Logging Evaluation Study On Low-Resistivity Reservoirs In The Northern Gulong Area Of Daqing Oilfield

The low-resistivity reservoirs is a special kind of oil reservoir, it is an one of the important goals in new reserves of old oil field, it is different from the conventional oil layer, Its resistivity does not match with conventional oil layer, the resistivity is very low, and is close to the shoulderbed's resistivity, even is almost similar with the water layer's resistivity. Therefore the identification and the development of low-resistivity reservoir have certain difficulty, in depth study and quantitative evaluation of low- resistivity reservoir is very necessary.The paper closely combined well logging, drilling core, well testing and otherwise data of northern Gulong area of Daqing Oilfield, through detailedly analysised and researched more than 200 wells in this region, had illuminated reservoir the basic geological features and logging curves features, analysised four character relations of low resistivity reservoir in this area; Compared lithology composition, physical property, electric property, microcosmic pore structure and fluid feature of conventional reservoir and low-resistivity reservoir, which analyzed the microcosmic mechanism and geologic origin of low-resistivity layers in Putaohua Group of Gulongbei Oilfield.In the respect of saturation model calculation, this paper had proposed four kinds of original oil saturation model for the Putaohua low-resistivity reservoir, In some regional which have data of sealing core drill, proposed to use the original oil saturation model which based on sealing core drill data; In view of the geological features which some areas of this regional have many oil/water in same layer, proposed to use relative permeability saturation model which based on porosity and RLLD/MSFL; In view of this regional widespread muddy and gray matter, proposed to use three elements conductive saturation model which was fit for all the region.In the respect of the fluid identification, introducted the concept of the instructions curves of the low resistivity genesis, constructed four feasible instructions curves which was shale content, median grain diameter, gray matter content, physical property etc, and had gave some quantitative discriminant criterions, in order to differentiate between low-resistivity oil layer and high-resistivity water layer; Further through gray correction, shaly correction and thin-layer correction of the resistivity in this field, proposed the SP-RLLD Electrical Plate which the resistivity was corrected; Based on the regularity of sectional oil-water interpretive chart, use sectional datas, geological multivariate statistical analysis technique, Bayes method to establish empirical model for oil and water qualitative discrimination; When had the new technology, gave full play to the advantage of fluid identification which used the nuclear magnetic resonance logging(NMR) and the array induction logging, according to the characteristics of low-resistivity reservoir.Use conventional logging and new technologies logging to establish comprehensive method to identify low-resistivity oil layer.The new methods was practical applied in northern Gulong area of Daqing Oilfield, which was testified practically and effedtively. the paper may also provide some important clues and methods to study low-resistivity reservoirs and provides the interpretation flow chart, the interpretation coincidence rate was significantly improved, and achieved the desired purpose. It may fully enhance the other oil field to further study in low-resisitivity reservoirs.