Research On Deep Buried Reservoir Characteristics In Qiaokou Area Of Dongpu Depression

Using the observation and description of core and casting thin section, and analysis on fluid inclusion as mean methods, with the use of collected date about mercury injection, petrophysical property and so on, this thesis researched the deep reservoir in Qiaokou Area, Dongpu Depression. Combined with the former research results, based on the analysis of regional geological background, we studied the diagenetic features, reservoir space characteristics and the controlling factors of reservoir development of the deep reservoir in Qiaokou Area.During the study, the features of the deep reservoir in Qiaokou are more clear:(1) The reservoirs are mainly composed of feldspar quartz sandstone with relatively low textual maturity. Siltstone is the main kind of stones developed and the grains are mostly fine-coarse silt. Fine grain sand and mudstone are rare in the study reservoirs. The content of matrix is low and the grains are mainly cemented by calcium cements.(2) There are various diagenesis such as secondary quartz overgrowth, cementation, Fe-carbonate metasomatism, compaction and pressure solution.(3) Because of the great depth of study reservoir, the primary pores are preserved relatively small under the strong diagenesis, the effective pores in deep reservoir are mainly mix pores and secondary pores.(4) The porosity of deep reservoir mainly between 5% and 10%, and the permeability mainly between 0.1×10-3μm2 and 1×10-3μm2, so the reservoirs belong to low porosity and low permeability reservoir. Porosity is found to be correlated with permeability. Compared to the reservoirs of same formation in other areas of Dongpu Depression, reservoirs here have better physical properties.According to the analysis on controlling factors of deep reservoir development, we can summarize thoroughly the formation mechanism of effective deep reservoirs, and then predict the distribution of deep high quality reservoirs. Through the comprehensive study, we find that there are many reasons control the development of deep reservoirs in Dongpu Depression, including hydrocarbon filling, distribution of abnormally high pressure, development of gypsolith and salt layers, distribution of microfractures, thickness and granularity level difference of mono-layer reservoir, and so on. These factors restrict and influence each other to make their relationship more complex. Based on this point, we study deep into the relationship between the development of deep reservoir and the main controlling factors, such as sedimentary environment, diagenesis and abnormally high pressure.On the basis of the research of the influence of abnormally high pressure on reservoir properties in Qiaokou Area, combined with analysis on reservoir features in detail, we establish classification and evalution standard of effective deep reservoirs.