Formation Mechanism And Reservoir Significance Of Diagenetic Zeolites In Permian Glutenite Reservoirs At Zhongguai Area Of The Northwestern Junggar Basin,NW China

Zeolite minerals are closely related to hydrocarbon accumulation,especially reservoirs,and are the focus of current petroleum geology research.However,the genetic mechanism and specific reservoir significance are still controversial,which is a difficult point in the field of research.Taking the Permian glutenite in Zhongguai area,northwest margin of Junggar Basin,where zeolite minerals are widely developed in recent exploration as an example,the formation mechanism and Reservoir Significance of zeolite diagenetic minerals in glutenite reservoirs in the study area are comprehensively analyzed by means of mineralogy,petrology,sedimentology and geochemistry.(1)The types and spatial distribution of zeolites are clarified.There are six kinds of zeolite minerals developed in the study area,including laumontite,heulandite,analcime,clinoptilolite,scolecite,and natrolite.Among them,laumontite is widely developed,heulandite is found in some areas,analcime is a little,occasionally clinoptilolite,scolecite,and natrolite are found.The distribution of zeolite minerals is divided into plane zones and vertical zones.(2)Two types and five controlling factors of zeolite cements were identified.Zeolite minerals in the study area are mainly cemented,accompanied by a small amount of zeolite as metasomatic origin.The metasomatic origins are debris alteration,matrix alteration,plagioclase albitization and the transformation of zeolite minerals.The composition of parent rock,sedimentary facies and stratum depth control the development of zeolite minerals.(3)The influence of zeolite minerals on reservoir quality is clarified.In the early stage,the cementation of zeolite minerals occupied a large number of intergranular pore in the reservoir,which greatly reduced the porosity of the reservoir;however,the cementation of zeolite minerals supported the grain skeleton and effectively inhibited the reservoir compaction;laumontite was easy to dissolve to form secondary pore,which improved the reservoir porosity.(4)The growth pattern of high-quality reservoir of Glutenite with zeolite-bearing diagenetic mineral is revealed.The growth and dissolution of zeolite minerals are the key to improve reservoir physical properties in the study area.Combining the growth and dissolution patterns of zeolite minerals,a high-quality reservoir development model based on sedimentary facies control and dominated by diagenesis control has been established,which is of great significance for guiding oil and gas exploration and development.These understandings can be used as a reference for the next exploration and development in the study area,as well as for other zeolite reservoir geology and reservoir formation studies at home and abroad.