4D signal enhancement using singular value decomposition, application to mapping OWC movement across the Nelson field

In this paper we present a new method for time-lapse signal enhancement using singular value decomposition (SVD). Singular value decomposition is used to separate a 4D signal into its constituent parts: common geology, time-lapse response and noise. This signal enhancement technique is used to map out both the original and moved oil-water contact across the Nelson field. The SVD technique allows the oil-water contact (OWC) to be mapped across regions which would have been missed using traditional methods. The oil-water contact is observed to move upwards across the field with the largest movements being associated as anticipated with natural production. The results obtained are consistent with those predicted by the reservoir simulator model. Singular value decomposition is demonstrated to be a useful tool for enhancing the time-lapse signal and for gaining confidence in areas where traditional differencing fails.