Research On The Method Of Well-logging Evaluation Of Complex Sand Resevivor In Nanpu Depression

With the petroleum exploration and development deepening, exploration target has been diverted from simple high amplitude structural hydrocarbon reservoir to complex reservoir. The Hydrocarbon logging response of complex reservoir is character with complexity and stealthiness, which leads to great difficulty in well logging recognition and evaluation. Therefore, the research on effective well logging evaluation in complex reservoir provides advantageous support to exploration development and has greatly important significance.Based on research objectives of Guantao and Dongying formation in Nanpu Sag, this paper comprehensively analyzes the data of mud logging, drilling, coring, and well logging, and further studies the interpretation and evaluation method in complex reservoir.By analyzing petrophysical experimental data and four properties ' relations.We found that the reservoir in Nanpu Sag is character with great variation of lithology and physical property, strong heterogeneity, low and variable formation water salinity. The complex lithology and physical property are considered as major factors that lead to complex electric property. The complex water disturbs the electric comparing basis of oil-gas layers and water layers. The complex lithology results in high bound water saturation and cation exchange capacity, and then enhances conductivity of oil-gas layers. Thin sand shale interbedding reduces the sensitivity of electric logging response to true formation resistivity.According to the strong heterogeneity of complex reservoir, this paper introduces flow unit theory to classify reservoir and build logging interpretation models. The reservoirs in Nanpu Sag are divided into four types through flow unit index method, and the permeability model based on flow unit has obviously improved interpretation precision, which indicates the rationality of flow unit classification. The flow unit index model is built with GR, AC and DEN in coring intervals, and applied into non-coring intervals to classify the flow units of Guantao and Dongying reservoir. The interpretation accuracy of water saturation model, irreducible water saturation model and oil and water layer identification chart based on flow unit are improved obviously.The Archie parameters m and n vary in a large range and the lithology, physical properties and water are key factors which affect the Archie parameters greatly. The m and n models are built on cation exchange capacity, pore structure and formation water resistivity according to different bed sets, which improves the selection method of Archie parameters.The conventional rock electricity experiment get the irreducible water saturation with centrifugation,we think it is higher than its actual value.At present,we think the irreducible water saturation that get from mercury intrusion method is accurate.In view of the disadvantages of mercury intrusion method,we analysis the effect of bark of bluish dogbane and correct the experiment data,finally get reasonable data.Through analyzing mud logging information and well logging information comprehensively, the oil-water layer identification chart is established using multi-information fusion technology. For different logging environments, the sensible parameters reflecting fluid property are researched, and the differences between oil-gas and water layers are enlarged by reasonable collocation of characteristic parameters after analyzing the effects of lithology, irreducible water saturation and gas logging characteristic. The interpretation standards are quantified. Application results shows that the oil-water identification charts obtain good results.