NUCLEAR MEASUREMENTS in
LAMINATED, VUGGY, and FRACTAL
--------------------------------------------------- Doctor Neutron has added a brief description of his two patents on the use of neutron activation analyses in frac height and frac location detection for the fracking industry. These new methods greatly reduce the environmental impact caused by using nuclear technology in this burgeoning field.
He had previously added a .pdf image of his paper entitled "PORE SIZE, ORIENTATION AND SHAPE; LAMINAE; AND FRACTAL DIMENSION EFFECTS ON THE RESPONSE OF SEVERAL NUCLEAR LOGGING TOOLS".
This paper was first published in the Proceedings of the 2009 SPWLA Annual Logging Symposium, The Woodlands, Texas, as Paper Y.
For the laminae examples, small formal effects on formation sigma were observed and much larger effects on neutron porosity. Some interesting results are predicted for open hole bulk densities in sand-shale laminae. These heterogeneous predictions are based on non-linear mixing of the gamma ray linear attenuation coefficients with the result that gamma transmission n the two media becomes interdependent.
The insensitivity of a new cased hole bulk density measurement to Montmorillonite laminae intrusion into an oil sand needs further investigation using both the new Transmission Probability Method and Monte Carlo modeling. These same methods can also be used to continue study of the impact of pore size, laminae, and fractal dimension on direct measurement of the thermal neutron diffusion coefficient from the Chappell Hill Logging multi-detector pulsed neutron logging tool.
Periodically this site will present fresh new examples with LVFPM concerning the impact of pore size and laminae properties on bulk density, Pe, dual-spaced neutron porosity, thermal neutron diffusion coefficient, and neutron capture cross section.
In particular, the density and Pe computations no longer utilize Filippov's method. Instead, a new and very accurate interpolation scheme based more directly on the NIST data tables of Hubbell and Seltzer is used. As in the previous Filippov formulation, the new LVFPM calculations still account for energy losses during gamma ray propagation, corrections for multiple scatterings, and the gamma detector energy-dependent counting efficiency.
One new feature has been added to the LVFPM Program Internals Output Pane: Material 1 and Material 2 MCNP5 Mass Fractions.
In the XY plot shown further on, the impact of fractal dimension variations on neutron-density crossplots is illustrated using concepts presented in the 2009 SPWLA Annual Logging Symposium, Paper Y.
As the fractal dimension increases, pore size dramatically decreases. Since scattering and diffusing neutrons tend to avoid water, when the fractal dimension is low and the pores are larger, they don’t “see” some water internal to these larger pores and they propagate more in the rock matrix and the sensed neutron porosity is lower. But then, as the pores are reduced in size with higher fractal dimensions, the neutrons “find” all the water present, they are more spatially confined, and the sensed neutron porosity is higher.
Conversely, gamma rays attempt to avoid the higher density of the matrix and tend to propagate in the lower density fluid, reporting relatively more water than matrix when the fractal dimension is low, and inversely.