3D Structural Modelling and Restoration of a Deformed Alpine Karst Reservoir: Insights into the Groundwater Flows of the Dévoluy Massif (French Alpine Foreland)

This study integrated three-dimensional (3D) structural and petrophysical models to establish the reservoir characteristics of the Mangahewa Formation within the Pohokura Gas-Condensate Field. The 3D structural model, in which 3 horizons and 51 faults were interpreted, was developed using an algorithm for volume-based modeling. The complex structural mechanism was observed as compressional and extensional stresses resulting in steeply dipping normal and reverse faults. The fault throw was estimated to be up to 85 m, and 33% of the faults had throws of less than 10 m. This explains the fault growth system as small, younger faults have merged to develop larger faults. Well log analysis was used to evaluate important petrophysical parameters such as effective porosity, net-to-gross ratio, shale volume, and water and hydrocarbon saturation. After applying a cutoff, the estimated values for effective porosity, net-to-gross ratio, shale volume, and water and hydrocarbon saturation were 12–18%, 13–31%, 13–26%, 6–22%, and 78–94%, respectively. The estimated values were then incorporated into the grid cells to design 3D petrophysical modeling using the algorithm for sequential Gaussian simulation. The structural model indicated effective trapping and the presence of a conduit mechanism for hydrocarbons. The well log analysis identified significant effective porosities containing substantial hydrocarbon saturation, whereas the petrophysical models showed very good dissemination of the petrophysical parameters. From these models, which also incorporate the gas–water contact, proposed drilling sites for future exploration and well development were proposed. The results characterize the Mangahewa Formation as a good reservoir within the Pohokura Gas-Condensate Field.

Shale oil and gas fields usually contain many horizontal wells. The key of 3D structural modeling for shale reservoirs is to effectively utilize all structure-associated data (e.g., formation tops) in these horizontal wells. The inclination angle of horizontal wells is usually large, especially in the lateral section. As a result, formation tops in a horizontal well are located at the distinct lateral positions, while formation tops in a vertical well are usually stacked in the same or similar lateral position. It becomes very challenging to estimate shale layer thickness and structural map of multiple formation surfaces using formation tops in horizontal wells. Meanwhile, the large inclination angle of horizontal wells indicates a complicated spatial relation with shale formation surfaces. The 3D structural modeling using horizontal well data is much more difficult than that using vertical well data. To overcome these new challenges in 3D structural modeling using horizontal well data, we developed a method for 3D structural modeling using horizontal well data. The main process included 1) adding pseudo vertical wells at formation tops to convert the uncoupled formation tops to coupled formation tops as in vertical wells, 2) estimating shale thickness by balancing the shale thickness and dip angle change of a key surface, and 3) detecting horizontal well segments landing in the wrong formations and adding pseudo vertical wells to fix them. We used our improved method to successfully construct two structural models of Longmaxi–Wufeng shale reservoirs at a well pad scale and a shale oil/gas field scale. Our research demonstrated that 3D structural modeling could be improved by maximizing the utilization of horizontal well data, thus optimizing the quality of the structural model of shale reservoirs.

For a well in the Permian Basin, openhole (OH) triple combo logs from five nearby offset wells and gamma ray from a horizontal well were used to deduce a workflow to define the 3D structural geometry of the drilled horizontal section. After establishing the structural architecture of the drilled lateral section to determine which part of the lateral is in or out of zone, lithology and petrophysical properties from the offset wells were propagated using geostatistical algorithms to match the horizontal well path. A relatively distant offset well with an advanced log suite was also utilized to generate synthetic mechanical rock properties along the lateral. These data were used for optimized completion design by placing stimulation stages in similar rock and intelligently placing perforation clusters. Placement was guided by rock type and geomechanical properties as opposed to geometrical spacing along the lateral. The assumption that rock properties are homogenous and structural dip is fairly constant in horizontal drilling has been proven to be untrue in recent studies, and production logs have shown that not all stages/perforation clusters contribute to production. The consequence of not using image log measurements in geosteering the lateral to ensure that the lateral is in the target reservoir can lead to ineffective stimulation treatment and possibly skipping stages in parts of the lateral that is landed in a higher stress rock. The successful application of the workflow enabled us to determine the structural geometry along the drilled horizontal well and also build a 3D structural and property model, which was successfully used for the optimized stimulation staging and completion design. This produced a more successful stimulation treatment with approximately 67% more sand placed per stage compared to an offset well drilled in the same target zone.

CX3CR1, a G protein-coupled receptor solely expressed by microglia in the brain, has been repeatedly reported to be associated with neurodevelopmental disorders including schizophrenia (SCZ) and autism spectrum disorders (ASD) in transcriptomic and animal studies but not in genetic studies. To address the impacts of variants in CX3CR1 on neurodevelopmental disorders, we conducted coding exon-targeted resequencing of CX3CR1 in 370 Japanese SCZ and 192 ASD patients using next-generation sequencing technology, followed by a genetic association study in a sample comprising 7054 unrelated individuals (2653 SCZ, 574 ASD and 3827 controls). We then performed in silico three-dimensional (3D) structural modeling and in vivo disruption of Akt phosphorylation to determine the impact of the detected variant on CX3CR1-dependent signal transduction. We detected a statistically significant association between the variant Ala55Thr in CX3CR1 with SCZ and ASD phenotypes (odds ratio=8.3, P=0.020). A 3D structural model indicated that Ala55Thr could destabilize the conformation of the CX3CR1 helix 8 and affect its interaction with a heterotrimeric G protein. In vitro functional analysis showed that the CX3CR1-Ala55Thr mutation inhibited cell signaling induced by fractalkine, the ligand for CX3CR1. The combined data suggested that the variant Ala55Thr in CX3CR1 might result in the disruption of CX3CR1 signaling. Our results strengthen the association between microglia-specific genes and neurodevelopmental disorders.

Partial D status is a major concern for transfusion and pregnancy, due to the possibility of carriers becoming immunized. When known carriers of a D variant have never been exposed to complete D, they are assumed to have D partial status based on the position of the amino acid substituted. New approaches for predicting immunization risk are required. We built a three-dimensional (3D) structural model to investigate the consequences of substitutions of Amino Acid 223 involved in a large number of D variants. Homology modeling was performed with multiple templates. The model was evaluated by comparing the interactions of the known p.Phe223Val variant (RHD*08.01) and a new p.Phe223Ser variant (RHD*52) to RhD reference allele (p.Phe223). The consequences predicted by modeling the variants were compared with serologic data. The 3D structural model was generated from two related protein structures and assessed with state-of-the-art approaches. An analysis of the interactions of the variant Residue 223 in the proposed 3D model highlighted the importance of this position. Modeling predictions were consistent with the serologic and clinical data obtained for the D antigen with a substitution of Amino Acid 223. We used a 3D structural model to evaluate the effect of the p.Phe223 substitution on the conformation of the RhD protein. This model shed light on the influence of substitutions on the structure of the RhD protein and the associated alloimmunization risk. These initial findings indicate that the p.Phe223Ser variant can be considered partial.

Formal representation of 3D structural geological models

BackgroundWe have made an attempt to understand the main mechanism which controls the conductive heat transfer in the Årvollskogen borehole. This has been done in order to determine the 2D subsurface temperature distribution within the deep-seated crystalline rocks and, therefore, to estimate the geothermal potential in the Moss area near Oslo.MethodsAn integrated 2D density, magnetic and conductive thermal analysis has been performed in order to recognise the major structural features and thermal pattern of the crystalline crust.ResultsBased on 2D density and magnetic modelling, a 2D structural model has been constructed for the Moss area. This 2D model has been used during the 2D thermal modelling. The results of the 2D thermal modelling demonstrate that a significant decrease of the Earth’s surface temperatures during the last glaciations still affects the subsurface thermal field of the study area in terms of reduced temperatures within the uppermost crystalline crust. The modelled temperatures are characterised by almost horizontal isotherms without considerable vertical disturbances, reflecting the predominance of subhorizontal layering within the crystalline crust of the Moss area.ConclusionThe 2D density and magnetic modelling, with consideration of all available geological and structural data, allows us to reveal the deep structure of the crystalline crust within the Moss area. According to the results of the 2D thermal modelling, the predicted temperatures within the upper crystalline crust are in the range of expected values for this part of Fennoscandia.

F040 3D Structural Modelling and Backstripping of the Northern Northeast German Basin M.B. Hansen* (University of Hamburg) M. Scheck-Wenderoth (GFZ Potsdam) C.P. Hubscher (University of Hamburg) H. Lykke-Andersen (University of Aarhus) & D. Gajewski (University of Hamburg) SUMMARY A 3D structural model of the northern part of the Northeast German Basin was evaluated with special emphasis on the structural framework and its Mesozoic and Cenozoic evolution. The model was the basis for a 3D backstripping approach considering salt flow as a consequence of spatially changing overburden load distribution isostatic rebound and sedimentary compaction for each backstripping step in order to

Basin evolution of the northern part of the Northeast German Basin — Insights from a 3D structural model

Reconstruct the 3D load redistribution paths of framed structures subjected to local column failure and multi-floor fire

Most current approaches for building structural reservoir models focus on geometrical aspects and consistency with seismic and well data. Few approaches account for the validity of 3D geological models regarding structural compatibility. It may be done using restoration to check the kinematics or mechanics. This is generally performed a posteriori, which also provides critical insights on the basin/reservoir history, but requires significant modeling efforts. This paper presents an approach introducing a first-order kinematic and mechanical consistency at the early stages of the structural modeling. Because the full deformation path is generally poorly constrained, we suggest using simplified approaches to generate plausible structures and assess first-order deformations, making efficiency and robustness more important than physical accuracy. A mechanical deformable model based on rigid elements linked by a non-linear energy has been adapted to geological problems. The optimal deformation is obtained by minimizing the total energy with appropriate boundary conditions. Last, the displacement field is transferred to the geological objects embedded into the rigid elements. With this approach, 3D structural models can be obtained by successively modeling the tectonic events. The underlying tectonic history of resulting models is explicitly controlled by the interpreter and can be used to study structural uncertainties.

Three-dimensional discrete network modeling of structural fractures based on the geometric restoration of structure surface: Methodology and its application

(TYPE=abstract)The Central European Basin System is one of the basins where the sedimentary cover is strongly affected by salt tectonics. The most significant stage of salt movement occurred during the Triassic. The largest Triassic subsidence occurred in the different sub-basins surrounding the Ringkoebing-Fyn High such as the Horn Graben, the Danish Basin and the Glueckstadt Graben. Furthermore, the thickest Triassic succession is observed in the Glueckstadt Graben where it reaches more than 9000 m. In the present study, the structure and the Permian to recent evolution of the Glueckstadt Graben are investigated by use of borehole data, seismic lines and 3D structural modelling. The evaluation of the diverse deformation patterns of the sedimentary cover and their relations to salt structures show that the strongest salt movements occurred at the beginning of the Keuper when the Gluckstadt Graben was affected by extension. The onlap patterns of the Jurassic sediments onto the top of the Keuper succession indicate essential changes of the sedimentation style during the Jurassic. Thick Jurassic sediments are only observed around salt structures and are thinning away from salt walls or salt stocks. The Upper Cretaceous strata have an approximately constant thickness and the parallel reflections patterns indicate a quiet tectonic setting with very minor salt movements in the Late Cretaceous. Renewed salt flow during the Paleogene-Neogene caused rapid subsidence along the marginal parts of the Central Triassic Graben in the Westholstein, the Eastholstein and the Hamburger troughs. The thick Paleogene-Neogene strata within the marginal troughs may also be related to a regional component of tectonic subsidence in the area, contemporary with rapid subsidence in the North Sea. The 3D modelling approach has been used to determine salt distribution at certain paleo-levels in response to unloading due to sequential removing of the stratigraphic layers. The modelling approach was also aimed to reconstruct the original Permian salt distribution immediately after deposition. The initial salt thickness varies from 1300 m at the flanks of the basin up to 3000 m within the central part and demonstrates a clear NNE-SSW trend of the basin. The regional trend of the restored salt distribution points to a westward continuation of the Permian salt basin. The formation of the deep Central Triassic Graben and the subsequent Jurassic- Cenozoic marginal troughs was strongly controlled by the development of salt structures through time. It is shown that the depocentre of sedimentation was moving away from the central part of the of the original Graben structure towards its margins. The evaluation of the available data and results of the 3D reverse modelling demonstrate that a greater amount of subsidence occurred close to the active salt structures, and may have resulted in gradual depletion of Permian salt. Thus, this study indicates that the source of such long-term subsidence is derived from gradual depletion of the Permian salt, which started within the axial part of the basin and moved towards the basin flanks with time. In this sense, the Glueckstadt Graben was formed at least partially as a “basin-scale rim syncline” during post-Permian times. Therefore, the results show that salt withdrawal may have played an important role during the Meso-Cenozoic evolution and that the effects of salt-driven subsidence during the Meso-Cenozoic can be considered the main reason for the formation of the deep Central Triassic Graben and the subsequent Jurassic-Cenozoic marginal troughs.

Faults and fractures of multiple scales are frequently induced and generated in compressional structural system. Comprehensive identification of these potential faults and fractures that cannot be distinguished directly from seismic profile of the complex structures is still an unanswered problem. Based on the compressional structural geometry and kinematics theories as well as the structural interpretation from seismic data, a set of techniques is established for the identification of potential faults and fractures in compressional structures. Firstly, three-dimensional (3D) patterns and characteristics of the faults directly interpreted from seismic profile were illustrated by 3D structural model. Then, the unfolding index maps, the principal structural curvature maps, and tectonic stress field maps were obtained from structural restoration. Moreover, potential faults and fractures in compressional structures were quantitatively identified relying on comprehensive analysis of these three maps. Successful identification of the potential faults and fractures in Mishrif limestone formation and in Asmari dolomite formation of Buzurgan anticline in Iraq demonstrates the applicability and reliability of these techniques.

Prediction of weathering paleokarst reservoirs by combining paleokarst landform with unconformity: A case study of Sinian Dengying Formation in Leshan-Longnüsi paleo-uplift, Sichuan Basin