Reservoir Fluid Geodynamics in Brazilian Presalt Carbonate Field

Bertolini, Andre; Monteiro, J; Canas, Jesus Alberto; Betancourt, Soraya S.; Mullins, Oliver C.; Colacelli, Santiago; Polinski, Ralf

doi:10.2118/194841-ms

Cited by 7 publications

(12 citation statements)

References 10 publications

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“…DFA log data (asphaltene gradients) for DFA stations in all six wells depicted in Figure 8. 6,13,130 The nearly vertical gradients in wells B, C, and E are consistent with a molecular dispersion of asphaltenes for this light oil. Wells B and C have coincident asphaltene gradients and are known to be connected from production data.…”

Section: ■ Results and Discussionsupporting

confidence: 65%

“…Figure 9. DFA log data (asphaltene gradients) for DFA stations in all six wells depicted in Figure8 6,13,130. The nearly vertical gradients in wells B, C, and E are consistent with a molecular dispersion of asphaltenes for this light oil.…”

mentioning

confidence: 53%

“…Figure 10. (a) Asphaltene gradients for wells B and C, which are connected 6,13,130. The bimodal gradient of well C is consistent with a molecular dispersion of asphaltenes in most of the column and a nanoaggregate dispersion toward the base of the column.…”

mentioning

confidence: 81%

“…An industry-wide study of 28 deepwater Gulf of Mexico reservoirs showed that 75% of the reservoirs underperformed in production rate or total recovery primarily as a result of unrecognized compartmentalization . Many reservoir studies have confirmed that if the reservoir crude oils are in thermodynamic equilibrium, then the reservoir is connected; it takes massive fluid compositional redistribution to equilibrate reservoir fluids, thus requiring connectivity. ,− In contrast, pressure equilibration among different compartments requires only small mass transport and does not require excellent connectivity in reservoirs. − Pressure communication is a necessary but insufficient condition to establish flow communication in reservoirs.…”

Section: Introductionmentioning

confidence: 99%

“…Asphaltene gradients are the most recent reservoir fluid property to be addressed by a proper thermodynamic treatment, − and they provide the most stringent test of thermodynamic equilibrium. ,− Asphaltene gradients can be measured accurately, especially through the use of in situ fluid measurements in oil wells, referred to as “downhole fluid analysis” (DFA) in oilfield well logging . The latest generation of well logging tools that performs DFA can measure fluid gradients accurately and efficiently .…”

Section: Introductionmentioning

confidence: 99%

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Yen–Mullins Model Applies to Oilfield Reservoirs

Chen¹,

Bertolini²,

Dubost³

et al. 2020

Energy Fuels

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Fluid distributions throughout oilfield reservoirs have been measured with increasing accuracy and coverage, both vertical and laterally, in recent years. Currently, a routine observation is that, when reservoir crude oils are in thermodynamic equilibrium, then the reservoir is a single flow unit with fluid flow communication, addressing the most important oil production risk associated with reservoir structure. The most accurate method of determining fluid equilibration is by measurement and analysis of the distribution of dissolved (or suspended) asphaltenes in the oil. This analysis employs the Flory–Huggins–Zuo equation of state (EoS) with its reliance on the Yen–Mullins model of asphaltene nanostructures. This capability has enabled the introduction of a new technical discipline, reservoir fluid geodynamics, which provides a significant advance in the understanding of oilfield reservoirs. Other reservoir fluid components are also measured to assess equilibration of reservoir fluids, including dissolved gas, liquid-phase components, various biomarkers, and methane isotopic ratios. Often, there is a single species of asphaltenes in the reservoir in accordance with the Yen–Mullins model (molecules, nanoaggregates, and clusters). However, for some reservoirs, two species of asphaltenes are evident. These reservoirs provide a stringent test to (1) discern nanostructures of asphaltenes and (2) determine whether there are other prominent aggregate species of asphaltenes in addition to those indicated in the Yen–Mullins model. This paper explores five reservoirs: three of these reservoirs exhibit one dominant species; two exhibit two species of the Yen–Mullins model; and none of the reservoirs exhibits additional species, providing validation of asphaltene nanostructures in the Yen–Mullins model and its application with the Flory–Huggins–Zuo EoS for novel characterization of reservoirs.

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Section: ■ Results and Discussionsupporting

confidence: 65%

mentioning

confidence: 53%

mentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Yen–Mullins Model Applies to Oilfield Reservoirs

Chen¹,

Bertolini²,

Dubost³

et al. 2020

Energy Fuels

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Overview of Asphaltene Nanostructures and Thermodynamic Applications

et al. 2020

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Previously, asphaltene science had been hindered by many significant uncertainties regarding molecular weight, molecular structure, and nanocolloidal characteristics in laboratory solvents and crude oils. These debates were of sufficient magnitude to forestall development and utility of asphaltene modeling for various applications. In the last 2 decades, advances in asphaltene science using many sophisticated techniques have greatly reduced corresponding uncertainties, enabling development of simple asphaltene models for a variety of applications. Here, we provide an overview of key findings in asphaltene science; dominant molecular and nanocolloidal structures are described. These structures with simple thermodynamic formalisms are shown to work well in oilfield reservoirs, specifically including light oils, black oils, and heavy oils. This novel thermodynamic approach using asphaltene nanostructures has enabled characterization of different processes that impact or preclude equilibration of reservoir fluids in geologic time. These processes combine to form the new technical discipline, "reservoir fluid geodynamics", that has proven value in many reservoir studies. In addition, these asphaltene nanostructures are shown to apply to interfacial tension of asphaltene solutions, using simple thermodynamics for surfaces. In addition, we contrast past and current debates in asphaltene science, especially regarding asphaltene molecular architecture, which has been largely resolved. Molecular structural characterization of asphaltenes reviewed herein shows that asphaltenes are dominated by island structures, but some asphaltenes also have a secondary content of structures with an "aryl-linked core", which we propose as a third class of molecular architecture along with island and archipelago designations. The aryl-linked core structure is defined as having a single, contiguous sp 2 -hybridized carbon network containing one or more aryl linkages, in which adjacent aromatic rings are directly bonded together but do not share a common bond in a ring. In contrast, a traditional island structure also has a single, contiguous sp 2 -hybridized carbon network but has adjacent aromatic rings exclusively fused (sharing a common bond in a ring) with no aryl linkages. The definition of archipelago remains unchanged and consists of multiple, discontinuous sp 2 -hybridized carbon networks, in which these different aromatic ring systems are connected by one or more sp 3 -hybridized carbons. This new classification, "aryl-linked core", has been assigned to both island and archipelago structures in different publications; thus, this new designation should reduce confusion and help resolve structure− function relations, especially regarding aggregation and reactivity. More broadly, the advances in asphaltene science have ushered in powerful, new applications that are continuing to expand.

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Structure–Dynamic Function Relations of Asphaltenes

et al. 2021

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Asphaltene molecular and nanocolloidal structures have largely been resolved enabling development of structure–function relations of asphaltenes. Atomic force microscopy (AFM) and scanning tunneling microscopy (STM) have provided the first direct molecular structures of many asphaltenes with extension into broader distributions of petroleum pitch. These studies confirmed previous findings of dominant island architecture, moderate-sized polycyclic aromatic hydrocarbons (PAHs) with significant variability in the number and geometry of these rings. The Yen–Mullins model of centroids of molecular and nanocolloidal species of asphaltenes continues to provide foundations for thermodynamic treatment of crude oils, for both bulk and surface. Herein, these asphaltene structures are subject to the stringent test of modeling dynamic function along with static function. Recent results impact evaluation of the molecular management of heavy oil refining for the hydrotreatment process. Roughly, 25,000 reactions were considered acting on ∼17,000 molecules. Reactants and products are probed with ultrahigh-resolution mass spectrometry. In modeling, consistency is required with AFM molecular imaging results of asphaltenes. Excellent agreement is obtained between modeling and experiment, increasing accuracy and robustness. Thermodynamic treatments of asphaltenes in bulk and surface are shown within a structure–dynamic function setting. Two oilfield reservoirs are reviewed which are undergoing different diffusive processes in geologic time. The dynamic model to evaluate both reservoirs couples the simplest solution of the diffusion equation with a quasi-equilibrium state employing the Yen–Mullins model in parts distant from the diffusive process, and excellent agreement between modeling and measurement is obtained. For interfacial tension (IFT), a static model employing the simple Langmuir equation successfully treats solutions of moderate asphaltene concentrations and is consistent with AFM images of asphaltenes. A first-order dynamic correction of time evolution of the IFT can be accounted for considering some molecular polydispersity. Structure–dynamic function relations are established for asphaltenes in three very different arenas.

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Reservoir Fluid Geodynamics in Brazilian Presalt Carbonate Field

Cited by 7 publications

References 10 publications

Yen–Mullins Model Applies to Oilfield Reservoirs

Yen–Mullins Model Applies to Oilfield Reservoirs

Overview of Asphaltene Nanostructures and Thermodynamic Applications

Structure–Dynamic Function Relations of Asphaltenes

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