Study Of The Relationship Of Four Characteristics Property For He8Reservoir In Cui Jiapo, Northern Ordos Basin

Reservoirs of low porosity and low permeability are the focus of oil and gas exploration and development in Ordos Basin. Especially in the field of gas reservoir identification, the high clay content, low gas saturation and the gas influence to the recognition system itself reduces the accuracy of the interpretation. It is difficult to identify the low porosity and low permeability reservoir with logging service, especially in studying and analysising the relationship of four characteristics property, the key one of log interpretation. Therefore, improvement of the accuracy is very important for parameters calculation and identification of gas reservoir.Member8of Lower Shihezi Formation of Mid-Permian is the typical gas reservoir of low porosity and low permeability in Cui Jiapo area. Management and analysis of the data of lithology, physical property, gas testing, log, laboratory, analysis of multiple correspondence and restricting relationship between these factors via mathematics, physics and computer explanation. Consequently, the relationships between lithology, physical properties, gas saturation and electricity, are presented distinctly in mathematics equation or chart performance. On the basis of electrical data, clear relationship between the various factors, parses the lithologic physical information. Then reservoir properties and containing gas information are researched accurately combined with regional geological features.Electrical standards of mudstone and sand stones are obtained from the figure of lithologic and electrical intercourse, which determines the layer coarse-grained sandstone with high levels of wide distribution, porosity and permeability characteristics. The equation of acoustic travel time (△t), porosity ((?)), and permeability (K) is gained with the use of linear regression and the crossplot approach in order to calculate the well reservoir sandstone porosity and permeability values. The reservoir gas is identified qualitativly with three pore overlap, ratio and the (?)p-(?)w method, and identified quantitativly with rock electrical test, Archie’s equation and gas saturation (Sg). The porosity ((?)), the electrical data, the gas saturation (Sg) and gas test data are caculated to construct cross plots and confirm the classification criteria of the gas and water layers, water layers and dry layer. Finally, the He-8-layer segment is predicted with gas identification method and gas well test data. It concludes that he-8member has five potential blocks, which all show the traits of stable mudstone, thick sand stones, high porosity and permeability, excellent gas well test result.