Fine Sedimentary Cycles And Heterogeneity Of Qingshankou Formation In Gulong Sag,Songliao Basin (NE China)

In recent years,conventional oil and gas exploration has become less and less,which has prompted geologists to change their targets.Fine-grained sedimentary rocks account for about 2/3 of the earth's crust and become an important substitute for conventional oil and gas exploration.But at the moment,there is no unified standard for fine-grained sedimentary rock in cycle division,the heterogeneity also has a certain difficulty.It has become important unconventional oil and gas exploration zones in West Gulong sag within K1qn1.The development of dark mudstone can not only as a good hydrocarbon source rocks for the traditional reservoir,but also has important exploration value of itself due to the large thickness of dark mudstone and high abundance of organic matter,good type.The Qingshankou Formation in Gulong sag as an example(focus on the first section of Qingshankou formation),summarize the results of previous research,using logging data and wavelet transform method for the cycle identification and classification of fine grained sedimentary rock.And the typical wells in the study area were analyzed for continuous sampling,The pattern of sedimentary environment evolution was confirmed in different cycle.At the same time we put forward a new scheme of lithofacies classification that applicable to the area according to three standards of the abundance of organic,sedimentary tectonic and rock mineral composition.The distribution of vertical lithofacies filling sequence and lithofacies distribution in plane of the study area are determined.In order to evaluate the reservoir heterogeneity,organic heterogeneity and sedimentary heterogeneity of the 2 aspects were rasised to evaluate the K1qn1 plane reservoir heterogeneity.Source rock quality,reservoir quality and engineering quality of the 3 aspects were put out to evaluate the vitical reservoir heterogeneity in Qingshankou formation.Controlling factors were confirmed through the oil test.The results show that the plane heterogeneity and vertical heterogeneity are strong in Gulong sag.There are great differences in electrical properties,physical properties,oil content and mechanical properties in different lithofacies.The main control factors of plane oil in SSC1 layer are the average value of TOC,the inflection point,Bd and dimension 2.The main control factors of plane oil in SSC2 layer are the average value of TOC,the inflection point,the variation coefficient and Hurst index.The main control factors of plane oil in SSC3 layer are the average value of TOC,the coefficient of variation,and dimension 2.The main control factors of plane oil in all Qingshankou formation are the number of non clay layers and the cumulative thickness.The evaluation results show that the four conditions of lithofacies,TOC,anisotropy index and brittleness index are the important factors that affect the oil content of the reservoir in vertical heterogeneity.It provides a basis for the new and old drilling development.The mathematical methods of ?log R,single fractal,multifractal and logging modeling were used to study the reservoir heterogeneity of shale reservoir.It provides a new way to study the reservoir heterogeneity of the mud shale reservoir.