Nuclear Magnetic Resonance (NMR)
Nuclear magnetic resonance (NMR) is often used to calibrate downhole logs in geologic environments that possess paramagnetic minerals, tight gas formations, and complicated carbonates having bi-modal or tri-modal pore body systems.
Weatherford laboratories employs NMR technology, which provides a non-destructive and fast method to calibrate porosity data from the NMR logging tool, to obtain an estimation on movable and bound fluid at reservoir conditions.
Conventional nuclear magnetic resonance can provide the following:
Effective porosity/free fluid porosity
Pore size distribution/pore geometry. 100% T2 results nearly mimic high pressure HgPc curves.
Fluid saturations and distribution
Free fluids, mobile oil, and water
Capillary bound water
Clay bound water
Weatherford is at the forefront of the industry with the following capabilities:
Whole core NMR analysis (up to 4x4-in. sample size)
-Samples that are brittle and cannot be subsampled
Overburden NMR (1.5-in. diameter x up to 4-in. length)
-Can run NMR at reservoir conditions
Up to 5,000 psi
Up to 200°F
Three 2MHz Rock Core Analyzers
Weatherford Laboratories is equipped to meet today's industry challenges. Some of the things we can provide with our NMR system in sandstones, shaly sandstones, and carbonates, include:
Free water – Bound water cutoff (commonly known as T2 cutoff)
Free Fluid Index (FFI) or moveable fluids
Bulk volume irreducible (BVI) or immovable fluids, including the clay bound portion
As-received state, 100% water saturation, and Swi (using customer-supplied pressure data or targeting an endpoint to match a Dean-Stark value or customer-supplied value).
T1T2 2D map data can help identify fluid types and production potential in complex environments
Weatherford Laboratories is always in the pursuit of technology enhancements. We work hand-in-hand with our clients to expand our applications and test designs.
NMR versus Capillary Pressure
Pc is a function of pore throat size distribution
NMR T2 is a function of grain surface area to pore volume ratio (S/V)
We say we can relate S/V to pore body size distribution so NMR T2 is a function of pore body size distribution
We are looking for relation between Pc (pore throats) and T2 (pore bodies)
Pore body = hallways……….Pore throats = doors