| Panguliang area of Jing’an oilfield is located in the North Shaanxi Slope, middle part of Ordos Basin. The exploration and development prospect of study area is favourable. But it also has some problems such as the reservoir enters in the stage of middle water cut, the velocity of water has increased, the characteristic of water drive is not obvious, the production in the middle part of the reservoir is rapidly falling with the exploration and development in the study area in recent years. So it is urgent to carry out the research of description in Chang6 reservoir of the Panguliang area and the reasonable developing technology policy which is based on the refined research of geology and comprehensive evaluation of reservoir.In this paper, the author has classified and evaluated the reservoir comprehensively with the integrated use of a variety of interdisciplinary theory and method after the word of detailed description to Chang6 reservoir in the Panguliang area, by the organic combination of the logging information and data, core observation and some kinds of test methods. Acknowledge is the following:1) Structure is gentle in the study area and small nose-like structure uplift develops on the basic of homocline trended from east to west.2) The research suggest that Chang6 reservoir develops delta front sub-facies of braided river includes three kinds of microfacies such as underwater distributary channel, estuarine bar and underwater interdistributary bay; 3) The rock types are mainly arcose sandstone and lithic arkose sandstone, and the interstitial material are primary the chlorite and carbonas in study area.4) Mesopore and fine pore whose contents are respectively 35.9% and 28.9% predominate in the Chang6 reservoir. The most important reservoir space and main pore types in target zone are intergranular pore and feldspar dissolved pore. Content of intergranular pore increases while feldspar dissolved pore is so little difference with the depth.5) Throat types is given priority to medium throat and average of throat radius is 2.75μm, content is 53%. Fine throat whose content is 30% occupies a secondary position.6) Porosity is commonly from 11% to 14% and permeability from 0.1 mD to 1 mD. average of Porosity and permeability is 12.35% and, lower limit is 9% and 0.1 mD. Chang6 reservoir belongs to low porosity-ultralow permeability reservoir.7)The property of Chang621+2 is the most favorable, which gradually becomes worse to the upper and lower sides. Property of northeast area close to provenance is better.8) Diagenesis types are more abundant. Mechanical compaction, cementation, pressure solution and dissolution dominate.In conclusion, on the basis of all kinds of geological analysis above, the author has classified the Chang6 reservoir as three types with the method of K-Means clustering analysis. In those types of the Chang6 reservoir, the reservoir types of G and F are mainly distributed in the middle of the underwater distributary channel and estuarine bar that the best reservoir performance of type is G, and then the type F. The reservoir of type P is mainly distributed in the underwater interdistributary bay or the edge of underwater distributary channel and has the worst reservoir performance. The reservoir types of G and F mainly hold dominant position in the Chang621+2, while types of P and F in the Chang611 Chang612 and Chang623. |
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