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72ndEAGE Conference & Exhibition incorporating SPE EUROPEC 2010

Barcelona, Spain, 14 - 17 June 2010

H002

Evolution of Seismic Imaging in Colombia

H. Alfonso* (Ecopetrol SA)

SUMMARY

Over many decades ECOPETROL (Oil state company of Colombia)has done efforts in improving thequality of seismic in Colombia, through different seismic campaigns and applying different technologies.Imaging complex environments, or specific structural features are often difficult, so you have to use theright technology to achieve the best result, regarding also cost benefit relationship.

The primary goal of this paper is to show seismic lines that illustrate the evolution of seismic imaging inseveral Colombian basins, highlighting the key aspects in improving the image and the use of geophysicaltechnology.


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from different contractors. When making a decision about drilling having accurate images can assure

the millions of dollars invested. On fig 4 and 5 an example is shown on the advantages you can find

when different companies process your data.

A B

Figure 4Same seismic section from Middle Magdalena Valle basin, both are PSTM processed bytwo different companies, notice the lack of character on section B, the target zone below 2 seconds is

hardly visible as it is on section A.

Figure 5Seismic sections from Upper Magdalena Valley Basin. Both are PSTM processed by twodifferent companies. It turns out the right hand side image was modelled with statics and post stack

enhance filters, causing a false structure.

The final example is from the llanos basin in Colombia, showing a dramatic improvement in the

seismic data quality. In this case they believe that the quaternary formation outcropping on the area

causes the lack of signal . Further tests and analysis came up to the conclusion that better sampling

and higher charges were needed to get better results. The display on fig. 6 shows the result of a new

seismic line depicting a nice structure just where the blur zone was present on the previous data(seismic section A)




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A B

Figure 6New seismic from the 90s shows the dramatic improvement on the central part of theseismic section on image B. Key factors in this example, new seismic parameters, better sampling and

detail processing.

Conclusions

Through many examples in different basins from Colombia we conclude that it is important to apply

the right technology to solve specific imaging problems. The seismic method offers us many options

regarding processing and acquisition technology reducing the risk in drilling prospects. Having

different options when you process your data is crucial, so using many contractors processing thesame survey is really worthed.

The use of extensive field test is a good practice to select the right seismic parameters. The success in

our basins in Colombia has to do with test lines at level of stack and migration that were shot in at

least 6 kilometres of length. Experimental tests done with single shot points do not guarantee the

right analysis.

It is also important to notice that the use of post stack migration procedures are not used anymore as

final migrations. Prestack migration algorithms are most common procedures used regarding the

complexity of data. New methods like RTM or full wave inversion will add even more value to thedata, keeping in mind that you have to be aware of the data regularization in your designs.

Acknowledgements

This work is the result of a team approach, so I want to thank ECOPETROL S. A for the support

toward these projects for many years, and to all my colleagues at Exploration Vicepresidency. Also

many thanks to all the local and international contractors that have worked with us looking for the

best image to explore for hydrocarbons in Colombia.


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