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The significance of pressure transient analysis has grown over the years, as it has become a key source of subsurface information needed both for surveillance and effective reservoir management. However, it could be quite challenging especially in complex analysis and having an interpretation representative of the reservoir system could be daunting amidst widely varying uncertainties, data quality, limited geological and engineering data. It is therefore quite imperative that the analysis and interpretation approach be robust enough in order to give information that is representative of the reservoir in consideration.While the objectives for acquiring well test data in the first place varies over the life of a field, the interpretation methodology remains practically the same and it is the focus of this paper to give a more practical approach to PTA interpretation for a field at its developmental stage and help resolve one of the problems associated with PTA interpretation which is having a well defined, logical and consistent interpretation approach across different interpreters.This paper presents the application of a divergent thinking approach in well test analysis using multi scenario modeling and then following logical steps using all available geological and engineering data to converge to the most likely interpretation. The application of this approach is discussed using three different fields in the Niger Delta region of Nigeria as case studies which have been carefully selected from a field with little less than 2 years of consistent production (relatively new) to fields with an average production of about 25 years to reflect different level of understanding of the reservoir system based on available data. Analysis was carried out on well test data acquired from these fields using SAPHIR software by KAPPA. The results obtained show that regardless of what model were chosen, a relatively good model match can be obtained for the available data and except all available geological and engineering data are applied in an integrated manner, a non-representative model can be chosen for the said reservoir further leading to more uncertainties. |
