Comprehensive Evaluation of PCA-based Engineering Sweet Spot Logging in Tight Sandstone Reservoirs -- Example of Y96 Well in Long 7 Section of Tiezhuzi Block in Ordos Basin

Under the geological conditions of sandstone reservoirs in the long 7 sections of Tiezhuizi block, with the increase in the depth of burial and the complexity of geological structure, it leads to the status quo of generally low production capacity of horizontal wells. In the face of this challenge, the optimisation of fracturing engineering desserts is particularly difficult. To cope with this challenge, this study is dedicated to finding a high-precision method for quantitative evaluation of reservoir engineering sweet spots. In this study, principal component analysis was adopted to comprehensively and meticulously analyse nine key engineering sweet spot factors, including core density, elastic modulus, Poisson's ratio, and perimeter pressure. The screening criteria of eigenvalue > 1 accurately identified 2 factors that mainly affect the engineering sweet spot. The cumulative explained variance of these two principal components reaches 91.199 %, which almost covers most of the information. By analysing the positive and negative correlations between the factor loading coefficients of these 2 principal components affecting the engineering sweet spot, these two principal components were identified as the damage resistance factor and the external confining stress factor, respectively. By analysing the rock number composite scores of the principal components, the specific locations of the dominant reservoirs were precisely located, and the dominant reservoirs were located at 2085-2095m, 2035-2045m, 1955-1965m, 1975-1985m and 2005-2015m. This result is more conducive to the realisation of the project, with high accuracy.