Research On Tight Oil Reservoirs Logging Evaluation Based On Division Of The Formation Structure

Tight oil is short for the tight reservoir oil, it is stored in tight sandstone or tight limestone reservoir, belongs to unconventional oil and gas resources. Tight oil has unique characteristics, such as a small reservoir pore space, poor percolation, complex pore structure, strong heterogeneity, etc. so it is difficult to evaluate reservoir. Therefore, how to effectively use logging data to evaluate the tight oil reservoir is of great significance for the exploration and development.This paper first introduces the geological situation of the research area, analyzes the lithology、the physical property and the pore structure characteristics of tight oil reservoir in the research area. Then put forward the concept of the formation structure, analyzes Massive sandstone、Argillaceous sandstone、Sand mud interbed and Massive mudstone which are the main development four structures in the research area, and writes a program to automatically identify. identifying steps include: ① automatic layering of the logging curve; ② extracting the characteristic parameters which are reflecting the shape of the logging curves; ③by using Bayes identification method establishes the discriminant models of the formation structure to identify the formation structure. By using discriminant result establishes plane distribution diagrams of the formation structure, for looking for tight oil reservoirs dessert distributed to lay the foundation. In addition, according to the division of the formation structure, the porosity, permeability and saturation models based on division of the formation structure are established, they improve the accuracy of reservoir parameters calculation, and sealed coring saturation studies, and achieves good results. Finally by means of core, logging, oil test data to establish the tight oil reservoir the effectiveness limit standards, and through the analysis of the lithology、the physical property and the pore structure characteristics, the reservoirs in the research area are divided into 3 classes, analyses the effect of various parameters for reservoir quality, and ultimately through optimized porosity, permeability, movable fluid saturation, displacement pressure and the pore throat radius value of 5 parameters to construct a comprehensive reservoir classification index, by using this index to reservoir classification, reservoir classification results are compared with the results of the test oil, the higher the degree of agreement between the two, it illustrates the correctness of the reservoir classification.