Rock Deformation
Assignment Rock Deformation
You have just received data which describes a section of core that intersects a carbonate reservoir interval of interest. The reservoir has a high volume of stylolites that appear to be parallel with bedding. Would this pose a problem during production and are there any risks that should be considered?
Solution
Stylolites are geologic structures produced by pressure solution. Bedding plane stylolites are commonly observed in carbonates and are often found parallel to bedding planes.
Stylolites indicate that the rock has undergone a significant amount of pressure which may alter the original porosity, a risk that must be considered when modeling fluid flow and production rates. Stylolites are often the insoluble residue from the dissolved carbonate and this may also affect production of hydrocarbons.
Assessment Rock Deformation
1. Which of these stress-strain responses is characterized by hysteresis and the development of permanent strain?
A .Viscoelastic
B .Viscoelastic-plastic ✔
C .Linear elastic
2. A deformation mechanism is a physical process by which _________.
A .only brittle deformation is considered
B .the shear failure envelope is a straight line
C .a material deforms in response to applied stress ✔
D .only elastic deformation is considered
E .a material deforms in response to applied strain
4. The Mohr shear failure criterion ________.
A .represents the shear failure envelope as a straight line
B .relates rock strength to strain
C .is a special case of Coulomb’s shear failure criterion
D .relates rock strength to stress ✔
5. Grain crushing is an important deformation mechanism that operates under __________ stress.
6. Which of the following time-dependent processes are most likely to occur over the producing life of a reservoir? (Select all that apply.)
A .Pressure solution
B .Crystal plasticity
C .Fluid flow ✔
D .Creep ✔
7. Who developed the first quantitative description of rock shear strength?
A .Mohr
B .Amonton
C .Coulomb ✔
D .Patterson
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