Page 50 - Petrophysics

24 PETROPHYSICS: RESERVOIR ROCK PROPERTIES

Also discrete particles injected into a formation with water for secondary
recovery of EOR fluids can cause serious formation damage. Methods for
diagnosing formation damage are included in this chapter.

PROBLEMS

1. What are the principal natural processes that affect the petrophysical
properties of sedimentary rocks?
2. As shown in Table 1.1, the total bulk chemical analysis of rock samples
is clearly different from the surface analysis. What effect does this have
on the rock properties?
3. Since all rocks have a single source (molten magma from below the
crust), what general processes produce the differentiation into many
different recognizable rocks?
4. List three natural processes that are constantly operating to produce
sedimentary rocks.
5. The average particle sizes from a sieve analysis are, in millimeters,
2.00, 0.050, 0.10, and 0.06. What are the respective phi-sizes?

GLOSSARY (CHAPTER 1)

Aphanitic: refers to rock texture that contains minerals that are too
small to see.
Arkose: sandstone that contains a large amount of feldspar.
Batholith: large intrusive body of rock, generally granite.
Breccia: similar to tuff, but contains large angular fragments (>2 mm)
within the fine matrix.
Cleavage: a separation along a plane of weakness that produces a
smooth plane which reflects light when broken. A fracture is an irregular
break of the rock.
Conglomerate: rock composed of fragments of pre-existing rocks
greater than 2 mm and inclusion of other rocks (pebbles, cobbles, and
boulders; see Table 1.7)
Continental shelf the gently inclined, flat portions of the continent
below sea level, extending from the shore to the continental slope where
it slopes into the deep ocean platform. The shelfis generally covered with
clastic sediments and the slope with fine sediments.
Diagenesis: the chemical and physical changes that a sediment
undergoes after deposition. Most of the diagenesis occurs after burial of
the sediment. In deep burial (>3,000 m) the principal diagenetic changes
are compaction and lithification.