oa Carbon Dioxide (CO2) Distribution in the Malay Basin, Malaysia

The carbon dioxide content in both associated and non-associated gases in Malay Basin fields varies up to a maximum of 90%. High CO2 content in natural gas reduces the resource value by lowering the sales gas volume, as well as reducing the BTU content. Also, with CO2 content, special infrastructure is required to develop and process these accumulations. Understanding the reasons for CO2 regional distribution patterns of CO2 will assist the<br>explorationist in targeting prospects with a lower CO2 content. General current understanding of the CO2 distribution in the basin are CO2 percentage increases with depth and high percentage CO2 accumulation are of inorganic origin and tend to be associated with structures with deep seated faults to facilitate CO2 migration up dip from basement. However, we observe that CO2 percentage varies vertically in a field and does not necessarily<br>increases with depth and could also decreases with depth. CO2 of same basement origin are present in different reservoirs of a field; and yet one reservoir may have very low CO2 compared to the other reservoirs.<br>Therefore depth of accumulation and origin of CO2 does not influence the percentage distribution. Geology of traps dictates how much CO2 the container can hold. In closures with good lateral and top seal, high relief structures will accumulate higher percentage CO2 as compared to low relief structures.