Presenter
Viktoriya Nam from Baker Hughes
Abstract
Quantification of zonal contributions in deviated wells is challenging due to complexities associated with downhole flow regimes. The limitations of conventional production logging tools and challenges of interpretation methodologies make this a unique challenge during production evaluation. Generally, mature oil wells deplete gradually with time and the constantly changing downhole environment usually present more water-dominated flow regimes. These dynamics frequently result in uncertainties in downhole hydrocarbon rates determination and incorrect estimation of the water holdup which, if not managed efficiently, can lead to poor reservoir management decisions and costly well interventions. In order to reduce the uncertainty, best logging practices, appropriate technology deployment, and accurate data interpretation are essential to help oil companies make timely decisions over the entire life of the well.
This case study presents production logging interpretation techniques used in deviated multi-phase mature oil well that led to a successful production optimization within a challenging North Sea environment.
The old well from the Northern part of the UK North Sea was completed in 1999 and originally perforated three production zones with TCP guns. The well is known to be a gas lift oil producer with a high water cut, that was expected to be around 92% prior to the logging and client provided the value of 89% as BS & W during flowing survey. The main objectives of the survey were to determine intervals of hydrocarbon production and preferably their rates, total well production rates and to confirm if any oil production is coming from below 14005 ft MD.
As the result of this survey it was confirmed that the lowest hydrocarbons entry seen by the Resistivity Array Tool was coming from the perforation below 14005 ft. Oil/Water production zones were identified. The PLT survey discovered interval of production out with the perforated zones provided by the Client this corresponded well with the findings from the PMFC run, with identified casing integrity failure at these depths.
These findings were vital for decision making. The discovery of hydrocarbon production from below 14005 ft has led to decision of not setting a plug just above this zone, but to go ahead and re-perforate, providing incremental 100 bopd. The provided analysis of water producing zones helped the client to save on two further perforating runs.
Biography
Viktoriya Nam holds a MEng in Computer Science and BSc in “Geology and Exploration of Mineral Deposits”. She has worked in Baker Hughes for 14 years in Cased Hole Geoscience. Overall, she has over 20 years of Oil and Gas industry experience including Wireline Field Engineer position, as well as cased hole data acquisition and analysis roles.