Study Of Logging Technical Evaluation For Beach-bar Sand Reservoir

The bar sandstone from shallow lake environment of Shengli Oil Field has the characteristics of thin bed thickness, low porosity and low permeability. This kind of reservoir now becomes the main targeting area for exploration.In the past, because of the limitations for petroleum equipment and technique, the logging curves can not effectively reveal the hydrocarbon bearing formations and can not identify this kind of reservoir correctly and efficiently. As a result, the reservoir potential has been underestimated for a long time. Based on the core analysis, lab test and image logging, combined with the mud logging and well test, the recognization of bar sandstone reservoir has been enhanced and a series of evaluation methods have been made, which depend on the full use of conventional logging and image logging. The exploration and development economic benefit have been enhanced accordingly.In this thesis, the Upper Sha 4 member in Gao89 block in Shengli Oil Field has been studied. The typical lithological combination of bar sandstone has been established through detailed analysis of well logging and core data. The well logging data has been standardized based on the whole area cross well correlation. Micro-resistivity image logging(FMI) with 5mm high resolution has been used to study the different features of different formations.With this study, the FMI images can be calibrated by core data and conventional logging data can be in turn calibrated by FMI images. With the mud logging and well test data, necessary corrections have been conducted on GR, Sonic and Resistivity logging. As a result, the calculation accuracy on shale content, reservoir porosity and water saturation have been enhanced. By means of walsh function, scattered vertical response function, and vertical resolution match between relatively higher and lower vertical resolution logs,the bed resolution of conventional logging has been increased significantly, which lays down the basis of reservoir recognization and reservoir parameter calculations.According to the petroleum geological reservoir knowledge, the lithology, porosity and permeability, logging characters and effective thickness of reservoir have been researched in Gao89 block of Shengli Oil Field. The logging identification criteria of lime-siltstones from oil bearing zone, abnormal pressure zone and normal pressure zone have been set up. Based on the above research and criteria, the relations between well logging data and core analysis data have been studied and the reservoir parameter calculation models have been established by regression methodology. The bar sandstone reservoirs have been evaluated comprehensively and three categories have been identified according to the lithology and physical property of the reservoir. The horizontal and vertical distribution trends of the reservoir sandbody have been summarized and well logging evaluation has been enhanced with the much higher interpretation correctness. This plays an very important role in reserve estimation and registration.In this thesis, the method of calibrating conventional logging by core data and image logging data have been brought forward. With this method, the resolution of conventional logging has been enhanced. The effective thickness cutoff values of well logging in bar sandstone reservoir has been studied. we first find that both the positive and negative difference between micro resistivity logs(ML) are sensitive to reservoir properties, and based on this the new method of reservoir recognizing, an new method has been founded.