Fine Stratigraphic Correlation Methods and Application of Horizontal Wells of Strongly Heterogeneous Porous Bioclastic Limestone Reservoir

Abstract

Fine stratigraphic correlation is one of the most fundamental and vital tasks in reservoir characterization, and quantitative evaluation of reservoir parameters. However, it is an enormous challenge in fine stratigraphic correlation of horizontal wells of porous bioclastic limestone reservoir with strong heterogeneity due to poorer log responses reflecting bedding plane compared to siliciclastic reservoir. This paper concentrates on the study for fine stratigraphic correlation of horizontal wells, Kh reservoir of A oilfield with horizontal wells of 75% in total well numbers, Middle-east, which developed in horizontal wells modes. First and foremost in this study, optimally sensitive data, including DT (MSFL/RHOB), GR (NPHI), ILD, and direction change of trajectory, were selected through integrated analysis of detect depth and vertical resolution of down-hole tools, which can more reasonably reflect the bedding plane of horizontal wells; Then typical pattern figures were established for down-hole tools passing through the bedding plane in 4 different modes, and on the basis, the realistic standard charts of log responses were built for 4 sub-layers in views of its unique character; Next, sub-layers including thinner SPZs were divided based on the established standard charts through fine stratigraphic correlation between horizontal and vertical wells, verified and further modified based on trajectory distribution in structure mode. The sub-layer division from log data of horizontal wells were proved to be more useful for petrophysical evaluation and production performance analysis through permeability comparison of SPZs from log re-interpretation using old and new sub-layers.