Coarse and Ultra-Fine Scale Compartmentalization by Downhole Fluid Analysis

Mullins, Oliver C.; Fujisawa, Go; Elshahawi, Hani; Hashem, Mohamed

doi:10.2523/iptc-10034-ms

Cited by 27 publications

(14 citation statements)

References 14 publications

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“…It turns out what you do not know can hurt you. There is a growing realization that fluids indeed are often heterogeneous in the reservoir; [1][2][3] this after all is earth science, where little is homogenous. A variety of factors can lead to hydrocarbon compositional grading including gravity, [4] thermal gradients, [5] biodegradation, [6] active charging, water washing, and leaky seals.…”

Section: Introductionmentioning

confidence: 99%

Asphaltene Gravitational Gradient in a Deepwater Reservoir as Determined by Downhole Fluid Analysis

Mullins¹,

Cribbs²,

Betancourt³

et al. 2007

Proceedings of International Symposium on Oilfield Chemistry

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fax 01-972-952-9435. AbstractThe fluids in large reservoirs can be in equilibrium -especially if conditions conducive to convective mixing prevail. A large vertical column of reservoir hydrocarbons offers a unique laboratory to investigate potential gravitational grading. Asphaltenes are known to exist in crude oils as a colloidal suspension, but which had not been well characterized in the laboratory until recently. In this paper, we review a gravitational gradient of asphaltenes in a reservoir and a simple theory is shown to apply. The corresponding downhole and laboratory analyses are consistent; asphaltenes exist in these crude oils in nanoaggregates. The corresponding asphaltene gradients provide a stringent and new method to test reservoir connectivity (as opposed to compartmentalization), which is key to the efficient economic development for many deepwater projects.

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Section: Introductionmentioning

confidence: 99%

Asphaltene Gravitational Gradient in a Deepwater Reservoir as Determined by Downhole Fluid Analysis

Mullins¹,

Cribbs²,

Betancourt³

et al. 2007

Proceedings of International Symposium on Oilfield Chemistry

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“…In large measure, history matching is effectively precluded in deepwater because the bulk of the capex is spent before first oil. There are three reasons why compartments are such a big problem in deepwater [6,12]: 1) there is no known physics that can image thin sealing barriers at the reservoir length scale from a great distance through kilometers of earth, 2) contrary to common belief, pressure communication (which can occur in geologic time through low permeability) is a necessary but insufficient condition to establish flow communication and 3) all geostatistics teaches that small geophysical objects are numerous while large geophysical objects are rare, exactly opposite to routine industry expectations for compartment size. The significance of compartmentalization on flow assurance is that different compartments can contain strikingly different fluids with correspondingly different flow assurance implications.…”

Section: Reflected Intensitymentioning

confidence: 99%

The Impact of Reservoir Fluid Compositional Variation and Valid Sample Acquisition on Flow Assurance Evaluation

Mullins¹,

Elshahawi²,

Flannery³

et al. 2009

Proceedings of Offshore Technology Conference

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“…In particular, the objective of an entirely new type of log, a continuous downhole fluids log, is being realized 11 . Optical spectrometry sensors (LFA, CFA) support the contamination monitoring of viscous oils in complex situations such as OBM by offering a real time presentation of water, oil and gas fraction, fluorescence, hydrocarbon composition (C1, other hydrocarbon gases (C2-C5) and hydrocarbon liquids (C6+) groups) and GOR.…”

Section: Downhole Fluid Analysis (Dfa)mentioning

confidence: 99%

Viscous Oil Dynamics Evaluation for Better Fluid Sampling

et al. 2005

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fax 01-972-952-9435. AbstractProductivity potential evaluation in viscous reservoirs has been difficult in the past due to difficulties in native fluid sampling and in-situ dynamic formation testing evaluations. This is the result of the high oil viscosity and the unconsolidated sands in which they are usually deposited, which create limitations to natural flowing and smooth well testing / production.There is no unique answer to the main question "how do we sample heavy oils in unconsolidated sands". However, from the experience Schlumberger has acquired during years, several modifications have been done to the wireline formation testers (WFT) 1 , such as the Modular Formation Tester (MDT*), and new modules have been developed which, linked to new best practices, have allowed high viscous oil sampling and in-situ formation testing. Some of the new modules and practices include, the extra large diameter (XLD) probe, dual packer with customized gravel pack screens, extra high-pressure displacement unit pump for low flow rates, advanced down hole flow analysis monitoring (DFA*) and special sampling techniques.In this paper, we present a methodology, which integrates formation tester pressure and water-cut measurements with detailed reservoir characterization from logs to better understand the viscous oil dynamics in sandstones reservoirs in order to optimize fluid sampling. _________________________ * Mark of SchlumbergerA commercial reservoir simulator ECLIPSE* in fully implicit, black oil mode is used to simulate the multiphase flow during WFT pumping. Around the wellbore very fine grids are used, which, linked to a multi-segmented wellbore option, allows to model the clean out (contamination level versus time curve) and fluid drainage for different scenarios of oil viscosity, reservoir anisotropy, drilling fluid invasion, flow rate and WFT position relative to the top boundary.The modeling results were validated using WFT field data with different rock and fluid properties. Some correlations were developed for field use that estimates filtrate contamination as a function of clean out time for several WFT modules.A good understanding of the limitations and benefits of each tool under each scenario contributes to a better collaboration in the design and optimization of sampling jobs (best practice and calibration of available analytical planners for field use).

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Coarse and Ultra-Fine Scale Compartmentalization by Downhole Fluid Analysis

Cited by 27 publications

References 14 publications

Asphaltene Gravitational Gradient in a Deepwater Reservoir as Determined by Downhole Fluid Analysis

Asphaltene Gravitational Gradient in a Deepwater Reservoir as Determined by Downhole Fluid Analysis

The Impact of Reservoir Fluid Compositional Variation and Valid Sample Acquisition on Flow Assurance Evaluation

Viscous Oil Dynamics Evaluation for Better Fluid Sampling

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