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Collaborating Authors
Results
Abstract Overtime the reliability of production forecast had been a major challenge in the oil industry. Reliable production forecast is critical part of planning and decision making in the oil and gas industry. Only about 45% of production forecast meet its target rate and reserves. With oil prices fluctuation there is huge value to be created in production forecast numbers that are reliable for business plan purpose. Area A has wells under natural production, artificial lift (gas lift) and reservoirs under waterflood. The field historical oil production span over 50 years. Clearly there is need for reliable production forecast for business plan for these matured fields. Up to 2011 field decline rates (determined from field decline curve analysis (DCA)) and the current production rates were used for production forecast. The use of this method showed actual oil production outside the forecasted production range at the confidence level of P10 and P90. To improve the production forecast reliability to be within the range of confidence level of P10 to P90 the methodology was reviewed and a new method was proposed to determine the field decline rate using roll-up of well by well decline rate by statistical method and incorporate uncertainties in the production start rate range. This paper will share the applicability of roll-up well by well decline rate to determine field decline rates used for a reliable production forecast range confidence level (P10, P50 and P90) for short term business plan by incorporating the uncertainties from known historical planned and unplanned downtime. The result from this method showed improvement in production forecast by actual production always within the range of P10 to P90 in the last three years.
- Africa > Nigeria (0.71)
- North America (0.47)
Abstract As Oil fields containing stacked reservoirs are developed, it is not uncommon for these reservoirs to be in pressure communication. The extent of pressure depletion may determine the viability of potential new drills. Possible communication of the X1 reservoir with the Y1 reservoir was initially suspected when a Material Balance study earlier conducted on the X1 reservoir did not yield a reliable historical pressure match using mapped volumes of the X1 thereby suggesting potentially larger Oil in Place number in the X1 reservoir. Also, the structural overlay of the X1 over the Y1 reservoir having compatible hydrocarbon contacts seemed to also indicate possible communication between the X1 and Y1 reservoirs. The conclusion of the Material Balance study recommended a more detailed probe into the X1 reservoir to ascertain the impact of communication on the reservoir development strategy. A simulation study was conducted primarily to evaluate the impact of communication uncertainty on the new drill recovery. Three scenarios were considered namely: Communication of the Y1 with the X1 through the aquifer; Communication of the Y1 with the X1 through the hydrocarbon and the Y1 completely isolated from the X1. The history match indicates reservoir communication through the aquifer as the most plausible scenario. However, due to active reservoir drive mechanism of gas Cap expansion and strong aquifer support in the X1 reservoir and possibly same in the Y1, all three scenarios did not adversely affect the potential recovery in this instance with recoveries between 50-59%. Hence incorporating surveillance information from offset producers is vital in evaluating production potential of zones which may be unproduced but not virgin.
- Africa > Nigeria (0.71)
- Asia > Middle East > Saudi Arabia (0.16)
- Reservoir Description and Dynamics > Fluid Characterization > Phase behavior and PVT measurements (0.95)
- Reservoir Description and Dynamics > Reservoir Simulation > History matching (0.93)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Drillstem/well testing (0.90)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (0.67)