Methods to minimize water production in the Mississippian Lime play
The Mississippian formation is a prolific but problematic reservoir with secondary porosity features. The secondary porosity systems assist in creating fluid migration paths that will produce at much greater rates than can be anticipated from permeability/porosity relationships. Water segments may be inter-bedded between hydrocarbon traps. The water and the hydrocarbon portions of the reservoir may have the same resistivity. A method is required that can establish accurate effective porosity, effective estimates of permeability, and quantitative estimates of fluid type in place in the reservoir. Magnetic-resonance (MR) logs were added to the evaluation program to obtain this evaluation. This technology can directly measure effective porosity. The relaxation (T2) response from MR can be used to evaluate permeability. Two-dimensional maps of the MR signal can be used to quantify fluid type and compartmentalization within the reservoir, independent of the resistivity in the formation. Because the MR only measures fluids in pore spaces, porosity can be directly established. Estimated permeability can be used to establish reservoir quality for production through the Bray-Smith permeability equation. Fluid identity can be established without consideration of resistivity measurements through appropriate application of two-dimensional maps of MR data.
AAPG Datapages/Search and Discovery Article #90221 © 2015 Mid-Continent Section, Tulsa, Oklahoma, October 4-6, 2015