Advanced Forward Modeling Helps Planning and Interpreting NMR Logs

fax 01-972-952-9435. AbstractThe Milne Point field in Alaska produces from the Kuparuk, Schrader, and Ugnu formations. The Kuparuk formation contains light oil, while the Schrader and Ugnu contain heavy oil. The ranges of viscosities are 200 to 10,000 cp in the Ugnu, 20 -200 cp in the Schrader, and about 3 cp in the Kuparuk.Over 200 wells have been completed in the Kuparuk and Schrader formations at Milne Point. The Ugnu contains the largest oil in place in the field; however, it has not been developed yet due to the high oil viscosities. To date, only one well has been completed in the Ugnu.BP is engaged in new studies to find a way to make the Ugnu commercial. This paper discusses an attempt to identify lower-viscosity "sweet spots" within the Ugnu using nuclear magnetic resonance (NMR) measurements.In 2004, full suites of logging while drilling (LWD) and wireline data were acquired in two newly drilled wells. The primary goal was to compare viscosity predictions from NMR log measurements to geochemical measurements made on fluids extracted from core plugs. For the first time, on a footby-foot basis, using LWD NMR, lower viscosity sweet-spots were identified in the viscous Schrader formation and in the very heavy oil in the Ugnu formations.

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“…We have used forward modeling (Bonnie, et al, 2001) to generate the NMR T 2 spectra displayed in Fig. 3.…”

Section: Chasing the Sweet Spotsmentioning

confidence: 99%

Ranking Oil Viscosity in Heavy-Oil Reservoirs

Seccombe¹,

Bonnie

Smith³

et al. 2005

SPE International Thermal Operations and Heavy Oil Symposium

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Characterizing the Complex Shaly Sand Oil Reservoirs in San Jorge Basin, Argentina, Using Advanced Magnetic Resonance Techniques

Fam

Vieiro²

2007

Latin American &Amp; Caribbean Petroleum Engineering Conference

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fax 01-972-952-9435. AbstractEvaluating the complex clastic reservoirs in El Tordillo field of the San Jorge Basin in Argentina using conventional logs is greatly affected by variations in formation water salinity, texture, and lithology (primarily the amount of volcanic tuff material) combined with extreme changes in rock permeability and wide variations in oil viscosity. All of these factors affect most of the conventional logs responses in such a way that traditional log analysis methods may fail to provide proper results and consequently may not achieve appropriate forecasts. Such failures have been proven by the high degree of mismatch between conventional log analysis and test/production results.To address uncertainties in conventional log evaluations, operators may resort to excessive well testing for reservoir characterization and production verification. However, well testing is known to be costly (considering the rig time and the frac jobs used). On the other hand, if the operator does not proceed with well testing, productive zones can be bypassed. That is why an effective log evaluation would be the optimum, cost effective method when it demonstrates agreement with production results.The latest acquisition and interpretation techniques of the magnetic resonance imaging logs (MRIL) have demonstrated promising results in the complex shaly-sand reservoirs of El Tordillo field. The magnetic resonance imaging (MRI) technology run on wireline provides an in-situ evaluation of the reservoir properties vital for producibility predictions. The ability of MRI to estimate the type of fluid in terms of viscosity influences the selection and elimination of zones to be tested based on their mobilities. MRI also helps in properly preparing for the testing procedure by pre-identifying the type of hydrocarbon in a zone and by identifying its reservoir quality in terms of permeability and porosity. Thus, the MRI serves well when determining the need for well testing and in enhancing the effectiveness of any particular well test.This article discusses the effectiveness of applying the MRI logging technology to the characterization of the shalysands of El Tordillo field in both the Comodoro Rivadavia and Mina El Carmen formations. It also argues for the value of MRI technology in minimizing the cost (and associated risk) of well testing by identifying best candidate zones for testing and by providing necessary "prior-to-testing" information on the fluid type (i.e., water, light oil, heavy oil or gas) present in a zone and rock properties, such as porosity and permeability.

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Optimizing Hydrocarbon Pay Estimates Using the Magnetic Resonance Imaging Logs in Development Wells of El Furrial Field, East Venezuela

Fam

August

Maestre

et al. 2007

International Oil Conference and Exhibition in Mexico

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fax 01-972-952-9435. AbstractOptimizing production in mature fields depends greatly on proper reservoir characterization. After a certain period of production, a reservoir may exhibit changes in its properties because of changes in formation water salinity arising from water injection, left-behind residual oil in the rock, and changes in pressure regime. These factors, combined with complexities in the original reservoirs properties, such as rapid variations in permeability and oil viscosity, strongly affect the degree of uncertainty in evaluating and predicting productive zones when using only conventional logging methods.These variations affect the responses of most conventional logs. Consequently, traditional log analysis models may fail to provide realistic evaluation results and may not achieve appropriate production forecasts. Common examples of such failures have been recognized when producing high water content from a zone believed to be hydrocarbon or when perforating an interval that does not produce.New logging technologies, such as magnetic resonance imaging (MRI), demonstrate promising formation evaluation results in mature fields. The MRI technology helps to properly distinguish candidate production zones and provide key in-situ reservoir properties, including hydrocarbon type, reservoir quality in terms of permeability and porosity, and barrier zones. The ability of MRI to determine oil viscosity influences the selection and elimination of zones to be produced based on its fluids mobilities. Thus, MRI serves well in the selection of hydrocarbon producing intervals.This paper discusses the effectiveness of applying the MRI technology in characterizing the reservoir fluid properties in the El Furrial field, East Venezuela. It also highlights the value of this technology in minimizing the cost of mis-identified zones for production or testing by identifying best candidate intervals. Verification of the MRI results with actual production testing and/or formation pressure measurements will be demonstrated in the article.

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Advanced Forward Modeling Helps Planning and Interpreting NMR Logs

Cited by 3 publications

References 0 publications

Ranking Oil Viscosity in Heavy-Oil Reservoirs

Ranking Oil Viscosity in Heavy-Oil Reservoirs

Characterizing the Complex Shaly Sand Oil Reservoirs in San Jorge Basin, Argentina, Using Advanced Magnetic Resonance Techniques

Optimizing Hydrocarbon Pay Estimates Using the Magnetic Resonance Imaging Logs in Development Wells of El Furrial Field, East Venezuela

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