Geometry and Rock Properties Modelling of the Callovo-Oxfordian Claystone from a 3D High Resolution Seismic Cube

2015 ◽  
Author(s):  
B. Yven ◽  
M.G. Garcia ◽  
A.C. Chabiron
Keyword(s):  
High Resolution ◽  
Rock Properties

Geomechanical Model as the Key Step to Proppant Fracturing Success in Shallow Carbonate Reservoir of Bahrain

2021 ◽  
Author(s):  
Ahmed AlJanahi ◽  
Feras Altawash ◽  
Hassan AlMannai ◽  
Sayed Abdelredy ◽  
Hamed Al Ghadhban ◽  
...  
Keyword(s):  
High Resolution ◽  
Horizontal Wells ◽  
Carbonate Reservoir ◽  
Rock Properties ◽  
Stress Profile ◽  
Geomechanical Model ◽  
Breakdown Pressure ◽  
Matrix Permeability ◽  
Geomechanical Analysis ◽  
Horizontal Strain

Abstract Geomechanics play an important role in stimulation design, especially in complex tight reservoirs with very low matrix permeability. Robust modelling of stresses along with rock mechanical properties helps to identify the stress barriers which are crucial for optimum stimulation design and proppant allocation. Complex modeling and calibration workflow showcased the value of geomechanical analysis in a large stimulation project in the Ostracod-Magwa reservoir, a complicated shallow carbonate reservoir in the Bahrain Field. For the initial model, regional average rock properties and minimum stress values from earlier frack campaigns were considered. During campaign progression, advanced cross dipole sonic measurements of the new wells were incorporated in the geomechanical modeling which provided rock properties and stresses with improved confidence. The outputs from wireline-conveyed microfrac tests and the fracturing treatments were also considered for calibration of the minimum horizontal stress and breakdown pressure. The porepressure variability was established with the measured formation pressure data. The geomechanically derived horizontal stresses were used as input for the frack-design. Independent fracture geometry measurements were run to validate the model. The poro-elastic horizontal strain approach was taken to model the horizontal stresses, which shows better variability of the stress profile depending on the elastic rock properties. The study shows variable depletion in porepressure across the field as well as within different reservoir layers. The Ostracod reservoir is more depleted than Magwa, with porepressure values lower than hydrostatic (∼7 ppg). The B3 shale layer in between the Magwa and Ostracod reservoirs is a competent barrier with 1200-1500psi closure pressure. The closure pressures in the Ostracod and Magwa vary from 1000-1500psi and 1100-1600psi, respectively. There is a gradual increasing trend observed in closure pressure in Magwa with depth, but no such trend is apparent in the shallower Ostracod formation. High resolution stress profiles help to identify the barriers within each reservoir to place horizontal wells and quantify the magnitude of hydraulic fracture stress barriers along horizontal wells. The geomechanical model served as a key part of the fracturing optimization workflow, resulting in more than double increase in wells productivity compared to previous stimulation campaigns. The study also helped to optimize the selection of the clusters depth of hydraulic fracturing stages in horizontal wells. The poroelastic horizontal strain approach to constrain horizontal stresses from cross dipole sonic provides better variability in the stress profile to ultimately yield high resolution. This model, calibrated with actual frac data, is crucial for stimulation design in complex reservoirs with very low matrix permeability. The geomechanical model serves as one of the few for shallow carbonates rock in the Middle East region and can be of significant importance to many other shallow projects in the region.

scholarly journals X-Ray CT analyses, models and numerical simulations – a comparison with common analytical methods of an experimental CO<sub>2</sub> study

2016 ◽  
Author(s):  
Steven Henkel ◽  
Dieter Pudlo ◽  
Frieder Enzmann ◽  
Viktor Reitenbach ◽  
Daniel Albrecht ◽  
...  
Keyword(s):  
High Resolution ◽  
Numerical Simulations ◽  
Analytical Methods ◽  
Rock Properties ◽  
Similar Data ◽  
Sample Material ◽  
Thin Sections ◽  
Deutschland Gmbh ◽  
Before And After ◽  
Reservoir Sandstones

Abstract. An essential part of the collaborative research project H2STORE ("hydrogen to store"), which is founded by the German government, was a comparison of various analytical methods to characterize reservoir sandstones from different stratigraphic units. In this context Permian, Triassic and Tertiary reservoir sandstones were analysed. Rock core materials, provided by RWE Gasspeicher GmbH (Dortmund), GFD Suez E&amp;P Deutschland GmbH (Lingen), E.ON Gas Storage GmbH (Essen) and RAG Rohöl-Aufsuchungs Aktiengesellschaft (Wien), was processed by different laboratory techniques; thin sections were prepared, rock fragments were crushed, cubes of 1 cm edge length and plugs of 5 cm in length were sawn from macroscopic homogenous cores. With this prepared sample material, polarized light microscopy and scanning electron microscopy – coupled with image analyses, specific surface area measurements (BET), He-porosity and N2-permeability measurements and high resolution micro-computer-tomography (µ-CT), which were used for numerical simulations were conducted. All these methods were applied to most of the same sample material, before and after static CO2 experiments under reservoir conditions. A major concern in comparing the results of these methods is an appraisal of the reliability of the given porosity, permeability and mineral specific reactive (inner) surface areas data. The CO2 experiments are modifying the petrophysical as well the mineralogical/geochemical rock properties. These changes are detectable by all applied analytical methods. Nevertheless, a major outcome of the high resolution µ-CT analyses and proceeded numerical data simulations results in quite similar data sets and data interpretations maintained by the different standard methods; even regarding only CT-single scan of the rock samples. Moreover, this technique is not only time saving, but also none destructive. This is an important point, if only minor sample material is available and a detailed comparison before and after the experimental tests on micro meter, pore scale of specific rock features is envisaged.

Bringing slow slip processes into focus

2020 ◽  
Author(s):  
Rebecca Bell
Keyword(s):  
High Resolution ◽  
Subduction Zones ◽  
Seismic Velocity ◽  
Numerical Models ◽  
Fluid Pressure ◽  
Geophysical Methods ◽  
Rock Properties ◽  
Slow Slip ◽  
Velocity Models ◽  
The North

&lt;p&gt;The discovery of slow slip events (SSEs) at subduction margins in the last two decades has changed our understanding of how stress is released at subduction zones. Fault slip is now viewed as a continuum of different slip modes between regular earthquakes and aseismic creep, and an appreciation of seismic hazard can only be realised by understanding the full spectrum of slip. SSEs may have the potential to trigger destructive earthquakes and tsunami on faults nearby, but whether this is possible and why SSEs occur at all are two of the most important questions in earthquake seismology today. Laboratory and numerical models suggest that slow slip can be spontaneously generated under conditions of very low effective stresses, facilitated by high pore fluid pressure, but it has also been suggested that variations in frictional behaviour, potentially caused by very heterogeneous fault zone lithology, may be required to promote slow slip.&lt;/p&gt;&lt;p&gt;Testing these hypotheses is difficult as it requires resolving rock properties at a high resolution many km below the seabed sometimes in km&amp;#8217;s of water, where drilling is technically challenging and expensive. Traditional geophysical methods like travel-time tomography cannot provide fine-scale enough velocity models to probe the rock properties in fault zones specifically. In the last decade, however, computational power has improved to the point where 3D full-waveform inversion (FWI) methods make it possible to use the full wavefield rather than just travel times to produce seismic velocity models with a resolution an order of magnitude better than conventional models. Although the hydrocarbon industry have demonstrated many successful examples of 3D FWI the method requires extremely high density arrays of instruments, very different to the 2D transect data collection style which is still commonly employed at subduction zones.&lt;/p&gt;&lt;p&gt;&amp;#160;The north Hikurangi subduction zone, New Zealand is special, as it hosts the world&amp;#8217;s most well characterised shallow SSEs (&lt;2 km to 15 km below the seabed).&amp;#160; This makes it an ideal location to collect 3D data optimally for FWI to resolve rock properties in the slow slip zone. In 2017-2018 an unprecedentedly large 3D experiment including 3D multi-channel seismic reflection, 99 ocean bottom seismometers and 194 onshore seismometers was conducted along the north Hikurangi margin in an 100 km x 15 km area, with an average 2 km instrument spacing. In addition, IODP Expeditions 372 and 375 collected logging-while drilling and core data, and deployed two bore-hole observatories to target slow slip in the same area. In this presentation I will introduce you to this world class 3D dataset and preliminary results, which will enable high resolution 3D models of physical properties to be made to bring slow slip processes into focus. &amp;#160;&lt;/p&gt;

The application of geophysics during evaluation of the Century zinc deposit

Geophysics ◽  
2000 ◽  
Vol 65 (6) ◽  
pp. 1946-1960 ◽  
Author(s):  
Andrew J. Mutton
Keyword(s):  
High Resolution ◽  
Imaging Techniques ◽  
Geophysical Methods ◽  
Rock Properties ◽  
Quality Data ◽  
Yield Potential ◽  
Mining Operations ◽  
Zinc Deposit ◽  
Geophysical Logging ◽  
Drill Holes

During the period 1990 to 1995, experimental programs using high‐resolution geophysics at several Australian operating mines and advanced evaluation projects were undertaken. The primary aim of those programs was to investigate the application of geophysical technology to improving the precision and economics of the ore evaluation and extraction processes. Geophysical methods used for this purpose include: 1) borehole geophysical logging to characterize ore and rock properties more accurately for improved correlations between drill holes, quantification of resource quality, and geotechnical information. 2) imaging techniques between drill holes to map structure directly or to locate geotechnical problems ahead of mining. 3) high‐resolution surface methods to map ore contacts and variations in ore quality, or for geotechnical requirements. In particular, the use of geophysics during evaluation of the Century zinc deposit in northern Australia demonstrated the potential value of these methods to the problems of defining the lateral and vertical extent of ore, quantitative density determination, prediction of structure between drill holes, and geotechnical characterization of the deposit. An analysis of the potential benefit of using a combination of borehole geophysical logging and imaging suggested that a more precise structural evaluation of the deposit could be achieved at a cost of several million dollars less than the conventional evaluation approach based on analysis from diamond drill‐hole logging and interpolation alone. The use of geophysics for the Century evaluation also provided substance to the possibility of using systematic geophysical logging of blast holes as an integral part of the ore extraction process. Preliminary tests indicate that ore boundaries can be determined to a resolution of several centimeters, and ore grade can be estimated directly to a usable accuracy. Applying this approach routinely to production blast holes would yield potential benefits of millions of dollars annually through improved timeliness and accuracy of ore boundary and quality data, decreased dilution, and improved mill performance. Although the indications of substantial benefits resulting from the appropriate and timely use of geophysics at Rio Tinto’s mining operations are positive, some challenges remain. These relate largely to the appropriate integration of the technology with the mining process, and acceptance by the mine operators of the economic value of such work. Until the benefits are demonstrated clearly over time, the use of geophysics as a routine component of evaluation and mining is likely to remain at a low level.

Impact of 3D Seismic Technologies on Sedimentology Study

2012 ◽  
Vol 463-464 ◽  
pp. 1041-1046
Author(s):  
Ru Tai Duan ◽  
Zhen Kui Jin ◽  
Chong Hui Suo
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Vital Role ◽  
Rock Properties ◽  
Data Mapping ◽  
3D Seismic ◽  
Analytical Methodology ◽  
New Approach ◽  
Basin Scale ◽  
3D Seismic Data

Progress of 3D seismic technologies has played a vital role in the developments of sedimentology in terms of analytical methodology and concepts. High-density and high-resolution 3D seismic data can be used to reconstruct 3D views of sedimentary paleo-evironment by direct imaging of depositional elements and can also be used to analyze sedimentary paleo-evironment evolution in 3D detail by mapping facies variability at a specific geologic time by slicing though it. And such data connected with well logging data can be used for predictions of rock properties distribution to delineate sedimentologic heterogeneity. High resolution of 3D seismic data mapping can also be used to image the geometry of diagenesis front to a resolution of a few meters over thousands of square kilometers, which is a new approach to the study of diagenesis process in basin scale. The potential for future developments in this field is considerable. Relative methods and examples of such Studies on the aspects mentioned above are presented.

Digital rock physics: Segmentation of sub-resolution features

2020 ◽  
Author(s):  
Martin Balcewicz ◽  
Erik H. Saenger
Keyword(s):  
Computed Tomography ◽  
High Resolution ◽  
Rock Physics ◽  
Rock Properties ◽  
X Ray ◽  
Digital Rock Physics ◽  
Tomography Image ◽  
X Ray Computed ◽  
Computed Tomography Image ◽  
Elastic Rock

&lt;p&gt;Digital rock physics (DRP) became a complementary part in reservoir characterization during the last two decades. Deriving transport, thermal, or effective elastic rock properties from a digital twin requires a three-step workflow: (1) Preparation of a high-resolution X-ray computed tomography image, (2) segmentation of pore and grain phases, respectively, and (3) solving equations due to the demanded properties. Despite the high resolution &amp;#181;-CT images, the numerical predictions of rock properties have their specific uncertainties compared to laboratory measurements. Missing unresolved features in the &amp;#181;-CT image might be the key issue. These findings indicate the importance of a full understanding of the rocks microfabrics. Most digital models used in DRP treat the rock as a heterogeneous, isotropic, intact medium which neglect unresolved features. However, we expect features within the microfabrics like micro-cracks, small-scale fluid inclusions, or stressed grains which may influence the elastic rock properties but have not been taken into account in DRP, yet. Former studies have shown resolution-issues in grain-to-grain contacts within sandstones or inaccuracies due to micro-porosity in carbonates, this means the micritic phase. Within the scope of this abstract, we image two different sandstone samples, Bentheim and Ruhrsandstone, as well as one carbonate sample. Here, we compare the mentioned difficulties of X-ray visualization with further analytical methods, this means thin section and focused ion beam measurements. This results into a better understanding of the rocks microstructures and allows us to segment unresolved features in the X-ray computed tomography image. Those features can be described with effective properties at the &amp;#181;-scale in the DRP workflow to reduce the uncertainty of the predicted rock properties at the meso- and fieldscale.&lt;/p&gt;

scholarly journals Look Ahead of the Bit While Drilling: Potential Impacts and Challenges of Acoustic Seismic While Drilling in the McMurray Formation

SPE Journal ◽  
2020 ◽  
Vol 25 (05) ◽  
pp. 2194-2205 ◽  
Author(s):  
Siavash Nejadi ◽  
Nasser Kazemi ◽  
Jordan A. Curkan ◽  
Jean Auriol ◽  
Paul R. Durkin ◽  
...  
Keyword(s):  
Wave Equation ◽  
High Resolution ◽  
Acoustic Properties ◽  
Rock Properties ◽  
Drill Bit ◽  
Depth Of Penetration ◽  
Well Placement ◽  
Mcmurray Formation ◽  
Look Ahead ◽  
Interactive Decision Making

Summary The oil and gas industry, operating and service companies, and academia are actively searching for ways to look ahead of the drill bit while drilling to reduce the risks and costs of the operation and improve the well-placement process. Optimal drilling in challenging and highly heterogeneous reservoirs, where geological data cannot adequately constrain high-frequency variations in rock properties, requires reliable subsurface information from around and ahead of the drill bit. To provide this, we have developed a seismic-while-drilling (SWD) imaging algorithm using signal processing, drillstring modeling, and prestack wave-equation migration. To extend the visibility ahead of the bit, we use the drill bit as a seismic source and image the changes in acoustic properties of rocks both around and ahead of the drill bit. The common practice is to build reverse vertical seismic profile (R-VSP) gathers. Here, we use a blind deconvolution algorithm to estimate the drill-bit source signature from the data directly. Alternatively, we can estimate such a signature through drillstring modeling and surface measurements (i.e., hookload and hook speed). The drillstring dynamics are modeled and analyzed using Riemann's invariants and a backstepping approach in a field-verified model. Next, we enter the estimated source signature into the prestack wave-equation depth-imaging workflow. Our simulations show that providing the drill-bit source signature to the prestack wave-equation depth migration consistently delivers reliable subsurface images around and ahead of the drill bit. The output of our workflow is a high-resolution subsurface image, which is then applied to provide vital information in oil-sands reservoirs for placement of steam-assisted-gravity-drainage (SAGD) well pairs. Compared with conventional practices, the proposed methodology images around and ahead of the drill bit enable interactive decision making and optimal well placement. The key feature of the presented methodology is that instead of cross correlating the SWD data with the pilot trace and building R-VSP gathers, we use the estimated drill-bit source signature and deliver high-resolution prestack depth-migrated images. Through numerical modeling, we tested the potential impacts, validity, and challenges of the proposed methodology in drilling horizontal wells in SAGD settings with an emphasis on the McMurray Formation. We further compared the results with the conventional drilling practice. In contrast to existing tools that have limited depth of penetration, interpreting SWD data in real time confidently maps key target features ahead of the drill bit. This imaging workflow provides sufficient time to precisely control the borehole trajectory and stay within the desired reservoir zone. Accordingly, it mitigates the risk of intersecting mudstone-filled channels and lean zones.

High-resolution acoustic impedance inversion to characterize turbidites at Marlim Field, Campos Basin, Brazil

2014 ◽  
Vol 2 (3) ◽  
pp. T143-T153 ◽  
Author(s):  
Tatiane M. Nascimento ◽  
Paulo T. L. Menezes ◽  
Igor L. Braga
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Acoustic Impedance ◽  
Structural Information ◽  
Low Frequency ◽  
Seismic Inversion ◽  
Background Model ◽  
Rock Properties ◽  
High Porosity ◽  
Campos Basin

Seismic inversion is routinely used to determine rock properties, such as acoustic impedance and porosity, from seismic data. Nonuniqueness of the solutions is a major issue. A good strategy to reduce this inherent ambiguity of the inversion procedure is to introduce stratigraphic and structural information a priori to better construct the low-frequency background model. This is particularly relevant when studying heterogeneous deepwater turbidite reservoirs that form prolific, but complex, hydrocarbon plays in the Brazilian offshore basins. We evaluated a high-resolution inversion workflow applied to 3D seismic data at Marlim Field, Campos Basin, to recover acoustic impedance and porosity of the turbidites reservoirs. The Marlim sandstones consist of an Oligocene/Miocene deepwater turbidite system forming a series of amalgamated bodies. The main advantage of our workflow is to incorporate the interpreter’s knowledge about the local stratigraphy to construct an enhanced background model, and then extract a higher resolution image from the seismic data. High-porosity zones were associated to the reservoirs facies; meanwhile, the nonreservoir facies were identified as low-porosity zones.

scholarly journals Combining high-resolution sequence stratigraphy and mechanical stratigraphy for improved reservoir characterisation in the Fahud field of Oman

GeoArabia ◽  
2005 ◽  
Vol 10 (3) ◽  
pp. 17-44 ◽  
Author(s):  
Elena Morettini ◽  
Anthony Thompson ◽  
Gregor Eberli ◽  
Keith Rawnsley ◽  
Roeland Roeterdink ◽  
...  
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Dynamic Modelling ◽  
Rock Properties ◽  
Production Data ◽  
Reservoir Quality ◽  
Sequence Stratigraphic ◽  
Mechanical Stratigraphy ◽  
Petroleum Development ◽  
Fracture Distribution

ABSTRACT In the Fahud field of Oman, the integration between hierarchies of sequence stratigraphic units and fracture systems has proven to be crucial to explain the distribution of flow and mechanical units. The study focused on the Upper Cretaceous, Albian to Lower Cenomanian Natih e unit (Natih Formation, Wasia Group), a 170-mthick carbonate sequence/reservoir, which exhibits heterogeneities in both facies and reservoir quality. Based on a core-derived high-resolution sequence stratigraphic analysis, the Natih e reservoir can be subdivided into four orders of depositional cycles (from 6th- to 3rd-order). Each cycle consists of a transgressive and regressive hemicycle with characteristic facies and rock properties. The facies and diagenetic overprint of the higher-order cycles vary according to their position within the 3rd-order sequences. Analysis of core, borehole images, seismic, tracer and production data indicate a hierarchy of fractures and faults that seems to follow the stratigraphic subdivisions. A relationship between depositional and diagenetic architecture of the cycles, and the aforementioned data, led to the identification of mechanical layering and stratigraphy within the reservoir. This finding was validated and supported by the successful history match of the three-phase production data within the dynamic model of the reservoir. The combination of sequence and mechanical stratigraphy provides a framework for the correlation of facies and mechanical units across the field. Furthermore, the facies and mechanical units are related to reservoir quality and fracture distribution for consistent upscaling into large-scale reservoir models. Through close co-operation between geologists and reservoir engineers utilising dynamic data, it was possible to determine the most appropriate scale for flow and ensure that such a scale was then used as input for dynamic modelling and for planning of the future exploitation of the Fahud field. As a result of this study, Petroleum Development Oman (PDO) has evaluated a 20% increase in risked reserves, and a 25% reduction of well costs.

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