Application of Neural Networks Technique in Depositional Environment Interpretation for the Niger Delta - a Novel Computer-Based Methodology for 3-D Reservoir Geological Modelling and Exploration Studies (A Pilot Application in X-Field, Niger Delta, Nigeria)

Emeka M. Iloghalu, Nnamdi Azikiwe University Awka, Nigeria, P.O. Box 1225, Awka, Anambra State, Awka, Awka, Nigeria, phone: 234-48-553784, emeka_iloghalu@yahoo.com, Ifeanacho P. Orajaka, Dean, School of Postgraduate Studies, Nnamdi Azikiwe University Awka, Nigeria, P.M.B 5025, Awka, Anambra State, Awka, Nigeria, and Ufot E. Ebong, DPE- T4T5, Shell Petroleum Development Company of Nigeria Ltd, PortHarcourt, Nigeria.

Artificial neural network is a virtual intelligence tool, which mimics the human brain to do analysis and come out with results. Its application in petroleum engineering is very recent and is gradually evolving and is set to dominate or take over other analytical tools used in the Exploration and Production industry.

There are two types of neural network namely, unsupervised and supervised neural networks. A proper combination of these two types of neural networks produces high-resolution results.

In this work, interpreted core data was depth matched to well logs and 8 genetic units were calibrated to define the combined log responses for each genetic unit. These combined log responses were then used to train the supervised neural networks to recognise and interpret these units elsewhere in the field. Thereafter, the unsupervised neural network was run to generate classes within the cored interval. The results were then compared with the supervised network output and were then extrapolated vertically and laterally to other parts of the field.

This technique having been used successfully to perform automatic interpretation of genetic units and lithofacies associations in reservoir scale is also very useful and applicable in exploration. Specific reservoirs or stratigraphic units can be automatically interpreted across a wide area using well data controlled by one or a combination of lithostratigraphy, allostratigraphy, sequence stratigraphy and biostratigraphy.

Using this technique well data cost and time are saved tremendously. It is the key to achieving computerised Basin-Scale Reservoir Characterisation for the Niger Delta.

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