Methodology | group18

These are the methods that we used throughout the project. Here, we attached the screenshots and videos that we have taken during completion of this project:

Data loading: Our group were given raw data set C for this project. To load a data in Petrel for the first time, we started by clicking on "New Project" and then click "Import data" to import the data set C in the Petrel. After we have import our data set into the petrel, we have done the quality checking (QC) in order to check the data was correct.

3. Phase/Polarity checking: We have done phase checking based on realized data to make sure the position of seismic data processing after undergo shifting phase and acquisition of seismic data are done in correct way. In order to check the seismic phase, a horizon is used as guideline as the wiggle would be most obvious. The region in the red circle shows the zero phase and the region in blue circle shows minimum phase.

4. Horizon picking: We have picked 5 horizons for this project. Horizon refers to reflectors (or seismic events) picked on individual profiles. These reflectors were picked based on relatively change in rock properties across a boundary between two layers of rock in terms of seismic velocity and density.

5. Making surface map: From the horizons that we have picked, the horizons were converted into a surface map to model the reflector. These surface maps were used for surface attributes analysis. The video below shows on method to create a surface map 5 using seismic horizon 5.

Fig. 1. This is the details of our data set C that we used for our project.

2. Data realization: We have done realization data set C which allow us to work efficiently with large volumes of seismic data. Purpose of realization is also to create a physical copy from virtual seismic data

6. Making isochron map: The isochron map was done to determine the thickness of sediment between 2 surface maps. We need at least 2 horizons in order to create isochron map. The video below shows the method to create a thickness map between surface map 4 and surface map 5.

7. Fault interpretation: The faults were manually picked at abrupt amplitude and these manually picked fault horizon were converted into a fault plane or fault model.

8. Application of seismic attributes: Seismic attributes help to enhance information that might be subtle in conventional seismic, leading to a better understanding and interpretation of data. They are also very essential for interpretation as the attribute are sensitive to desired geological features or reservoir property of interest. Throughout this project, we have used 2 types of attributes in this project which were:

8.1 Surface attributes: The video below shows on a method to apply the surface attributes on a surface. The same method can be used for other surface attribute. Throughout this project, the suface attributes that we used are:

RMS (Root Mean Square): The Root Mean Square (RMS) amplitude, or quadratic mean, is a popular statistical measure of the magnitude of variation over a dataset. The RMS proves particularly useful when values run through the positive and negative domain like in sinusoids or seismic traces.. Amplitude that can measure reflectivity in order to map direct hydrocarbon indicators in a zone of interest. However, it sensitive to noise as it squares every value within the window.
Maximum amplitude: used to map the strongest direct hydrocarbon indicator within a zone of interest that can enhance DHI hydrocarbon. Maximum amplitude also can generate at the boundaries where the acoustic impedance changes in identification of hydrocarbons.

8.2 Volume attributes: The video below shows on a method to apply the volume attributes using the realized data set C. The same method can be used for other volume attribute. Volume attributes that used in this project are:

Dip deviation: Seismic attribute to make the edges or subtle truncations become more visible by tracking the rapid changes in orientation field. Dip deviation is a new approach for the faults and fractures mapping. It provides more information on the fault as it is effective for softer rocks in passive rock as well, hence, it can determine the significant dip of the downthrown side of the fault.
Local structural dip: Edge detection method which designates rapid changes in local dip such as fractures and channel margins. It has a good ability for detecting features from dip of reflections such as channel edges and faults. Not only that, this attribute can be used to outline channel geometry and channel edge in seismic geomorphology interpretation. The combination of structural dip attribute with other attributes can enhance interpretation of seismic geomorphology.
Structural smoothing: We apply structural smoothing on the input to increase the continuity of the seismic reflectors using principal components of dip and azimuth to determine the local structure followed by structural smoothing. This structural smoothing attributes can helpful in reducing the noise and can also be used to illuminate “flat spots” within the seismic volume thus it can stabilize the result.
Coherence-variance: It can be used to imaging discontinuity of seismic data related faulting or stratigraphy. This attributes are very effective tool for delineation faults and channel edges on both horizon slices and vertical seismic profile. Other than that, it proved to help imaging of channels and faults (Pigott et al., 2013) and is also used to display directly the major fault zones, fractures, unconformities and the major sequence boundaries.
Sweetness: attributes designed to identify “sweet spots” places that are oil and gas prone. It also improves the imaging of relatively coarse-grained (sand) intervals or bodies. Sweetness attribute is very helpful in detecting discontinuities such as pinch-outs and channels in stratigraphic traps. Besides, it can also be useful for distinguishing shale from sands. Sands are said to have high amplitude and lower frequencies.
Acoustic impedance: Running sum of regularly sampled amplitude values. It is a physical rock property given as the product of density and interval velocity. In the industry, application of acoustic impedance is usually by doing inversion of the seismic to get the correct values of the acoustic impedance.

Fundamental of Attributes

5. Making surface map: From the horizons that we have picked, the horizons were converted into a surface map to model the reflector. These surface maps were used for surface attributes analysis. The video below shows on method to create a surface map 5 using seismic horizon 5.

Fig. 1. This is the details of our data set C that we used for our project.

2. Data realization: We have done realization data set C which allow us to work efficiently with large volumes of seismic data. Purpose of realization is also to create a physical copy from virtual seismic data

6. Making isochron map: The isochron map was done to determine the thickness of sediment between 2 surface maps. We need at least 2 horizons in order to create isochron map. The video below shows the method to create a thickness map between surface map 4 and surface map 5.

7. Fault interpretation: The faults were manually picked at abrupt amplitude and these manually picked fault horizon were converted into a fault plane or fault model.

8.1 Surface attributes: The video below shows on a method to apply the surface attributes on a surface. The same method can be used for other surface attribute. Throughout this project, the suface attributes that we used are:

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Maximum amplitude: used to map the strongest direct hydrocarbon indicator within a zone of interest that can enhance DHI hydrocarbon. Maximum amplitude also can generate at the boundaries where the acoustic impedance changes in identification of hydrocarbons.

8.2 Volume attributes: The video below shows on a method to apply the volume attributes using the realized data set C. The same method can be used for other volume attribute. Volume attributes that used in this project are:

​