Research On Lithology Characteristics And Diagenesis Of Sandstone Reservoirs Of The Upper Paleozoic In Eastern Ordos Basin

Based on detailedly observing and describing the core of the Upper Paleozoic in Eastern Ordos Basin, this thesis do the systemic research of provenance,the distribution of sedimentary facies,lithology characteristics. pore structures characteristics and diagenesis style to sandstone reservoirs of the Upper Paleozoic in Eastern Ordos Basin, Combined with various analytical and measurement methods including identification and quantitative statistics of normal thin sections and casting thin sections under microscope, grain size analysis, cathodeluminescence, electron scan microscope (ESM), capillary pressure, well log and existing research data. There are some results as below:The sediments of oddment rock in this area originating from Yinshan-Alashan old land which lie to the northern part of Ordos Basin in the period of the Upper Paleozoic. The same direction of provenance reflects the good succession since Benxi stage to Shanxi stage. Based on the source direction, depositional characteristics and studying in the fields, barrier coast facies is identified in Benxi stage; delta front is identified in Shanxi stage, thereinto barrier island is identified in part of the south in Shan2 stage.It was shown that the sandstone of Benxi formation is mainly quartz sandstone, followed by clastic sandstone and detrital silicarenite; the sandstone of Shanxi formation is mainly detrital silicarenite, followed by quartz sandstone and clastic sandstone. The particle size is variety, the psephicity is mainly hypo-angularity to hypo-roundness. Particles supported, porosity typed cementation。The content of interstitial material is low-rise in the mass but changing broadly, while the amount of cements observed is same as matrix in Shanxi formation, but more in Benxi formation。It was also shown that the main types of pores are remnant intergranular pores, intergranular dissolved pores, framework grain dissolved pores and micro-pore and micro-fractures.The diagenesis types in study area mainly include mechanical compaction, pressure solution, cementation,dissolution and rupture. The sandstones of Benxi formation are in the A-B stage of middle diagenesis while part of them are in the late diagenesis; The sandstone of Shanxi formation are in the B stage of middle diagenesis generally while part of them are in the late diagenesis. The compaction and cementation are the main reasons of destroying the porosity and permeability, while the dissolution protects the protoplast intergranular pores and produces secondary solution pores, It plays some good effects for the physical property of reservoir.