PDB 1023: INTRODUCTION TO PETROLEUM GEOSCIENCE EXERCISE2 TRUE OR FALSE Gravity S
ID: 293685 • Letter: P
Question
PDB 1023: INTRODUCTION TO PETROLEUM GEOSCIENCE EXERCISE2 TRUE OR FALSE Gravity Surveys make use of the Earth's magnetic field to determine the presence of gravity anomalies Gravity Surveys data may be collected on land, at sea or by air. Gravity Surveys can be obtained and used where seismic data are difficult to acquire, higher cost than seismic survey, resolution is lower than seismic survey Gravimeter measures anomalies of the Earth's density Gravitational attraction would be the same everywhere on the surface if Earth was perfectly spherical, homogeneous throughout, and not rotating A gravity reading higher than the normal regional gravity is called a negative anomaly Gravity anomalies are caused by the heterogeneous distributions of rocks of TRUE FALSE TRUE FALSE TRUE | FALSE TRUE FALSE TRUE FALSE TRUE FALSE TRUE | FALSE different density TRUE FALSE netic survey, the objective is to ascertain the presence of metamorphic basins and to map their approximate boundaries. Magnetic Surveys provide the quickest and least expensive way to study gross TRUE FALSE subsurface geology over a broad area. igneous rock formation at shallow depth will affect the magnetometer more strongly than a similar mass at great depth TRUE FALSE TRUE FALSE A magnetmeter is an instrument used to measure the strength of Earth's magnetic field TRUE FALSE Regional magnetic anomalies may be due to circulation patterns in the solid outer core TRUE I FALSE A negative magnetic anomaly is a reading of magnetic field strength that is higher than the regional average FALSE nomaly can be used to calculate thethicknessTRUE The magnitude of the magnetic a of the sedimentary rocksExplanation / Answer
Answers:
1. FALSE. Gravity survey does determine the gravity anomaly but it makes use of earth's gravitational field, not magnetic field. Magnetic survey uses earth's magnetic field.
2. TRUE. Gravity survey data are more commonly collected on land, by taking gravimeter readings from station to station or at a regular intervals along boarding ship tracks at sea. But besides these two, airborne gravity surveys are also done for larger areas which have good potentiality of petroleum and huge gravity anomalies due to large block displacements.
3. FALSE. Gravity surveys can be obtained and used where seismic data are difficult to acquire. But gravity surveys not at all cost more than seismic surveys. In fact, the gravity surveys bear modest cost in comparison to gravity survey. Moreover, gravity surveys are now possessing a much improved data resolution.
4. TRUE. Gravimeter is used to measure the acceleration due to gravity. Gravity anomaly is the difference between acceleration due to gravity. So, gravimeter measures the difference, which is, in tuen, gravity anomaly.
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