This paper illustrates how pressure data acquired from permanent downhole gauges in a shallow water offshore field are analyzed to provide insight into well performance and reservoir monitoring required for key business decisions. A continuous productivity index is generated to analyze the progressive well performance. Near wellbore damage or water influx into the wellbore in the case of unfavourable mobility ratio is easily flagged off. Combination of productivity index, bottomhole flowing pressure and production data provide robust analysis of the well performance based on which quicker decisions can be made on whether a remedial intervention is required or not. Where the right remedial interventions are made, for example when no stimulation is carried out because variation in productivity index is due to increasing water influx and not near wellbore damage, the derivable benefits are sustained oil or gas production, optimisation of recovery, reduction of operational expenditure, all leading to maximised life cycle economics for the well.
Deployment of downhole gauges in wells is continuing to gain popularity in the oil and gas industry because of its real time application in quality decision-making concerning well and reservoir performance and economic impact on well intervention. Various applications of downhole permanent pressure gauges have been demonstrated by many authors (Gringarten, A. C. et al, 2003, Kuchuk, F. J. et al, 2005 and Chorneyko, D. M., 2006).
The business benefits depend on the analysis and utilization of the data acquired. Well and reservoir performance indicators such as productivity index, permeability impairment, drive mechanism, influx of water or gas into the wellbore at the expense of oil can easily be detected. For example, the continuous evaluation of the productivity index can trigger off further analysis, which might require pressure build-up data for better understanding of a well performance. Overlay of several build-up analyses of a well on the same graph gives an idea of the time-line condition of the drainage area as the reservoir's depletion progresses. Some of these benefits have been captured in a shallow water offshore field in the Niger Delta.
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