Core invasion studies using deuterium oxide tracer

Fig 1.Deuterium oxide tracer can be used in oil exploration studies

The main objective of a coring operation is to get accurate information about the oil reservoir. Parameters like oil and water composition determine the saturation levels of a reservoir. Information about the reservoir is evaluated by analysis of the collected cores and samples.

In case of drilling mud core invasion, the recovered liquid does not represent the native liquid but rather a mixture of drilling fluid and reservoir fluid. The amount of coring fluid contamination contained in the formation water of a core sample can be determined using a tracer.

Deuterium oxide or heavy water can be used to trace water base mud systems. Prior to coring a quantity of deuterium oxide is added to the aqueous drilling fluid and samples of the coring fluid taken periodically before, during and after the coring process. The levels of deuterium in the extracted water and coring fluid samples can determine the contamination degree.