Page 531 - Petrophysics

TABLE 8.1
[
SUMMARY OF DETECTION TECHNIQUES NATURAL FRACTURES 141
FOR
Core FMS/FMI Litho Density Stoneley Wave Mud Loss
What is Localized Mud invasion into Contrast in Invasion density Stoneley energy Flow of mud into
detected? fracture fracture acoustic of drill solids reflected by fractures
porosity properties into fracture the fracture
How narrow On the order On the order of 1 mm 5 mm lmm 0.20 mm
fracture of microns microns given
aperture can sufficient
be detected? electrical
conductivity
contrast
Fracture Fracture Fracture porosity Fracture porosity Fracture Washout bed None
mistaken for porosity. Induced Induced porosity. boundaries
permeable Induced fractures. fractures. High Drilling
fractures fractures Drilling impedance damage.
damage bedding and Mineralization
certain healed
fractures
Depth of Diameter of 10 mm 3 mm 100 mm Less than Depth of mud
investigation core 1.8 m invasion >1 m
Can it provide Yes Yes Yes No No No
strike and dip?
Mud limitations None Water-based Mud weight must Mud weight None None
muds only be less than must be
14 Ib/gal. greater than
10 Ib/gal.
Additional Highly fractured Has difficulty in Has difficulty in Fractures Yields information on
comments “rubble distinguishing distinguishing plugged with degree of formation
zones” not high-permeability high-permeability mud solids damage and
recovered fractures from fractures from are often not stimulation
low-permeability low-permeability detected requirements
ones ones