Reservoir Sedimentary-Digenesis And Characteristics Pore Structure Of Lower Shihezi Formation In Shie Area, The Ordos Basin

Ordos basin is a large scale superimposed basin who have began to evolutes independently since the Mesozoic, It has rich mineral resources and is the most important energy and heavy industry base of our country. Shie area is located in the north of the Ordos basin which is our study area, who has across the two first class structure unit of Yishan slope and Yimeng uplift, it has a total area of appomixtely2.8×104km2.Lots of Study found that the upper Paleozoic is rich of natural gas, based on these study results, our study have integrated used the sedimentary, petrology geophysics and geochemistry etc, and combined with the previous research results on regional tectonics and sedimentary system to achieve the goals of find out the deposition sedimentary digenesis process and its influence to the reservoir properties.(1) Starting from the sedimentation, firstly, under the generally recognized iconic formations of study area, standardization wells of geophysical logging and sedimentary cycles to detailed the sequence stratigraphic division of sedimentary and strata in the study area.(2) Combined with previous research data we have discussed on the study of sedimentary environments, sedimentary faces and provenance, etc. in detail. Through detailed analysis of the composition of the components of the original detrital material, geochemistry characteristics of original sedimentary aqueous media, from physical, environmental and power conditions of digenesis on the occurrence and development of digenesis in the study area to do a detailed analysis and a certain degree of recovery.(3) Three sections of Lower Shihezi formation of the Upper Paleozoic digenesis of Shihezi reached to digenetic B period. Digenesis degree is high and complex, with compaction, cementation and dissolution mainly, which carbonate cementation and feldspar dissolution is particularly evident; divided digenetic evolution and quantitative analysis the influence degree to the reservoir and recovered the reservoir porosity evolution, various of digenesis on analysis found out compaction and cementation is the main destructive digenesis (compaction rate and cementation rates which averaged47%and74%), presence of secondary dissolution pores so that the holes increased permeability (dissolution rate of49%); combined porosity and permeability characteristics of the study area and digenetic factors, study area can be integrated into six divisions digenetic faces.(4) mainly with reservoir capillary pressure curves and pore structure characteristics under the thin section of reservoir rocks, from the intensity of digenesis, digenetic faces, porosity evolution of the study area, we have do a detailed analysis on the microscopic pore type, pore structure roar degree of matching and a combination of correlation between the parameters and reservoir characteristics proved reservoir characteristics and types of microscopic holes roar.(5) combine the study area tectonic, sedimentary ancient geographical environment, digenesis and pore structure of the quantitative relationship between reservoir properties of reservoir of Shie region we have done a comprehensive quantitative assessment. Eventually, the reservoir of Shie area have been divided into four levels, then draw and analyzed the characteristics of hierarchical classification superimposed plane distribution under conditions of study area sedimentary faces, sand thickness and reservoir properties.