scholarly journals Research of Temperature Conditions of Organic Sediments Formation in the Productive Formation at Paraffinic Oil Well Production

2021 ◽  
Vol 21 (2) ◽  
pp. 84-93
Author(s):  
Mikhail S. Sandyga ◽  
◽  
Ivan A. Struchkov ◽  
Mikhail K. Rogachev ◽  
◽  
...  
Keyword(s):  
Free Volume ◽  
Pore Space ◽  
Experimental Studies ◽  
Saturation Temperature ◽  
Reservoir Rock ◽  
Core Material ◽  
Reservoir Rocks ◽  
Temperature Conditions ◽  
Before And After ◽  
Paraffinic Oil

The paper presents the studies results of the temperature conditions for the formation of organic (asphalt-resin-paraffinic) deposits in the productive formation during the downhole production of paraffinic oil, including the results of experimental studies to assess the temperature of oil saturation with paraffin in the pore space of reservoir rocks. The studies were carried out in order to substantiate and develop a technology for preventing such deposits in the "reservoir - well" system. The results of filtration and rheological studies showed that for the same oil, the wax saturation temperature in the pore space of the reservoir rock could exceed the value of this parameter in the free volume. It was found that for the investigated solutions (models of highly paraffinic oils), the phase transition of paraffin from liquid to solid state, the formation of wax crystals in the pore space occured at a temperature 3-4° C higher than in the free volume. The results of tomographic studies of the core material, performed before and after filtration of a paraffin-containing solution through it with a decrease in temperature, showed that the open porosity of rock samples decreased on average four times due to the clogging of their pore space with paraffin. Based on the results of the filtration experiment and computed tomography, a digital core model was created, which allowed modeling the fluid flow in the pore space of the rock before and after the formation of paraffin deposits in it. The calculations results of the changes dynamics in the thermal field around the injection well confirmed the probability of cooling the bottomhole zone of the well to a temperature equal to the temperature of the onset of wax crystallization, as well as the probability of the cold water front advancing to neighboring production wells, which could cause a significant decrease in the productivity due to the formation of paraffin deposits in pore space of reservoir rocks. The research results are recommended to be taken into account when developing oil fields in conditions of possible formation of organic (asphalt-resin-paraffinic) deposits in the productive formation. This will make it possible to more reliably predict and effectively prevent its formation in the "reservoir - well" system.

scholarly journals Investigation on Compressibility and Microstructure Evolution of Intact Loess During Wetting Process

2021 ◽  
Author(s):  
Tao Jian ◽  
Ling-wei Kong ◽  
Wei Bai ◽  
Zhi-liang Sun
Keyword(s):  
Water Content ◽  
Pore Space ◽  
Experimental Studies ◽  
Vertical Stress ◽  
Dry Density ◽  
Compression Index ◽  
Rapid Reduction ◽  
Before And After ◽  
Wetting Process ◽  
Intact Loess

Abstract Loess is widely deposited in arid and semi-arid areas and is characterized by low dry density, developed pore space, and loose structure, which is not commensurate with that high structural strength and shear strength in the dry state. Many natural phenomena and experimental studies show that intact loess is very sensitive to the change of water content, with slight increases in water content causing a rapid reduction in strength. Abundant information is available in the literature for collapsibility of loess; however, the research on the evolution of loess compressibility during wetting is still minimal, which is very helpful to understand the loess collapsible deformation caused by long-term irrigation. In this paper, the evolution of compressibility of intact loess during wetting are studied by oedometer test, and the microstructure and pore size distribution (PSD) is characterized on intact loess specimens with different water content before and after oedometer tests by scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) methods. The results show that the compression index (Cc) and secondary compression index (Cα) of intact loess depend on water content and vertical stress and change abruptly after the vertical stress exceeds the yield stress. The Cα/Cc values of the intact loess are not constant, which increased with the vertical stress to peak and then gradually decreased and tend to 0.025. Both wetting and loading can cause microstructural damage to the intact loess, in which loading leads to the collapse of the overhead structure and transformation from a bimodal PSD into a single PSD, and wetting intensifies the collapse of microstructure to form a compacted interlocking structure and promotes the transformation of medium pores into small pores.

Machine-Learning-Assisted Segmentation of Focused Ion Beam-Scanning Electron Microscopy Images with Artifacts for Improved Void-Space Characterization of Tight Reservoir Rocks

SPE Journal ◽  
2021 ◽  
pp. 1-20
Author(s):  
Andrey Kazak ◽  
Kirill Simonov ◽  
Victor Kulikov
Keyword(s):  
Image Segmentation ◽  
Focused Ion Beam ◽  
Pore Space ◽  
Ion Beam ◽  
Reservoir Rock ◽  
Data Sets ◽  
Sem Images ◽  
Reservoir Rocks ◽  
Tight Reservoir

Summary The modern focused ion beam-scanning electron microscopy (FIB-SEM) allows imaging of nanoporous tight reservoir-rock samples in 3D at a resolution up to 3 nm/voxel. Correct porosity determination from FIB-SEM images requires fast and robust segmentation. However, the quality and efficient segmentation of FIB-SEM images is still a complicated and challenging task. Typically, a trained operator spends days or weeks in subjective and semimanual labeling of a single FIB-SEM data set. The presence of FIB-SEM artifacts, such as porebacks, requires developing a new methodology for efficient image segmentation. We have developed a method for simplification of multimodal segmentation of FIB-SEM data sets using machine-learning (ML)-based techniques. We study a collection of rock samples formed according to the petrophysical interpretation of well logs from a complex tight gas reservoir rock of the Berezov Formation (West Siberia, Russia). The core samples were passed through a multiscale imaging workflow for pore-space-structure upscaling from nanometer to log scale. FIB-SEM imaging resolved the finest scale using a dual-beam analytical system. Image segmentation used an architecture derived from a convolutional neural network (CNN) in the DeepUNet (Ronneberger et al. 2015) configuration. We implemented the solution in the Pytorch® (Facebook, Inc., Menlo Park, California, USA) framework in a Linux environment. Computation exploited a high-performance computing system. The acquired data included three 3D FIB-SEM data sets with a physical size of approximately 20 × 15 × 25 µm with a voxel size of 5 nm. A professional geologist manually segmented (labeled) a fraction of slices. We split the labeled slices into training, validation, and test data. We then augmented the training data to increase its size. The developed CNN delivered promising results. The model performed automatic segmentation with the following average quality indicators according to test data: accuracy of 86.66%, precision of 54.93%, recall of 83.76%, and F1 score of 55.10%. We achieved a significant boost in segmentation speed of 14.5 megapixel (MP)/min. Compared with 0.18 to 1.45 MP/min for manual labeling, this yielded an efficiency increase of at least 10 times. The presented research work improves the quality of quantitative petrophysical characterization of complex reservoir rocks using digital rock imaging. The development allows the multiphase segmentation of 3D FIB-SEM data complicated with artifacts. It delivers correct and precise pore-space segmentation, resulting in little turn-around-time saving and increased porosity-data quality. Although image segmentation using CNNs is mainstream in the modern ML world, it is an emerging novel approach for reservoir-characterizationtasks.

Detection and Estimation of Dead-End Pore Volume in Reservoir ROCK by Conventional Laboratory Tests

1966 ◽  
Vol 6 (03) ◽  
pp. 206-212 ◽  
Author(s):  
I. Fatt ◽  
M. Maleki ◽  
R.N. Upadhyay
Keyword(s):  
Laboratory Tests ◽  
Saline Solution ◽  
Pore Space ◽  
Flow Behavior ◽  
Reservoir Rock ◽  
Formation Factor ◽  
Pressure Transient ◽  
Reservoir Rocks ◽  
Reservoir Flow ◽  
Dead End

Abstract Conventional laboratory core analysis tests on samples of two limestone reservoir rocks indicate that about 20 per cent of PV is in dead-end pores. These tests (electric logging formation factor. mercury injection capillary pressure and miscible displacement) were carried out on 3/4-in. diameter test plugs. Test results show a clear difference between these samples and sandstone or homogeneous limestone reservoir rock. Although the amount of dead-end pore space can be only roughly estimated, the presence of such pore space seems clearly indicated. Pressure transient studies also show presence of dead-end PV. Although they do not give quantitative results, pressure transient data yield a reasonable estimate of the size of the neck connecting dead-end pores to the main flow channels. Introduction Equations conventionally used to describe reservoir flow behavior contain the implicit assumption that all connected pore spaces contributed to both porosity and permeability. Several authors have pointed out the changes in pressure transient behavior and in electric log interpretation that may result if this assumption is incorrect and, instead, dead-end or cul-de-sac pores are present. There is a need for laboratory tests that can detect presence of dead-end pores in core samples. With such information on hand the petroleum engineer can make more rational use of the mathematical tools now available for analysis of reservoir flow behavior. This paper describes laboratory studies designed to detect and, if possible, give a quantitative measure of dead-end PV in laboratory-size core plugs. Three reservoir rocks were used, two of which were limestones suspected of having dead- end pore spaces and a well-known sandstone, used as a comparison standard, in which there is believed to be little or no dead-end pore space. All the studies were designed to measure the natural dead-end PV; i.e., the pore space which is dead-ended because of rock structure. During multiphase flow in a rock without dead-end pores, some parts of one of the phases can become surrounded by the other, thereby giving (for certain flow behavior) an effective dead-end PV 8,9. Such behavior will not be described here. FORMATION FACTOR THEORY One of the simplest laboratory measurements which can be made on core plugs is the electric logging formation factor F. By definition: (1) where Ro is the resistivity of the core plug saturated with a saline solution of resistivity Rw. Difficulties in using this definition of F may arise when the solid framework of the rock is electrically conducting. These difficulties may be largely circumvented by using a highly conducting saline solution so that the conduction contribution of the solid is negligible. There are no useful theoretical relationships between F and the porosity phi. A widely used empirical relation is the one given by Archie: (2) where m, called the cementation factor, is expected to be a constant for a given type of rock. Pirson shows that for reservoir rocks, m varies from about 1.3 for loosely cemented sandstones to 2.2 for highly cemented sandstones or carbonate rocks. SPEJ P. 206ˆ

Petrophysical models of deposits of the Menilite suite of the Oligocene flysh of the Carpathians and the Precarpathian deep

2021 ◽  
Vol 3-4 (185-186) ◽  
pp. 33-43
Author(s):  
Ihor Kurovets ◽  
Ihor Hrytsyk ◽  
Oleksandr Prykhodko ◽  
Pavlo Chepusenko ◽  
Zoryana Kucher ◽  
...  
Keyword(s):  
Physical Properties ◽  
Acoustic Waves ◽  
Geophysical Methods ◽  
Reservoir Rock ◽  
Core Material ◽  
Mutual Position ◽  
Reservoir Rocks ◽  
The Carpathians ◽  
Fluid Saturation ◽  
Geological Factors

Petrophysical and collecting properties of the reservoir rocks of low-porous, low-permeable deposits of the Menilite suite of the Oligocene flysh of the Carpathians and the Precarpathian deep were studied as well as their interconnections and interactions under normal conditions and in conditions that simulated the formation conditions, and their typical geological-geophysical cross-sections were constructed. Creation of identical petrophysical models of reservoir rocks was based on the system integrated approach with which the reservoir rock is considered as a system formed in the geological time and consists of interconnected and interacted elements. Petrophysical investigation of the reservoir rocks as the system includes the studies of the characteristics of their elements, the character of interconnections between them taking the conditions of their occurrence into consideration. On the basis of statistical processing and analysis of the results of laboratory studies of core material, the parametric petrophysical models of “core-core”-type were constructed: statistical dependences between porosity factor, permeability factor, water-saturation, specific weight, parameter of porosity, interval time for arriving acoustic waves and parameter of oil-saturation for atmospheric conditions and effective pressures being comparable to formational ones. Using the method of basic components of factor analysis it was possible to study the influence of geological factors upon geophysical parameters of the reservoir rocks in terrigenous sections and the informative value of geophysical methods while singling-out producing seams in the geological section. Oil- and gas-saturation of the reservoir rocks, their mineralogical composition and porosity of the reservoir rocks have the most influence on the indications of geophysical methods in the boreholes, somewhat lesser: a depth of their occurrence and the thickness of the seams. Producing and water-bearing beds differ in the value of electrical resistance most of all. The influence of lithogeodynamic factors upon the collecting and physical properties of the reservoir rocks was studied. The main geological factors that determine collecting parameters of terrigenous rocks and their physical properties are the following: a mineral composition, a shape, a size of fragmental grains and pores and their mutual position, a type of fluid-saturation, a rate of catagenetic transformations and a thermodynamic state.

scholarly journals Evaluation of carbonate-clay cement impact on the permeability factor of reservoir rocks by geophysical data

2018 ◽  
pp. 48-56
Author(s):  
T. V. Potiatynnyk
Keyword(s):  
Hydrogen Content ◽  
Pore Space ◽  
Geophysical Data ◽  
Reservoir Rock ◽  
Core Material ◽  
Carbonate Content ◽  
Gas Field ◽  
Permeability Factor ◽  
Natural Gamma ◽  
G Value

Control over the process of reservoir flooding provides an opportunity to conduct efficient and rational operation of hydrocarbon deposits. Detailed monitoring of the flooding process requires the creation of geologicalfiltration models. The basis of the reservoir filtration model is the permeability factor; its reliability depends on various factors. It was proved that the reliability of permeability factor determination of Hidnovytske field is significantly affected by carbonate content. The research to determine connection of the natural gamma field intensity with the radiation capture of neutrons intensity on the basis of geological and geophysical borehole survey of the Hidnovitske gas field was performed. The model of reservoir rock neutron properties reflects the hydrogen content in the pore space and the characteristic of the mineral composition of the reservoir rock cement. This characteristic makes it possible to use neutron gamma logging to evaluate the carbonate content impact in determining the permeability factor. To evaluate the carbonate content, it was suggested to use relative parameter G, indicating the part of the rockdispersed fraction in the unit of hydrogen content. According to the results of laboratory measurements on core material and geophysical data of radioactive logging, the dependence of parameter G value on carbonate content was developed. The obtained dependence will allow to determine the proportion of carbonates in clay cement by parameter G value and correct the equation to determine the permeability factor. 

scholarly journals New Method of Oil Reservoir Rock Heterogeneity Quantitative Estimation from X-ray MCT Data

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5103
Author(s):  
Irena Viktorovna Yazynina ◽  
Evgeny Vladimirovich Shelyago ◽  
Andrey Andreevich Abrosimov ◽  
Vladimir Stanislavovich Yakushev
Keyword(s):  
Quantitative Estimation ◽  
Pore Space ◽  
Core Sample ◽  
New Method ◽  
Reservoir Rock ◽  
Core Material ◽  
Oil Reservoir ◽  
Pore Scale ◽  
X Ray ◽  
Rock Heterogeneity

This paper considers a new method for “pore scale” oil reservoir rock quantitative estimation. The method is based on core sample X-ray tomography data analysis and can be directly used to both classify rocks by heterogeneity and assess representativeness of the core material collection. The proposed heterogeneity criteria consider the heterogeneity of pore size and heterogeneity of pore arrangement in the sample void and can thus be related to the drainage effectiveness. The classification of rocks by heterogeneity at the pore scale is also proposed when choosing a reservoir engineering method and may help us to find formations that are similar at pore scale. We analyzed a set of reservoir rocks of different lithologies using the new method that considers only tomographic images and clearly distributes samples over the structure of their pore space.

scholarly journals Effect of an Improved Yasutomi Pressure-Viscosity Relationship on the Elastohydrodynamic Line Contact Problem

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Vincenzo Petrone ◽  
Adolfo Senatore ◽  
Vincenzo D'Agostino
Keyword(s):  
High Pressure ◽  
Film Thickness ◽  
Free Volume ◽  
Experimental Studies ◽  
Line Contact ◽  
Volume Model ◽  
Free Volume Model ◽  
Pressure Area ◽  
New Formulation ◽  
Lubricant Viscosity

This paper presents the application of an improved Yasutomi correlation for lubricant viscosity at high pressure in a Newtonian elastohydrodynamic line contact simulation. According to recent experimental studies using high pressure viscometers, the Yasutomi pressure-viscosity relationship derived from the free-volume model closely represents the real lubricant piezoviscous behavior for the high pressure typically encountered in elastohydrodynamic applications. However, the original Yasutomi correlation suffers from the appearance of a zero in the function describing the pressure dependence of the relative free volume thermal expansivity. In order to overcome this drawback, a new formulation of the Yasutomi relation was recently developed by Bair et al. This new function removes these concerns and provides improved precision without the need for an equation of state. Numerical simulations have been performed using the improved Yasutomi model to predict the lubricant pressure-viscosity, the pressure distribution, and the film thickness behavior in a Newtonian EHL simulation of a squalane-lubricated line contact. This work also shows that this model yields a higher viscosity at the low-pressure area, which results in a larger central film thickness compared with the previous piezoviscous relations.

The effects of aquatic therapy on mobility of individuals with neurological diseases: a systematic review

2014 ◽  
Vol 29 (8) ◽  
pp. 741-751 ◽  
Author(s):  
Andresa R Marinho-Buzelli ◽  
Alison M Bonnyman ◽  
Mary C Verrier
Keyword(s):  
Randomized Controlled Trials ◽  
Gait Speed ◽  
Neurological Diseases ◽  
Dynamic Balance ◽  
Experimental Studies ◽  
Controlled Trials ◽  
Aquatic Therapy ◽  
Randomized Controlled ◽  
Randomized Studies ◽  
Before And After

Objective:To summarize evidence on the effects of aquatic therapy on mobility in individuals with neurological diseases.Data sources:MEDLINE, EMBASE, PsycInfo, CENTRAL, CINAHL, SPORTDiscus, PEDro, PsycBITE and OT Seeker were searched from inception to 15 September 2014. Hand-searching of reference lists was performed in the selected studies.Review methods:The search included randomized controlled trials and quasi-experimental studies that investigated the use of aquatic therapy and its effect on mobility of adults with neurological diseases. One reviewer screened titles and abstracts of retrieved studies from the search strategy. Two reviewers independently examined the full texts and conducted the study selection, data extraction and quality assessment. A narrative synthesis of data was applied to summarize information from included studies. The Downs and Black Scale was used to assess methodological quality.Results:A total of 116 articles were obtained for full text eligibility. Twenty studies met the specified inclusion criteria: four Randomized Controlled Trials (RCTs), four non-randomized studies and 12 before-and-after tests. Two RCTs (30 patients with stroke in the aquatic therapy groups), three non-randomized studies and three before-and-after studies showed “fair” evidence that aquatic therapy increases dynamic balance in participants with some neurological disorders. One RCT (seven patients with stroke in the aquatic therapy group) and two before-and-after tests (20 patients with multiple sclerosis) demonstrated “fair” evidence on improvement of gait speed after aquatic therapy.Conclusion:Our synthesis showed “fair” evidence supporting the use of aquatic therapy to improve dynamic balance and gait speed in adults with certain neurological conditions.

Application of Thermo-Frictional and Chemical-Thermal Methods Treatments for Surface Strengthening of Materials

2021 ◽  
Vol 1038 ◽  
pp. 93-99
Author(s):  
Alexander Levterov ◽  
Julia Nechitailo ◽  
Tatyana Plugina ◽  
Oleg Volkov
Keyword(s):  
Cross Sections ◽  
Experimental Studies ◽  
Metallographic Analysis ◽  
Thermal Treatments ◽  
Strengthening Effect ◽  
Thermal Methods ◽  
Surface Strengthening ◽  
Before And After ◽  
The Cross

In the article, the issues of using the methods of thermo-frictional and chemical-thermal treatments for surface strengthening of steel tools were disclosed. 65G steel and U8A steel were considered. A flat graver and a cylindrical root roller were considered to be tools in need of hardening. The nature of the jewellery work using such a tool has been described. Hardening techniques, experimental studies and macro photographs of the samples were presented in this article. A detailed metallographic analysis and measurement of the microhardness of the cross-sections of the prototypes after their strengthening using various methods was carried out. The metallographic nature of the reinforcement with the formation of surface "white layers" was shown. Comparison of the properties of the samples before and after strengthening was carried out. Conclusions about the strengthening effect of the thermo-frictional and chemical-thermal methods of strengthening were made.

scholarly journals Does Social Exclusion Alter Sensory and Pain Thresholds in Children and Adolescents with Functional Abdominal Pain? – Results from a Preliminary Study

Pain Medicine ◽  
2018 ◽  
Vol 20 (8) ◽  
pp. 1472-1478
Author(s):  
Marco Daniel Gulewitsch ◽  
Aiste Jusyte ◽  
Katja Weimer ◽  
Michael Schönenberg
Keyword(s):  
Abdominal Pain ◽  
Social Exclusion ◽  
Experimental Studies ◽  
Control Group ◽  
Childhood And Adolescence ◽  
Sensory Threshold ◽  
Functional Abdominal Pain ◽  
Pain Thresholds ◽  
Before And After ◽  
Underlying Mechanisms

Abstract Objective Functional abdominal pain (AP) is a prevalent issue in childhood and adolescence. The contribution of psychosocial factors in the development and maintenance of this health problem is rather unclear, and experimental studies about underlying mechanisms are lacking. This study investigates whether experimentally induced social exclusion decreases sensory and pain thresholds in children suffering from AP. Subjects Twenty children/adolescents with AP and 22 healthy controls. Methods Children/adolescents participated in the Cyberball paradigm, which affects an experience of social exclusion. Thermal sensory and pain thresholds were measured before and after Cyberball. Results Children/adolescents with AP showed a divergent reaction regarding their sensory threshold after social exclusion: The control group exhibited a tendency toward a decreased sensory threshold whereas the AP group remained stable. Concerning the pain threshold, no effect of social exclusion could be identified. The increase of both thresholds (“numbing”) after Cyberball was positively correlated with symptoms of mental health issues. Conclusions This is the first study to investigate changes in sensory and pain thresholds following painful social interactions in a sample of children/adolescents with a chronic pain condition. Results suggest that AP and control children differ in their reaction of sensory thresholds, which might indicate an altered processing of social exclusion. Replication and further methodological improvements are needed.

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