Research On Reservoir Characteristics And Control Gas Action In The He-8 And Shan-1 Formation In Etuokeqi Area Of Ordos Basin

Basing on examination and analysis of cores, thin section, physical properties, grain size analysis, cathodoluminescence, SEM, gas test data, and combining with experimental data of x-ray diffraction, fluid inclusion temperature, and others, we have comprehensively analysised and studied the reservoir, diagenesis and distribution of gas and water in the He-8 and Shan-1 formation in Etuokeqi area. On the basis of above, the paper have analysised the controlling factors on development of reservoir and effects of reservoir on the distribution of gas and water, then predicted the favorable exploring block. The comprehensive research holding that:The rock types of sandstone reservoir are mainly quartz sandstone, less lithic quartz sandstone and the lest lithic sandstone in study area. The detrital composition of sandstone reservoir generally has higher quartzose, higher lithic and lower feldspar content. The separation of sandstone particles are mediocre. The argillaceous matrix, kaolinite, ferruginous calcite, and siliceous are the mainly interstitial materials. Except slightly differences among small layers, reservoir pore characteristics are basically identical;pore types of sandstone are primary intergranular pore,secondary dissolution pore,kaolinic intergranular microporosity and microfissure,among those secondary dissolution pore and kaolinic intergranular microporosity are main; permeability distribution is mainly dominated by the degree of pore development, and there is positive correlation between permeability and porosity; reservoir character is tight reservoir of low porosity and low permeability; porosity and permeability increases gradually from Shan-1 formation and He-8 formation, so reservoir physical properties of He-8 formation is relatively superior, has higher porosity and permeability.The gas reservoir and gas wells of He-8 formation and Shanl formation are mainly distributed the east of Jier-Sulige-Habuhawusu and gas-water well in its west. The numbers of gas wells and water wells.The reservoir in Shanl formation are mainly continuous distributive single and thiner gas layers, average thickness of gas layer is 5 meters; thickness of gas layer in He-8 formation is thicker than in Shanl formation, average thickness of gas layer is between 10-15 meters, the distribution of main production layer in He-8 formation is stable,continuous and banding. There are great positive correlations among the rock types, physical properties and reservoir space of reservoir, but those have weaker control effect on distribution of gas and water in this study area; sandstone's physical properties of gas layer and gas-water layer is better than of water layer in He-8 formation and Shanl formation, this show physical properties of reservoir obviously control the enrichment regularity of gas, simultaneously permeabilit's heterogeneity of reservoir is strong in study area,and the zones of weaker heterogeneity have more pure gas wells and gas-water wells,and have higher single well production than the zones of stronger heterogeneity,so permeabilit's heterogeneity of reservoir also obviously control the enrichment regularity of gas.Then, comprehensively analysis on sedimentation, diagenesis, character of porosity and permeability, pore types, connectivity and continuity of effective sandstone,and so on, we comprehensively have classified to reservoir in study area, and proclaimed that favorable exploration areas have distributed in sand belt of channel and distributary channel with better physical properties, comparative developing primary intergranular pore and secondary dissolution pore.