Studies of Mid-Jurassic Thin Beds in Conditions of Presence of the Anomalous Bazhen Suite (Shirotnoe Priobje Case)

Authors propose guidelines for investigation of thin reservoirs in conditions of overlaying amplitude anomalies noise. The Mid-Jurassic rocks were deposited in different sedimentary environments. The lower part represents fluvial bodies deposited inland and in delta plain, and the upper part is transgressive shoreface sand. Small thicknesses of the sand bodies do not allow to be resolved in seismic due to the vertical resolution limitation. However, these bodies can be laterally resolved and mapped. The presence of coal beds and overlaying anomalous section of the Bazhen Suite complicates the interpretation. The proposed solutions include creation of the mask of the Bazhen Suite amplitude anomalies, combination of attribute analysis, inversion, Bayes probability classification and well data. The overlapped Bazhen mask with maps can filter the influence of the anomalous Bazhen Suite. As a result of the Bayes classification, the effective thickness map was formed. Shapes of the various attribute anomalies underline the lateral distribution of sand bodies and help in tracing of those. Well data provided facies control of the identified sand bodies. The applications of the proposed methods cover Shirotnoe Priobje region and other fluvial systems around the world, which are prospective in terms of discoveries of hydrocarbon accumulations.