Research Of Log Evaluation For Oil Shale Formations In Southern Songliao Basin

In recent years, active exploration and development of oil shale and other unconventionalnew resources is an effective way to alleviate the world’s energy shortage problem. Songliaobasin contains a wealth of oil shale and gas resources, Qingshankou and Nenjiang oil shaleconstitute the main source rocks of southern Songliao basin. How to distinguish oil shale fromother formations, how to achieve accurate calculation of oil rate and other issues have become akey issue in oil shale exploration and development, so the use of logging methods in recognitionof oil shale and accurate calculation of oil rate have practical significance.At present domestic and foreign scholars are more concentrated in terms of regionalgeology, metallogenic regularity, etc., on oil shale in Songnan area,but withnot laboratorymeasuring of related petrophysical parameters. Here, considering the level of existing laboratoryinstruments, by measuring the parameters of density, porosity, acoustic velocity and dielectricconstant, the petrophysical properties of oil shale are summarized to provide references for thephysical parameters of oil shale in other areas and subsequent shale reservoir logging evaluation.Based on the difference of oil shale and other rocks in log responses, a sample databaserepresenting different lithologies in the study area has been created. Bsaed on support vectormachines, naive Bayes discrimination and Fisher discrimination method these three methods,considering the differences in principle and other aspects to establish " multiple integratedlithology identification method”. From the application effect of this method in the study area,lithological identification results are consistent with lithology logging, average recognitionaccuracy has reached86.3%, so oil shale can be effectively distinguished from other rocks bythis method.Building petrophysica model is an important part of oil shale log evaluation, this paper hasachieved the organic shales model proposed by Dicman Alfred in2012and oil shale reservoirporosity in Songnan area has been calculated by this model. Oil shale four-component model hasbeen achieved to calculate component content in the area; based on the four-component model,"oil shale five-component model" has been proposd, that is "non-clay mineral+organic matter+clay mineral+free oil+free water ", by building acoustic time, natural gamma responseequation, combined with sand-mudstone conductive equation, response equations ofcomponents in the model has been established, using simulated annealing algorithm implementsto achieve the content calculation of the various components, the average relative error betweencalculated and laboratory porosity is0.11.Total oil rate calculation model of oil shale has been set up.The oil rate calculation isdivided into two parts, first establishing a computational model of the oil content of organicmatter in Songnan region,the oil rate of free oil is calculated by the result of the five-component model, and finally the total oil rate of oil shale is achieved by adding the two parts, the total oilrate in study area is about10%of the average.The "Comprehensive log evaluation system for oil shale formations in southern SongliaoBasin" and related oil shale log evaluation software have been established and the actual oilshale data in Songnan area are processed.