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Based on the characteristics of injection-production units in fractured-vuggy carbonate reservoirs, nine groups of experiments were designed and performed to analyze the interference characteristics and their influencing factors during water flooding. Based on percolation theory, an inversion model for simulating waterflooding interferences was proposed to study the influence laws of different factors on interference characteristics. The results show that well spacing, permeability ratio, cave size, and cave location all affect the interference characteristics of water flooding. When the cave is located in high permeability fractures, or in the small well spacing direction, or close to the producer in an injection-production unit, the effects of water flooding are much better. When the large cave is located in the high-permeability or small well spacing direction, the well in the direction with lower permeability or smaller well spacing will see water breakthrough earlier. When the cave is in the higher permeability direction and the reserves between the water injector and producer differ greatly, the conductivity differences in different injection-production directions are favorable for water flooding. When the injection-production well pattern is constructed or recombined, it's better to make the reserves of caves in different injection-production directions proportional to permeability, and inversely proportional to the well spacing. The well close to the cave should be a producer, and the well far from the cave should be an injector. Different ratios of cave reserves to fracture reserves correspond to different optimal well spacings and optimal permeability ratios. Moreover, both optimal well spacing and optimal permeability ratio increase as the ratio of cave reserves to fracture reserves increases.

Low salinity water flooding is an approach used during the EOR process to alter the surface wettability the IFT reduction. However, implementation of this method in shaly sandstone layers has not b...

A large number of researchers have endeavored to delineate the effects of injecting brine with a low ionic strength in oil reservoirs in the past decade. However, we still cannot conclude the overr...

This study aims to develop a grid-based smart proxy model (G-SPM) for water flooding enhancement under different injection/production scenarios. The contribution of this work is combining experimen...

Injection of low-salinity water into carbonate reservoirs has gained attention as a viable and efficient enhanced oil recovery approach through wettability alteration as prevailing mechanism. However, modeling and implementation of wettability alteration during simulation of low-salinity water injection are challenging because of the complex ion interactions and chemical reactions in the brine and oil mixture as well as on the rock surface. It is noteworthy that wettability alteration is usually considered instantaneous in black oil simulation. The main purpose of this work was to put this assumption into perspective; thus, it aims at discerning under what circumstances the instantaneous wettability alteration approach is plausible during simulation of low-salinity water flooding. To answer this question, an approach was proposed to consider gradual wettability alteration during simulation of low-salinity water flooding and the results were compared with instantaneous wettability alteration method. The results show that the impacts of simultaneous increase in $${\text{SO}}_{4}^{2 - } ,{\text{Ca}}^{2 + }$$ concentrations and temperature cause the difference between gradual and instantaneous wettability alteration to be more noticeable at the early times of injection. Therefore, the results highlight that the impact of gradual consideration would be important at the early time of low-salinity water flooding process.

Establishing an effective displacement system for conventional water flooding development in low-permeability reservoirs is difficult, with generally low liquid and oil production and a worse water flooding effect. Imbibition oil recovery technology has received increasing attention from oil development workers because of its simple operation, low cost, and good oil increase effect. To explore the method and mechanism to further improve the effect of imbibition oil recovery, we study the imbibition and oil recovery effect and its influencing factors in a low-permeability reservoir in the Dagang Oilfield based on evaluation indexes of the adhesion work reduction factor, ratio of capillary force to gravity NB–1, regression analysis of the recovery rate of imbibition, proportional relationship with spontaneous imbibition, and dynamic imbibition effect in crack rocks. Results show that reducing the interfacial tension of the surfactant on the imbibition process has a dual effect. The selection of the surfactant for fractured tight reservoirs should not excessively pursue ultralow interfacial tension, and it should consider the surface wettability environment favorable for imbibition to ensure that a sufficient driving force can be provided. In the initial imbibition stage, the capillary force is large, the velocity of water imbibition in pores is fast, and the oil recovery rate is high; the holding time of the imbibition process is important to imbibition recovery. With the increase in imbibition time, the capillary force weakens, and the imbibition speed decreases to zero. With the increase in injection volume, reservoir pressure, pressure holding time, and imbibition cycles, the oil recovery increases, but the amplification of oil recovery decreases. From the technical and economic viewpoints, the optimal slug size, throughput cycle, and pressure holding time of the target reservoir are recommended as follows: 0.5 PV,three3 rounds, and greater than 96 h, respectively.

Microfluidics is an appealing method to study processes at rock pore scale such as oil recovery due to the similar size range. It also offers several advantages over the conventional core flooding methodology, for example, easy cleaning and re-use of the same porous network chips or the option to visually track the process. In this study, the effect of injection rate, flood volume, micromodel structure, initial brine saturation, aging, oil type, brine concentration, and composition are systematically investigated. The recovery process is evaluated based on a series of images taken during the experiment. The remaining crude oil saturation reaches a steady state after injection of a few pore-volumes of the brine flood. The higher the injection rate, the higher the emulsification and agitation, leading to unstable displacement. Low salinity brine recovered more of the oil than the high salinity brine. Aging, initial brine saturation, and presence of divalent ions in the flood showed to decrease the oil recovery. Most of the tests in this study showed viscous fingering. The analysis of the experimental parameters allowed to develop a reliable and repeatable procedure for microfluidic water flooding. With the method in place, the enhanced oil recovery test developed based on different variables showed an increase of up to 2% of the original oil in place at the tertiary stage. This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.

Pore structure characteristics of ultra-low permeability reservoirs are studied in this paper. The impact of pore structure characteristics on permeability and reservoir development effect is analyzed by conventional and constant-rate mercury penetration experiments. The results show that the frequency curve of pore radius distribution of ultra-low permeability reservoirs has little change with permeability. The average pore radius in ultra-low permeability reservoirs with different permeability levels had little difference, and its distribution ranges from 98.5 to 110.1 μm. With decrease of permeability, the frequency distribution curves of throat radius and pore-throat ratio change significantly. The peak value of throat radius curve moves to the left and increases significantly, and the average throat-radius distribution decreases from 2.33 to 0.91 μm. However, the impact of pore-throat ratio on permeability is contrary to that of throat radius. Both throat radius and pore-throat ratio has strong correlation with permeability, and they are in exponential relationship. With the in-depth study, it is found that seepage capacity of reservoirs is restricted mainly by throat radius and pore-throat ratio. When throat radius decreases to less than 1 μm and pore-throat ratio increases more than 130, permeability decreases sharply and obviously. When permeability is less than 2 × 10−3μm2, the proportion of fine throats and medium throats under the condition of effective water injection is significantly lower, and the production of single well and the recovery efficiency by water flooding in ultra-low permeability reservoirs are low. The study explains effectively the fundamental reason for the poor efficiency of production and recovery of ultra-low permeability reservoirs from the mechanism.

Carbonate reservoirs worldwide are complex in structure, diverse in form, and highly heterogeneous. Based on these characteristics, the reservoir stimulation technologies and fluid flow characteristics of carbonate reservoirs are briefly described in this study. The development methods and EOR technologies of carbonate reservoirs are systematically summarized, the relevant mechanisms are analyzed, and the application status of oil fields is catalogued. The challenges in the development of carbonate reservoirs are discussed, and future research directions are explored. In the current development processes of carbonate reservoirs, water flooding and gas flooding remain the primary means but are often prone to channeling problems. Chemical flooding is an effective method of tertiary oil recovery, but the harsh formation conditions require high-performance chemical agents. The application of emerging technologies can enhance the oil recovery efficiency and environmental friendliness to a certain extent, which is welcome in hard-to-recover areas such as heavy oil reservoirs, but the economic cost is often high. In future research on EOR technologies, flow field control and flow channel plugging will be the potential directions of traditional development methods, and the application of nanoparticles will revolutionize the chemical EOR methods. On the basis of diversified reservoir stimulation, combined with a variety of modern data processing schemes, multichannel EOR technologies are being developed to realize the systematic, intelligent, and cost-effective development of carbonate reservoirs.

The adjustment and control of the water injection rate is a commonly used method for increasing the cumulative oil production of waterflooded reservoirs. This article studies the production optimization problem under the condition of a fixed total water injection rate. The production process is divided into several segments. Considering the correlation between the segment’s time intervals and the well’s injection rate distribution, a simultaneous optimization of both segmented time and injection rate is proposed for enhancing net present value. Both empirical simulations and field application demonstrate that the suggested methods produce the highest increase in net present value – of approximately 13% and 10%, respectively – and significantly improve water flooding efficiency compared to other conventional schemes, such as segmented oil production optimization, cumulative oil production optimization and Bang-Bang control. The proposed methods under a 2-segment division increase oil production efficiency and greatly reduce adjustment costs.

The purpose of this study was to determine the displacement and dynamic distribution characteristics of the remaining oil in the two development stages of water flooding and subsequent alkaline surfactant polymer (ASP) flooding. The well pattern types in the water and ASP flooding stages are a long-distance determinant well pattern and short-distance five-point well pattern, respectively. The type A displacement characteristic curve can be obtained using the production data, and the slope of the straight-line section of the curve can reflect the displacement strength of the oil displacement agent. A numerical simulation was carried out based on the geological model. The results revealed that the injected water advances steadily with a large-distance determinant water-flooding well pattern. The single-well water production rate increases monotonically during water flooding. There is a significant positive correlation between the cumulative water-oil ratio and the formation parameter. Differential seepage between the oil and water phases is the main factor causing residual oil formation after water flooding, while the residual oil is still relatively concentrated. The effect of the chemical oil-displacement agent on improving the oil-water two-phase seepage flow has distinct stages during ASP flooding. The remaining oil production is extremely sporadic after ASP flooding.

Interfacial tension (IFT) plays a vital role in petroleum industry for enhanced oil recovery. In recent years, a new technology called ‘low salinity water flooding’ has brought the attention of res...

Engineered water (EW) flooding is one of the enhanced oil recovery (EOR) techniques in carbonate reservoirs. In this method, the wettability of reservoir rock is altered by controlling the amount o...

It is preliminary estimated that the proved geological reserves of original low-oil-saturation reservoirs (OLOSRs) of 54 blocks in China are more than 820 million tons. As same as the high water-cut stage of a reservoir after water flooding, the initial water cut of OLOSRS is higher than 80%. The industrial application of EOR technology could efficiently enhance oil recovery rate from 8.4% to 20.1% of reservoirs after water flooding. The suitable measurements of EOR to the OLOSRs probably have a profound impact on achieving higher oilfield reserves and production. In this paper, the main characteristics and reserves potential of OLOSRs have been studied by investigations and laboratory experiments. The relationship between initial oil saturation and displacement efficiency is also analyzed. The feasibility of EOR technologies for different OLOSRs is discussed. The results show that the OLOSRs could be divided into two categories (primary and secondary) by origin of low oil saturation. The two categories contain abundant reserves in China’s major oilfields, but their occurrence states of crude oil are quite different. If the average oil saturation of the OLOSR is defined at 40%, there are 13.1%–54.2% crude oil that could be recovered by using the existing EOR technology, especially in the primary OLOSRs with low permeability and the secondary OLOSRs with high permeability. Keywords: Low oil saturation, Transition zones, Occurrence state, Oil displacement efficiency, Gas flooding, Surfactant flooding

In order to study the microscopic oil displacement mechanism of polymeric surfactant in chemical cold flooding for heavy oil, the indoor microscopic visualization displacement experiments were carried out. The flooding experiment of heavy oil was conducted by using water, osmotic modified oil displacing agent (a kind of polymeric surfactant) and water-in-oil emulsion (obtained by mixing polymeric surfactant and heavy oil) as displacing phases to study the mechanism of polymeric surfactant to enhance oil recovery in heavy oil reservoir. The experimental results show that the polymeric surfactant can increase the viscosity of the water phase, reduce the water-oil mobility ratio, expand the swept area, and there is no obvious fingering phenomenon which occurs during water flooding. The polymeric surfactant has the surfactant characteristics which can reduce the interfacial tension between oil and water to promote the formation of oil droplets with smaller droplet diameter. And the interfacial film composed of polymeric surfactant molecules will be formed on the surface of oil droplets to prevent the coalescence of oil droplets and improve the flow ability of oil phase. The water-in-oil emulsion can be miscible with the oil in heavy oil displacement process, and thus sweeps the areas such as the dead pores which cannot be swept by water and polymeric surfactant flooding, which increases the sweep efficiency to a certain extent. Cited as : Xu, F., Chen, Q., Ma, M., Wang, Y., Yu, F., Li, J. Displacement mechanism of polymeric surfactant in chemical cold flooding for heavy oil based on microscopic visualization experiments. Advances in Geo-Energy Research, 2020, 4(1): 77-85, doi: 10.26804/ager.2020.01.07

This study investigates the impact of design parameters on oil recovery performance in polymer flooding (PF) with low-salinity water-flooding (LSWF). Convergence technology for enhanced oil recover...

To reduce water cut and improve sweep efficiency of water flooding, a novel pore-scale microsphere (NMPS) as profile control agent was firstly prepared through inverse emulsion polymerization techn...

The role of emulsions should be an important factor in additional oil recovery during low-salinity water flooding (LSWF); however, it has been rarely discussed in previous studies. In this study, t...

The results are presented of modeling the “contour water flooding” biotechnology aimed at cleaning heavily petroleum-polluted agrosoddy-podzolic soils (Albic Retisols (Loamic, Aric)) by application of bacterial–yeast consortium, microalgae, and algal–bacterial–yeast consortium, and mineral fertilizers are presented. The patterns of biotic indicators and the total petroleum hydrocarbon content at various stages of oil destruction are identified. Changes in the number of hydrocarbon-oxidizing microorganisms in the microcosms depend on the biological agent applied. In the case of the soil treatment with microalgae, the population of hydrocarbon-oxidizing microorganisms declines by an order of magnitude at the end of the experiment, whereas in the case of bacterial–yeast and algal–bacterial–yeast consortia, their population has been restored to the 90th day. The biochemical activity in microcosms remains high during the experiment. The results of the experiment prove the efficiency of application oil-oxidizing microbial consortia, including those with microalgae. While being fertilized,the bacterial–yeast and algal–bacterial–yeast consortia exert the maximum purification effect in simulation microcosm experiments. The efficiency of soil purification from total petroleum hydrocarbons reaches 60–63% over 90 days of the experiment. IR spectroscopic data indicate the decline in the share of saturated aliphatic structures and the accumulation of bio-thermodynamically stable aromatic hydrocarbons and oxygen-containing residual components of oil, which are intermediate products of metabolism in the microbial oxidation of oil hydrocarbons.

Thief zones are highly permeable zones in oil reservoirs which affect the performance greatly during water flooding. The most effective way to prevent the invalid circle of thief layer is the injection of high-concentration polymer slugs. In this paper, the plugging effect of nano-micron polymer flooding on the thief zone is studied by experimental and theoretical analysis. The changes of water content and flow resistance were analyzed under different conditions. The result shows that the model presented here has good agreement with the experimental results. The displacement effect is the best when the thief zone is located on the upper part of the reservoir. And the water content will decrease with the increase of flow resistance after nano-micron polymer injection. Besides, the higher the polymer concentration, the more obvious the decrease of water content, and more effective the plugging. This study has provided a quick and reasonable guide in the later adjustment of water flooding development of carbonate reservoirs with thief layers.

Water flooding is widely applied for pressure maintenance or increasing the oil recovery of reservoirs. The heterogeneity and wettability of formation rocks strongly affect the oil recovery efficiency in carbonate reservoirs. During seawater injection in carbonate formations, the interactions between potential seawater ions and the carbonate rock at a high temperature can alter the wettability to a more water-wet condition. This paper studies the wettability of one of the Iranian carbonate reservoirs which has been under Persian Gulf seawater injection for more than 10 years. The wettability of the rock is determined by indirect contact angle measurement using Rise in Core technique. Further, the characterization of the rock surface is evaluated by molecular kinetic theory (MKT) modeling. The data obtained from experiments show that rocks are undergoing neutral wetting after the aging process. While the wettability of low permeable samples changes to be slightly water-wet, the wettability of the samples with higher permeability remains unchanged after soaking in seawater. Experimental data and MKT analysis indicate that wettability alteration of these carbonate rocks through prolonged seawater injection might be insignificant.

The bottom water heavy oil reservoir has high natural energy, and the bottom water body multiple of the reservoir is 300 times or even higher. The natural energy of the reservoir can keep the superior condition that the formation energy does not decrease under the condition of large liquid volume and high recovery rate. In view of this reservoir condition, we take C oilfield as an example to carry out the oilfield development effect under the condition of large liquid volume and high-speed production, and analyze the influence of high-speed production and medium low-speed production on recovery rate of similar heavy oil bottom water-reservoir. The results show that the rising trend of water cut in oilfield is the same whether high-speed development with large liquid volume or conventional low-speed development is adopted. Under the condition of high liquid production, the sweep efficiency of water flooding is high in the same period of time, which has certain advantages of enhanced oil recovery. The development mode of early large liquid production is explored, which provides certain guidance for the efficient development of heavy oil reservoir with bottom water.

This paper proposed a method of injection-production system adjustment to solve the problem that the water flooding effect was restricted because of the horizontal and vertical contradictions during the development process of fault block reservoirs. Considering the heterogeneity of reservoir, the Buckley-Leverett water flooding theory was applied to establish the relationship between the recovery and cumulative water injection. In order to achieve the goal of vertically balanced recovery of each section, the calculation method of vertical sectional injection allocation was proposed. The planar triangular seepage unit was assumed and sweep coefficients of different oil-water distribution patterns were characterized using multi-flow tube method. In order to balance and maximize the plane sweep coefficient, the calculation method of plane production system optimization was obtained. Then the injection-production system stereoscopic adjustment method based on equilibrium displacement was proposed with vertical sectional injection allocation and plane production system optimization. This method was applied to injection and production adjustment of BZ oilfield in southern Bohai. The effect of water control and oil increase was obvious. This method can greatly improve the effect of water flooding of offshore fault block reservoirs with the adjustment of injection-production system.

In order to understand the water-flooding characteristics of different fracture systems in metamorphic rock buried hill reservoirs and the mechanism of improving water-flooding development effect, a three-dimensional physical model of fractured reservoirs is established according to the similarity criterion based on the prototype of metamorphic buried hill reservoirs in JZ Oilfield in Bohai Bay Basin. Combined with the fractured reservoir characteristics of JZ Oilfield, the water displacement characteristics of the top-bottom staggered injection-production well pattern in different fracture network mode and different fracture development degree of buried hill reservoir are studied. The experimental results show that: 1) the more serious the fracture system irregularity is, the shorter the water-free oil production period is and the lower the water-free oil recovery is. After water breakthrough of production wells, the water cut rises faster, and the effect of water flooding development is worse; 2) under the condition of non-uniform fracture development, the development effect of the bottom fracture undeveloped is better than that of the middle fracture undeveloped. Water injection wells are deployed in areas with relatively few fractures, while oil wells are deployed in fractured areas with higher oil recovery and better development effect.

A new method for estimating the strength of granular profile control agents during ASP water flooding was proposed considering the transport behavior for granular profile control agents in the reservoir. The strength of granular profile control agents (size over 80 mesh) passing through the sieve (diameter 0.1 mm) is determined by the value of the breakthrough pressure. The strength of profile control agent particles (size 20-60 mesh) is determined by the breakthrough pressure value, measured on a sieve with a diameter of 0.3 mm. Breakthrough pressure values of 8 types of granular profile control agents were determined under various experimental condition (for particle expansion time of 24 hours, 120 hours, and 30 days, respectively). The results show that the longer the expansion time of granular profile control agents, the smaller the strength. According to the results of a study conducted on a granular profile control agent of the same type (of example: QC5050) with different particle sizes (80-120 mesh, 80 mesh, and 20-40 mesh), it can be concluded that the larger the size of the particles of the profile control agents, the greater the value of the corresponding breakout pressure. A new parameter has been introduced – a rebound coefficient – for evaluating elasticity of granular profile control agents. The rebound coefficient was measured for 8 types of granular profile control agents at different pressures (2, 4, 6, and 8 MPa). The results show that the number of samples with a rebound ratio higher than 20% reached more than 70% in 64 experiments conducted on 8 samples. A negative correlation relationship between the rebound coefficient and the breakthrough pressure was determined, and a method was proposed for estimating the strength and elasticity of the granular profile control agents considering the influence of the rebound coefficient and the breaking pressure through the sieve.

Unitized regenerative fuel cells (URFC) are capable of generating, storing, and releasing energy on demand in a sustainable manner. Water management is of vital importance to achieve maximum performance, durability, and round-trip efficiency in URFCs. However, URFCs suffer from critical issues related to their mode-switching process, water flooding, and membrane dehydration. The essential problem of water management is maintaining a subtle equilibrium between membrane drying and liquid water flooding to prevent membrane dehydration and ensure high URFC performance. This paper provides an overview of the operating principle of URFCs and describes the underlying phenomena related to water management issues. It also summarizes state-of-the-art studies of water management with a focus on recent developments and discusses the technical challenges of water management strategies. In addition, we propose a novel system design to address these critical water management issues. Overall, this review identifies the gaps in the research and development of URFC water management and identifies several essential future developments and research directions for future investigation.

For more than a century, fossil fuels dominate in the energy market. For the better part of this time, petroleum and natural gas stand in the summit of our interest. Wars have been fought and history is shaped around the black gold. Since its first commercial use, a powerful industry has been built for the better understanding of the oil-bearing regions and the best exploitation of the oil fields. Since the early years of the oil industry, research has been given a lot of funds in order to secure a steady and cheap constant flow of oil in the market. Technologies are revolutionized and breakthroughs succeed one another. The aim of the current research is to define a reference of data sensitivity in order to select the ideal concept of an oil field exploitation, through water injection, according the calculations of the mathematical model of Buckley - Leverett or according the simulation environment of the Integrated Production Modelling software (IPM) by Petroleum Experts – PetEx. To validate the results, a process of a theoretical project has been examined, approached by both methods independently. The results of those processes have been analyzed, compared and accuracy - integrity checked. At the same time, some critical notes and improvements have been proposed. Based on these remarks, improved versions of the approaching technics have been modeled that encompass the final artifacts of the current research., Για περισσότερο από έναν αιώνα, τα ορυκτά καύσιμα κυριαρχούν στην αγορά ενέργειας. Κατά το μεγαλύτερο μέρος αυτού του χρόνου, το πετρέλαιο και το φυσικό αέριο βρίσκονται στην κορυφή του ενδιαφέροντός μας. Πόλεμοι έχουν γίνει και η ιστορία διαμορφώνεται γύρω από το μαύρο χρυσό. Από την πρώτη του εμπορική χρήση, έχει δημιουργηθεί μια ισχυρή βιομηχανία για την καλύτερη κατανόηση των πετρελαιοφόρων περιοχών και την καλύτερη εκμετάλλευση των κοιτασμάτων πετρελαίου. Από τα πρώτα χρόνια της πετρελαϊκής βιομηχανίας, η έρευνα έχει λάβει πολλά κονδύλια προκειμένου να εξασφαλιστεί μια σταθερή και φθηνή ροή πετρελαίου στην αγορά. Οι τεχνολογίες φέρνουν επανάσταση και οι καινοτομίες διαδέχονται η μία την άλλη. Στόχος της παρούσας έρευνας είναι ο καθορισμός της ευαισθησίας των δεδομένων, για την επιλογή της ιδανικής μεθόδου εκμετάλλευσης ταμιευτήρων, μέσω εισπίεσης νερού, σύμφωνα με τους υπολογισμούς του μαθηματικού μοντέλου των Buckley - Leverett ή σύμφωνα με το περιβάλλον προσομοίωσης του ολοκληρωμένου λογισμικό μοντελοποίησης της παραγωγής (IPM) από την Petroleum Experts – PetEx. Για την επικύρωση των αποτελεσμάτων, εξετάστηκε μια διαδικασία θεωρητικής εργασίας, η οποία προσεγγίστηκε και από τις δύο μεθόδους ανεξάρτητα. Τα αποτελέσματα αυτών των διαδικασιών έχουν αναλυθεί, συγκριθεί και ελεγχθεί για την ακρίβεια και την ακεραιότητά τους. Ταυτόχρονα, έχουν προταθεί ορισμένες κρίσιμες σημειώσεις και βελτιώσεις. Με βάση αυτές τις παρατηρήσεις, έχουν μοντελοποιηθεί βελτιωμένες εκδόσεις των προσεγγιζόμενων τεχνικών που περιλαμβάνουν τα τελικά ευρήματα της τρέχουσας έρευνας., Σε συνεργασία με: Γεωλογίας και Γεωπεριβάλλοντος (Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών), Μηχανικών Μεταλλείων Μεταλλουργών (Εθνικό Μετσόβιο Πολυτεχνείο), Οικονομικών Επιστημών (Δημοκρίτειο Πανεπιστήμιο Θράκης)

Under conditions of the same type of oil deposits with hard-to-recover reserves in Jurassic terrigenous reservoirs of the West Siberian oil and gas province, a study was made about the influence of the geological structure features of objects and water flooding technologies on the response degree of production wells to water injection. Response degree of the wells was determined by analyzing the time series of production rates and injection volumes of injection wells with the calculation of inter-correlation function (ICF) values. It was believed that with ICF values in a given injection period of more than 0.5, production well responds to the injection. Factors that have a prevailing effect on water flooding success have been identified. Among them: effective oil-saturated thickness of the formation in production wells, relative amplitude of the self polarization of the formation in both production and injection wells, grittiness coefficient of the formation in injection wells, monthly volume of water injection and distance between wells. Methodological approach is proposed based on the application of the proposed empirical parameter of water flooding success, which involves the use of indirect data in conditions of limited information about the processes occurring in the formation at justification and selection of production wells for transferring them to injection during focal flooding, drilling of additional production and injection wells – compaction of the well grid, shutdown of injection and production wells, use of a transit wells stock, use of cyclic, non-stationary flooding in order to change the direction of filtration flows, determining the design of dual-purpose L-shaped wells (determining length of the horizontal part), limitation of flow rate in highly flooded wells with a high degree of interaction, determination of decompression zones (without injection of indicators), stagnant zones for drilling sidetracks, improving the location of production and injection wells, transferring wells from other horizons, choosing the purpose of the wells during implementation of the selective water flooding system in order to increase the efficiency of using the resource base of liquid hydrocarbons.

Constructing an efficient catalytic layer through the design of catalyst structures is an effective way to reduce sustainably platinum loading for proton exchange membrane fuel cells (PEMFCs). Here...

In order to meet the requirements of air foam flooding in Dagang Gangdong Oilfield, two kinds of foaming agents, GFPA-1 and GFPA-2, were prepared by sulfonation, neutralization and high-temperature hydrolysis of α-olefins with different carbon chain lengths in the laboratory. The test results of foaming agents for its properties showed that when the concentration of foaming agent was over 0.5%, the initial foaming volumes of the two foaming agent systems were more than 500mL, and the foam half-life of GFPA-2 was about 3.5 hours, obviously longer than that of GFPA-1. Therefore, GFPA-2 was selected as the foaming agent for air foam flooding. The experimental results of static adsorption, plugging and core displacement performance of GFPA-2 foaming agent showed that the initial foaming volume of GFPA-2 foaming agent could still maintain 500mL after 48 hours of adsorption at a concentration of 0.5%, and when the ratio of gas to liquid was 1: 1, the resistance factor was more than 50. When a 0.4% foaming agent was injected with 0.35 PV slug, the displacement efficiency of air foaming flooding was 17.4% higher than that of water flooding.

Having a high water cut reduces the economic viability of oil production. Water production increases, as less-viscous water tends to flow through high-permeability zones, leaving behind large volumes of unswept oil. Since the 1920s, different materials have been used in order to plug high-permeability thief zones. Gels are often preferred for this purpose, as they provide deeper penetration than cement or mud suspensions. Moreover, some gels reduce permeability to water more than that to oil. And can be economically feasible at low oil prices if applied correctly. This article reviews permeability reduction of several widely used inorganic and organic bulk gels, with separate discussions of their application in fractures and matrix rocks of sandstone and carbonate reservoirs. The presented information is to help with proper well treatment design. Keywords: Conformance control, Water shut off, Polymer gel, Water flooding, In-depth fluid diversion, Oil production

The Jiyuan oil field is a tight sandstone reservoir, and water injection does not effectively enhance the oil recovery. The microscopic seepage characteristics of water flooding are studied...