Application of Logging Data to the Sediment Size-Grading Inversion

Rock particle-size and grading are the main features of sedimentary rocks, and also the main indicators to evaluate the deposition environment and ancient geographical analysis of the sediment. Meanwhile, it's also the controlling factors that influence sediment's diagenetic environment and physical property. Because of the widely use of PDC bit, there is a greater error between logging lithology and size grade, which has restricted the further development of geologic research. By utilizing GR, CNL, DEN, DT and resistivity curves, we abstract the parameters M, N, which is sensitive to particle size and lithology, and another parameters-the ratio of deep resistivity and shallow resistivity, combining with the particle-size analysis data of core. Then, we establish the inversion model for particle size of sediment through logging geology analysing. The field data processing and contrast of core data has proved this model feasible in inverting the sedimentary particle-size, and providing a sequential size graded profile.