Characterization of in-Situ Stress and Permeability in Fractured Reservoirs

Abstract

Numerical modeling and field data tests are presented on the Transfer Function/Scattering Index Method for estimating fracture orientation and density in subsurface reservoirs from the 'coda' or scattered energy in the seismic trace. Azimuthal stacks indicate that scattered energy is enhanced along the fracture strike direction. A transfer function method is used to more effectively indicate fracture orientation. The transfer function method, which involves a comparison of the seismic signature above and below a reservoir interval, effectively eliminates overburden effects and acquisition imprints in the analysis. The transfer function signature is simplified into a scattering index attribute value that gives fracture orientation and spatial variations of the fracture density within a field.The method is applied to two field data sets, a 3-D Ocean Bottom Cable (OBC) seismic data set from an offshore fractured carbonate reservoir in the Adriatic Sea and a 3-D seismic data set from an onshore fractured carbonate field in the Middle East. Scattering index values are computed in both fields at the reservoir level, and the results are compared to borehole breakout data and Formation MicroImager (FMI) logs in nearby wells. In both cases the scattering index results are in very good agreement with the well data. Field data tests and well validation will continue.In the area of technology transfer, we have made presentations of our results to industry groups at MIT technical review meetings, international technical conferences, industry workshops, and numerous exploration and production company visits. I. Executive SummaryThe purpose of this project is to develop and implement large-scale numerical models to quantify the effects of fracture parameter variations on seismic reflection signals and insitu stress variations on flexural modes in boreholes. These models will be used as the basis of data analysis and inversion routines for estimating the heterogeneous fracture distribution in fractured reservoirs from seismic and borehole field data. Fracture property distributions estimated from seismic data will be used to estimate the permeability tensor in the reservoir for input to reservoir simulators.In this period we continued work on numerical modeling and field data tests on the Transfer Function/Scattering Index Method for estimating fracture orientation and density in subsurface reservoirs from the 'coda' or scattered energy in the seismic trace.Modeling results indicate that in the direction normal to aligned fractures, forward and backscattered energy creates a complex wavefield that will not constructively interfere in the stacking process. In the direction parallel to the fractures there is only forward scattering present and the resulting wavefield can be enhanced in the stacking process.Laboratory physical modeling of acoustic scattering from a grooved surface (Schultz and Toksoz, 1995) shows similar behavior. Azimuthal stacking, therefore, will enhance the scattered energy along the fracture strik...

1,n-Diamines. Part 4: synthesis of 1-aryl-2-alkyl-1,4,5,6,7,8-hexahydro-1,3-diazocines

“…All these compounds are of biochemical and pharmacological interest as natural polyamine analogs. [14][15][16] The reported synthetic method for N-benzoyl-N 0 -aryl pentamethylenediamines involves the reaction of N-acylpiperidines with PCl 5 followed by aminolysis. 17 The overall yields are moderate, and the procedure is restricted to N-acyl derivatives without a-hydrogens.…”