B Rock Phys 2
4D seismics
4D seismics
Set of flashcards Details
| Flashcards | 13 |
|---|---|
| Language | English |
| Category | Nature Studies |
| Level | University |
| Created / Updated | 11.04.2013 / 21.04.2013 |
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why is Vs less affected by pore fluids
they have no shear strength
how does less compressible fluids affect the Vp/Vs ration (Poissons)?
less compressible fluids=higher Poissons
(no shear strength in fluid)
4D effects of common production processes
water flood
gas injection
gas production
gas out of solution
.
4D vs. 4C seismics
4D seismics = 3D surveys repeated a number of times 4C seismics = 4 components; i.e. 3 geophone and hydrophone (pressure)
Primary changes in the reservoir during production of hydrocarbons
Pore pressure Pore fluids (saturation, viscosity, compressibility, fluid type Temperature (water flood, steam injection)
Secondary changes in the reservoir during production of hydrocarbons
Compaction overburden stress porosity, fracturing chemical changes
bulk modulus
(one word)
stiffness
how do porosity and bulk modulus affect how observeable a change in pore fluids is
Higher the porosity the greater the impact of fluid composition Stiffer the rock the more difficult it is to see the effects of fluid composition
Rocks saturated with less compressible fluids e.g. oil and brine show...
higher Vp and impedances
higher Vp/Vs
Vs is much less affected by pore fluids because...
fluids have no rigidity affected by density changes
Rocks with less compressible fluids have...
higher Vp/Vs
higher Vp and impedances
Low porosity rock with crack-like low aspect ratio pores may have a lower velocity than a high porosity rock with spherical high aspect ratio pores because...
former are more compressible
different classes of
bright spot dim spot polarity changes
bright spot class 3
polarity change class 2
dim spot class 1
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