Stratigraphic interpretation of a complex channel system using SEA3D

The Project:

As a mature field, the stratigraphic interpretation work was more or less complete. We were challenged, by Marathon, to re-interpret the seismic data using ffA technology, with no recourse to the wells, and only a limited description of the reservoirs location. We were given a subset of the seismic reflectivity volume and a small structural map of the Base Cretaceous unconformity which lies about 100ms above the upper reservoir.

The Volumes:

Using SeisMath™ an amplitude based attribute was created on the reflectivity data that highlighted the reservoir but also contained extraneous clutter (a). This clutter correlated with a high level of instability in instantaneous frequency that could be seen with a frequency based attribute (b).
The two attributes were combined resulting in an attribute that highlighted the reservoir from the surrounding matrix (c).
Using SeisMine™ the highlighted area was then body labelled to help understand the connectivity and the geometry of the reservoir (d).
Understanding the internal characteristics of the reservoir was also an important consideration. The bodies were used as a mask to "cookie cut" the relevant area of reflectivity data, resulting in a volume of seismic data that matched the reservoir shape and size (e).
The volumes were created at ffA's dedicated services centre in Aberdeen and illustrate the quality of results achievable by asset geoscientists using ffA's SEA 3D™ image processing and analysis software.

The Results:

• An attribute was created to highlight the areas of high amplitude and frequency instability that characterise the reservoir.

• The three main reservoir compartments were recognised and segmented from the attribute.

• The internal makeup of the reservoir could be interpreted using the cookie cut volume that only contained seismic data within the reservoir bodies.

• Ties with previously unseen well information were made following the semi-blind interpretation, and showed the bodies to be an accurate representation of the reservoir.

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(a) Amplitude based attribute highlighting potential reservoir

(b) Frequency based attribute highlighting surrounding clutter

(c) Combined attribute highlighting potential reservoir with minimal surrounding clutter

(d) Three distinct reservoir compartments were identified and body labelled

(e) Internal reservoir properties can be interpreted using the 'cookie cut' volume