1. 1. UNIVERSITY OF AZAD JAMMU AND KASHMIR MUZAFFARABAD PRESENTED TO: Respected Sir Fahad Sab PRESENTED BY: Azhar Mahmood Roll No: 225 Date : 15/01/2015
2. 2. PRESNETATION # 01 TOPIC Applications of the following Gravity survey Magnetic survey Electrical resistivity survey Seismic survey
3. 3. 01: GRAVITY SURVEY METHOD
4. 4. Definition: It is a method of measuring the force of gravity in drill holes by means of gravimeters in order to determine the mean density values of rocks at differen t depths in their natural bed.
5. 5. Application of Gravity Method Survey:
6. 6. Hydrocarbon exploration Regional geological studies Isostatic compensation determination Exploration for mass estimation of mineral deposits Detection of subsurface cavities Location of buried rock valley Determination of glacier thickness Shape of earth(geodesy) Monitoring volcanoes
7. 7. Hydrocarbon exploration This is also called oil and gas exploration is the search by geophysicist for hydrocarbon deposits beneath the Earth's surface such as oil and natural gas . Oil and gas exploration are grouped under the science of petroleum geology.
8. 8. Engineering application Gravity surveys can be carried out to locate iron rich accumulations within furnace, cinder piles .
9. 9. Accumulations Of Hydrocarbons Gravity Surveys are used either alone or in conjunction with magnetic surveys, to determine the location and size of the major source structures which contain accumulations of hydrocarbons.
10. 10. Hydrogeology Determination of the major structures that control the location of aquifers. Additionally, Magneto telluric and Magnetics surveys may also be used for the same purpose
11. 11. The gravity method is a nondestructive geophysical technique that measures differences in the earths studies including locating voids and karst features, buried stream valleys, water table levels and the determination of soil layer thickness.
12. 12. karst features
13. 13. Gravity data in engineering and environmental applications should be collected in a grid or along a profile with stations spacing 5 meters or less. In addition, gravity station elevations must be determined to within 0.2m Using the highly precise locations and elevations plus all other quantifiable disturbing effects, the data are processed to remove all these predictable effects.
14. 14. 02: Magnetic survey method
15. 15. Magnetic survey Magnetic survey is one of a number of methods used in archaeological geophysics Magnetic surveys record variation in the Earth's magnetic field. In archaeology , magnetic surveys are used to detect and map archaeological artifacts and features. Magnetic surveys are used in both terrestrial and marine archaeology.
16. 16. Basic Concepts The Earth possesses a magnetic field caused primarily by sources in the core. The form of the field is roughly the same as would be caused by a dipole or bar magnet located near the Earth's center and aligned sub parallel to the geographic axis
17. 17. Magnetic survey of an archaeological site
18. 18. APPLICATION OF MAGNETIC METHOD SURVEY
19. 19. Locating buried Pipes, cables, tank and drums Fault studies Ore exploration identification of metalliferous deposits, for example massive sulphides Geothermal exploration Mapping buried utilities
20. 20. Exploration of fossil fuels (oil and gas) Exploration of ore deposit Regional and global tectonics Large scale of geological structures ,volcanology Engineering construction site investigation Burried foundation ,fine pits for archeology Mineral exploration
21. 21. Locating buried Pipes, cables, tank and drums Magnetic geophysical surveys measure small, localized variations in the Earth's magnetic field. The magnetic properties of naturally occurring materials such as magnetic ore bodies and basic igneous rocks. Magnetometer surveys find underground storage tanks, drums, piles and reinforced concrete foundations by detecting the magnetic anomalies they produce.
22. 22. Exploration Mineral Magnetic survey, one of the tools used by exploration mineral-bearing ore bodies or even oil-bearing sedimentary structures and locate on map the remains of buried structures.
23. 23. Marine Magnetic Methods Magnetic methods, as employed in marine applications, differ little in theory from surface magnetic surveys. The instrument measures the earths total magnetic field at each measurement location. However, practical applications of field techniques, field equipment, and geographic control can vary greatly between surface and marine surveys.
24. 24. Magnetics surveys measure the magnitude and orientation of the Earths magnetic field. Magnetic field at Earths surface depends on field generated in Earths core, magnetic mineral content of surface materials, and remnant magnetization of surface rocks.
25. 25. 03: Electrical Resistance Survey Method
26. 26. Definition: Electrical resistance survey also called earth resistance or resistivity survey is one of a number of methods used in archaeological geophysics. In this type of survey electrical resistance meters are used to detect and map subsurface archaeological features and patterning.
27. 27. Electrical resistance survey of an archaeological site using a twin probe system. (Wenner electrode array.)
28. 28. APPLICATION ELECTRICAL RESISTANCE SURVEY METHOD
29. 29. The presence of certain metallic ore The temperature of sub surface Geothermal energy The presence of archeological feature Graves Fire pits Pot holes .
30. 30. Amount of ground water present I. Amount of dissolved salt II.Presence of contaminants III.% porosity and permeability
31. 31. Specific Applications Determine electrical characteristics of surrounding area. Determine depth of water table Detect contaminant plumes Determine extent of saltwater intrusion Detect fracture zones and faults Detect areas of potentially unstable ground, e.g. mine shafts, sinkholes, voids
32. 32. Assist in dam stability analysis Determine overburden depth Locate buried mafic dikes Provide data for corrosion control design Determine lithology/structure.
33. 33. Electrical resistivity method is also useful for simultaneously detecting lateral and vertical changes in subsurface electrical properties
34. 34. 04 :Seismic Surveys Methods
35. 35. Definition Seismic survey, method of investigating subterranean structure, particularly as related to exploration for petroleum, natural gas, and mineral deposits. A seismic survey is a technique similar to an ultrasound that is used to develop images of the rock layers below ground.
36. 36. Seismic Surveys Methods
37. 37. Applications Seismic Surveys Methods
38. 38. Seismic surveys are used to locate and estimate the size of offshore oil and gas reserves. To carry out such surveys, ships tow multiple air gun arrays that emit thousands of high-decibel explosive impulses to map the seafloor. The auditory assault from seismic surveys has been found to damage or kill fish eggs and larvae and to impair the hearing and health of fish and marine mammals.
39. 39. Hydrocarbon exploration It is used by the hydrocarbon industry to provide a high resolution map of acoustic impedance contrasts at depths of up to 10 km within the subsurface. This can be combined with seismic attribute analysis and other exploration geophysics tools and used to help geologists build a geological model of the area of interest.
40. 40. Land survey Land seismic surveys tend to be large entities, requiring hundreds of tons of equipment and employing anywhere from a few hundred to a few thousand people, deployed over vast areas for many months.
41. 41. Marine survey Traditional marine seismic surveys are conducted using specially-equipped vessels that tow one or more cables containing a series of hydrophones at constant intervals
42. 42. Seismic surveying is also play vital part of exploring for oil and gas. That makes it critical to producing the energy we need to power our homes and businesses.
43. 43. THANKS!