Did Time-Lapse Seismic Deliver the Anticipated Value of Information?

Delfiner, Pierre¹, Frederick Lefeuvre², Jean-Marc Rodriguez³ (1) Total E&P, Paris La Defense Cedex, France (2) Total E&P, Pau Cedex, France (3) Total USA E&P Inc, Houston, TX

Time-lapse seismic has become a key reservoir management tool. However, as it carries a significant cost the return on investment must be carefully evaluated. The feasibility phase involves two main questions.

Will a reliable, usable and useful time-lapse signal be present or not? This is a technical problem solved by geoscientists. A probability of success captures the confidence of the geoscientist in the time-lapse technique applied to a particular field at a particular time.

Will the answer given by the measured information bring real additional value to the field? This question requires preparing a “business case” which compares the value of the project with and without the time-lapse seismic information, the difference being the “Value of Information” (VOI). It is a cooperative effort between the reservoir engineer, who is the key “customer”, the geophysicist, the geologist, the petrophysicist, often the driller, the economist, and the VOI expert acting as a catalyst. The exercise involves modeling the impact of the information on field development decisions, and the specification of various probabilities, which inevitably have some degree of subjectivity. Therefore it would be quite informative to compare how things turned out with what was anticipated.

Such feedback should be available for at least two of the most recent VOI studies done at TOTAL, one in deep offshore West Africa, and one in deep offshore GOM. The latter is a marginal field where time-lapse seismic was decided to solve a direct operational reservoir management problem, i.e., where to drill a potential injector to stimulate production in exist­ing wells, and should be especially interesting.