scholarly journals Influence of formation heterogeneity on foam flooding performance using 2D and 3D models: an experimental study

2019 ◽  
Vol 17 (3) ◽  
pp. 734-748 ◽  
Author(s):  
Ling-Zhi Hu ◽  
Lin Sun ◽  
Jin-Zhou Zhao ◽  
Peng Wei ◽  
Wan-Fen Pu
Keyword(s):  
Oil Recovery ◽  
3D Models ◽  
Reduction Factor ◽  
Mobility Control ◽  
Displacement Efficiency ◽  
Vertical Heterogeneity ◽  
Oil Displacement Efficiency ◽  
Heterogeneous Formations ◽  
Major Factors ◽  
Foam Flooding

AbstractThe formation heterogeneity is considered as one of the major factors limiting the application of foam flooding. In this paper, influences of formation properties, such as permeability, permeability distribution, interlayer, sedimentary rhythm and 3D heterogeneity, on the mobility control capability and oil displacement efficiency of foam flooding, were systematically investigated using 2D homogeneous and 2D/3D heterogeneous models under 120 °C and salinity of 20 × 104 mg/L. The flow resistance of foam was promoted as the permeability increased, which thus resulted in a considerable oil recovery behavior. In the scenario of the vertical heterogeneous formations, it was observed that the permeability of the high-permeable layer was crucial to foam mobility control, and the positive rhythm appeared favorable to improve the foam flooding performance. The additional oil recovery increased to about 40%. The interlayer was favorable for the increases in mobility reduction factor and oil recovery of foam flooding when the low permeability ratio was involved. For the 3D heterogeneous formations, foam could efficiently adjust the areal and vertical heterogeneity through mobility control and gravity segregation, and thus enhancing the oil recovery to 11%–14%. The results derived from this work may provide some insight for the field test designs of foam flooding.

scholarly journals Preparation of Modified Colloidal Gas Aphrons and Analysis of the Oil Displacement Effect

2020 ◽  
Vol 10 (3) ◽  
pp. 927
Author(s):  
Shaohua You ◽  
Xiaofei Sun ◽  
Xiaoyu Li
Keyword(s):  
Oil Recovery ◽  
Sodium Dodecyl ◽  
Displacement Efficiency ◽  
Displacement Effect ◽  
Oil Displacement ◽  
Displacement Experiments ◽  
Oil Displacement Efficiency ◽  
Foam Flooding ◽  
Enhance Oil Recovery ◽  
Colloidal Gas Aphrons

Colloidal gas aphrons (CGAs) offer some advantages in improving oil recovery, but resin and asphaltene deposition problems still occur in CGA flooding. Based on this phenomenon, a new modified colloidal foam system is developed by incorporating a modifier in CGA preparation. The results indicate that the modified CGAs prepared by adding foaming agent sodium dodecyl sulfate (SDS) (concentration: 5 g/L) and GXJ-C (a CGAs modifier from a light fraction of petroleum; concentration: 0.1 g/L) attained the best performance. Oil displacement experiments show that modified CGA flooding had a better effect than water or CGA flooding. There are two important mechanisms via which modified CGAs enhance oil recovery, including decreasing the interfacial tension and enhancing the heavy components in the recovered oil. The developed modified CGA system attained a good oil displacement effect, which is of guiding significance to further improve the oil displacement efficiency and application of foam flooding.

Research and Application of Multi-Slug and Equi-Fluidity Oil Displacement Mechanism

2015 ◽  
Vol 733 ◽  
pp. 43-46
Author(s):  
Jiang Min Zhao ◽  
Tian Ge Li
Keyword(s):  
Pressure Gradient ◽  
Flow Rate ◽  
Oil Recovery ◽  
Recovery Rate ◽  
Actual Situation ◽  
Displacement Efficiency ◽  
Displacement Method ◽  
Oil Displacement ◽  
Oil Displacement Efficiency ◽  
Swept Volume

In this paper, several aspects of the improvement of the oil recovery were analyzed theoretically based on the mechanism that equi-fluidity enhances the pressure gradient. These aspects include the increase of the flow rate and the recovery rate, of the swept volume, and of the oil displacement efficiency. Also, based on the actual situation, the author designed the oil displacement method with gathered energy equi-fluidity, realizing the expectation of enhancing oil recovery with multi-slug and equi-fluidity oil displacement method.

Exploring Low-IFT Foam EOR in Fractured Carbonates: Success and Particular Challenges of Sub-10-md Limestone

SPE Journal ◽  
1900 ◽  
Vol 25 (02) ◽  
pp. 867-882
Author(s):  
Pengfei Dong ◽  
Maura Puerto ◽  
Guoqing Jian ◽  
Kun Ma ◽  
Khalid Mateen ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Surfactant Solution ◽  
Mineral Dissolution ◽  
Mobility Control ◽  
Matrix Permeability ◽  
Geochemical Properties ◽  
Remaining Oil ◽  
The Matrix ◽  
Incremental Oil Recovery ◽  
Foam Flooding

Summary The high formation heterogeneity in naturally fractured limestone reservoirs requires mobility control agents to improve sweep efficiency and boost oil recovery. However, typical mobility control agents, such as polymers and gels, are impractical in tight sub-10-md formations due to potential plugging issues. The objective of this study is to demonstrate the feasibility of a low-interfacial-tension (low-IFT) foam process in fractured low-permeability limestone reservoirs and to investigate relevant geochemical interactions. The low-IFT foam process was investigated through coreflood experiments in homogeneous and fractured oil-wet cores with sub-10-md matrix permeability. The performance of a low-IFT foaming formulation and a well-known standard foamer [alpha olefin sulfonate (AOS) C14-16] were compared in terms of the efficiency of oil recovery. The effluent ionic concentrations were measured to understand how the geochemical properties of limestone influenced the low-IFT foam process. Aqueous stability and phase behavior tests with crushed core materials and brines containing various divalent ion concentrations were conducted to interpret the observations in the coreflood experiments. Low-IFT foam process can achieve significant incremental oil recovery in fractured oil-wet limestone reservoirs with sub-10-md matrix permeability. Low-IFT foam flooding in a fractured oil-wet limestone core with 5-md matrix permeability achieved 64% incremental oil recovery compared to waterflooding. In this process, because of the significantly lower capillary entry pressure for surfactant solution compared to gas, the foam primarily diverted surfactant solution from the fracture into the matrix. This selective diversion effect resulted in surfactant or weak foam flooding in the tight matrix and hence improved the invading fluid flow in the matrix. Meanwhile, the low-IFT property of the foaming formulation mobilized the remaining oil in the matrix. This oil mobilization effect of the low-IFT formulation achieved lower remaining oil saturation in the swept zones compared with the formulation lacking low-IFT property with oil. The limestone geochemical instability caused additional challenges for the low-IFT foam process in limestone reservoirs compared to dolomite reservoirs. The reactions of calcite with injected fluids—such as mineral dissolution and the exchange of calcium and magnesium—were found to increase the Ca2+ concentration in the produced fluids. Because the low-IFT foam process is sensitive to brine salinity, the additional Ca2+ may cause potential surfactant precipitation and unfavorable over-optimum conditions. It, therefore, may cause injectivity and phase-trapping issues especially in the homogeneous limestone. Results in this work demonstrated that despite the challenges associated with limestone dissolution, the low-IFT foam process can remarkably extend chemical enhanced oil recovery (EOR) in fractured oil-wet tight reservoirs with matrix permeability as low as 5 md.

scholarly journals Low-Abundance Dietzia Inhabiting a Water-Flooding Oil Reservoir and the Application Potential for Oil Recovery

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Peike Gao ◽  
Hongbo Wang ◽  
Guanxi Li ◽  
Ting Ma
Keyword(s):  
Oil Recovery ◽  
Water Flooding ◽  
Oil Reservoir ◽  
Displacement Efficiency ◽  
Oil Displacement ◽  
Recovery Potential ◽  
Oil Displacement Efficiency ◽  
Application Potential ◽  
Nutrient Injection

With the development of molecular ecology, increasing low-abundance microbial populations were detected in oil reservoirs. However, our knowledge about the oil recovery potential of these populations is lacking. In this study, the oil recovery potential of low-abundance Dietzia that accounts for less than 0.5% in microbial communities of a water-flooding oil reservoir was investigated. On the one hand, Dietzia sp. strain ZQ-4 was isolated from the water-flooding reservoir, and the oil recovery potential was evaluated from the perspective of metabolisms and oil-displacing test. On the other hand, the strain has alkane hydroxylase genes alkB and P450 CYP153 and can degrade hydrocarbons and produce surfactants. The core-flooding test indicated that displacing fluid with 2% ZQ-4 fermentation broth increased 18.82% oil displacement efficiency, and in situ fermentation of ZQ-4 increased 1.97% oil displacement efficiency. Furthermore, the responses of Dietzia in the reservoir accompanied by the nutrient stimulation process was investigated and showed that Dietzia in some oil production wells significantly increased in the initial phase of nutrient injection and sharply decreased along with the continuous nutrient injection. Overall, this study indicates that Dietzia sp. strain has application potential for enhancing oil recovery through an ex situ way, yet the ability of oil recovery in situ based on nutrient injection is limited.

Low-IFT Foaming System for Enhanced Oil Recovery in Highly Heterogeneous/Fractured Oil-Wet Carbonate Reservoirs

SPE Journal ◽  
2018 ◽  
Vol 23 (06) ◽  
pp. 2243-2259 ◽  
Author(s):  
Pengfei Dong ◽  
Maura Puerto ◽  
Guoqing Jian ◽  
Kun Ma ◽  
Khalid Mateen ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Fractured Reservoirs ◽  
Surfactant Solution ◽  
Capillary Forces ◽  
Mobility Control ◽  
Carbonate Reservoirs ◽  
Residual Oil ◽  
High Permeability ◽  
The Matrix ◽  
Foam Flooding

Summary Oil recovery in heterogeneous carbonate reservoirs is typically inefficient because of the presence of high-permeability fracture networks and unfavorable capillary forces within the oil-wet matrix. Foam, as a mobility-control agent, has been proposed to mitigate the effect of reservoir heterogeneity by diverting injected fluids from the high-permeability fractured zones into the low-permeability unswept rock matrix, hence improving the sweep efficiency. This paper describes the use of a low-interfacial-tension (low-IFT) foaming formulation to improve oil recovery in highly heterogeneous/fractured oil-wet carbonate reservoirs. This formulation provides both mobility control and oil/water IFT reduction to overcome the unfavorable capillary forces preventing invading fluids from entering an oil-filled matrix. Thus, as expected, the combination of mobility control and low-IFT significantly improves oil recovery compared with either foam or surfactant flooding. A three-component surfactant formulation was tailored using phase-behavior tests with seawater and crude oil from a targeted reservoir. The optimized formulation simultaneously can generate IFT of 10−2 mN/m and strong foam in porous media when oil is present. Foam flooding was investigated in a representative fractured core system, in which a well-defined fracture was created by splitting the core lengthwise and precisely controlling the fracture aperture by applying a specific confining pressure. The foam-flooding experiments reveal that, in an oil-wet fractured Edward Brown dolomite, our low-IFT foaming formulation recovers approximately 72% original oil in place (OOIP), whereas waterflooding recovers only less than 2% OOIP; moreover, the residual oil saturation in the matrix was lowered by more than 20% compared with a foaming formulation lacking a low-IFT property. Coreflood results also indicate that the low-IFT foam diverts primarily the aqueous surfactant solution into the matrix because of (1) mobility reduction caused by foam in the fracture, (2) significantly lower capillary entry pressure for surfactant solution compared with gas, and (3) increasing the water relative permeability in the matrix by decreasing the residual oil. The selective diversion effect of this low-IFT foaming system effectively recovers the trapped oil, which cannot be recovered with single surfactant or high-IFT foaming formulations applied to highly heterogeneous or fractured reservoirs.

scholarly journals Differences of microscopic seepage mechanisms of water flooding and polymer flooding and prediction models of final oil recovery for conglomerate reservoir

2019 ◽  
Vol 74 ◽  
pp. 13
Author(s):  
Fengqi Tan ◽  
Changfu Xu ◽  
Yuliang Zhang ◽  
Gang Luo ◽  
Yukun Chen ◽  
...  
Keyword(s):  
Pore Structure ◽  
Polymer Solution ◽  
Oil Recovery ◽  
Particle Surface ◽  
Polymer Flooding ◽  
Water Flooding ◽  
Residual Oil ◽  
Displacement Efficiency ◽  
Oil Saturation ◽  
Oil Displacement Efficiency

The special sedimentary environments of conglomerate reservoir lead to pore structure characteristics of complex modal, and the reservoir seepage system is mainly in the “sparse reticular-non reticular” flow pattern. As a result, the study on microscopic seepage mechanism of water flooding and polymer flooding and their differences becomes the complex part and key to enhance oil recovery. In this paper, the actual core samples from conglomerate reservoir in Karamay oilfield are selected as research objects to explore microscopic seepage mechanisms of water flooding and polymer flooding for hydrophilic rock as well as lipophilic rock by applying the Computed Tomography (CT) scanning technology. After that, the final oil recovery models of conglomerate reservoir are established in two displacement methods based on the influence analysis of oil displacement efficiency. Experimental results show that the seepage mechanisms of water flooding and polymer flooding for hydrophilic rock are all mainly “crawling” displacement along the rock surface while the weak lipophilic rocks are all mainly “inrushing” displacement along pore central. Due to the different seepage mechanisms among the water flooding and the polymer flooding, the residual oil remains in hydrophilic rock after water flooding process is mainly distributed in fine throats and pore interchange. These residual oil are cut into small droplets under the influence of polymer solution with stronger shearing drag effect. Then, those small droplets pass well through narrow throats and move forward along with the polymer solution flow, which makes enhancing oil recovery to be possible. The residual oil in weak lipophilic rock after water flooding mainly distributed on the rock particle surface and formed oil film and fine pore-throat. The polymer solution with stronger shear stress makes these oil films to carry away from particle surface in two ways such as bridge connection and forming oil silk. Because of the essential attributes differences between polymer solution and injection water solution, the impact of Complex Modal Pore Structure (CMPS) on the polymer solution displacement and seepage is much smaller than on water flooding solution. Therefore, for the two types of conglomerate rocks with different wettability, the pore structure is the main controlling factor of water flooding efficiency, while reservoir properties oil saturation, and other factors have smaller influence on flooding efficiency although the polymer flooding efficiency has a good correlation with remaining oil saturation after water flooding. Based on the analysis on oil displacement efficiency factors, the parameters of water flooding index and remaining oil saturation after water flooding are used to establish respectively calculation models of oil recovery in water flooding stage and polymer flooding stage for conglomerate reservoir. These models are able to calculate the oil recovery values of this area controlled by single well control, and further to determine the oil recovery of whole reservoir in different displacement stages by leveraging interpolation simulation methods, thereby providing more accurate geological parameters for the fine design of displacement oil program.

Study on Influence of Injection Method on the Effect of Oil Displacement of Nanometer Microspheres

2013 ◽  
Vol 734-737 ◽  
pp. 1272-1275
Author(s):  
Ji Hong Zhang ◽  
Zhi Ming Zhang ◽  
Xi Ling Chen ◽  
Qing Bin He ◽  
Jin Feng Li
Keyword(s):  
Oil Recovery ◽  
Experimental Result ◽  
Displacement Efficiency ◽  
Oil Displacement ◽  
Profile Control ◽  
Oil Displacement Efficiency ◽  
Injection Methods ◽  
The One ◽  
Deep Profile ◽  
Enhance Oil Recovery

Nanometer microspheres injection is a new deep profile control technology. Nanometer microspheres could inflate with water, resulting in plugging step by step in reservoirs, which could improve the swept efficiency in the reservoir and enhance oil recovery. By using non-homogeneous rectangular core, oil displacement efficiency experiment was conducted for studying the influence of different injection methods on the effect of injection nanometer microspheres. The experimental result shows that, compared with development effect of single-slug injection or triple-slug injection, the one of double-slug injection is better. Nanometer microspheres can enhance oil recovery significantly in medium and low permeability reservoir.

scholarly journals The Study of Effect of Pore Structure on Oil Displacement Efficiency of Polymer Flooding

2016 ◽  
Vol 9 (1) ◽  
pp. 55-64
Author(s):  
Ma Wenguo
Keyword(s):  
Pore Structure ◽  
Oil Recovery ◽  
Water Flooding ◽  
Displacement Efficiency ◽  
Throat Radius ◽  
Oil Displacement ◽  
Oil Displacement Efficiency ◽  
Ct Technology ◽  
Micro Level ◽  
The Relationship

Characteristics of pore structure have an important influence on the development of water flooding. In order to improve the recovery rate, it is important to investigate the relationship between pore structure and oil displacement efficiency. The permeability of the artificial cores in this experiment is 189×10-3μm2, 741×10-3μm2and 21417×10-3μm2. We used the CT technology method to scan the pore structure of the three cores, and did oil displacement experiment to investigate the effect of pore structure on the oil displacement efficiency. The result shows that the pore and throat common affect oil displacement efficiency: the bigger the pore and throat radius, the better is the oil displacement efficiency; the smaller the pore and throat radius, the worse is the oil displacement efficiency. The experiment studied the influence of pore structure on oil displacement efficiency deep into microcosmic pore structure without damaging the core skeleton, thereby improving the basis of oil recovery from the micro level and the mechanism.

scholarly journals Study on the Flow Mechanism of Shale Oil with Different Injection Media

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Lanlan Yao ◽  
Zhengming Yang ◽  
Haibo Li ◽  
Bo Cai ◽  
Chunming He ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Bohai Bay ◽  
Shale Oil ◽  
Formation Water ◽  
Displacement Efficiency ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Oil Displacement ◽  
Oil Displacement Efficiency ◽  
Effective Development

Chinese shale oil has high recoverable resources and great development potential. However, due to the limitation of development technology, the recovery rate of shale oil is not high. In this paper, the effects of different injection media on the development of shale oil reservoirs in Dongying formation, Qikou depression, Huanghua depression, and Bohai bay basin, were studied by means of imbibition and nitrogen flooding. Combining nuclear magnetic resonance (NMR) technology with imbibition and gas displacement experiments, the mechanism of shale injected formation water, active water (surfactant), and nitrogen was reproduced. The displacement process of crude oil under different injection media and injection conditions was truly demonstrated, and the relationship between different development methods and the pore boundaries used was clarified. A theoretical basis for the effective development of shale oil was provided. At the same time, Changqing tight oil cores with similar permeability to Dagang shale oil cores were selected for comparison. The results showed that, as the imbibition time of shale samples increased, the imbibition efficiency increased. Pores with T2 < 10 ms contributed the most to imbibition efficiency, with an average contribution greater than 90%. 10 ms < T2 < 100 ms and more than 100 ms pores contributed less to imbibition efficiency. Active water can change the wettability of shale, increase its hydrophilicity, and improve the efficiency of imbibition. The imbibition recovery ratio of injected active water was 17.56% higher than that of injected formation water. Compared with tight sandstone with similar permeability, the imbibition efficiency of shale was lower. As the nitrogen displacement pressure increased, the oil displacement efficiency also increased. The higher the shale permeability was, the greater the displacement efficiency would be. T2 > 100 ms pore throat of shale contributed to the main oil displacement efficiency, with an average oil displacement efficiency contribution of 63.16%. And the relaxation interval 10 < T2 < 100 ms pore throat displacement efficiency contributed to 28.27%. T2 < 10 ms pore throat contributed the least to the oil displacement efficiency, with an average oil displacement efficiency contribution of 8.58%. Compared with tight sandstone with similar permeability, shale had lower oil displacement efficiency. The findings of this study can help for better understanding of the influence of different injection media on shale oil recovery effect.

Study on Ultimate Recovery Factor and Oil Recovery Rate of Water-Flooded Sandstone Oil Fields in Eastern South China Sea

2021 ◽  
Author(s):  
Qi Xiong ◽  
Zhenghe Yan ◽  
Li Li ◽  
Yong Yang ◽  
Yahui Wang ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Oil Recovery ◽  
Recovery Rate ◽  
Optimal Recovery ◽  
Oil Fields ◽  
Displacement Efficiency ◽  
China Sea ◽  
Oil Displacement ◽  
Oil Displacement Efficiency

Abstract Under the natural energy development of Marine sandstone oil fields in the east of the South China Sea, the recovery degree of some oil fields has exceeded 65%, and the production capacity is still strong. The high-speed development model does not seem to have an adverse effect on oil recovery. Based on the existing knowledge and technical conditions, it is difficult to analyze and predict the final recovery rate of oil field. The reasonable boundary between the oil rate and recovery is also unclear. In this study, we investigate the correlation between oil rate and recovery rate by experiment and field practice. Based on the microscopic displacement experiment, the variation rules of phase permeability, wettability, residual oil, displacement efficiency and sweep volume of different displacement multiples are studied. The variation law of oil rate and recovery under different fluidity and well control conditions is studied by mathematical statistics according to the production dynamic data. Thus, the influencing factors and percolation mechanism of the optimal recovery under high multiples water flooding are clarified, and the relationship between the reasonable oil rate and optimal recovery under different reservoir conditions is formed. Micro experiments show that high multiples water flooding can improve the reservoir property, change wettability of rocks, reduce the residual oil saturation, improve oil displacement efficiency and the final oil displacement efficiency can reach 80%. Statistical research shows that when the oil recovery rate is less than 10%, the recovery rate increases with the increase of oil rate. For bottom water reservoirs, the recovery rate is recommended to be no more than 8%. The paper innovatively studies the correlation between the reasonable oil rate and optimal recovery in Marine sandstone oilfield from microscopic experimental analysis and macroscopic statistical research. The research results effectively guide the oil field production practice of more than 200 Wells in more than 20 oil fields in the eastern South China Sea in 2019, with a cumulative oil increase of more than 5 million barrels. And it has important guiding significance to the efficient and economical development of Marine sandstone oilfield.

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