Block PM301 is located in the north Malay Basin adjacent to the Malaysia Thailand Joint Development Area (MTJDA) gas hub. Seven gas fields have been discovered in the block to date. In order to move the project through the production value chain, an integrated subsurface study was carried out to gain a deeper understanding of the fields’ potential and an insight into how to optimally develop these complex reservoirs.

The PM301 fields will be challenging to develop as they are relatively small (typically 200Bcf each, GIIP) and geologically complex, associated with deposition in a fluvial to shallow marine setting. There are also petrophysical issues, including fine scale reservoir heterogeneity, complex mineralogy and low-resistivity low-contrast pay. Seismic interpretation is challenging due to shallow gas, the presence of coal and resolution of thin reservoir intervals.

A detailed, integrated data gathering and interpretation effort involved the development of a depositional model, a stratigraphic layering scheme, definition of key depositional and lithofacies and a reservoir characterisation study. Reservoirs have been characterised in terms of rock types and pore types based on petrographic and core analysis data which have been combined with detailed log evaluations to determine potential flow units, baffles and barriers. Detailed analysis of rock property data tied to seismic is one of the most important aspects of the project.

Key lessons learnt include the importance of acquiring good subsurface rock data and the need for meticulous seismic interpretation in order to filter out acquisition artifacts and optimise the data. Also, the application of Lorenz plots and Winland R35 analysis, calibrated to test data provided key rock quality and heterogeneity information. This study and the techniques applied have application in other complex fields.

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