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 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.

The use of geophysical prospecting for imaging active faults in the Roer Graben, Belgium

Geophysics ◽  
2001 ◽  
Vol 66 (1) ◽  
pp. 78-89 ◽  
Author(s):  
Donat Demanet ◽  
François Renardy ◽  
Kris Vanneste ◽  
Denis Jongmans ◽  
Thierry Camelbeeck ◽  
...  
Keyword(s):  
High Resolution ◽  
Physical Properties ◽  
Fault Zone ◽  
Geophysical Methods ◽  
Depth Range ◽  
Electrical Tomography ◽  
Reflection Seismic ◽  
Refraction Seismic ◽  
Geophysical Surveys ◽  
Geophysical Techniques

As part of a paleoseismological investigation along the Bree fault scarp (western border of the Roer Graben), various geophysical methods [electrical profiling, electromagnetic (EM) profiling, refraction seismic tests, electrical tomography, ground‐penetrating radar (GPR), and high‐resolution reflection seismic profiles] were used to locate and image an active fault zone in a depth range between a few decimeters to a few tens of meters. These geophysical investigations, in parallel with geomorphological and geological analyses, helped in the decision to locate trench excavations exposing the fault surfaces. The results could then be checked with the observations in four trenches excavated across the scarp. Geophysical methods pointed out anomalies at all sites of the fault position. The contrast of physical properties (electrical resistivity and permittivity, seismic velocity) observed between the two fault blocks is a result of a differences in the lithology of the juxtaposed soil layers and of a change in the water table depth across the fault. Extremely fast techniques like electrical and EM profiling or seismic refraction profiles localized the fault position within an accuracy of a few meters. In a second step, more detailed methods (electrical tomography and GPR) more precisely imaged the fault zone and revealed some structures that were observed in the trenches. Finally, one high‐resolution reflection seismic profile imaged the displacement of the fault at depths as large as 120 m and filled the gap between classical seismic reflection profiles and the shallow geophysical techniques. Like all geophysical surveys, the quality of the data is strongly dependent on the geologic environment and on the contrast of the physical properties between the juxtaposed formations. The combined use of various geophysical techniques is thus recommended for fault mapping, particularly for a preliminary investigation when the geological context is poorly defined.

A faster method for erosion and dilation of reservoir pore-complex images

1988 ◽  
Vol 25 (7) ◽  
pp. 1128-1131 ◽  
Author(s):  
J. R. Parker
Keyword(s):  
Flow Behavior ◽  
Reservoir Rock ◽  
Two Dimensional ◽  
Thin Sections ◽  
Reservoir Rocks ◽  
Image Processing Techniques ◽  
The Third ◽  
Computer Image Processing ◽  
Third Dimension ◽  
Processing Techniques

Studies of thin sections of reservoir rock have been conducted for some time with the goal of understanding flow behavior and estimating physical properties. These sections are essentially two dimensional, but it has always been assumed that the results obtained can be extrapolated to the third dimension. Computer image-processing techniques are often used in this sort of analysis because of the large amounts of data contained in a single digitized section image. One of the methods used to process these images is erosion–dilation, wherein layers of each pore are stripped off (erosion) and then replaced (dilation). This results in a smoothing of the pore perimeters and can be used to estimate pore radii, volume, and roughness. Because of the size of each image, erosion–dilation of images of the pore complex of reservoir rocks is a time-consuming process. A new method called global erosion is much faster, with no increase in memory requirement or decrease in accuracy. This should permit the processing of larger images or a greater number of small images than does the standard method.

scholarly journals Groundwater Chemistry of Some Selected Areas in Southeastern Norway

1980 ◽  
Vol 11 (1) ◽  
pp. 33-54 ◽  
Author(s):  
Jens-Olaf Englund ◽  
Jan Aug Myhrstad
Keyword(s):  
Land Surface ◽  
Mineral Water ◽  
Sea Water ◽  
Electrical Conductance ◽  
Reservoir Rock ◽  
Rock Fractures ◽  
Sea Salts ◽  
Reservoir Rocks ◽  
Rock Types ◽  
Groundwater Samples

Within three areas in Southeastern Norway, Lake Mjøsa district, Ås and Moss - Jeløy, groundwater samples for chemical analysis were collected during the years 1971–77 from 98 drilled wells in bedrocks. The water was taken at depths ranging from 15 m to 110 m below the land surface. The groundwater surface is usually present well below the overlying unconsolidated deposits of glacial, glacifluvial or marine origin. The movement of groundwater within the aquifers investigated is so slow that regional changes in water quality is not only dependent on weathering in the unsaturated zone, but also dependent on the solution of reservoir rocks below the groundwater surface. Variations in specific electrical conductance (20°C) largely reflects the different reservoir rock types. The highest values, around 550 μS/cm, are typically found in dark calcareous shales, while sandstones and gneisses give values around 300 μS/cm. The areas Ås and Moss-Jeløy are situated below the Late-Postglacial marine limit. The groundwater is here more or less influenced by ancient sea salts, perhaps also by fossil sea water, left over in sediments or in rock fractures. Brackish groundwater was also found. The composition of groundwater is largely governed by mineral-water equilibria. Most investigated water samples have not reached equilibrium with their surrounding minerals.

Adsorption/Desorption of Sulfonate by Reservoir Rock Minerals in Solutions of Varying Sulfonate Concentrations

1985 ◽  
Vol 25 (03) ◽  
pp. 343-350 ◽  
Author(s):  
P. Somasundaran ◽  
H. Shafick Hanna
Keyword(s):  
Surfactant Concentration ◽  
Memory Effects ◽  
Reservoir Rock ◽  
Complex Nature ◽  
Reservoir Rocks ◽  
Batch Type ◽  
Surfactant Solutions ◽  
Major Interest ◽  
Considerable Work ◽  
Rock Minerals

Abstract In micellar flooding, reservoir rocks are exposed to surfactant solutions of varying concentrations as the surfactant slug advances through the reservoir. Therefore, the attachment and detachment of sulfonates with rocks that are already exposed to surfactant solutions of higher or lower concentrations is of major interest. In this study, the abstraction behavior of purified Na-dodecylbenzenesulfonate on Na-kaolinite by stepwise increase in surfactant concentration is determined. Deabstraction* occurring after reductions in surfactant concentrations at various stages also is determined. Most importantly, the results of incremental abstraction, individual abstraction, and deabstraction showed the system to exhibit hysteresis or memory effects. Also, abstractions obtained at various pH values and during stepwise changes in pH exhibited marked differences. The deabstraction isotherms showed the presence of maximum in certain cases, indicating the occurrence of maximum on the abstraction isotherms to be a real phenomenon. Possible reasons for the hysteresis are phenomenon. Possible reasons for the hysteresis are considered, and the practical implications of these memory effects on micellar flooding and depletion experiments using cores are discussed. Introduction Loss of surfactants owing to their interactions with reservoir rocks and fluid is possibly the most important factor that can determine the efficiency of a micellar flooding process. While there has been considerable work with process. While there has been considerable work with dilute surfactant solutions, mechanisms by which surfactants interact with rocks in their critical micelle concentration (CMC) range have not been studied in detail. Nevertheless, some limited data that have been reported in the literature do suggest that the adsorption characteristics of systems made up of concentrated surfactant solutions (above the CMC) are markedly different from those of systems involving dilute solutions. Adsorption isotherms above CMC have been reported to exhibit shapes that have not been encountered elsewhere. Our past work on abstraction of dodecylbenzenesulfonate on Na-kaolinite clearly showed the complex nature of the process, which depends on a number of system variables such as the nature and concentration of inorganic electrolytes, surfactant concentration, pH, and temperature. Under certain conditions, the systems exhibited a maximum in the region of CMC and, in some cases, a minimum at higher concentrations. Most interestingly, the presence of the maximum in the abstraction isotherm depended strongly on the type of inorganic electrolyte in the system. From a practical point of view, it would indeed be useful to be able to control the abstraction of sulfonates by rock minerals by controlling the inorganic electrolytes in the system. However, laboratory batch-type adsorption tests cannot be used directly for micellar flooding systems for a number of reasons. One important consideration in this regard is that the reservoir rocks are exposed to surfactant solutions of varying concentration as the surfactant slug advances through the reservoir. To examine the role of this effect, the abstraction behavior of sulfonates by kaolinite during incremental increase and decrease in surfactant concentration has been determined in this study. Comparison of the abstraction isotherms obtained by conventional batch-type tests (B-isotherms) with those obtained by stepwise changes in surfactant concentration (S-isotherms) and the deabstraction of isotherms of sulfonate upon dilution of the system should help in developing an understanding of the surfactant abstraction behavior as well as the phenomenon of abstraction maximum. Materials and Methods Kaolinite Kaolinite used was a well-crystallized Georgia sample with a B.E.T. surface area of 9.8 m2/g [105 sq ft/g]. Homoionic Na-kaolinite prepared according to a procedure described earlier was used for all the procedure described earlier was used for all the adsorption tests discussed here. Surfactants and Chemicals Sodium dodecylbenzenesulfonate (DDBS) purchased from Lachat Chemical Inc. (specified to be 95 % active but analyzed to be 85 %) was purified in the following manner. purified in the following manner. SPEJ P. 343

THE INTERPRETATION OF GEOPHYSICAL DATA

Geophysics ◽  
1937 ◽  
Vol 2 (2) ◽  
pp. 95-113 ◽  
Author(s):  
Ludwig W. Blau
Keyword(s):  
Physical Properties ◽  
Geophysical Methods ◽  
Present Knowledge ◽  
Geophysical Data ◽  
Surface Mapping ◽  
Contour Maps ◽  
Physical Effects ◽  
Data Result ◽  
Geologic Information

Geophysical data result from measurements of physical properties. The geophysicist postulates certain possible physical causes of the observed effects. The geologist reasons from observed geologic effects to geologic causes. The difficulties confronting the interpretation of physical effects as reflected in geophysical data in terms of geologic causes are pointed out. The author takes the position that geophysical data must be worked up independently. A competent geophysicist‐geologist may combine geophysical and geologic information in the preparation of a report which will then, and only when this procedure is followed, include all present knowledge of the area under investigation. The requirement that geophysical data be immediately translatable into geologic language and furnish material for drawing geologic contour maps is shown to be incompatible with the nature of geophysical data. Attention is drawn to the changing geophysical scene and to the tendency to use geophysical methods after they have ceased to be adequate for the solution of prospecting problems. It is suggested that geology can aid geophysics principally through library reconnaissance and advance surface mapping. Geophysics has become a serious competitor of geology in the search for oil, and the geophysic‐geological ecotone has advanced steadily into geologic territory.

Simultaneous Interpretation of Three-Phase Relative Permeability and Capillary Pressure for a Tight Carbonate Reservoir From Wireline Formation Testing

2019 ◽  
Vol 142 (6) ◽  
Author(s):  
Xiangnan Liu ◽  
Daoyong Yang
Keyword(s):  
Capillary Pressure ◽  
Relative Permeability ◽  
History Matching ◽  
Carbonate Reservoir ◽  
Reservoir Rock ◽  
Fluid Saturation ◽  
Three Phase ◽  
Tight Carbonate ◽  
Wet Condition ◽  
Oil Gas

Abstract In this paper, techniques have been developed to interpret three-phase relative permeability and water–oil capillary pressure simultaneously in a tight carbonate reservoir from numerically simulating wireline formation tester (WFT) measurements. A high-resolution cylindrical near-wellbore model is built based on a set of pressures and flow rates collected by dual packer WFT in a tight carbonate reservoir. The grid quality is validated, the effective thickness of the WFT measurements is examined, and the effectiveness of the techniques is confirmed prior to performing history matching for both the measured pressure drawdown and buildup profiles. Water–oil relative permeability, oil–gas relative permeability, and water–oil capillary pressure are interpreted based on power-law functions and under the assumption of a water-wet reservoir and an oil-wet reservoir, respectively. Subsequently, three-phase relative permeability for the oil phase is determined using the modified Stone II model. Both the relative permeability and the capillary pressure of a water–oil system interpreted under an oil-wet condition match well with the measured relative permeability and capillary pressure of a similar reservoir rock type collected from the literature, while the relative permeability of an oil–gas system and the three-phase relative permeability bear a relatively high uncertainty. Not only is the reservoir determined as oil-wet but also the initial oil saturation is found to impose an impact on the interpreted water relative permeability under an oil-wet condition. Changes in water and oil viscosities and mud filtrate invasion depth affect the range of the movable fluid saturation of the interpreted water–oil relative permeabilities.

scholarly journals Effect of matching relation of multi-scale, randomly distributed pores on geometric distribution of induced cracks in hydraulic fracturing

2020 ◽  
Vol 38 (6) ◽  
pp. 2436-2465
Author(s):  
Peihuo Peng
Keyword(s):  
Physical Properties ◽  
In Situ Stress ◽  
Reservoir Rock ◽  
Particle Model ◽  
Bonded Particle Model ◽  
Multi Scale ◽  
Pore Structures ◽  
Fracturing Fluids ◽  
Seepage Characteristics

Reservoir rock contains many multi-scale, unevenly distributed pores, and the pore structures of shale in different reservoirs and geological environments vary greatly. Because the seepage velocity and pressure field are related to the pore spatial variations, the inhomogeneity of the seepage is superimposed on the anisotropy of the rock’s physical properties, which will affect the distribution of the induced cracks. A method for calculating the pore size in the bonded particle model, based on Delaunay triangulation, is proposed. A modeling approach capable of simulating the multi-scale pore distribution of actual rock is presented based on the proposed method. To understand how microcracks connect micropores in the process of fracturing, several bonded particle model samples with different pore structures were established, and numerical experiments were conducted based on the coupling calculation of the discrete seepage algorithm and discrete element method. The focus of this study was on the interactions between the distribution characteristics of multi-scale pores, the specific physical properties of the fracturing fluid, and the distribution differences of the induced cracks caused by the special seepage characteristics when using different fracturing fluids. The numerical results showed that the advantages of supercritical CO2 fracturing are maximized in deep reservoirs (high in-situ stress) and that a suitable in-situ stress condition is required (i.e. a stress ratio close to 1).

APPLICATION OF CONTINUOUS VELOCITY LOGS TO DETERMINATION OF FLUID SATURATION OF RESERVOIR ROCKS

Geophysics ◽  
1956 ◽  
Vol 21 (3) ◽  
pp. 739-754 ◽  
Author(s):  
Warren G. Hicks ◽  
James E. Berry
Keyword(s):  
Field Data ◽  
Acoustic Velocity ◽  
Gas Oil ◽  
Laboratory Measurements ◽  
Reservoir Rocks ◽  
Fluid Saturation ◽  
Saturated Sands ◽  
Similar Character ◽  
Water Saturated

Recent studies of continuous acoustic velocity logs indicate that these logs may provide important assistance in differentiating gas, oil, and water saturations in reservoir rocks. In general, velocities are appreciably lower in sands carrying oil or gas than in water‐saturated sands of otherwise similar character. Specific examples from field logs illustrate this application. Laboratory measurements have been made of acoustic velocity of synthetic and natural rocks. Published studies, both empirical and theoretical, of other workers concerned with the transmission of sound in porous media have been considered. All of these at least qualitatively confirm the conclusions drawn from field data.

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