scholarly journals High Resolution Characterization of Lithological Heterogeneity of the Paaratte Formation, Otway Basin (Australia), a Coastal to Shallow-Marine Deposit

Geosciences ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 278 ◽  
Author(s):  
Mishra ◽  
Pajank ◽  
Haese
Keyword(s):  
High Resolution ◽  
Reactive Transport ◽  
Rock Type ◽  
Field Studies ◽  
Research Facility ◽  
Shallow Marine ◽  
Rock Types ◽  
Wireline Logs ◽  
Well Correlation ◽  
Lithological Heterogeneity

Coastal to shallow-marine deposits are inherently highly heterogeneous in sediment composition due to variable depositional conditions. Representation of heterogeneity at sub-seismic scales is required for understanding flow and geochemical processes and poses two challenges: Firstly, the representation of different rock types in geological models requires high resolution sampling vertically and laterally. Secondly, the heterogeneity in petrophysical, flow and mineralogical properties within each rock type needs to be sufficiently characterized in order to support (multiphase) flow and reactive transport simulations. This study addresses these challenges for the Paaratte Formation, Otway Basin (Australia), at the CO2CRC’s Otway Research Facility to enable detailed simulations of CO2 flow and reactions. Based on the analysis of wireline logs, hyperspectral core logs and discrete samples from wells CRC-2 and CRC-3, five rock types are defined and characterized for two coastal to shallow-marine parasequences comprising four depositional facies. A combination of wireline logs is used to derive rock type logs for the wells CRC-2 and CRC-3 at 10 cm vertical resolution and allows high resolution cross-well correlation providing insights into the lateral extent of deposits. Findings of this study will inform future desktop and field studies at the CO2CRC’s Otway Research Facility requiring information on sub-seismic lithological heterogeneity.

Enhanced and Rock Typing-Based Reservoir Characterization of the Palaeocene Harash Carbonate Reservoir-Zelten Field-Sirte Basin-Libya

2021 ◽  
Author(s):  
Mohamed Masoud ◽  
W. Scott Meddaugh ◽  
Masoud Eljaroshi ◽  
Khaled Elghanduri
Keyword(s):  
Rock Type ◽  
Carbonate Reservoir ◽  
Classification Model ◽  
Reservoir Rocks ◽  
The Core ◽  
Core Samples ◽  
Rock Types ◽  
Rock Typing ◽  
Open Hole ◽  
Type Classification

Abstract The Harash Formation was previously known as the Ruaga A and is considered to be one of the most productive reservoirs in the Zelten field in terms of reservoir quality, areal extent, and hydrocarbon quantity. To date, nearly 70 wells were drilled targeting the Harash reservoir. A few wells initially naturally produced but most had to be stimulated which reflected the field drilling and development plan. The Harash reservoir rock typing identification was essential in understanding the reservoir geology implementation of reservoir development drilling program, the construction of representative reservoir models, hydrocarbons volumetric calculations, and historical pressure-production matching in the flow modelling processes. The objectives of this study are to predict the permeability at un-cored wells and unsampled locations, to classify the reservoir rocks into main rock typing, and to build robust reservoir properties models in which static petrophysical properties and fluid properties are assigned for identified rock type and assessed the existed vertical and lateral heterogeneity within the Palaeocene Harash carbonate reservoir. Initially, an objective-based workflow was developed by generating a training dataset from open hole logs and core samples which were conventionally and specially analyzed of six wells. The developed dataset was used to predict permeability at cored wells through a K-mod model that applies Neural Network Analysis (NNA) and Declustring (DC) algorithms to generate representative permeability and electro-facies. Equal statistical weights were given to log responses without analytical supervision taking into account the significant log response variations. The core data was grouped on petrophysical basis to compute pore throat size aiming at deriving and enlarging the interpretation process from the core to log domain using Indexation and Probabilities of Self-Organized Maps (IPSOM) classification model to develop a reliable representation of rock type classification at the well scale. Permeability and rock typing derived from the open-hole logs and core samples analysis are the main K-mod and IPSOM classification model outputs. The results were propagated to more than 70 un-cored wells. Rock typing techniques were also conducted to classify the Harash reservoir rocks in a consistent manner. Depositional rock typing using a stratigraphic modified Lorenz plot and electro-facies suggest three different rock types that are probably linked to three flow zones. The defined rock types are dominated by specifc reservoir parameters. Electro-facies enables subdivision of the formation into petrophysical groups in which properties were assigned to and were characterized by dynamic behavior and the rock-fluid interaction. Capillary pressure and relative permeability data proved the complexity in rock capillarity. Subsequently, Swc is really rock typing dependent. The use of a consistent representative petrophysical rock type classification led to a significant improvement of geological and flow models.

scholarly journals Petrographic analysis of carbonate rocks for alkali-aggregate reactivity

1970 ◽  
Vol 14 ◽  
pp. 15-20
Author(s):  
Naresh Kazi Tamrakar ◽  
Lalu Prasad Paudel
Keyword(s):  
Rock Sample ◽  
Rock Type ◽  
Significant Proportion ◽  
Carbonaceous Material ◽  
Petrographic Analysis ◽  
Rock Types ◽  
Alkali Silica Reactivity ◽  
Alkali Carbonate ◽  
Alkali Aggregate Reactivity

Quality of aggregate is of extreme concern when it is to be used for infrastructures. Besides, many physical and mechanicalproperties of the aggregate, presence or absence of deleterious constituents and alkali-silica reactivity are especially importantwhen aggregates are to be used in concrete structures. High potential of alkali-silica reactivity or alkali-carbonate reactivity andpresence of deleterious constituents may impair the infrastructures.A ledge rock sample from the heap to be taken for crushing was petrographically analysed for alkali-silica reactivity. Inoverall, two rock clans (dolosparstone and dolomicrosparstone) with three sub clans (rock type X, Y and Z) from the sample 2 areidentified. Rock type X (dolosparstone) constitutes 82.94% of the whole sample, and shows notable amount of quartz and calciteveins, and carbonaceous material and hematite on the mosaic of dolospars. Rock types Y (dolosparstone) and Z (dolomicrosparstone)contain trace amount of microquartz, mega quartz (>15 mm) and carbonaceous opaques. The rock type Z is dominantly composedof dolomicrospars. Major portions of all the rock types are characterised by mosaics of dolomite in association with variableamounts of muscovite, quartz, and calcite. Calcite often replaces the mosaics of dolomite and bands of quartz, forming a veinnetworks in rock types X and Y. Silica is represented by a low-temperature mega quartz either in ground or in veins, a trace amountof microquartz in rock types Y and Z. There is no other reactive silica components, thus showing a low potential to alkali-silicareactivity. However, the sample shows potential of alkali-carbonate reactivity as significant proportion of rock type havingdolomicrospars are found.DOI: http://dx.doi.org/10.3126/bdg.v14i0.5433Bulletin of the Department of Geology Vol.14 2011, pp.15-20

Advanced Modeling Capability to Enhance Near-Wellbore and Far-Field Bridging in Acid Fracturing Field Treatments

2021 ◽  
Author(s):  
Abdul Muqtadir Khan ◽  
Denis Emelyanov ◽  
Rostislav Romanovskii ◽  
Olga Nevvonen
Keyword(s):  
High Resolution ◽  
Fluid Transport ◽  
Field Studies ◽  
Particulate Material ◽  
Injection Rate ◽  
Far Field ◽  
Field Scale ◽  
Fracture Width ◽  
Acid Fracturing ◽  
Modeling Approach

Abstract Different applications of fracture bridging and diversion are used regularly in carbonate acid fracturing without an in-depth understanding of the physical phenomena that dominate the processes involved in the bridging and diversion process. The extension of modeling capabilities in conjunction with yard-scale and field-scale experiences will increase our understanding of these processes. A robust multimodal diversion pill and polylactic acid fiber-laden viscous acid were utilized for near-wellbore and far-field bridging, respectively. Numerous field treatments demonstrated the uncertainty of achieving effective diversion. An existing multiphysics model was extended to develop functionalities to model diversions at different scale. Extensive laboratory testing was conducted to understand the scale of bridging and diversion mechanisms. Finally, a bridging yard test was designed, and field case studies were used to integrate all the branches. Field cases showed a diversion pressure up to 4,000 psi depending on perforation strategy, pill volume, and pill seating rate. Correlations showed the interdependence of multiple parameters in diversion processes. The field studies motivated modeling capabilities to simulate the critical diversion processes at high resolution and quality. The model simulates diverting agents that reduce leakoff in the fracture area and their effects on fracture geometry. The approach considers the acid reaction kinetics coupled with geomechanics and fluid transport. Different diverting agent concentrations required for bridging can be modeled effectively. A yard test was designed to confirm the integrity of the pill material through completion valves (minimum inside diameter 9.5 mm) and analyzed with high-resolution imaging. All the theoretical, mathematical, and numerical findings from modeling were integrated with laboratory- and yard-scale experimentation results to develop and validate near-wellbore and far-field diversion modeling. Analytical correlations were formulated from injection rate, particulate material concentration, pill volumes, fracture width, etc., to incorporate and validate the model. This study enhances understanding of the different diversion mechanisms from high-fidelity theoretical modeling approach integrated with a practical experimental view at laboratory and field scale. Current comprehensive research has significant potential to make the modeling approach a reliable method to develop tight carbonate formations around the globe.

Mimicking the process of manual sequence stratigraphy well correlation

2021 ◽  
pp. 1-65
Author(s):  
Huijing Fang ◽  
Yihuai Lou ◽  
Bo Zhang ◽  
Huaimin Xu ◽  
Man Lu
Keyword(s):  
Euclidean Distance ◽  
Well Logs ◽  
Stratigraphic Correlation ◽  
Time Warping ◽  
Error Matrix ◽  
Stratigraphic Model ◽  
Wireline Logs ◽  
Well Correlation ◽  
Dynamic Time ◽  
Error Computation

Stratigraphic correlation of well logs is based on interactive, interpreter-based pattern recognition. A skilled interpreter identifies similar patterns (such as upward fining and coarsening) in user-defined well sections and links them using either a conscious or subconscious stratigraphic model. This manual stratigraphic correlation of numerous wells in mature fields can be both time consuming and error prone. To expedite the process of stratigraphic correlation, we perform the semi-automatic stratigraphic correlation of wireline logs from multiple wells using the Improved Dynamic Time Warping (IDTW). The IDTW employs semblance, which compares the shape of the well logs, to replace the Euclidean distance in the pairwise error computation. The resulting error matrix is compatible with the lateral nonstationary variation of well logs in the same formation. The workflow begins with interpreting stratigraphic well tops on user-defined well sections that is similar to current process of stratigraphy analysis. The interpreted wells are then treated as reference wells to aid in interpreting well tops for other wells. Necessary manual interventions are incorporated during the process of the semi-automatic stratigraphic correlation. We applied the proposed method to two experimental fields: a sand-rich reservoir and a mud-rich reservoir. The applications illustrate that the proposed method performs well in aggradational strata and successfully predicts the discontinuities with manual interventions.

Use of Pre-Stack Seismic Data to Guide the 3D Rock-Type Distribution of Arab-D inMaydan Mahzam High-Resolution Geological Model

2010 ◽  
Author(s):  
Ahmed A. Mandani Al-Emadi ◽  
Scott Robinson ◽  
Nizar Jedaan ◽  
Nicolas Desgoutte ◽  
Marie-Stéphanie Blum ◽  
...  
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Rock Type ◽  
Geological Model ◽  
Type Distribution
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