up to 30%?70%.After diagenesis in growing period,sediments basically consolidate into rocks,primary porosity is reduced iinto 10%O/O?25%.in the Shallow burial stage,the main types of diagenesis include cementation,compaction and pressure solution,silication,the effective porosity of rocks plunged to below 10%.In the epidiagenesis stage,cementation,compaction and pressure solution;in the late diagenetic stage,cementation,compaction and pressure solution,recrystallization,dissolution.After the transformation of diagenesis,the effective porosity down to about 5%.The formation of dolomite reservoir in Dengying Formation is mainly controlled by deposition,diagenesis,multi-stage tectonic movements.The depositional environment controlled reservoir's development,it is the material basis for the formation of the reservoir,Among them,the inter-tidal algae dolomite and under tidal crystalline dolomite is more conducive to the development of reservoir.Diagenesis control the formation of reservoirs,secondary porosity,It is the main controlling factor of reservoir's development,lots of inter-crystal pores?dissolution pores caused by recrystallization and dissolution are the main reservoir space of Dengying reservoir.Cracks caused by many tectonic movement increases the permeability of the reservoir,diagenesis and tectonic movement greatly changed the reservoir properties of reservoir.