A system for determining the hydrogen potential (pH value) of water flood wastewater and the irreducible water saturation

Abstract

A system (100) for determining the hydrogen potential (pH) of flood wastewater and the irreducible water saturation, the system (100) comprising: a Dean-Stark apparatus (102) configured to clean core plug samples using a 50:50 solvent mixture of toluene and methanol at a temperature of 40°C; an ultrasonic cleaner (104) connected to the Dean-Stark device (102) and configured to remove surface deposits from the core samples after cleaning; a humidity-controlled oven (106) connected to the ultrasonic cleaner (104) and configured to dry and heat the core samples for 72 hours; a helium porosimeter (TPI-219) (108) connected to the moisture control furnace (106) and configured to determine the porosity of the core plug samples, including billets of different volumes, for measuring grain volume; an X-ray diffractometer (110) connected to the helium porosimeter (TPI-219) (108) and configured to determine the mineral composition of the sandstone rocks; a core flooding unit (112) comprising a core holder (112a), hydraulic pumps (112b), a back pressure regulator (BPR) (112c) and a heat source (112d) connected to the X-ray diffractometer (110) and designed to maintain certain temperatures of the core plugs during flooding, thereby enabling the injection of brine and oil under controlled conditions; a water analyzer (114) connected to the core flooding unit (112) and configured to measure the pH of the core wastewater; a liquid permeability meter (116) connected to the water analyzer (114) and configured to determine the permeability of the core plugs after initial water saturation; a receiving unit (118) connected to the liquid permeameter (116) and configured to collect wastewater after flooding; and a water bath (120) connected to the receiving unit (118) and configured to maintain a stable temperature during wastewater separation.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to enhanced oil recovery (EOR) techniques. More particularly, the present invention relates to a system for enhancing oil recovery in sandstone reservoirs using temperature-controlled low-salinity water (LSWF) flooding. More specifically, the present invention relates to a system for determining the hydrogen potential (pH) of floodwater effluents and the irreducible water saturation. BACKGROUND OF THE INVENTION

[0002] Wettability is a crucial property of petroleum reservoirs, as it significantly influences the efficiency of oil recovery during waterflooding. The variation in wettability of sandstone reservoirs, which is primarily influenced by the interaction between crude oil, rock, and brine, has attracted extensive research attention, particularly in the context of oil recovery optimization. Waterflooding is widely used to enhance oil recovery, with brine composition, initial water saturation, and reservoir temperature playing a critical role in the crude oil-rock-brine interactions that alter wettability. The surfactant components in crude oil contribute to changes in the wetting properties of the rock, an effect that increases with increasing temperatures.In particular, studies indicate that higher aging temperatures tend to increase the change in wettability of sandstone and make it more oil-wet, which may impair the effectiveness of waterflooding.

[0003] Salinity, pH, and ion concentration in the brine are considered important parameters for wettability. In particular, sandstones with higher mineralogical heterogeneity exhibit a smaller change in wettability due to the spatial distribution of minerals such as quartz, illite, and kaolinite. Research has shown that increasing reservoir temperature leads to an increase in the pH of the floodwater, especially in formations containing these minerals. However, in low-salinity water floods, temperatures above 100 °C lead to a decrease in the pH of the wastewater, thereby reducing the desorption of oil from clay surfaces and limiting the water-wet conditions favorable for oil recovery. Conversely, at temperatures below 100 °C, sandstones exhibit significant desorption of polar constituents from clay, which improves their water-wet properties and supports enhanced oil displacement.

[0004] The effects of temperature on the relative permeability of oil and water in sandstone rocks are well documented and show a direct relationship with oil flow efficiency and irreducible water saturation. As temperature increases, the relative permeability of oil and water shifts, with irreducible water saturation increasing and residual oil saturation decreasing. Studies have shown that the ratio of relative permeability of oil and water depends on water saturation; when water saturation is above 55%, relative permeability becomes temperature independent. In sandstone reservoirs with different degrees of consolidation, temperature changes affect relative permeability differently, with unconsolidated sand exhibiting increased relative permeability at higher temperatures, while consolidated rocks exhibit a decrease.

[0005] The interaction between rock mineralogy, the salt content of the brine, and reservoir temperature further complicates the process of changing wettability. When low-salt water hits mineral-rich sandstone, the resulting change in wettability is influenced by the mineral composition, the pH of the floodwater, and petrophysical properties. However, previous studies have rarely integrated all of these parameters into a single analysis and often focused on isolated variables without a comprehensive approach. This limitation underscores the need for a more comprehensive investigation of how rock mineralogy and formation water chemistry affect wettability in high-temperature environments.

[0006] To overcome the above limitations, a system for determining the hydrogen potential of floodwater effluents and irreducible water saturation needs to be developed. The system uses an integrated approach that includes core flood experiments, pH analyses, and mineralogical characterization of sandstone cores from the Upper Assam Basin. Experimental observations have demonstrated temperature-dependent changes in wettability, irreducible water saturation, and interactions of clay minerals with low-salt brine, thus providing a comprehensive profile of wettability behavior in response to temperature variations.Such findings provide valuable insights into optimizing waterflooding operations, improving oil recovery, and minimizing formation damage through a deeper understanding of wettability changes influenced by temperature, brine composition, and rock mineralogy in real reservoir environments. The system therefore represents a novel approach with significant implications for improving recovery techniques and expanding the understanding of fluid-rock interactions in sandstone reservoirs.

[0007] The technical advances disclosed by the present invention overcome the limitations and disadvantages of existing and conventional systems and methods. SUMMARY OF THE INVENTION

[0008] The present invention relates to a system for determining the hydrogen potential (pH) of floodwater wastewater and the irreducible water saturation. The system aims to enhance oil recovery in sandstone reservoirs through the use of temperature-controlled low-salinity water (LSWF) flooding. The system allows precise control of the saltwater composition, pH, salinity, and flood temperature, and influences important rock-fluid interactions to achieve desirable wetting conditions. Core flood experiments are conducted at different temperatures (70 °C, 85 °C, and 105 °C) to assess how pH gradients and the irreducible water saturation (Swir) change with increasing temperatures.The system is specifically designed to induce wettability changes in sandstone formations, resulting in increased water wetness and optimized relative permeability for enhanced oil recovery. The process enables effective oil displacement and reservoir fluid flow by exploiting the temperature-dependent behavior of pH and water saturation during low-salinity water floods.

[0009] An object of the present invention is to provide a system for determining the hydrogen potential of flood water and the irreducible water saturation.

[0010] Another object of the present invention is to achieve wettability modification in sandstone rock by controlling the core flood temperature, salinity and pH of the injected brine, resulting in increased water moisture and improved oil recovery.

[0011] Another objective of the present invention is to analyze the effects of temperature on the pH gradient of flood wastewater and its relationship to changes in wettability to enable a temperature-dependent strategy for optimizing flood processes.

[0012] Another object of the present invention is to evaluate the effects of irreducible water saturation (Swir) on the change in wettability by measuring the Swir values ​​at progressively increasing core flooding temperatures and to establish a linear relationship between temperature and Swir.

[0013] Another objective of the present invention is to investigate the process of altering wettability without formation damage by alternating injections of low salinity water, avoiding the use of synthetic mineralogical columns and instead focusing on the mineralogy of the natural sandstone rock.

[0014] Another objective of the present invention is to provide indirect information on wettability behavior by monitoring the pH of post-flood wastewater to determine whether sandstone surfaces exhibit acidic or basic properties under different temperature conditions.

[0015] Another objective of the present invention is to investigate how temperature, rock mineralogy and initial wettability affect the wettability behavior of sandstone reservoirs, particularly the Barail Sandstone Formation in the Upper Assam Basin.

[0016] The present invention aims to provide a system for determining the hydrogen potential (pH) of floodwater wastewater and the irreducible water saturation, the system comprising: a Dean-Stark apparatus for cleaning core plug samples with a 50:50 solvent mixture of toluene and methanol at a temperature of 40°C; an ultrasonic cleaner for removing surface deposits from the core samples after cleaning; a humidity-controlled oven for drying and heating the core samples for 72 hours; a helium porosimeter (TPI-219) for determining the porosity of the core plug samples, including bars of different volumes for measuring grain volume; an X-ray diffractometer for determining the mineral composition of the sandstone rocks;a core flooding unit with a core holder, hydraulic pumps, a back pressure regulator (BPR), and a heat source to maintain specific temperatures of the core plugs during flooding, enabling the injection of brine and oil under controlled conditions; a water analyzer to measure the pH of the core wastewater; a liquid permeability meter to determine the permeability of the core plugs after initial water saturation; a receiving unit to collect wastewater after flooding; and a water bath to maintain a stable temperature during wastewater separation.

[0017] To further clarify the advantages and features of the present disclosure, a more detailed description of the invention will be given with reference to specific embodiments thereof illustrated in the accompanying drawings. It should be noted that these drawings represent only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained in additional detail and in greater detail with reference to the accompanying drawings. SHORT DESCRIPTION OF THE FIGURE

[0018] These and other features, aspects, and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawings, in which like characters represent like parts throughout. Fig.1 shows a block diagram of a system for determining the hydrogen potential (pH) of floodwater wastewater and the irreducible water saturation according to an embodiment of the present disclosure, Fig. 2 shows a TPI-219 porosity measurement setup according to an embodiment of the present disclosure, and Fig. 3 illustrates a core flood structure for WF according to an embodiment of the present disclosure.

[0019] Furthermore, those skilled in the art will appreciate that elements in the drawings are shown for convenience and may not necessarily be drawn to scale. For example, the flowcharts illustrate the method by key steps to enhance understanding of aspects of the present disclosure. Furthermore, with respect to device construction, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only the specific details relevant to understanding embodiments of the present disclosure in order not to clutter the drawings with details that would be readily apparent to those skilled in the art who would benefit from the description herein. DETAILED DESCRIPTION:

[0020] To facilitate an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and described in specific language. It is to be understood, however, that no limitation upon the scope of the invention is thereby intended, since such changes and further modifications to the illustrated system, and such further applications of the principles of the invention as illustrated therein, are contemplated as would normally occur to one skilled in the art to which the invention pertains.

[0021] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be limiting thereof.

[0022] References in this specification to "one aspect," "another aspect," or similar language mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Therefore, the occurrences of the phrase "in one embodiment," "in another embodiment," and similar language throughout this specification may or may not all refer to the same embodiment.

[0023] The terms "comprises," "comprising," or other variations thereof are intended to cover non-exclusive inclusion, such that a process or method comprising a list of steps not only includes those steps, but may also include other steps not expressly listed or inherent in such process or method. Likewise, one or more devices or subsystems or elements or structures or components preceded by "comprises..." does not preclude, without further limitation, the existence of other devices or other subsystems or other elements or other structures or other components or additional devices or additional subsystems or additional elements or additional structures or additional components.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The system, methods, and examples provided herein are for illustrative purposes only and should not be considered limiting.

[0025] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0026] Fig.1 shows a block diagram of a system (100) for determining the hydrogen potential (pH) of floodwater wastewater and the irreducible water saturation, the system (100) comprising: a Dean-Stark apparatus (102) for cleaning core plug samples with a 50:50 solvent mixture of toluene and methanol at a temperature of 40°C; an ultrasonic cleaner (104) connected to the Dean-Stark apparatus (102) and configured to remove surface deposits from the core samples after cleaning; a humidity-controlled oven (106) connected to the ultrasonic cleaner (104) and configured to dry and heat the core samples for 72 hours; a helium porosimeter (TPI-219) (108) connected to the humidity-controlled furnace (106) and configured to determine the porosity of the core plug samples, including billets of different volumes for measuring grain volume;an X-ray diffractometer (110) connected to the helium porosimeter (TPI-219) (108) and configured to determine the mineral composition of the sandstone rocks; a core flooding unit (112) comprising a core holder (112a), hydraulic pumps (112b), a back pressure regulator (BPR) (112c), and a heat source (112d), and connected to the X-ray diffractometer (110) and configured to maintain specific temperatures of the core plugs during flooding, thereby enabling the injection of brine and oil under controlled conditions; a water analyzer (114) connected to the core flooding unit (112) and configured to measure the pH of the core wastewater; a liquid permeameter (116) connected to the water analyzer (114) and configured to determine the permeability of the core plugs after initial water saturation;a receiving unit (118) connected to the liquid permeation meter (116) and configured to collect wastewater after flooding; and a water bath (120) connected to the receiving unit (118) and configured to maintain a stable temperature during the separation of the wastewater.

[0027] In one embodiment, the helium porosimeter (TPI-219) (108) uses a Boyle's law double cell to measure the porosity of sandstone core plugs.

[0028] In one embodiment, the core holder (112a) is equipped with a rubber sleeve to ensure a tight seal and to ensure that injected fluids flow through the core plug without leakage.

[0029] In one embodiment, the core flooding unit (112) operates under overburden pressures of up to 400 psi to simulate reservoir conditions.

[0030] In one embodiment, the BPR (112c) is connected to the core flooding unit (112) to monitor the internal temperature and outlet pressure during flooding.

[0031] In one embodiment, the core flooding unit (112) used to determine the irreducible water saturation is carried out at different temperatures of 70 °C, 85 °C and 105 °C, and oil is injected at a rate of 0.5 cm 3 / min to calculate the effective permeability.

[0032] In one embodiment, the core flooding unit (112) uses synthetic brines with salt contents of 3100 ppm and 1000 ppm for water flooding analysis.

[0033] In one embodiment, the wastewater collected during core flooding is monitored in real time to record flow and pressure data.

[0034] Fig.Figure 2 shows a TPI-219 setup for measuring porosity according to one embodiment of the present disclosure. The setup for measuring the porosity of sandstone core samples uses the Boyle Law Double Cell. The TPI-219 helium porosimeter with a 1.5-inch diameter die cup accommodates billets that vary the core plug length for porosity evaluation. Five billets of varying volumes and lengths (AE) are used to vary the core plug lengths, with volumes ranging from 7,209 to 43,414 cm3 and lengths ranging from 0.248 to 1.498 inches. Additionally, the mineral composition of the sandstone is determined by X-ray diffraction analysis.

[0035] Fig.Figure 3 shows the test setup for core flooding analysis, in which hydraulic pumps supply oil and saltwater to core plugs in the core system. During the test, the core plugs are placed in a Hassler core holder located in a furnace to maintain a constant temperature. A hydraulic pump applies the required overburden pressure to the core plugs, ensuring that the rubber sleeve in the core holder secures the plugs and directs fluids exclusively through them. The overburden pressure prevents leaks in the annulus between the sleeve and the core plug. A heat source equipped with a thermometer maintains the temperature, while an electronic display and a back pressure regulator (BPR) monitor the internal temperature and the core holder's outlet pressure.

[0036] Current analysis identifies feldspar, primarily as plagioclase and alkali feldspar, along with quartz, illite, and kaolinite in sandstone formations. These minerals enhance the water wettability of the sandstone. Furthermore, an asphaltene concentration of 1.12% was found in crude oil samples from the Upper Assam Basin, with a high tendency to adsorb on feldspar surfaces, suggesting a possible alteration in wettability. Kaolinite, a low-swelling clay, was detected in the Barail Formation with more than 10% by weight in some samples, along with smectite, a swelling clay with a 2:1 layered structure. The combined presence of these minerals favors the water wettability of sandstone rocks during flooding.

[0037] In core flood tests, the pH of the wastewater from sandstone plug X1 varies depending on NaCl concentration and temperature. With 3100 ppm NaCl at 70 °C, the pH decreases from 7.1 to 6.8 after 1.5 pore volumes (PV) and then increases to 9.4 upon flooding with 1000 ppm NaCl, demonstrating a pH increase of approximately 2.3 units. Successive brine floods with a 3100 ppm solution lower the pH, while a 1000 ppm NaCl brine increases it, suggesting that the core can reach alkaline conditions that reduce the adsorption of organic molecules to feldspar. Flooding temperatures above 100 °C further lower the pH. Core X2 shows similar trends with initial pH values ​​of approximately 6.9–7.1 across all temperatures and stronger pH shifts with 1000 ppm NaCl at 85 °C, attributed to the feldspar content.This suggests that feldspar increases water moisture by increasing pH and temperature, thus leading to a shift in wettability towards water-moist conditions.

[0038] The pH screening test for sandstone outcrop core X3 is conducted at core flood temperatures of 70 °C, 85 °C, and 105 °C. At 70 °C, the initial pH of the first flood batch stabilizes at 7.2 after an initial drop to 6.7. As the flooding sequence changes from the first batch (3100 ppm) to the second batch (1000 ppm), the pH of the brine flood effluent increases significantly from 7.2 to 9.6, corresponding to an incremental pH gradient of approximately 2.4. However, upon returning to the third batch with 3100 ppm flooding, the pH drops back to 7.2.

[0039] In the second flood cycle at 85 °C, the initial pH for the first batch of 3100 ppm NaCl solution remains at 7.2. For the second batch at 1000 ppm, an incremental pH gradient of 2.5 is recorded, slightly higher than at 70 °C. Switching back to the third batch lowers the pH from 9.7 to 7.2 for the sandstone core, which contains 16.72 wt% kaolinite clay. At 105 °C, the first injection batch records a pH of 6.8, 0.4 units lower than at 70 °C and 85 °C. Switching from the first to the second batch at this temperature results in a pH increase to 9.8.

[0040] The results show that outcrop core X3, containing 16.72 wt% kaolinite clay, exhibits an increasing pH trend with increasing core flood temperatures during the 1000 ppm saline flood. However, the pH continuously decreases during the third batch of the 3100 ppm solution and stabilizes at 7.2 after 6 pore volumes of injection. The increasing pH gradients with temperature are likely due to changes in sandstone wettability influenced by the significant kaolinite content.

[0041] In one embodiment, the present system investigates core plugs DG4 and DG5 with kaolinite contents of 14.83 wt% and 14.02 wt%, respectively, to evaluate pH changes in brine effluents at temperatures of 70 °C, 85 °C, and 105 °C. The results show that the pH gradients increase during brine flooding with a 1000 ppm NaCl solution over these temperatures. Core X4 exhibits incremental pressure gradients of 2.3 at 70 °C ( Fig. ), 2.4 at 85 °C ( Fig. ) and 2.46 at 105 °C ( Fig. ). Similarly, core X5 shows incremental pressure gradients of 2.1 at 70 °C ( Fig. ), 2.3 at 85 °C ( Fig. ) and 2.26 at 105 °C ( Fig. ) in the second saltwater flooding batch.

[0042] The study shows that saltwater flooding continuously increases the pH of flood wastewater as temperatures rise. Furthermore, cores with higher kaolinite weight fractions lead to higher pH values ​​as core flood temperatures increase.

[0043] In one embodiment, the present system investigates the effect of temperature on the irreducible water saturation (Swir) in sandstone core plugs X1, X2, X3, X4, and X5 by flooding experiments at temperatures of 70°C, 85°C, and 105°C with NaCl solutions of 1000 ppm and 3100 ppm. For core plug X1, a Swir of 0.29 is measured at 70°C, which increases to 0.33 at 85°C and to 0.34 at 105°C. A similar trend is observed when flooding with 3100 ppm NaCl, where the Swir increases from 0.27 at 70°C to 0.31 and 0.32 at 85°C and 105°C, respectively.

[0044] For core X2, the Swir value is 0.26 at 70 °C and increases to 0.31 and 0.32 at higher temperatures. When flooded with 3100 ppm NaCl, the Swir values ​​remain constant and increase from 0.26 to 0.33 and 0.34 with increasing temperatures. Core plug X3 shows a similar pattern, with Swir values ​​of 0.3 at 70 °C, increasing to 0.33 at 85 °C, consistent with the trend observed in X1 and X2.

[0045] Cores X4 and X5 also exhibit increased Swir values ​​with increasing temperatures, confirming the results of previous studies. A linear correlation between Swir and flood temperature was observed across all cores, highlighting the significant influence of temperature on irreducible water saturation in porous sandstone media. The results are further illustrated below with tabular data, highlighting the increasing trend of Swir with temperature across all core samples: Porous media Core diameter, D, Flood temperature, °C Brine salinity, injection rate, ppm cm 3 / min Porosity, Φ, fraction Pore ​​volume, PV, cc S we, % X1 1.5 70 °C 1000 0.5 0.1525 12.4617 0.29 1.5 85 °C 1000 0.5 0.1525 12.4617 0.33 1.5 105 °C 1000 0.5 0.1525 12.4617 0.34 1.5 70 °C 3100 0.5 0.1525 12.4617 0.27 1.5 85 °C 3100 0.5 0.1525 12.4617 0.31 1.5 105 °C 3100 0.5 0.1525 12.4617 0.32 X2 1.48 70 °C 1000 0.8 0.1328 8.4014 0.26 1.48 85 °C 1000 0.8 0.1328 8.4014 0.31 1.48 105 °C 1000 0.8 0.1328 8.4014 0.32 1.48 70 °C 3100 0.8 0.1328 8.4014 0.26 1.48 85 °C 3100 0.8 0.1328 8.4014 0.33 1.48 105 °C 3100 0.8 0.1328 8.4014 0.34 X3 1.47 70 °C 1000 1 0.1525 9.8518 0.3 1.47 85 °C 1000 1 0.1525 9.8518 0.33 1.47 105 °C 1000 1 0.1525 9.8518 0.33 1.47 70 °C 3100 1 0.1525 9.8518 0.29 1.47 85 °C 3100 1 0.1525 9.8518 0.32 1.47 105 °C 3100 1 0.1525 9.8518 0.33 X4 1.5 70 °C 1000 0.5 0.1235 8.7297 0.29 1.5 85 °C 1000 0.5 0.1235 8.7297 0.32 1.5 105 °C 1000 0.5 0.1235 8.7297 0.33 1.5 70 °C 3100 0.5 0.1235 8.7297 0.28 1.5 85 °C 3100 0.5 0.1235 8.7297 0.32 1.5 105 °C 3100 0.5 0.1235 8.7297 0.33 The X5 1.5 70 °C 1000 1 0.1726 12.7907 0.31 1.5 85 °C 1000 1 0.1726 12.7907 0.33 1.5 105 °C 1000 1 0.1726 12.7907 0.33 1.5 70 °C 3100 1 0.1726 12.7907 0.3 1.5 85 °C 3100 1 0.1726 12.7907 0.33 1.5 105 °C 3100 1 0.1726 12.7907 0.33

[0046] The drawings and the foregoing description provide examples of embodiments. Those skilled in the art will recognize that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be separated into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of the processes described herein may be changed and are not limited to the manner described herein. Furthermore, the actions of any flowchart need not be implemented in the order shown; nor do all actions necessarily need to be performed. Also, those actions that are not dependent on other actions may be performed in parallel with the other actions. The scope of the embodiments is in no way limited by these specific examples.Numerous variations, whether explicitly stated in the specification or not, such as differences in structure, dimensions, and use of materials, are possible. The scope of the embodiments is at least as broad as indicated in the following claims.

[0047] Advantages, other benefits, and solutions to problems have been described above with respect to specific embodiments. However, the advantages, benefits, solutions to problems, and any components that may cause an advantage or solution to occur or become more apparent are not to be construed as a critical, required, or essential feature or component of any or all of the claims. REFERENCES 100 System for determining the hydrogen potential (pH) of flood discharges and irreducible water saturation 102 Dean-Stark apparatus 104 ultrasonic cleaners 106 Humidity-controlled oven 108 Helium Porosimeter (TPI-219) 110 X-ray diffractometers 112 core flooding system 112a core holder 112b Hydraulic pumps 112c Back Pressure Regulator (BPR) 112d heat source 114 Water Analyzer 116 liquid permeameters 118 Receiving unit 120 water bath 202 back 204 measuring device 206 Helium source 208 ON / OFF valve 210 controllers 212 Pressure setting 214 100-psi converter 216 ad 218 Front 220 Insulation / Gas Supply 222 Reference cell 224 25 CC cell 226 GVC or core holder 228 To the core 230 Ventilation 302 Pressure Gauge 304 pressure transmitter 306 Temperature Controller 308 core holder 310 back pressure 312 Data collection 314 wastewater collectors 316 Pressure relief pump 318 Hydraulic pump 320 brine storage tanks 322 oil storage 324 brine storage

Claims

[1] A system (100) for determining the hydrogen potential (pH) of flood wastewater and the irreducible water saturation, the system (100) comprising: a Dean-Stark apparatus (102) configured to clean core plug samples using a 50:50 solvent mixture of toluene and methanol at a temperature of 40°C; an ultrasonic cleaner (104) connected to the Dean-Stark device (102) and configured to remove surface deposits from the core samples after cleaning; a humidity-controlled oven (106) connected to the ultrasonic cleaner (104) and configured to dry and heat the core samples for 72 hours; a helium porosimeter (TPI-219) (108) connected to the moisture control furnace (106) and configured to determine the porosity of the core plug samples, including billets of different volumes, for measuring grain volume; an X-ray diffractometer (110) connected to the helium porosimeter (TPI-219) (108) and configured to determine the mineral composition of the sandstone rocks; a core flooding unit (112) comprising a core holder (112a), hydraulic pumps (112b), a back pressure regulator (BPR) (112c) and a heat source (112d) connected to the X-ray diffractometer (110) and designed to maintain certain temperatures of the core plugs during flooding, thereby enabling the injection of brine and oil under controlled conditions; a water analyzer (114) connected to the core flooding unit (112) and configured to measure the pH of the core wastewater; a liquid permeability meter (116) connected to the water analyzer (114) and configured to determine the permeability of the core plugs after initial water saturation; a receiving unit (118) connected to the liquid permeameter (116) and configured to collect wastewater after flooding; and a water bath (120) connected to the receiving unit (118) and configured to maintain a stable temperature during wastewater separation. [2] The system (100) of claim 1, wherein the helium porosimeter (TPI-219) (108) uses a Boyle's law double cell to measure the porosity of sandstone core plugs. [3] The system (100) of claim 1, wherein the core holder (112a) is equipped with a rubber sleeve to provide a tight seal and ensure that injected fluids flow through the core plug without leakage. [4] The system (100) of claim 1, wherein the core flooding unit (112) operates under overburden pressures of up to 400 psi to simulate reservoir conditions. [5] The system (100) of claim 1, wherein the BPR (112c) is connected to the core flooding unit (112) to monitor the internal temperature and outlet pressure during flooding. [6] The system (100) of claim 1, wherein the core flooding unit (112) used to determine the irreducible water saturation is performed at different temperatures of 70°C, 85°C and 105°C and oil is injected at a rate of 0.5 cc / min to calculate the effective permeability. [7] The system (100) of claim 1, wherein the core flooding unit (112) uses synthetic brines having salt contents of 3100 ppm and 1000 ppm for water flooding analysis. [8] The system (100) of claim 1, wherein the wastewater collected during core flooding is monitored in real time to record flow and pressure data.

Images