In the field of geosciences for oil and gas, there is a disconcerting question that is not often ... more In the field of geosciences for oil and gas, there is a disconcerting question that is not often tackled: could we correctly model and predict what might not have been understood? The answer seems natural and obvious. Therefore, the capability of a geological modeling workflow to meet the needs of correctly predicting reservoir petrophysical properties in the 3D space requires that the geological processes driving the current organization of these properties have been correctly identified and characterized prior to the modeling phase. In the case of carbonate reservoirs, whether marine or lacustrine, the complexity of prediction is largely linked to the multiplicity of processes that have generated the heterogeneity of the reservoirs. Distributing in a reliable way the final properties resulting from geological history shaped both by different organizational logics and by dependence on successive heritages is an immense challenge with major technical and economic consequences. Claim...
A microseismic feasibility study is presented to monitor the injection of gas in the Arab-D reser... more A microseismic feasibility study is presented to monitor the injection of gas in the Arab-D reservoir of an offshore Middle East field. Full waveform modeling and detection sensitivity analysis have shown that the proposed network of installing sensors at reservoir depth in observation wells has high detection capabilities. However the modeling results reveal that interferences would exist between direct and refracted/reflected waves making it difficult to identify first P-wave and S-wave arrivals from microseismic events. Large location uncertainties are also expected with the proposed network. As a result the feasibility study recommends placing in each observation well some additional shallower sensors ~400 meters above the reservoir. Based on these feasibility results a decision will be made whether to proceed with a field trial survey.
The Eocene Roda sandstones outcrops have been studied in order to better understand the geometry,... more The Eocene Roda sandstones outcrops have been studied in order to better understand the geometry, the internal architecture and the stratigraphy of a low stand deltaic complex. The Roda sandstones are formed by several seaward prograding, vertically stacked and finally landward stepping sandbodies (X,Y,Z). Each sandbody is 10 to 40 m thick and corresponds to three main facies association: (1)
The current interest of the oil industry toward stochastic reservoir modeling has emphasized the ... more The current interest of the oil industry toward stochastic reservoir modeling has emphasized the importance of [open quotes]going back to the outcrop,[close quotes] in view of providing reliable geological input to these stochastic models. The roda Sandstone (Spain) offers excellent three-dimensional (3-D) exposures on a kilometric scale. As part of an E. E. C.-sponsored project, a study has been initiated
ABSTRACT The objective of the Geoscience Project JOUF-0034, which involved three European oil com... more ABSTRACT The objective of the Geoscience Project JOUF-0034, which involved three European oil companies and a number of research institutes located in four EC countries, was to calibrate probabilistic representations of reservoir heterogeneities to actual geological field observations. Three outcropping formations, the deltaic Roda sandstone (Spain), the alluvial fan system of Cajigar (Spain) and the storm deposits of Poulseur/Compagnie du Bois d'Anthisnes (Belgium) were the selected geological objects. For the three sites, the approach was similar: first, extensive geological field work led to the construction of a detailed geological model and to the acquisition of a number of geological field sections on each formation. The sections were then digitized and used as control points in the construction of a ‘reference model’ of each geological formation. The three models probably constitute the most significant results of the project. They describe, as accurately as possible, the geological heterogeneities of each formation at the reservoir scale. The reference models are three-dimensional for Roda and Cajigar, and two-dimensional for Poulseur/CBA. For Roda (and to a lesser degree Cajigar) the last step of the study consisted of simulating oil field appraisals by assuming that only a small number of stratigraphic field sections (or ‘wells’) were known, and reconstructing by geostatistical techniques the architecture of the reference model. This led, for the Roda study, to the development of a novel ‘random genetic simulation’ technique for reconstructing the architecture of deltaic prograding sandbodies. A number of conclusions were drawn from the three studies. The 3D approach proved to be more rigorous than standard 2D correlations of outcropping formations, because it imposes constraints on the spatial consistency of the models. The two-sided interaction between sequence stratigraphy considerations and the analysis of the reference models also proved very fruitful for validating the geological assumptions and understanding their impact on the distribution of heterogeneities. It is worth noting that quantitative geological modeling could only be achieved through a multi-disciplinary approach by geologists and geostatisticians.
In carbonate reservoirs, because of the diversity of geological processes involved in the reservo... more In carbonate reservoirs, because of the diversity of geological processes involved in the reservoir construction, the extrapolation of properties directly from well data to reservoir model gridblocks may lead to poorly predictive reservoir properties and then production forecasts. This paper proposes a modelling workflow in which new tools from disruptive technologies are associated in order to produce reservoir models consistently with reservoir geological construction. The workflow combines the simulation of the depositional facies and their transformation after diagenesis overprint. Original depositional facies are carried out from SED-RES™, a stratigraphic forward modelling software that generates and transports carbonate sediments according to ecological conditions and wind-induced currents. Then GODIAG™, a lattice gas, reproduces the evolution of the properties of the sediment after it has been deposited. The diagenesis history can be multi-stage and can involve different kind...
Proceedings of SPE Middle East Oil and Gas Show and Conference, 2007
The oil-bearing Upper Jurassic Arab reservoirs of an offshore Abu Dhabi fractured carbonate field... more The oil-bearing Upper Jurassic Arab reservoirs of an offshore Abu Dhabi fractured carbonate field (Abu Al Bukhoosh) have been producing for more than thirty years. All the available informations indicate that the producing layers, subdivided into Upper and Lower Arab, are fractured to varying extents. As a result, a better understanding of the fracture networks and their relationship with major and sub-seismic faults in this field is now critical to optimize infill drilling and produce the remaining reserves. The present paper focuses on the characterization of different types of fractures and faults identified on high-resolution image logs recorded in this field. The objective of this study is to provide a more detailed fracture network to explain the present-day reservoir behavior. A uniform classification scheme of fracture types was devised and specific properties, namely, density, orientation, apertures, and porosity of each fracture type, wherever applicable, were generated. These fracture properties were used as input to upgrade the existing reservoir model to study their influence on reservoir production. The relationship of the faults from the images with the seismic faults and the fractures were also studied. Interpretation of high-resolution image data from 24 wells indicates the presence of an organized fracture network within the Arab reservoirs. The impact of such fracture systems on mature carbonate reservoirs can range from very restricted to conduit for fluid flow. The exact implications depend on the type of fracture filling, geometry, connectivity and density. The fractures observed on the images have been classified into continuous and discontinuous open, continuous and discontinuous closed types. The Upper Arab reservoirs contain significantly more open than closed fractures, while Lower Arab reservoirs appear to have equal proportions of closed and open fractures. Open fractures show a dominant NE-SW strike direction for most of the wells both in the Upper and Lower Arab reservoirs. The closed fractures, on the other hand, are dispersed in their orientations. However, most of the studied wells in the Upper Arab show a major NW-SE trend, perpendicular to the direction of the open fractures. Only two areas within the field show closed fractures oriented in the same direction as the open fractures. This fact tends to confirm the interpretation of complex structural trends in these zones indicated from seismic and production data. The faults identified on the images were subdivided into major and minor ones, depending on their scale and relationship with seismic faults present in the field. A total of 8 major and 51 minor faults were observed, with a dominant NW-SE strike direction, consistent with the trend of the major faults interpreted from the seismic data. The majority of these faults are closed in nature.
In the field of geosciences for oil and gas, there is a disconcerting question that is not often ... more In the field of geosciences for oil and gas, there is a disconcerting question that is not often tackled: could we correctly model and predict what might not have been understood? The answer seems natural and obvious. Therefore, the capability of a geological modeling workflow to meet the needs of correctly predicting reservoir petrophysical properties in the 3D space requires that the geological processes driving the current organization of these properties have been correctly identified and characterized prior to the modeling phase. In the case of carbonate reservoirs, whether marine or lacustrine, the complexity of prediction is largely linked to the multiplicity of processes that have generated the heterogeneity of the reservoirs. Distributing in a reliable way the final properties resulting from geological history shaped both by different organizational logics and by dependence on successive heritages is an immense challenge with major technical and economic consequences. Claim...
A microseismic feasibility study is presented to monitor the injection of gas in the Arab-D reser... more A microseismic feasibility study is presented to monitor the injection of gas in the Arab-D reservoir of an offshore Middle East field. Full waveform modeling and detection sensitivity analysis have shown that the proposed network of installing sensors at reservoir depth in observation wells has high detection capabilities. However the modeling results reveal that interferences would exist between direct and refracted/reflected waves making it difficult to identify first P-wave and S-wave arrivals from microseismic events. Large location uncertainties are also expected with the proposed network. As a result the feasibility study recommends placing in each observation well some additional shallower sensors ~400 meters above the reservoir. Based on these feasibility results a decision will be made whether to proceed with a field trial survey.
The Eocene Roda sandstones outcrops have been studied in order to better understand the geometry,... more The Eocene Roda sandstones outcrops have been studied in order to better understand the geometry, the internal architecture and the stratigraphy of a low stand deltaic complex. The Roda sandstones are formed by several seaward prograding, vertically stacked and finally landward stepping sandbodies (X,Y,Z). Each sandbody is 10 to 40 m thick and corresponds to three main facies association: (1)
The current interest of the oil industry toward stochastic reservoir modeling has emphasized the ... more The current interest of the oil industry toward stochastic reservoir modeling has emphasized the importance of [open quotes]going back to the outcrop,[close quotes] in view of providing reliable geological input to these stochastic models. The roda Sandstone (Spain) offers excellent three-dimensional (3-D) exposures on a kilometric scale. As part of an E. E. C.-sponsored project, a study has been initiated
ABSTRACT The objective of the Geoscience Project JOUF-0034, which involved three European oil com... more ABSTRACT The objective of the Geoscience Project JOUF-0034, which involved three European oil companies and a number of research institutes located in four EC countries, was to calibrate probabilistic representations of reservoir heterogeneities to actual geological field observations. Three outcropping formations, the deltaic Roda sandstone (Spain), the alluvial fan system of Cajigar (Spain) and the storm deposits of Poulseur/Compagnie du Bois d'Anthisnes (Belgium) were the selected geological objects. For the three sites, the approach was similar: first, extensive geological field work led to the construction of a detailed geological model and to the acquisition of a number of geological field sections on each formation. The sections were then digitized and used as control points in the construction of a ‘reference model’ of each geological formation. The three models probably constitute the most significant results of the project. They describe, as accurately as possible, the geological heterogeneities of each formation at the reservoir scale. The reference models are three-dimensional for Roda and Cajigar, and two-dimensional for Poulseur/CBA. For Roda (and to a lesser degree Cajigar) the last step of the study consisted of simulating oil field appraisals by assuming that only a small number of stratigraphic field sections (or ‘wells’) were known, and reconstructing by geostatistical techniques the architecture of the reference model. This led, for the Roda study, to the development of a novel ‘random genetic simulation’ technique for reconstructing the architecture of deltaic prograding sandbodies. A number of conclusions were drawn from the three studies. The 3D approach proved to be more rigorous than standard 2D correlations of outcropping formations, because it imposes constraints on the spatial consistency of the models. The two-sided interaction between sequence stratigraphy considerations and the analysis of the reference models also proved very fruitful for validating the geological assumptions and understanding their impact on the distribution of heterogeneities. It is worth noting that quantitative geological modeling could only be achieved through a multi-disciplinary approach by geologists and geostatisticians.
In carbonate reservoirs, because of the diversity of geological processes involved in the reservo... more In carbonate reservoirs, because of the diversity of geological processes involved in the reservoir construction, the extrapolation of properties directly from well data to reservoir model gridblocks may lead to poorly predictive reservoir properties and then production forecasts. This paper proposes a modelling workflow in which new tools from disruptive technologies are associated in order to produce reservoir models consistently with reservoir geological construction. The workflow combines the simulation of the depositional facies and their transformation after diagenesis overprint. Original depositional facies are carried out from SED-RES™, a stratigraphic forward modelling software that generates and transports carbonate sediments according to ecological conditions and wind-induced currents. Then GODIAG™, a lattice gas, reproduces the evolution of the properties of the sediment after it has been deposited. The diagenesis history can be multi-stage and can involve different kind...
Proceedings of SPE Middle East Oil and Gas Show and Conference, 2007
The oil-bearing Upper Jurassic Arab reservoirs of an offshore Abu Dhabi fractured carbonate field... more The oil-bearing Upper Jurassic Arab reservoirs of an offshore Abu Dhabi fractured carbonate field (Abu Al Bukhoosh) have been producing for more than thirty years. All the available informations indicate that the producing layers, subdivided into Upper and Lower Arab, are fractured to varying extents. As a result, a better understanding of the fracture networks and their relationship with major and sub-seismic faults in this field is now critical to optimize infill drilling and produce the remaining reserves. The present paper focuses on the characterization of different types of fractures and faults identified on high-resolution image logs recorded in this field. The objective of this study is to provide a more detailed fracture network to explain the present-day reservoir behavior. A uniform classification scheme of fracture types was devised and specific properties, namely, density, orientation, apertures, and porosity of each fracture type, wherever applicable, were generated. These fracture properties were used as input to upgrade the existing reservoir model to study their influence on reservoir production. The relationship of the faults from the images with the seismic faults and the fractures were also studied. Interpretation of high-resolution image data from 24 wells indicates the presence of an organized fracture network within the Arab reservoirs. The impact of such fracture systems on mature carbonate reservoirs can range from very restricted to conduit for fluid flow. The exact implications depend on the type of fracture filling, geometry, connectivity and density. The fractures observed on the images have been classified into continuous and discontinuous open, continuous and discontinuous closed types. The Upper Arab reservoirs contain significantly more open than closed fractures, while Lower Arab reservoirs appear to have equal proportions of closed and open fractures. Open fractures show a dominant NE-SW strike direction for most of the wells both in the Upper and Lower Arab reservoirs. The closed fractures, on the other hand, are dispersed in their orientations. However, most of the studied wells in the Upper Arab show a major NW-SE trend, perpendicular to the direction of the open fractures. Only two areas within the field show closed fractures oriented in the same direction as the open fractures. This fact tends to confirm the interpretation of complex structural trends in these zones indicated from seismic and production data. The faults identified on the images were subdivided into major and minor ones, depending on their scale and relationship with seismic faults present in the field. A total of 8 major and 51 minor faults were observed, with a dominant NW-SE strike direction, consistent with the trend of the major faults interpreted from the seismic data. The majority of these faults are closed in nature.
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