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Eko is a prolific Deepwater brown field on production for 10+ years and cumulatively produced ~750MMSTB from 30+ producers and 25+ injectors (average cumulative production 25MMSTB/well). However, the actual ultimate recovery developed by producers vary from 90MMSTB which can be attributed to STOIIP distribution, reservoir complexity & development strategy. As the field has matured to production plateau and with sufficient static & dynamic data now available, a Deepwater Analogue study was kicked off to develop an Ultimate Recovery(UR) predictive model to benchmark the robustness of the simulation predictions for the next phase of in-fill development wells. This database will also support the quick evaluation of other Deepwater fields which are in advance stages of hydrocarbon maturation funnel. An integrated study was carried out to collate all static/dynamic data in each reservoir/well. Drainage area for each producer(s)-injector(s) well pair was defined (Figure 1) and associated average reservoir properties were estimated from latest history matched models. Several combinations of parameters were cross-plotted against the objective function (UR/Well) and a proxy function was established to predict UR for future wells. An error analysis was carried out on the reference case function to establish prediction uncertainty ranges. The simulation based P90/P50/P10 UR ranges for the future in-fill development wells were compared with this analogue database and where the forecasts from models were not in sync with actual observations in Eko field, modeling assumptions were revisited. As way forward, this analogue database will be updated with new well information, static re-modeling and/or history matching exercise. Also, the in-fill well results will be used as litmus test for the robustness of the analogue model. Figure-1 Amplitude Map Showing Definition of Drainage Areas for Major Reservoir (Red wells = Oil Producers, Blue wells =Water Injectors)

Deconvolution technique-which is based on nonlinear total least square (TLS) -is a mathematical tool that extracts the drawdown type curve from the rate and pressure history. This technique provides additional flow regime information that would not normally be seen within the specified time period of the buildup test through conventional analysis. It is an inverse process which aims to rebuild the theoretical reservoir pressure response during a single constant rate production period. This technique was adopted at different Tal Block wells in which conventional well test analysis didn't sight multiple no-flow boundaries due to small radius of investigation. A case is presented in this paper in which deconvolution was applied on a well, where reservoir pressure depletion effects were not matching during the test sequence with conventional analysis and the effect of negative superposition masked the boundary dominated flow, both of these issues were resolved using deconvolution technique. This technique have resulted in additional data/info of tested intervals which helped to resolve certain structural and reservoir uncertainties. However, application of this technique and yielded results should be considered/used keeping in view the assumptions involved in deconvolution, areas of its applicability and quality of data available. This paper presents principle, working, applications, limitations, and observations of deconvolution technique, available methods and a case study.