Lessons Learned from a 10 Year Industry-Wide DHI Consortium

摘要

The effect the presence of oil and especially gas has on the seismic amplitude response in many geological settings can have a dramatic impact in risking prospects. Seismic amplitude anomalies that display direct hydrocarbon indicators (DHIs) have played a major role in oil and gas exploration since the early 1970s. Over the last 40 years there have been tremendous advances in seismic acquisition, processing, and inter-pretation, as well as, improvements in the methodology to identity and risk seismic amplitude anomalies. Even with the use of advanced seismic technology and well-equipped interpretation workstations, the interpretation of hydrocarbon induced seismic amplitude characteristics is not always easy or straightforward. In order to avoid costly mistakes, a systematic, consistent and thorough work process is necessary to risk exploration prospects with seismic amplitude anomalies that may be associated with hydrocarbons. The process should be broad enough to cover reservoirs in geological settings that range from unconsolidated to consolidated sands. Traditionally, most oil companies employ a set of geologic chance factors to determine the risk of exploration prospects (Fig. 1). Typically each major geologic chance factor category is risked and multiplied together to determine the overall risk of the prospect. How does the presence of seismic amplitudes interpreted as DHIs impact these geologic chance factors? Does an amplitude defined area mean there is a source rock? Does a high amplitude anomaly mean a reservoir is present? Interpreters should avoid this circular reasoning in that if a true DHI is present, all the geologic chance factors (not just one or two) are working and a petroleum system is present Therefore, the key to evaluating these prospects is to determine whether a seismic amplitude anomaly truly is a DHI. Not all seismic amplitude anomalies are DHIs. This requires a systematic and consistent process to evaluating seismic amplitude anomalies.