Petroleum Production Operations Multiple Choice Questions on “Geologic Concepts Application in Carbonate Reservoirs”.
1. Calcite and Dolomite fall under which of the reservoir category?
a) Sandstone
b) Shale
c) Evaporites
d) Carbonate
View Answer
Answer: d
Clarification: Calcite and Dolomite fall under the carbonate reservoir category. The chemical formula of Calcite is CaCO3 and for Dolomite, it is CaMg (CO3)2. Carbonate is a type of reservoir rock. The Middle East is mainly dominated by carbonate rocks. Carbonates are having high heterogeneity. So an extended study is must to know the reservoir potential.
2. For carbonate reservoirs in Matrix Acidizing (10-15)% HCl is used.
a) True
b) False
Answer: a
Clarification: Yes, it is. HCl reacts with carbonate in the matrices, also with silica and clays. Matrix acidizing is mainly used to restore productivity. This method removes formation damage.
3. Porosity and Pore size increase when complete dolomitization is approached.
a) True
b) False
Answer: a
Clarification: Yes it is true. Dolomitization is the process when Limestone gets converted to Dolomite. It is a geological process. The chemical formula of Calcite is CaCO3 and for Dolomite, it is CaMg (CO3)2.
4. Which of the following rock type plays an important role in Mumbai Offshore Basin for Oil and Gas recovery?
a) Sandstone
b) Carbonate
c) Shale
d) Evaporites
Answer: b
Clarification: Carbonate plays an important role in the Mumbai Offshore Basin for Oil and Gas recovery. Oil and Natural Gas Corporation, India mainly operates this field and produce oil and gas from the off-shore region.
5. Which of the following is incorrect about the carbonate reservoir?
a) Carbonates are formed within the basin of the deposition locally
b) Carbonates are formed with different types of biological constituents
c) Diagenesis plays an important role in carbonate forming
d) Carbonates are less heterogeneous than sandstone reservoirs in most of the cases
Answer: d
Clarification: Carbonates are more heterogeneous than sandstone reservoirs. Ham and Pray (1962) recognized the other three characteristics particularly for carbonate reservoirs which are of immense importance in the application of geologic concepts in carbonate reservoirs.
6. Which of the following is correct regarding the given carbonate reservoir if it has good porosity and permeability?
a) It will have a good oil recovery factor
b) The oil recovery factor remains the same irrespective of whether the pore walls are water wet or oil wet
c) It will have a good water recovery factor
d) The force of adhesion for oil flow through the porous media will be more than the cohesion force
Answer: a
Clarification: It will have good oil recovery considering good permeability and porosity. Because when the pore wall is water wet then there exists a force of adhesion not a force of cohesion so sweep efficiency of the oil will be more and hence a good recovery factor is expected.