Advanced Petrophysical Log Suite Support for Acid Stimulation Design Optimization

Abstract

Enhanced oil recovery methods, i.e. acid stimulation, are widely used to increase well productivity in oilfield development. The necessity for reservoir stimulation is linked with negative processes related to well drilling and perforation. The correct estimation of damaged zone parameters is the key problem for acid stimulation planning. The proposed petrophysical methodology is based on available data integration: core data, drilling data, well logging, well testing etc. Modern well logging suite allows to solve following task with high accuracy. Sonic radial profiling based on compressional and shear waves registration and multisonde resistivity logging are the key methods to prognose wellbore damaged zone radius and parameters. The methodology based on integration of both these logging data is proposed in this paper. Currently, fullwave acoustic logging provides comprehensive data to estimate drilling mud penetration zone and character of the damage. The approach is based on alteration of sonic waves – compressional and shear waves. But not all the wells logged with sophisticated modern acoustic log tools. Therefore, estimation of mud filtrate penetration and damaged zone is possible based on multiarray resistivity measurements which are primary methods in all well logging suites. At least three different sondes with different radius of investigation are run in a well. These data are enough to use for accurate damaged wellbore zone radius estimation. Calculated results were supported by other available information and verified by data from modern sonic tools. Thus, allows to improve the methodology and use it widely in all wells in a field. Modern fullwave acoustic logging was performed by Schlumberger in few wells of carbonate field of the Company. In rest of the wells wellbore damaged zone estimation based on proposed integrated approach applied for multiarray resistivity interpretation. This workflow allowed to optimize acid near wellbore zone stimulation for the oil recovery enhancement.