RESERVOIR FEATURES OF THE UPPER CARBON SEDIMENTS (RUNOVSHCHYNSKA AREA OF THE DNIEPER-DONETS BASIN)

The main objective of this article is to highlight the results of investigations of filtration capacity features of sandstones and argillites of the Upper Carbon rocks in Runovshchynska area of The Dnieper-Donets basin. The purpose of the research was to assess the promising rocks as possible hydrocarbon reservoirs. The following reservoir features of rock samples such as the open porosity factor, permeability coefficients and residual water saturation factor have been investigated. The correlation of rock density with their porosity was also studied. The porosity study was carried out in atmospheric and reservoir conditions by gas volumetric method and fluid saturation. The bulk density of dry rock samples varies from 2,122 kg/m3 to 2,615 kg/m3 (average 2318 kg/m3), saturated rocks – from 2265 to 2680 kg/m3 (average 2449 kg/m3), and the specific matrix density – from 2562 to 2786 kg/m3 (average 2650 kg/m3). The open porosity coefficient of the studied rocks, in case they were saturated with the synthetic brine, varies from 0.058 to 0.190 (mean 0.126), but if they were saturated with N2 it varies from 0.066 to 0.203 (mean 0.145). Detailed analysis of reservoir conditions modeling revealed that porosity coefficient varies from 0.038 to 0.175 (mean 0.110). Due to the closure of microcracks under rock loading reduced to reservoir conditions the porosity decreases in comparison with atmospheric conditions, which causes a relative decrease in the porosity coefficient from 4.5% to 13.8% (mean 9.0%) from atmospheric conditions to reservoir conditions. The permeability coefficient of rocks varies from 0.03 fm2 to 240.57 fm2 (mean 11.87 fm2). The residual water saturation factor of rocks varies from 0.02 to 0.89 (mean 0.36). The classification of the reservoir characteristics of the investigated samples by the permeability coefficients and residual water saturation factors has been fulfilled. The correlation analysis has allowed establishing a series of empirical relationships between the reservoir parameters of the studied rocks (density, porosity coefficient, permeability coefficient and residual water saturation factor). The results of complex petrophysical researches indicated that the promising oil-bearing intervals of the horizons G-6, G-7v, G-7n have, in general increased values of reservoir parameters.

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LOWER PERMIAN CARBONATE DEPOSITS RESERVOIR PARAMETERS OF WESTERN PART OF HLYNSKO-SOLOHIVSKA AREA OF DNIEPER-DONETS DEPRESSION GAS-OIL-BEARING DISTRICT

Visnyk of Taras Shevchenko National University of Kyiv Geology ◽

10.17721/1728-2713.88.04 ◽

2020 ◽

pp. 25-33

Author(s):

S. Vyzhva ◽

V. Onyshchuk ◽

I. Onyshchuk ◽

O. Oliinyk ◽

M. Reva ◽

...

Keyword(s):

Open Porosity ◽

Permeability Coefficient ◽

Water Saturation ◽

Lower Permian ◽

Residual Water ◽

Gas Oil ◽

Reservoir Conditions ◽

Porosity Coefficient ◽

Saturation Factor ◽

Carbonate Deposits

The paper concerns the researches of the Lower Permian carbonate deposits reservoir properties of western part of Hlynsko-Solohivska area of gas-oil-bearing district of Dnieper-Donets depression. Such reservoir parameters as the open porosity factor, permeability coefficients and residual water saturation factor have been used to assess the promising rocks for the possible hydrocarbon reservoirs. Void structure of rocks with capillarimetric method and the correlation of rock density with their porosity were also studied. The porosity study was carried out in atmospheric and reservoir conditions. The bulk density of dry rock samples varies from 2212 kg/m3 to 2593 kg/m3 (mean 2413 kg/m3), water saturated rocks – from 2442 to 2642 kg/m3 (mean 2549 kg/m3), kerosene saturated rocks – from 2400 to 2622 kg/m3 (mean 2541 kg/m3); an apparent specific matrix density – from 2718 to 2828 kg/m3 (mean 2783 kg/m3). The open porosity coefficient of study rocks, saturated with the synthetic brine, varies from 0.045 to 0.181 (mean 0.127), if samples are saturated with kerosene then it varies from 0.049 to 0.184 (mean 0.128) and when N2 is used - from 0.063 to 0.217 (mean 0.149). The effective porosity has following values: 0.004-0.125 (0.036), and the residual water saturation factor - 0.4-0.97 (0.79). Analysis of reservoir conditions modeling revealed that porosity coefficient varies from 0.040 to 0.169 (mean 0.118). Due to the closure of microcracks under rock loading reduced to reservoir conditions the porosity decreases in comparison with atmospheric conditions, which causes a relative decrease in the porosity coefficient from 1.5 % to 11 % (mean 9.0 %). Capillar void of study rocks describes the prevalence of subcapillar pores (40-97 %, mean 79 %) while the overcapillars pores have range 1-22 % (mean 7 %) and the capillar pores - 2-38 % (mean 14 %). The permeability coefficient varies from 0.038 fm2 to 1.992 fm2 (mean 0.323 fm2). As result of petropysical researches the rocks have been classified with above mentioned reservoir parameters. The correlation analysis has allowed to establish a series of empirical relationships between the reservoir parameters (density, porosity coefficient, permeability coefficient and residual water saturation factor).

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POROSITY AND PERMEABILITY PROPERTIES OF CONSOLIDATED ROCKS OF THE NORTHERN NEAR EDGE ZONE OF THE DNIEPER-DONETSK DEPRESSION

Visnyk of Taras Shevchenko National University of Kyiv Geology ◽

10.17721/1728-2713.94.04 ◽

2021 ◽

pp. 37-45

Author(s):

S. Vyzhva ◽

V. Onyshchuk ◽

I. Onyshchuk ◽

M. Reva ◽

O. Shabatura

Keyword(s):

Permeability Coefficient ◽

Water Saturation ◽

Effective Porosity ◽

Integrated Analysis ◽

Residual Water ◽

Edge Zone ◽

Reservoir Conditions ◽

Porosity Coefficient ◽

Porosity And Permeability ◽

Saturation Factor

Paper concerned the researches of porosity and permeability properties of consolidated rocks (siltstones, poor-porous sandstones) of the northern near edge zone of the Dnieper-Donetsk depression. The purpose of the research was to study the petrophysical parameters of the consolidated reservoir rocks, as the basis of the integrated analysis of their physical properties. Such reservoir parameters as the open porosityfactor and void factor, permeability coefficient and residual water saturation factor were studied. Void structure of rocks with capillarimetric method was studied. The relationship of the density of rocks with their porosity was also studied. The porosity study was carried out in atmospheric and reservoir conditions. The bulk density of dry rock samples varies: for siltstones from 2232 kg/m3 to 2718 kg/m3 (mean 2573 kg/m3 ), for sandstones from 2425 kg/m3 to 2673 kg/m3 (mean 2555 kg/m3); water saturated rocks – for siltstones from 2430 to 2727 kg/m3 (mean 2622 kg/m3 ), for sandstones from 2482 kg/m3 to 2688 kg/m3 (mean 2599 kg/m3 ). An apparent specific matrix density varies: for siltstones from 2645 to 2740 kg/m3 (mean 2683 kg/m3 ), for sandstones from 2629 kg/m3 to 2730 kg/m3 (mean 2664 kg/m3). The open porosity coefficient of studied rocks, in a case they were saturated with the synthetic brine, varies: for siltstones from 0,008 to 0,074 (mean 0,034), for sandstones from 0,013 to 0,087 (mean 0,041), if samples were saturated with nitrogene (N2) then it varies: for siltstones from 0,013 to 0,076 (mean 0,040), for sandstones from 0,022 to 0.095 (mean 0.052). The effective porosity factor has following values: for siltstones 0,0003–0,0050 (mean 0,00026), for sandstones 0,0013–0,0293 (mean 0,0048). Analysis of reservoir conditions modeling revealed that porosity coefficient varies: for siltstones from 0,007 to 0,060 (mean 0,028), for consolidated sandstones from 0,011 to 0,081 (mean 0,037). Due to the closure of microcracks under rock loading reduced to reservoir conditions the porosity decreases in comparison with atmospheric conditions, which causes a relative decrease in the porosity coefficient for siltstones from 14 to 19,5 % (mean 17,0 %), for sandstones from 7,5 to 18.0 % (mean 10,5 %). Capillaryometric studies by centrifuging determined that the void space of the studied rocks has the following structure: for siltstones, the content of hypercapillary pores varies from 1 to 6 % (mean 3 %); the content of capillary pores – from 1 to 11 % (mean 5 %), the content of subcapillary pores – from 84 to 97 % (mean 92 %); for sandstones, the content of hypercapillary pores varies from 1 to 18 % (mean 4%); content of capillary pores – from 2 to 40 % (mean 10 %), the content of subcapillary pores – from 43 to 96 % (mean 86 %). According to the results of laboratory measurements of the permeability coefficient, this parameter varies: for siltstones from 0,002 fm2 to 1,981 fm2 (mean 0,279 fm2 ), for sandstones from 0,002 fm2 to 1,492 fm2 (mean 0,176 fm2 ). The correlation analysis has allowed to establish a series of empirical relationships between the reservoir parameters (density, porosity coefficient, permeability coefficient, effective porosity factor and residual water saturation factor). These relationships can be used in the data interpretation of geophysical studies of wells and in the modeling of the porosity and permeability properties of consolidated rocks of the northern near edge zone of the Dnieper-Donetsk depression.

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ELECTRICAL PARAMETERS OF THE UPPER CARBON ROCKS (RUNOVSHCHYNSKA AREA OF THE DNIEPER-DONETSK BASIN)

Visnyk of Taras Shevchenko National University of Kyiv Geology ◽

10.17721/1728-2713.85.05 ◽

2019 ◽

pp. 37-45

Author(s):

S. Vyzhva ◽

V. Onyshchuk ◽

I. Onyshchuk ◽

M. Reva ◽

O. Shabatura

Keyword(s):

Electrical Resistivity ◽

Water Saturation ◽

Pore Space ◽

Donets Basin ◽

Electrical Parameters ◽

Reservoir Water ◽

Reservoir Conditions ◽

Porosity Coefficient ◽

Specific Electrical Resistivity ◽

Formation Resistivity

The main objective of this article is to study electrical parameters of sandstones and argillites of the Upper Carbon rocks in the Runovshchynska area of the Dnieper-Donets basin. It has been determined that specific electrical resistivity of dry rock samples (specific electrical resistivity of rock matrix) varies from 44,802 kΩ·m to 6,115 МΩ·m (average 751,328 kΩ·m). Specific electrical resistivity of sandstones is 3,45 times more than argillitesdue to different shaliness of studied rocks. Specific electrical resistivity of saturated rocks samples varies from 0,54 Ω·m to 10,46 Ω·m (average 1,23 Ω·m). Specific electrical resistivity of argillites is 2,46 times more than sandstones because the latter had high content of reservoir water in their pores (sandstones had better conductivity). It has been determined that formation resistivity factor of sandstones in atmospheric conditions varies from 6,05 to 33,71 (argillites 11,8), and argillites – from 4,76 to 51,47 (average 17,4). Physical modelling of reservoir conditions (temperature t = 78,5°С, pressure p = 31–31,9 MPa, mineralization M= 170 g/l) showed that specific electrical resistivity varies from 0,3 Ω·m to 3,0 Ω·m (average 0,75 Ω·m). Sandstones in reservoir conditions had the range from 0,3 Ω·m to 2,3 Ω·m (average 0,7 Ω·m), and argillites – from 0,5 Ω·m to 3,0 Ω·m (average 1,2 Ω·m). In this case, specific electrical resistivity of argillites is 1,6 times more than sandstones. Due to the closure of microcracks and the deformation of the pore space, the electrical resistance of rocks increases with increasing pressure. The dependence of formation resistivity enlargement factor on pressure for the studied rocks is expressed by 2-order polynomials. The formation resistivity factor of the studied rocks in reservoir conditions has been determined. It was defined that sandstones in reservoir conditions had the range of the formation resistivity factor from 5,4 to 63,3 (average 20,3), and porosity coefficient – from 0,038 to 0,175 (average 0,113). The range of the formation resistivity factor for argillites was from 13,4 to 88,7 (average 34,3), and porosity coefficient – from 0,043 to 0,115 (average 0,086). Analysis of data of laboratory electrometric investigations has allowed establishing correlations between the porosity coefficient and formation resistivity factor. In addition, the correlation of electrical parameters of rocks in atmospheric and reservoir conditions and the formation resistivity enlargement factor from the water saturation coefficient, taking into account the lithological varieties of the studied rocks, was established.

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ELECTRICAL AND ACOUSTIC PARAMETERS OF LOWER PERMIAN CARBONATE ROCKS (WESTERN PART OF THE HLYNSKO-SOLOKHIVSKYI OF GAS-OIL-BEARING DISTRICT OF THE DNIEPER-DONETS BASIN)

Visnyk of Taras Shevchenko National University of Kyiv Geology ◽

10.17721/1728-2713.89.07 ◽

2020 ◽

pp. 49-58

Author(s):

S. Vyzhva ◽

V. Onyshchuk ◽

I. Onyshchuk ◽

M. Reva ◽

O. Shabatura

Keyword(s):

Electrical Resistivity ◽

Relative Permittivity ◽

Donets Basin ◽

Lower Permian ◽

Atmospheric Conditions ◽

Reservoir Water ◽

P Waves ◽

Reservoir Conditions ◽

Specific Electrical Resistivity ◽

Formation Resistivity

The main objective of this article is to study electrical parameters of Lower Permian carbonate rocks of Western part of the Hlynsko-Solokhivskyi gas-oil-bearing district of the Dnieper-Donets Basin (DDB) in normal (atmospheric) and modeling (reservoir) conditions. In atmospheric conditions it has been revealed that the resistivity of dry extracted limestones (the specific electrical resistivity of framework of grains was measured) varies from 12.147 kΩ⋅m to 111.953 MΩ⋅m (mean 1.542 MΩ⋅m). The resistivity of saturated limestone samples with kerosene varies from 44.478 kΩ⋅m to 14.449 MΩ⋅m (mean 1.435 MΩ⋅m). The resistivity of dry and saturated with kerosene samples is almost the same. The resistivity of limestones saturated with model of reservoir water (salinity M = 190 g/l) is lower and varies from 1.11 Ω⋅m to 23.16 Ω⋅m (mean 3.12 Ω⋅m). It has been determined that formation resistivity factor of limestones in atmospheric conditions varies from 13.5 to 230 Ω⋅m (mean 32.5 Ω⋅m). In addition to resistivity, the parameter of relative permittivity of investigated limestones was studied. It was determined that relative permittivity of dry limestones varies from 3.0 to 7.5 (mean 4.2). Relative permittivity saturated samples of limestones with kerosene varies from 2.8 to 8.8 (mean 4.5) and practically does not differ from dry ones but significantly lower than values of samples saturated with model of reservoir water (from 655 to 9565, mean 4280). That means when pores of limestones are saturated with NaCl solution their relative permittivity increases rapidly – from hundreds to thousands times (on average 944 times). It can be explained by the high conductivity of model of reservoir water. Limestones saturated with NaCl solution have velocities of P-waves in the range from 3346 m/s to 4388 m/s (mean 4030 m/s), and velocities of Swaves – from 1753 m/s to 2121 m/s (average 1942 m/s). If rocks are saturated with kerosene then velocities have strictly higher values – P-waves from 3433 m/s to 4514 m/s (mean 4011 m/s) and S-waves – from 2137 m/s to 2464 m/s (average 2344 m/s). Physical modelling of reservoir conditions (temperature 50 °С, pressure 30 MPa) showed that the specific electrical resistivity varies from 0.81 Ω⋅m to 13.19 Ω⋅m (mean 2.67 Ω⋅m), and limestones – from 0.49 Ω⋅m to 7.81 Ω⋅m (mean 1.95 Ω⋅m). Also, "specific electrical resistivity – pressure" connection was investigated. Due to the closure of microcracks and the deformation of the pore space, the electrical resistance of rocks increases with increase of pressure. The regression dependence of the formation resistivity enlargement factor with pressure for the studied rocks has a linear character. It was determined that in reservoir conditions the range of the formation resistivity factor for limestones varied from 17.3 to 271.9 Ω⋅m (mean 50.7 Ω⋅m), and range of variation of porosity coefficient was from 0.040 to 0.169 Ω⋅m (mean 0.118 Ω⋅m). The comprehensive analysis of petrophysical data has been resulted in a set of correlation ratios between reservoir, electric and elastic parameters of studied limestones in normal and modeling conditions.

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Experimental Study About Water Saturation Influence on Changes in Reservoirs Petrophysical Properties

Walailak Journal of Science and Technology (WJST) ◽

10.48048/wjst.2021.20594 ◽

2021 ◽

Vol 18 (13) ◽

Author(s):

Sudad Hameed AL-OBAIDI ◽

Victoria SMIRNOV ◽

Hiba Hussein ALWAN

Keyword(s):

Physical Properties ◽

Effective Permeability ◽

Water Saturation ◽

Residual Water ◽

Effective Pressure ◽

Petrophysical Properties ◽

Reservoir Conditions ◽

Water Saturated

Experimental determination of the physical properties of rocks under conditions simulating in situ reservoir conditions is of great importance both for the calculation of reserves and for the interpretation of well logging data. In addition, it is also important for the preparation of hydrocarbon field development projects. The study of the processes of changes in the petrophysical properties of the reservoir under controlled conditions allows not only to determine their reliability but also to evaluate the dynamics of these changes depending on the temperature and pressure conditions of the reservoir and the water saturation of the rocks. In this work, an evaluation of the dependence of the physical properties of hydrocarbon reservoirs on their water saturation (Sw) was carried out. Residual water saturation (Swr) was created in the rocks and the properties of these rocks were compared at the states of partial (25 %) and complete water saturation (100 %). The changes in petrophysical parameters of partially water saturated rocks during the increase in effective pressure were studied and estimates of these changes were obtained. The results showed that when the effective pressure is increased, the Swr increases by an average of 6 % compared to atmospheric conditions. This is accompanied by an increase in the velocity of longitudinal (by 51.9 % on average) and lateral waves (by 37.1 % on average). As residual water saturation increases, effective permeability decreases for both standard and reservoir conditions, with, gas permeability decreasing for both dry samples (by 23 % on average) and samples with residual water saturation (effective permeability decreases by 27 % on average). HIGHLIGHTS Changes in physical properties of hydrocarbon reservoirs by determining physical properties (permeability, porosity, elastic, electrical, deformation strength) under the standard conditions and in physical modelling of reservoir conditions and processes Assessment of the effectiveness of water saturation on the physical properties of the reservoir Comparisons between the petrophysical properties of reservoir core samples in which the pore space is fully saturated with the reservoir fluid model and samples with residual water saturation Experimental determination of the physical properties of rocks under conditions simulating in situ reservoir conditions Estimation of the changes in petrophysical parameters of partial water-saturated rocks during the increase in effective formation pressure GRAPHICAL ABSTRACT

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Impact of Pressure and Brine Salinity on Capillary Pressure-Water Saturation Relations in Geological CO2Sequestration

Advances in Condensed Matter Physics ◽

10.1155/2016/5603739 ◽

2016 ◽

Vol 2016 ◽

pp. 1-11 ◽

Cited By ~ 4

Author(s):

Jongwon Jung ◽

Jong Wan Hu

Keyword(s):

Contact Angle ◽

Interfacial Tension ◽

Capillary Pressure ◽

Water Saturation ◽

Theoretical Models ◽

Wettability Alteration ◽

Residual Water ◽

Atmospheric Conditions ◽

Pressure Water ◽

Brine Salinity

Capillary pressure-water saturation relations are required to explore the CO2/brine flows in deep saline aquifers including storage capacity, relative permeability of CO2/brine, and change to stiffness and volume. The study on capillary pressure-water saturation curves has been conducted through experimentation and theoretical models. The results show that as the pressure increases up to 12 MPa, (1) capillary pressure-water saturation curves shift to lower values at given water saturation, (2) after the drainage process, residual water saturation decreases, and (3) after the imbibition process, capillary CO2trapping increases. Capillary pressure-water saturation curves above 12 MPa appear to be similar because of relatively constant contact angle and interfacial tension. Also, as brine salinity increases from 1 M to 3 M NaCl, (1) capillary pressure-water saturation curves shift to lower capillary pressure, (2) residual water saturation decreases, and (3) capillary CO2trapping increases. The results show that pressure and brine salinity have an influence on the capillary pressure-water saturation curves. Also, the scaled capillary CO2entry pressure considering contact angle and interfacial tension is inconsistent with atmospheric conditions due to the lack of wettability information. Better exploration of wettability alteration is required to predict capillary pressure-water saturation curves at various conditions that are relevant to geological CO2sequestration.

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Analysis of the efficiency of models of transition zones to determine oil-saturation factors and position of contact of hydrocarbons with water

Oil and Gas Studies ◽

10.31660/0445-0108-2019-6-67-76 ◽

2020 ◽

pp. 67-76

Author(s):

G. E. Stroyanetskaya

Keyword(s):

Capillary Pressure ◽

Transition Zone ◽

Water Saturation ◽

Residual Water ◽

Oil Saturation ◽

Transition Zones ◽

The Core ◽

Geophysical Parameter ◽

Saturation Factor ◽

Geophysical Information

The article is devoted to the usage of models of transition zones in the interpretation of geological and geophysical information. These models are graphs of the dependences of oil-saturation factors of the collectors on their height above the level with zero capillary pressure, taking into account the geological and geophysical parameter. These models are not recommended for estimating oilsaturation factors of collectors in the transition zone. The height of occurrence of the collector above the level of zero capillary pressure can be estimated from model of the transition zone that take into account the values of the coefficients of residual water saturation factor of the collectors, but only when the model of the transition zone is confirmed by data capillarimetry studies on the core.

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