Research Of Logging Interpretation Method In Reservoir Of The Chang-9 Reservoir In Jiyuan Area

The previous exploration targets of Jiyuan area are mainly concentrated in Yan'an formation and the upper reservoir of Triassic section.The Chang-9 reservoir is the mainly successive formation for reserve growth.The reservoir belongs to secondary reconstructing deposit and has complex accumulation mechanism;the oil is not continuous and Oil-bearing abundance is low in the area.So far,the level of exploration and development in Chang-9 reservoir is low and the understanding of Chang-9 reservoir is not deep enough.In terms of well logging,the main difficulties are as such:fast changing formation water salinity,heavy inner formation heterogeneity,initial oil saturation of reservoir heavily affected by reservoir lithology,physical property,water and oil-bearing characteristics,water came from High resistance formation,oil came from medium and low resistance formation,oil and water layer hard to identify.By 2013,logging interpretation coincidence rate was only 62%.Based on the exposed problems in actual logging production,chang 9 reservoir in jiyuan area as the research object,rock physics experiments as the basement,reservoir parameter calculation as the core,and logging new technology comprehensive evaluation as a guide,This paper carried out the following 5 aspects of the research,i.e.(1)standardization of logging data,(2)research on the reservoir logging response characteristics and the correlation of five kinds of geophysical parameters,(3)fine modeling of reservoir parameter according to sanding belt and orientation,(4)identification method of reservoir oil-water and study on the lower limit of reservoir,(5)analysis of the influence on capacity by cracks.According to the researches,The following results are obtained after research: the variety law of lithology,physical property,water and oil-bearing characteristics in Chang-9 reservoir and the relationship between the crack development position and degree and the capacity were figured out;logging interpretation model about reservoir parameters such as porosity,permeability,saturation was established based on the distribution form of sand belt and the variety law of formation water in three sand belt with four different directions;measures such as differential recognition method,standard water layer comparison method,density &resistivity,acoustic &resistivity,?SP/RT&POR crossplot method,oil and water layer identification technology with the combination of logging and log data and the evaluation technology of oil and water layer by high resolution array induction,were used to establish the oil and water layer identification method,to set standard of reservoir lower limit,and to form a comprehensive log evaluation method which was appropriate for Chang-9 reservoir in Jiyuan area.The above research results played an important role in the evaluation Wells and development Wells,It had achieved good application effect.The advantages are as follows:(1)high accuracy reservoir parameters model based on the distribution form of sand belt in different directions was establish to meet the reserve calculation error requirements;(2)four oil-water layers with the total thickness of 8.6 m were newly found by the second fine interpretation with old well logging data;(3)with the lately forty well logging data,the interpretation coincidence rate was effectively increased to 81.75% and the interpretation accuracy rate was greatly improved.