scholarly journals Enhanced Oil Recovery by Cyclic Injection of Wettability Alteration Agent for Tight Reservoirs

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhijie Wei ◽  
Yuyang Liu ◽  
Xiaodong Kang
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Production Performance ◽  
Recovery Factor ◽  
Wettability Alteration ◽  
Oil Viscosity ◽  
Fracture Spacing ◽  
Matrix Permeability ◽  
Tight Reservoirs ◽  
Cyclic Injection

Low primary recovery factor and rapid production decline necessitates the proposal of enhanced oil recovery methods to mobilize the remaining oil resource of tight reservoirs, especially for oil-wet ones, and wettability alteration by injecting a chemical agent such as a surfactant is a promising option. A discrete-fracture-network-based mathematical model is developed with consideration of the displacement mechanisms and complicated physical-chemical phenomena during EOR by wettability alteration, and this model numerically solved by the fully implicit method. Simulation cases are conducted to investigate the production performance and key factors of cyclic injection of a surfactant. Cyclic injection can significantly improve the production of oil-wet tight reservoirs, and the ultimate recovery factor can be increased by 10 percent. The reason is that a surfactant can alter the wettability of a reservoir from oil wet to medium or even water wet, which triggers spontaneous imbibition and favors oil movement from a matrix into a fracture. Better EOR results can be achieved with decreasing oil viscosity, increasing matrix permeability, or decreasing fracture spacing. Cyclic surfactant injection is applicable to reservoirs with an oil viscosity of less than 7 mPa·s, a matrix permeability bigger than 0.01 mD, or a fracture spacing smaller than 150 m. It is favorable for the wettability alteration method by maintaining capillary pressure and reducing residual oil saturation as much as possible.

scholarly journals Experimental study of microbial enhanced oil recovery in oil-wet fractured porous media

2020 ◽  
Vol 75 ◽  
pp. 73
Author(s):  
Amin Abolhasanzadeh ◽  
Ali Reza Khaz’ali ◽  
Rohallah Hashemi ◽  
Mohammadhadi Jazini
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Low Cost ◽  
Fractured Reservoirs ◽  
Gas Production ◽  
Wettability Alteration ◽  
Oil Viscosity ◽  
Sweep Efficiency ◽  
The Matrix ◽  
Microbial Flooding

Without Enhanced Oil Recovery (EOR) operations, the final recovery factor of most hydrocarbon reservoirs would be limited. However, EOR can be an expensive task, especially for methods involving gas injection. On the other hand, aqueous injection in fractured reservoirs with small oil-wet or mixed-wet matrices will not be beneficial if the rock wettability is not changed effectively. In the current research, an unpracticed fabrication method was implemented to build natively oil-wet, fractured micromodels. Then, the efficiency of microbial flooding in the micromodels, as a low-cost EOR method, is investigated using a new-found bacteria, Bacillus persicus. Bacillus persicus improves the sweep efficiency via reduction of water/oil IFT and oil viscosity, in-situ gas production, and wettability alteration mechanisms. In our experiments, the microbial flooding technique extracted 65% of matrix oil, while no oil was produced from the matrix system by water or surfactant flooding.

Effect of Chemical Partition Behavior on Oil Recovery by Wettability Alteration in Fractured Tight Reservoirs

2022 ◽  
Author(s):  
Tesleem Lawal ◽  
Mingyuan Wang ◽  
Gayan A. Abeykoon ◽  
Francisco J. Argüelles-Vivas ◽  
Ryosuke Okuno
Keyword(s):  
Oil Recovery ◽  
Wettability Alteration ◽  
Tight Reservoirs ◽  
Chemical Partition ◽  
Partition Behavior

A Novel Coreflood Test to Evaluate EOR Potential of Wettability-Altering Surfactants in Oil-Wet Heterogeneous Carbonate Reservoirs

2021 ◽  
Author(s):  
Yue Shi ◽  
Kishore Mohanty ◽  
Manmath Panda
Keyword(s):  
Oil Recovery ◽  
Carbonate Reservoirs ◽  
Wettability Alteration ◽  
Low Permeability ◽  
High Permeability ◽  
Matrix Permeability ◽  
Rock Heterogeneity ◽  
The Matrix ◽  
Flow Through ◽  
Main Factors

Abstract Oil-wetness and heterogeneity (i.e., existence of low and high permeability regions) are two main factors that result in low oil recovery by waterflood in carbonate reservoirs. The injected water is likely to flow through high permeability regions and bypass the oil in low permeability matrix. In this study, systematic coreflood tests were carried out in both "homogeneous" cores and "heterogeneous" cores. The heterogeneous coreflood test was proposed to model the heterogeneity of carbonate reservoirs, bypassing in low-permeability matrix during waterfloods, and dynamic imbibition of surfactant into the low-permeability matrix. The results of homogeneous coreflood tests showed that both secondary-waterflood and secondary-surfactant flood can achieve high oil recovery (>50%) from relatively homogenous cores. A shut-in phase after the surfactant injection resulted in an additional oil recovery, which suggests enough time should be allowed while using surfactants for wettability alteration. The core with a higher extent of heterogeneity produced lower oil recovery to waterflood in the coreflood tests. Final oil recovery from the matrix depends on matrix permeability as well as the rock heterogeneity. The results of heterogeneous coreflood tests showed that a slow surfactant injection (dynamic imbibition) can significantly improve the oil recovery if the oil-wet reservoir is not well-swept.

Enhanced Oil Recovery: Wettability Alteration and Other Topics

2019 ◽  
pp. 281-302
Author(s):  
Chun Huh ◽  
Hugh Daigle ◽  
Valentina Prigiobbe ◽  
Maša Prodanović
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Wettability Alteration

Improved Fluids Characterization Model During Gas Huff-n-Puff EOR Processes in Unconventional Reservoirs

2021 ◽  
Author(s):  
Gang Yang ◽  
Xiaoli Li
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Fluid Model ◽  
Geometric Constraints ◽  
Confinement Effect ◽  
Recovery Factor ◽  
Unconventional Reservoirs ◽  
Compositional Simulation ◽  
Compositional Model ◽  
Characterization Model

Abstract Despite the great potential of unconventional hydrocarbons, the primary recovery factor from such reservoirs remain low. The gas-injection enhanced oil recovery (EOR) has been proved to be a promising approach by both laboratory and simulation studies. However, the fluid model for characterizing gas and oil in nanoscale pores has not been well understood and developed. Erroneous results can be generated if the bulk fluids model is applied, resulting in a large uncertainty for the numerical simulations. The objective of this work is to propose an improved fluids characterization model tailored for the compositional simulation of gas huff-n-puff in unconventional reservoirs. The Peng-Robinson equation of state (PR EOS) is used as the basic thermodynamic model in this work. Both the attraction parameter and the co-volume parameter in the PR EOS are simultaneously modified for the first time to reflect the effect of molecule-wall interaction and geometric constraints. The collected experimental data are used for validating the model. The newly generated PVT data are imported into the compositional model to numerically simulate the gas huff-n-puff process in the Middle Bakken formation to investigate the influence of modified fluid property on the production and ultimate recovery. The improved fluids characterization model is validated applicable to calculate the confined properties of reservoir fluids. It is demonstrated that the phase envelope of the confined reservoir fluids tends to shrink. At reservoir temperature, the bubble-point pressure of the Middle Bakken oil is reduced by 17.32% with consideration of the confinement effect. Such a significant suppression represents a late occurrence of the gas evaporation, which implies a potentially higher production of the shale oil reservoir. Compositional simulation predicts that the enhanced oil recovery efficiency of CO2 huff-n-puff is unsatisfactory for the specific well in this work, which is also demonstrated in the field pilot test. However, the confinement effect results in a 1.14% elevation of the oil recovery factor in 10 years production. This work not only deepens our understanding of the confinement effect on phase behavior characterization and also shed light on the computation of the thermodynamic properties of hydrocarbons in nanopores. The results also provide practical instructions for the EOR development of unconventional reservoirs.

An Optimized Experimental Investigation of Foam-Assisted N2 Huff-n-Puff Enhanced Oil Recovery in Fractured Shale Cores

2021 ◽  
Author(s):  
Xiaofei Xiong ◽  
James Jia Sheng
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Rapid Decline ◽  
Production Time ◽  
Experimental Conditions ◽  
Cycle Number ◽  
Injection Process ◽  
Matrix Permeability ◽  
Shale Reservoirs ◽  
Scale Matrix

Abstract Sustainable development of shale reservoirs and enhanced oil recovery have become a challenge for the oil industry in recent years. Shale reservoirs are typically characterized by nano Darcy-scale matrix, natural fractures, and artificially fractures with high permeability. Some of earlier studies have confirmed that gas huff-n-puff has been investigated and demonstrated as the most effective and promising solution for improving oil recovery in tight shale reservoirs with ultra-low permeability. Fractures provide an advantage in enhancing recovery from shale reservoirs but they also pose serious problems such as severe gas channeling, which led to rapid decline production from a single well. More studies are needed to optimize the process. This paper studies the method of foam-assisted N2 huff-n-puff to enhance oil recovery in fractured shale cores. The influence of foam on oil recovery was analyzed. The effect of matrix permeability, cycle number and production time on oil recovery are also considered. The shale core used in the experiment was from Sichuan Basin, China. For the purpose of comparation and validation, two groups of tests were conducted. One group of tests was N2 huff-n-puff, and the other was foam-N2 huff-n-puff. In the optimization experiment, matrix permeabilities were set as 0.01mD, 0.008mD and 0.001mD, cycle numbers ranged from one to five, the production time is designed to be 1 hour and 24 hours respectively. During the puff period of experiments, the history of oil recovery was closely monitored to reveal the mechanism. During a round of gas injection of fractured shale cores, foam-assisted N2 huff-n-puff oil recovery is 4.59%, which is significantly higher than that of N2 huff-n-puff is only 0.0126%, and the contrast becomes more obvious with the increase of matrix permeability. The results also showed that the cumulative oil recovery increased as the number of cycles was increased, with the same experimental conditions. There is an optimal production time to achieve maximum oil recovery. The cycle numbers, matrix permeability, and production time played important roles in foam-assisted N2 huff-n-puff injection process. Therefore, under certain conditions, foam-N2 huff-n-puff has a positive effect on oil development in fractured shale.

Improvement of oil recovery factor from geological perspectives

2021 ◽  
pp. 17-25
Author(s):  
D.Yu. Chudinova ◽  
◽  
D.S. Urakov ◽  
Sh.Kh. Sultanov ◽  
Yu.A. Kotenev ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Late Stage ◽  
Field Data ◽  
Recovery Factor ◽  
Wettability Alteration ◽  
Stage Of Development ◽  
Number Of Factors ◽  
Enhance Oil Recovery ◽  
The Given ◽  
Selection Of

At a late stage of development of any oilfield, there are big number of factors that affect recovery factor. One of them is related to presence of isolated zones, that were caused by combination of poor reservoir and oil properties of a rock. To solve the given problem variety of workover operations and enhance oil recovery (EOR) methods can be appled for the complex reservoirs such as Tevlinsko-Russinskoe oilfield. The number of particular studies were presented by reviewing of field data, construction of heterogeneity zones, revision of workover operations and selection of EOR methods. It has obtained that the reservoir has the lenticular structure, consists from 9 different facies and presented by 4 classes of heterogeneity. The immiscible gas injections of Nitrogen were selected as the most suitable EOR method for the given oilfield. Application of different composition of brine water was reccomended for wettability alteration.

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