The use of neural networks in the field of development geology is in its infancy. In this study, a neural network will be used to identify flow units in Happy Spraberry Field, Garza County, Texas. A flow unit is the mappable portion of the total reservoir within which geological and petrophysical properties that affect the flow of fluids are consistent and predictably different from the properties of other reservoir rock volumes (Ebanks et al., 1992). Ahr and Hammel (1999) further state a highly "ranked" flow unit (i.e. a good flow unit) would have the highest combined values of porosity and permeability with the least resistance to fluid flow. A flow unit may also include nonreservoir features such as shales and cemented layers where combined porosity-permeability values are lower and resistance to fluid flow much higher (i.e. a poor flow unit) (Ebanks et al., 1993).

Production from Happy Spraberry Field primarily comes from a 100 foot interval of grainstones and packstones, Leonardian in age, at an average depth of 4,900 feet. Happy Spraberry Field is unlike most fields in that the majority of the wells have been cored in the zone of interest. This fact more easily lends the Happy Spraberry Field to a study involving neural networks.

A neural network model was developed using a data set of 409 points were X and Y location, depth, gamma ray, deep resistivity, density porosity, neutron porosity, lab porosity, lab permeability and electrofacies were known throughout Happy Spraberry Field. The model contained a training data set of 205 cases, a verification data set of 102 cases and a testing data set of 102 cases. Ultimately two neural network models were created to identify electrofacies and reservoir quality (i.e. flow units). The neural networks were able to outperform linear methods and have a correct classification rate of 0.87 for electrofacies identification and 0.75 for reservoir quality identification.

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The Nam Con Son, Malay, and West Natuna basins, located offshore of SE Vietnam and Peninsular Malaysia, initially formed during Eocene(?)-Oligocene rifting, and underwent inversion during Miocene time. Following cessation of tectonic activity at the end of Miocene time, these basins were subjected to spatially and temporally variable tectonic subsidence, which affected regional sediment dispersal patterns and paleogeographic evolution. This study focused on the complex interactions between regional tectonic deformation, differential subsidence across the southern South China Sea (SCS), evolving drainage networks, and sediment dispersal systems, which influenced filling of basins across the southwestern SCS during Pliocene to Recent time.

Sediment flux to the southwestern SCS has varied during Cenozoic time due to tectonic activity in both onshore regions and offshore basins. Local basement highs such as the Natuna Arch, Khorat Platform, and Con Son High were sediment sources while they were emergent during eustatic lowstands, especially during Paleogene time, when the adjacent basins were underfilled. Major rivers that drained large parts of SE Asia, such as the Mekong River, have become progressively more important as sediment suppliers to the southern SCS during Neogene time. In addition, the drainage networks of many important rivers have evolved significantly in response to hinterland tectonics during Cenozoic time.

The amount of tectonic subsidence across the Sunda Shelf has varied over long wavelengths (>500 km). The Nam Con Son Basin (NCSB) has experienced more subsidence than the Malay and West Natuna basins during Pliocene to Recent time. The amount of Miocene inversion in these basins may be responsible for the differential subsidence. These differences in regional subsidence allowed the Malay and West Natuna basins to become overfilled during Pliocene to Recent time, while the NCSB is still incompletely filled and continues to receive sediments that bypass the Malay and West Natuna basins.

The paleo-Mekong River began to rapidly prograde into the NCSB during late Miocene time. A second depositional system added large volumes of sediment to the southern NCSB beginning in Pliocene time, after the Malay and West Natuna basins were effectively filled, and sediments were able to bypass these basins.

Paleogeographic reconstructions of Pliocene to Recent time show fluvial and shelf environments progressively shifted eastward across the Sunda Shelf. Sediment transport systems such as fluvial and submarine channels were identified across the entire study area and the spatial and temporal evolution of these channel networks is critical for understanding sediment dispersal across the Sunda Shelf.

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