Borehole Geophysics & Petrophysics

Certain logs can be recorded simultaneously, meaning that multiple logs can be recorded at the same time. This suggests that there is a capability or technology in place that allows for the concurrent recording of these logs. Therefore, the statement "It is possible to record certain logs simultaneously" is true.

The Induction Resistivity Tool is preferred over Latero-Type tools in non-conductive muds because it is specifically designed to measure resistivity in low-conductivity formations. Non-conductive muds have low electrical conductivity, which can cause inaccurate readings with Latero-Type tools. The Induction Resistivity Tool uses electromagnetic induction to measure resistivity, making it more accurate and reliable in non-conductive muds. Therefore, it is true that the Induction Resistivity Tool is preferred over Latero-Type tools in these conditions.

Because SP is natural Potential .

The temperature range for the oil window is 60-175 degrees Celsius. This range represents the optimal temperature range for the formation and maturation of oil. Below 60 degrees Celsius, the temperature is too low for oil formation, while above 175 degrees Celsius, the temperature is too high and the oil begins to break down. Therefore, the oil window refers to the specific temperature range in which oil can be formed and preserved.

Due to Good Vertical Resolution .

High resistivity is not always an indicator of hydrocarbons. Resistivity is a measure of how much a material resists the flow of electric current. While hydrocarbons generally have low resistivity, there are other factors that can also result in high resistivity, such as the presence of certain minerals or fluids in the subsurface. Therefore, it is not accurate to say that high resistivity always indicates the presence of hydrocarbons.

Exploration refers to the process of discovering new commercial units of hydrocarbon. This involves searching for and identifying potential sources of hydrocarbon, such as oil or natural gas, in order to extract and utilize them for commercial purposes. It includes activities such as geological surveys, seismic testing, and drilling to locate and evaluate the presence of hydrocarbon reserves. The goal of exploration is to find new and economically viable sources of hydrocarbon that can be developed and utilized for energy production.

To accurately identify a basin, you need to consider both the age and location. Age is important because different geological processes occur over time, shaping the basin's characteristics. The age of the basin can help determine its formation and the types of sediments present. Location is also crucial as it provides information about the geological setting, such as tectonic activity or proximity to water bodies, which can influence the basin's formation and sediment deposition. By considering both age and location, you can gain a comprehensive understanding of the basin and make a more accurate identification.

The correct answer is NMR Log. The Free Fluid Index (FFI) of a formation can be estimated from the NMR Log. NMR stands for Nuclear Magnetic Resonance, which is a geophysical logging tool used to measure the amount of fluid present in a formation. It provides information about the porosity and fluid saturation in the subsurface. By analyzing the NMR Log, geoscientists can determine the FFI, which is a measure of the amount of free fluid in the formation.

If Sw becomes 50 % i.e Sw=1/2 .
Then resistivity will increase by factor of 4.

Sonic logging is used to measure the travel time of sound waves through the formation. By analyzing the recorded data, sonic logging can provide information about the formation's mechanical properties, including the presence of fractures and the extent of fractured porosity. Therefore, sonic logging is the log that helps in finding the fractured porosity.

The presence of source rock does not guarantee the presence of hydrocarbons in a basin. While source rocks are responsible for generating hydrocarbons, other factors such as migration pathways and traps are also necessary for the accumulation of hydrocarbons. Therefore, the statement is false.

The given statement is false. Depth of investigation of focused current resistivity tools is actually greater than that of unfocused tools. Focused current resistivity tools use a smaller current electrode spacing, which allows for a more concentrated current and better resolution at greater depths. Unfocused tools, on the other hand, have a larger current electrode spacing, resulting in a wider current spread and shallower depth of investigation. Therefore, the depth of investigation of focused current resistivity tools is greater than unfocused tools.

India has a total of 26 sedimentary basins. Sedimentary basins are regions where sediments accumulate over time due to various geological processes. These basins are important for the exploration and extraction of oil, gas, and other natural resources. The sedimentary basins in India are spread across different regions and have varying levels of resource potential. Therefore, the correct answer is 26.

for remove the effect of mud in density logging

Fine grained sediments are the correct source rocks for petroleum. Petroleum is formed from the organic matter that gets buried and undergoes heat and pressure over millions of years. Fine grained sediments, such as shale, mudstone, and siltstone, have high organic content and are capable of preserving and generating petroleum. These rocks have small pore spaces and low permeability, which allows for the accumulation and trapping of petroleum. Therefore, fine grained sediments are the ideal source rocks for petroleum formation.

if porosity is more than invasion does not affects upto much depth .

Laterolog is a logging tool that has the largest depth of investigation compared to the other options provided. It is designed to measure the resistivity of the formation surrounding the wellbore at various depths. The tool uses multiple electrodes to measure the electrical properties of the rock formations, allowing for a deeper investigation into the subsurface.

Because it can be run in open hole as well as cased holes

Hint :::: Apply Archie's equation for flushed zone ..

The correct answer is Neutron-Epithermal Neutron Log and Neutron-Gamma Log. Radioactive logging is used to detect the presence of certain elements, such as chlorine, in a formation. The Neutron-Epithermal Neutron Log measures the epithermal neutron population, which is sensitive to the presence of chlorine. The Neutron-Gamma Log measures the gamma ray emission from the formation, which can also indicate the presence of chlorine. Therefore, combining these two logs allows for a more accurate detection of chlorine in the formation.

The Litho-density Log works on the principle of photoelectric absorption. This principle states that when X-rays pass through a material, they may be absorbed by the atoms in the material, resulting in the ejection of electrons. The degree of absorption depends on the atomic number of the material, which allows the Litho-density Log to measure the density of the formation being logged. Compton scattering and pair production are not directly related to the working principle of the Litho-density Log.

The correct answer is "Gamma Ray scattered from the formation." In a density log, gamma rays are emitted from a source and then scattered by the formation. The scattered gamma rays are detected, and the intensity of the detected gamma rays is related to the density of the formation. This scattering process allows for the measurement of the formation's density.

Rmf > Rw

Illite contains potassium .