Introduction to Seismic Interpretation

If you want to find oil and gas accumulations, or produce them efficiently once found then you need to understand subsurface geology. At its simplest, this means mapping subsurface structure to find structures  where oil and gas may be trapped, or mapping faults that may be barriers to oil flow in a producing field. It would be good to have a map of the quality of the reservoir as well (e.g.i ts thickness and porosity), partly to estimate the volume of oil that may be present in a given trap, and partly to plan how best to get the oil or gas out of the sound. It would be better still to see where oil and gas are actually present in the subsurface reducing the risk of drilling an unsuccessful exploration well, or even following the way that oil flows throught he reservoir during production to make sure we don't leave any more of it than we can help behind in the ground. Ideally, we would like to get all this information cheaply which in the offshore case means using as few boreholes as possible.

One traditional way of understanding the subsurface is from geological mapping at the surface. In many areas however, structure and stratigraphy at depths of thousands of feet cannot be extrapolated from geological observation at the surface. Geological knowledge then depends on boreholes. They will give very detailed information at the points on the map where they are drilled. Interpolating between these control points, or extrapolating a way from them into undrilled areas is where geophysical methods can be most helpful.

Although some use has been made of gravity and magnetic  observations which respond to changes in rock density and magnetisation respectively it is the seismic method that is by far them most  widely used geophysical technique for subsurface mapping. The basic idea is very simple. Low-frequency sound waves are generated at the surface by a high-energy source (for example a small explosive charge). They travel down through the earth, and are reflected back from the tops and bases of layers of rock where there is a change in rock properties. The reflected sound travels back to the surface and is recorded by receivers resembling microphones. The time taken for the sound to travel from the source down to the reflecting interface and back to the surface tells us about the depth of the reflector, and the strength of the reflected signal tells us about the change of rock properties across the interface. This is similar to the way a ship's echo sounder can tell us the depth of water and whether the seabed is soft mud or hard rock.

So if you want to work in the sector oil and gas you have to know seismic method for sure because this method is the most powerful than any others methods in subsurface mapping.

Geophysics Expedition

I just wanna greet you. Today i am going to attend Geophysics Expedition which is located in Candi Umbul, Grabag, Magelang, Central Java.This is field session of Geophysics Expedition, in Candi Umbul lies Geothermal Surface Manifestation like hot springs, fumarol, hydrothermal deposits and maybe thermal alterations. 

Previously i have got Gravity Methods through oral selection so i will use Gravity Methods in structure identifying (you don't say!). Keep calm i am going to share my experience after Geophysics Expedition done, so happy waiting! :)

Essay To Submit As Fieldcamp Volunteer 2013 Requirement

What does exactly young geophysicist (undergraduate student) doing in fieldcamp? I don't know either, because i did neither fieldcamp nor learn geophysical methods, but i try to seek for information about fieldcamp from my senior. Now i know that fieldcamp is a final field assignment for undergraduate geophysics students where all participants have to already know about entire of geophysical methods. By using geophysical methods we must be known what exactly lies within earth sub-surface.

Fieldcamp is like knowledge and field-skill test, where we have an assignment to research geological phenomena by using the sake of geophysical methods such a deep intrusion which can be known its resistivity by using Audio Magnetotelluric (AMT) methods or Geoelectrical Sounding Methods and we also have to look for additional data like using Gravity Methods where local gravity difference can be influenced by intrusion depended on its density. Fieldcamp is an annualy program from Geophysics Departement of Universitas Gadjah Mada for Gophysics students in their 4th years, this year fieldcamp will be held in Grobogan, Central Java and has topic "Peeking Under An Oil Field" (don't look at me, i dunno either).

Honestly i haven't known yet about how geophysical tools work, thus i wanna join as a volunteer because by becoming as a volunteer i can help my seniors and myself out. By doing this "sacrifice" i hope i can build network among my seniors and i must be got a precious experience. I also wanna see the night when the result of research presented and tested by our lecturer like Prof Kirbani and the others, it must be an amazing moment and funny for sure.

But actually now i am considering whether submit this essay or not due to... #galau