scholarly journals Controlling Factors on Petrophysical and Acoustic Properties of Bioturbated Carbonates: (Upper Jurassic, Central Saudi Arabia)

2021 ◽  
Vol 11 (11) ◽  
pp. 5019
Author(s):  
Moaz Salih ◽  
John J. G. Reijmer ◽  
Ammar El Husseiny ◽  
Mazin Bashri ◽  
Hassan Eltom ◽  
...  
Keyword(s):  
Upper Jurassic ◽  
Acoustic Velocity ◽  
Controlling Factors ◽  
Acoustic Properties ◽  
Coarse Grain ◽  
Reservoir Quality ◽  
Petrophysical Properties ◽  
Quartz Content ◽  
Fine Grain ◽  
Porosity And Permeability

Many of the world’s productive Jurassic reservoirs are intensively bioturbated, including the sediments of the Upper Jurassic Hanifa Formation. Hydrocarbon exploration and production from such reservoirs require a reliable prediction of petrophysical properties (i.e., porosity, permeability, acoustic velocity) by linking and assessment of ichnofabrics and trace fossils and determining their impact on reservoir quality. In this study, we utilized outcrop carbonate samples from the Hanifa Formation to understand the main controlling factors on reservoir quality (porosity and permeability) and acoustic velocity of bioturbated carbonates, by using thin-section petrography, SEM, XRD, CT scan, porosity, permeability, and acoustic velocity measurement. The studied samples are dominated by Thalassinoides burrows that have burrow intensity ranging from ~4% to 27%, with porosity and permeability values ranging from ~1% to 20%, and from 0.002 mD up to 1.9 mD, respectively. Samples with coarse grain-filled burrows have higher porosity (average µ = 14.44% ± 3.25%) and permeability (µ = 0.56 mD ± 0.55) than samples with fine grain-filled burrows (µ = 6.56% ± 3.96%, and 0.07 mD ± 0.16 mD). The acoustic velocity is controlled by an interplay of porosity, bioturbation, and mineralogy. Samples with relatively high porosity and permeability values (>10% and >0.1 mD) have lower velocities (<5 km/s) compared to tight samples with low porosities and permeabilities (<10% and <0.1 mD). The mineralogy of the analyzed samples is dominated by calcite (~94% of total samples) with some quartz content (~6% of total samples). Samples characterized with higher quartz (>10% quartz content) show lower velocities compared to the samples with lower quartz content. Bioturbation intensity, alone, has no control on velocity, but when combined with burrow fill, it can be easier to discriminate between high and low velocity samples. Fine grain-filled burrows have generally lower porosity and higher velocities (µ = 5.46 km/s) compared to coarse grain-filled burrows (µ = 4.52 km/s). Understanding the main controlling factor on petrophysical properties and acoustic velocity of bioturbated strata can enhance our competency in reservoir quality prediction and modeling for these bioturbated units.

scholarly journals Reservoir Quality of Upper Jurassic Corallian Sandstones, Weald Basin, UK

Geosciences ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 446
Author(s):  
Dinfa Vincent Barshep ◽  
Richard Henry Worden
Keyword(s):  
Carbon Capture ◽  
Carbon Capture And Storage ◽  
Upper Jurassic ◽  
Reservoir Quality ◽  
Main Process ◽  
Shallow Marine ◽  
Porosity And Permeability ◽  
Calcite Cement ◽  
Diagenetic Evolution

The Upper Jurassic, shallow marine Corallian sandstones of the Weald Basin, UK, are significant onshore reservoirs due to their future potential for carbon capture and storage (CCS) and hydrogen storage. These reservoir rocks, buried to no deeper than 1700 m before uplift to 850 to 900 m at the present time, also provide an opportunity to study the pivotal role of shallow marine sandstone eodiagenesis. With little evidence of compaction, these rocks show low to moderate porosity for their relatively shallow burial depths. Their porosity ranges from 0.8 to 30% with an average of 12.6% and permeability range from 0.01 to 887 mD with an average of 31 mD. The Corallian sandstones of the Weald Basin are relatively poorly studied; consequently, there is a paucity of data on their reservoir quality which limits any ability to predict porosity and permeability away from wells. This study presents a potential first in the examination of diagenetic controls of reservoir quality of the Corallian sandstones, of the Weald Basin’s Palmers Wood and Bletchingley oil fields, using a combination of core analysis, sedimentary core logs, petrography, wireline analysis, SEM-EDS analysis and geochemical analysis to understand the extent of diagenetic evolution of the sandstones and its effects on reservoir quality. The analyses show a dominant quartz arenite lithology with minor feldspars, bioclasts, Fe-ooids and extra-basinal lithic grains. We conclude that little compactional porosity-loss occurred with cementation being the main process that caused porosity-loss. Early calcite cement, from neomorphism of contemporaneously deposited bioclasts, represents the majority of the early cement, which subsequently prevented mechanical compaction. Calcite cement is also interpreted to have formed during burial from decarboxylation-derived CO2 during source rock maturation. Other cements include the Fe-clay berthierine, apatite, pyrite, dolomite, siderite, quartz, illite and kaolinite. Reservoir quality in the Corallian sandstones show no significant depositional textural controls; it was reduced by dominant calcite cementation, locally preserved by berthierine grain coats that inhibited quartz cement and enhanced by detrital grain dissolution as well as cement dissolution. Reservoir quality in the Corallian sandstones can therefore be predicted by considering abundance of calcite cement from bioclasts, organically derived CO2 and Fe-clay coats.

Effect of Fluid Invasion to Formation Resistivity

2015 ◽  
Vol 1113 ◽  
pp. 285-295
Author(s):  
Wan Zairani Wan Bakar ◽  
Arina Sauki ◽  
Mohd Haziafiz Abd Halim ◽  
Norrulhuda Mohd Taib
Keyword(s):  
Grain Size ◽  
Clay Content ◽  
Exchangeable Cation ◽  
Petrophysical Properties ◽  
Fine Grain ◽  
Porosity And Permeability ◽  
Good Conductor ◽  
Formation Resistivity ◽  
Reaction With Water ◽  
Different Grain Size

Clay is the primary cause for resistivity reduction in most of the low resistivity pay cases. While dry clay acts as insulator, reaction with water made wet clay a good conductor. Clay conductivity is contributed by the exchangeable cation properties of the mineral. This reduces the actual resistivity of the formation, especially in the invaded zone. The effect is more severe if clay existed as dispersed type in the formation; which will also reduce other important petrophysical properties such as porosity and permeability. The study was conducted to observe the mechanism and reduction of formation resistivity due to mud invasion and find the relationship between resistivity reduction and petrophysical properties of the formation. The resistivity was measured on four types of samples with different grain size and sorting; well sorted fine grain size, well sorted medium grain size, well sorted coarse grain size and not well sorted sand. Three types of fluids were flushed into sand pack those are brine, crude oil and water based mud to simulate the invasion process. Sand pack with not well sorted sand and fine grain size had the most resistivity reduction, which possibly due to the high clay content that interacted with water.

Reservoir quality and its relationship to facies and provenance in Middle to Upper Jurassic sequences, northeastern North Sea

Clay Minerals ◽  
2000 ◽  
Vol 35 (1) ◽  
pp. 77-94 ◽  
Author(s):  
M. Ramm
Keyword(s):  
Grain Size ◽  
North Sea ◽  
Close Relationships ◽  
Upper Jurassic ◽  
Reservoir Quality ◽  
Burial History ◽  
Deep Burial ◽  
Porosity And Permeability ◽  
Reservoir Sandstones ◽  
Initial Texture

AbstractClose relationships are demonstrated between reservoir quality, lithofacies, provenance and burial history in the Jurassic Brent and Viking Groups in the Norwegian North Sea. Porosity and permeability are strongly and systematically related to the initial texture and composition of the sandstones. Porosity variations are related to the amount of compaction, which is more severe in matrix-rich than in clean facies, and quartz cementation, which is most important in clean facies. Permeability variations are related to porosity and facies-controlled variations in grain size, and abundance and texture of intergranular fines. Illitization of early diagenetic kaolins require K, which is derived mainly from dissolution of K-feldspar. Sediments were sourced from K-feldspar- poor provenances during the maximum progradation of the Brent Group, and sandstones deposited at this time are less exposed to illitization and have better permeability at deep burial than reservoir sandstones that initially contained more K-feldspar.

Comparison of the Diagenetic and Reservoir Quality Evolution Between the Anticline Crest and Flank of an Upper Jurassic Carbonate Reservoir, Abu Dhabi, United Arab Emirates

2017 ◽  
Author(s):  
Daniel Morad ◽  
Fadi Nader ◽  
Marta Gasparrini ◽  
Sadoon Morad ◽  
Fatima Al Darmaki ◽  
...  
Keyword(s):  
United Arab Emirates ◽  
Upper Jurassic ◽  
Carbonate Reservoir ◽  
Abu Dhabi ◽  
Reservoir Quality

Analysis of Cracking Process in Conditions of High-Temperature Creep of Castings Form the Modified Superalloy IN-713C

2013 ◽  
Vol 212 ◽  
pp. 247-254
Author(s):  
Marek Cieśla ◽  
Franciszek Binczyk ◽  
Marcin Mańka
Keyword(s):  
High Temperature ◽  
Creep Resistance ◽  
Nickel Superalloy ◽  
Morphological Properties ◽  
Coarse Grain ◽  
High Temperature Creep ◽  
Temperature Creep ◽  
Fine Grain ◽  
Initiation And Propagation ◽  
Cracking Process

mpact of complex modification and filtration during pouring into moulds on durability has been evaluated in this study in conditions of high-temperature creep of castings made from nickel superalloy IN-713C post production rejects. The conditions of initiation and propagation of cracks in the specimens were analysed with consideration of morphological properties of material macro-, micro-and substructure. It has been demonstrated that in conditions of high-temperature creep at temperature 980°C with stress σ =150 MPa creep resistance of the IN-713C superalloy increases significantly with the increase of macrograin size. Creep resistance of specimens made of coarse grain material was significantly higher than the resistance of fine grain material.

Machine Learning for Multiple Petrophysical Properties Regression Based on Core Images and Well Logs in a Heterogenous Reservoir

2021 ◽  
Author(s):  
Tao Lin ◽  
Mokhles Mezghani ◽  
Chicheng Xu ◽  
Weichang Li
Keyword(s):  
Machine Learning ◽  
Model Building ◽  
Image Features ◽  
Well Logs ◽  
Model Complexity ◽  
Rock Properties ◽  
Core Analysis ◽  
Petrophysical Properties ◽  
Blind Test ◽  
Porosity And Permeability

Abstract Reservoir characterization requires accurate prediction of multiple petrophysical properties such as bulk density (or acoustic impedance), porosity, and permeability. However, it remains a big challenge in heterogeneous reservoirs due to significant diagenetic impacts including dissolution, dolomitization, cementation, and fracturing. Most well logs lack the resolution to obtain rock properties in detail in a heterogenous formation. Therefore, it is pertinent to integrate core images into the prediction workflow. This study presents a new approach to solve the problem of obtaining the high-resolution multiple petrophysical properties, by combining machine learning (ML) algorithms and computer vision (CV) techniques. The methodology can be used to automate the process of core data analysis with a minimum number of plugs, thus reducing human effort and cost and improving accuracy. The workflow consists of conditioning and extracting features from core images, correlating well logs and core analysis with those features to build ML models, and applying the models on new cores for petrophysical properties predictions. The core images are preprocessed and analyzed using color models and texture recognition, to extract image characteristics and core textures. The image features are then aggregated into a profile in depth, resampled and aligned with well logs and core analysis. The ML regression models, including classification and regression trees (CART) and deep neural network (DNN), are trained and validated from the filtered training samples of relevant features and target petrophysical properties. The models are then tested on a blind test dataset to evaluate the prediction performance, to predict target petrophysical properties of grain density, porosity and permeability. The profile of histograms of each target property are computed to analyze the data distribution. The feature vectors are extracted from CV analysis of core images and gamma ray logs. The importance of each feature is generated by CART model to individual target, which may be used to reduce model complexity of future model building. The model performances are evaluated and compared on each target. We achieved reasonably good correlation and accuracy on the models, for example, porosity R2=49.7% and RMSE=2.4 p.u., and logarithmic permeability R2=57.8% and RMSE=0.53. The field case demonstrates that inclusion of core image attributes can improve petrophysical regression in heterogenous reservoirs. It can be extended to a multi-well setting to generate vertical distribution of petrophysical properties which can be integrated into reservoir modeling and characterization. Machine leaning algorithms can help automate the workflow and be flexible to be adjusted to take various inputs for prediction.

scholarly journals Constraining the Age of Floodplain Levels Along the Lower Section of River Tisza, Hungary

2016 ◽  
Vol 9 (1-2) ◽  
pp. 39-44 ◽  
Author(s):  
György Sipos ◽  
Tímea Kiss ◽  
Orsolya Tóth
Keyword(s):  
Flood Plain ◽  
Luminescence Dating ◽  
Coarse Grain ◽  
Lower Section ◽  
Vegetation Control ◽  
Fine Grain ◽  
Energy Environment ◽  
The Given ◽  
Luminescence Characteristics ◽  
Grain Size Fractions

Abstract During the Late Pelistocene-Holocene transition the fluvial landscape of the Great Hungarian Plain changed considerably as a consequence of tectonic, climatic and geomorphological factors. Geochronology, and especially luminescence dating, is a very important tool in reconstructing these changes. The present study focuses on the Lower-Tisza region and addresses the timing of the development of different floodplain levels. In the meantime the luminescence characteristics of the investigated alluvial sediments were also assessed, with a special emphasis on the comparison of silty fine grain and sandy coarse grain results, as in the given medium and low energy environment fine grain sediments are more abundant, however, based on the literature, coarse grain samples are more reliable in terms of luminescence dating. Measurements were performed on 12 samples originating from the point bars of two large palaeo-meanders, representing different floodplain levels along the river. Results indicate the applicability of both grain size fractions for dating purposes, though fine grain subsamples overestimate in average by 1.5 ka the ages yielded by coarse grain subsamples. Consequently, fine grain samples can be used for outlining only general trends, and results need to be controlled by coarse grain measurements where possible. Based on the ages received, the upper floodplain was actively formed until 13-15 ka, when incision and the development of an intermediate floodplain level started. The meander on the intermediate flood plain level developed then very actively until 9 ka. As indicated by the received age information the intensity of meander formation could be highly affected by climatic and especially vegetation control. However, reconstruction can be refined later by further sampling and the application of the results of the present paper.

scholarly journals Reservoir quality and its controlling diagenetic factors in the Bentiu Formation, Northeastern Muglad Basin, Sudan

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yousif M. Makeen ◽  
Xuanlong Shan ◽  
Mutari Lawal ◽  
Habeeb A. Ayinla ◽  
Siyuan Su ◽  
...  
Keyword(s):  
Clay Content ◽  
Petroleum Exploration ◽  
Reservoir Quality ◽  
Burial Depth ◽  
Petroleum Reservoir ◽  
Fine Grained ◽  
Porosity And Permeability ◽  
Negative Role ◽  
Crevasse Splay ◽  
Channel Deposits

AbstractThe Abu Gabra and Bentiu formations are widely distributed within the interior Muglad Basin. Recently, much attention has been paid to study, evaluate and characterize the Abu Gabra Formation as a proven reservoir in Muglad Basin. However, few studies have been documented on the Bentiu Formation which is the main oil/gas reservoir within the basin. Therefore, 33 core samples of the Great Moga and Keyi oilfields (NE Muglad Basin) were selected to characterize the Bentiu Formation reservoir using sedimentological and petrophysical analyses. The aim of the study is to de-risk exploration activities and improve success rate. Compositional and textural analyses revealed two main facies groups: coarse to-medium grained sandstone (braided channel deposits) and fine grained sandstone (floodplain and crevasse splay channel deposits). The coarse to-medium grained sandstone has porosity and permeability values within the range of 19.6% to 32.0% and 1825.6 mD to 8358.0 mD respectively. On the other hand, the fine grained clay-rich facies displays poor reservoir quality as indicated by porosity and permeability ranging from 1.0 to 6.0% and 2.5 to 10.0 mD respectively. A number of varied processes were identified controlling the reservoir quality of the studies samples. Porosity and permeability were enhanced by the dissolution of feldspars and micas, while presence of detrital clays, kaolinite precipitation, iron oxides precipitation, siderite, quartz overgrowths and pyrite cement played negative role on the reservoir quality. Intensity of the observed quartz overgrowth increases with burial depth. At great depths, a variability in grain contact types are recorded suggesting conditions of moderate to-high compactions. Furthermore, scanning electron microscopy revealed presence of micropores which have the tendency of affecting the fluid flow properties in the Bentiu Formation sandstone. These evidences indicate that the Bentiu Formation petroleum reservoir quality is primarily inhibited by grain size, total clay content, compaction and cementation. Thus, special attention should be paid to these inhibiting factors to reduce risk in petroleum exploration within the area.

scholarly journals An Integrated Microfacies and Well Logs-Based Reservoir Characterization of Yamama Formation, Southern Iraq

2021 ◽  
pp. 3570-3586
Author(s):  
Mohanad M. Al-Ghuribawi ◽  
Rasha F. Faisal
Keyword(s):  
Reservoir Characterization ◽  
Water Saturation ◽  
Effective Porosity ◽  
Well Logs ◽  
Petrophysical Properties ◽  
Reservoir Properties ◽  
Thin Sections ◽  
Porosity And Permeability ◽  
South Of Iraq ◽  
Southern Iraq

     The Yamama Formation includes important carbonates reservoir that belongs to the Lower Cretaceous sequence in Southern Iraq. This study covers two oil fields (Sindbad and Siba) that are distributed Southeastern Basrah Governorate, South of Iraq. Yamama reservoir units were determined based on the study of cores, well logs, and petrographic examination of thin sections that required a detailed integration of geological data and petrophysical properties. These parameters were integrated in order to divide the Yamama Formation into six reservoir units (YA0, YA1, YA2, YB1, YB2 and YC), located between five cap rock units. The best facies association and petrophysical properties were found in the shoal environment, where the most common porosity types were the primary (interparticle) and secondary (moldic and vugs) . The main diagenetic process that occurred in YA0, YA2, and YB1 is cementation, which led to the filling of pore spaces by cement and subsequently decreased the reservoir quality (porosity and permeability). Based on the results of the final digital  computer interpretation and processing (CPI) performed by using the Techlog software, the units YA1 and YB2 have the best reservoir properties. The unit YB2 is characterized by a good effective porosity average, low water saturation, good permeability, and large thickness that distinguish it from other reservoir units.

scholarly journals The Effect of Nonequilibrium Structure State on the Creep and Superplastic Behaviour of Materials

2008 ◽  
Vol 575-578 ◽  
pp. 1031-1037
Author(s):  
M.M. Myshlyaev
Keyword(s):  
Mechanical Behaviour ◽  
Coarse Grain ◽  
Zinc Alloy ◽  
Cobalt Alloy ◽  
Superplastic Behaviour ◽  
Fine Grain ◽  
Grain Zinc ◽  
Nonequilibrium Structure ◽  
Structure State ◽  
Kinetic Principle

Mechanical behaviour at creep and superplasticity of coarse grain and monocrystalline aluminum under torsion, of coarse grain molybdenum, of fine grain zinc alloy and amorphous cobalt alloy under tension are discussed from unified positions. It is shown that realization of their superplasticity requires fulfillment of structure-kinetic principle.

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