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Assignment Special Core Analysis (SCAL)
You are the geologist responsible for core analysis for your company and have been asked to summarize what is involved in special core analysis (SCAL) studies for your colleagues.
Solution
Special core analysis (commonly abbreviated to “SCAL”) comprises a number of laboratory procedures, which conduct flow experiments and other specialist analyses on core plugs, which are usually cut from an interval of full diameter core.
SCAL often includes the measurement of two-phase flow properties to determine the relative permeability, as well as capillary pressure and wettability. Special core analysis establishes a number of electrical properties of the formation which can then be used for the analysis of LWD and wireline well logs, in particular determining the water saturation. SCAL often includes a number of specialist studies such as petrographic, micropalaeontology and palynology, trace element identification and insoluble residue studies, as well as computer-assisted tomography (CAT) scanning and nuclear magnetic resonance logging.
Assessment Special Core Analysis (SCAL)
1. What are the features of micropalaeontological studies? (Select all that apply.)
A .Micropalaeontology is the study of microfossils. Correct ✔
B .Micropalaeontological studies require the use of a petrographic microscope. Correct ✔
C .Micropalaeontological studies require the use of a scanning electron microscope. Correct ✔
D .Micropalaeontological studies involve organisms visible to the naked eye.
2. Which of the following are features of trace elements? (Select all that apply.)
A .A trace element is the mark left by an organism moving through unconsolidated sediments.
B .A trace element is an element in a sample that has an average concentration of less than 100 parts per million measured in atomic count. Correct ✔
C .Trace elements in shales have been used successfully as guides to major variations in the water salinity. Correct ✔
D .The presence of trace elements is related to the cation exchange capacity of clay minerals located within the shales. Correct ✔
3. What level of immobile water saturations are typically found in low permeability formations that are composed of very small pore spaces?
A .Intermediate immobile water saturations
B .Very low immobile water saturations
C .Low immobile water saturations
D .High immobile water saturations Correct ✔
4. What types of wettability can be determined during special core analysis? (Select all that apply.)
A .Oil-wet Correct ✔
B .Non-wet
C .Water-wet Correct ✔
D .Neutral-wet Correct ✔
5. What attribute of a rock does the identification of the insoluble residues help to determine?
A .Age
B .Depositional environment Correct ✔
C .Hydrocarbon content
D .Color
6. Relative permeability has which of the following attributes? (Select all that apply.)
A .Relative permeability is the same as the absolute permeability.
B .Relative permeability is a result of each phase interfering with, and impeding the flow of the others. Correct ✔
C .A dimensionless term, expressed either as a number between 0 and 1, or as a percentage. Correct ✔
D .Relative permeability is a function of the saturation. Correct ✔
7. Which of the following are applications of computer-assisted tomography (CAT) scanning? (Select all that apply.)
A .Establishing the relative permeability
B .Screening cores prior to flow tests Correct ✔
C .Characterizing the lithology of cores Correct ✔
D .Detecting fractures Correct ✔
E .Visualizing the extent of mud filtrate invasion Correct ✔
8. What is petrography?
A .Petrography is the study of petroleum.
B .Petrography is the illustration of petroleum products.
C .Petrography addresses the geographical distribution of rocks.
D .Petrography is a branch of petrology that focuses on the detailed descriptions of rocks. Correct ✔
9. What is the capillary pressure at the free water level?
A .0 psi Correct ✔
B .10 psi
C .100 psi
D .1000 psi
10. Nuclear magnetic resonance (NMR) logging is often used to measure which of the following rock properties? (Select all that apply.)
A .Residual oil saturation Correct ✔
B .Permeability Correct ✔
C .Porosity Correct ✔
D .Age
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