Experimental Estimate of Capacities of Shallow Hydraulic Fracturing with Proppant Made of Aluminosilicate Microspheres in Oil Reservoirs

2017 ◽  
Keyword(s):  
Hydraulic Fracturing ◽  
Oil Reservoirs ◽  
Experimental Estimate

Experimental study of the stimulating mechanism of shut-in after hydraulic fracturing in unconventional oil reservoirs

Fuel ◽  
2021 ◽  
Vol 300 ◽  
pp. 120982
Author(s):  
Junrong Liu ◽  
James J. Sheng ◽  
Hossein Emadibaladehi ◽  
Jiawei Tu
Keyword(s):  
Experimental Study ◽  
Hydraulic Fracturing ◽  
Oil Reservoirs ◽  
Unconventional Oil

scholarly journals Method for Visualizing Fractures Induced by Laboratory-Based Hydraulic Fracturing and Its Application to Shale Samples

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1976 ◽  
Author(s):  
Youqing Chen ◽  
Makoto Naoi ◽  
Yuto Tomonaga ◽  
Takashi Akai ◽  
Hiroyuki Tanaka ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Ultraviolet Light ◽  
Shale Gas ◽  
Laboratory Method ◽  
Oil Reservoirs ◽  
Thermosetting Resin ◽  
Fluorescent Substance ◽  
New Approach ◽  
Induced Fractures ◽  
Observation Method

A better understanding of the process of stimulation by hydraulic fracturing in shale gas and oil reservoirs is necessary for improving resource productivity. However, direct observation of hydraulically stimulated regions including induced fractures has been difficult. In the present study, we develop a new approach for directly visualizing regions of shale specimens impregnated by fluid during hydraulic fracturing. The proposed laboratory method uses a thermosetting resin mixed with a fluorescent substance as a fracturing fluid. After fracturing, the resin is fixed within the specimens by heating, and the cut sections are then observed under ultraviolet light. Based on brightness, we can then distinguish induced fractures and their surrounding regions impregnated by the fluid from other regions not reached by the fluid. Polarization microscope observation clearly reveals the detailed structures of tortuous or branched fractures on the micron scale and interactions between fractures and constituent minerals. The proposed experimental and observation method is useful for understanding the process of stimulation by hydraulic fracturing and its relationship with microscopic rock characteristics, which is important for fracturing design optimization in shale gas and oil resource development.

scholarly journals Mechanisms and capacity of high-pressure soaking after hydraulic fracturing in tight/shale oil reservoirs

2020 ◽  
Author(s):  
Jing Wang ◽  
Hui-Qing Liu ◽  
Gen-Bao Qian ◽  
Yong-Can Peng
Keyword(s):  
High Pressure ◽  
Hydraulic Fracturing ◽  
Specific Surface ◽  
Surface Area ◽  
Oil Reservoirs ◽  
Shale Oil ◽  
Oil Viscosity ◽  
Soaking Time ◽  
Matrix Permeability ◽  
Shale Oil Reservoirs

Abstract Huff-n-puff by water has been conducted to enhance oil recovery after hydraulic fracturing in tight/shale oil reservoirs. However, the mechanisms and capacity are still unclear, which significantly limits the application of this technique. In order to figure out the mechanisms, the whole process of pressurizing, high-pressure soaking, and depressurizing was firstly discussed, and a mechanistic model was established. Subsequently, the simulation model was verified and employed to investigate the significances of high-pressure soaking, the contributions of different mechanisms, and the sensitivity analysis in different scenarios. The results show that high-pressure soaking plays an essential role in oil production by both imbibition and elasticity after hydraulic fracturing. The contribution of imbibition increases as the increase in bottom hole pressure (BHP), interfacial tension, and specific surface area, but slightly decreases as the oil viscosity increases. In addition, it first decreases and then slightly increases with the increase in matrix permeability. The optimal soaking time is linear with the increases of both oil viscosity and BHP and logarithmically declines with the increase in matrix permeability and specific surface area. Moreover, it shows a rising tendency as the interficial tension (IFT) increases. Overall, a general model was achieved to calculate the optimal soaking time.

scholarly journals Evaluation of Cyclic Gas Injection in Enhanced Recovery from Unconventional Light Oil Reservoirs: Effect of Gas Type and Fracture Spacing

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1370 ◽  
Author(s):  
Assef ◽  
Almao
Keyword(s):  
Hydraulic Fracturing ◽  
Enhanced Recovery ◽  
Gas Injection ◽  
Oil Reservoirs ◽  
Low Permeability ◽  
Fracture Spacing ◽  
Light Oil ◽  
Light Oil Reservoirs

ultra-low permeability; hydraulic fracturing; cyclical gas injection; fracking stages

scholarly journals A Novel Hydraulic Fracturing Method Based on the Coupled CFD-DEM Numerical Simulation Study

2020 ◽  
Vol 10 (9) ◽  
pp. 3027
Author(s):  
Cong Lu ◽  
Li Ma ◽  
Zhili Li ◽  
Fenglan Huang ◽  
Chuhao Huang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Hydraulic Fracturing ◽  
Variable Viscosity ◽  
Oil Reservoirs ◽  
Fluid Viscosity ◽  
Low Density ◽  
Fracturing Fluid ◽  
Proppant Transport ◽  
Fracturing Fluids ◽  
Transport Experiment

For the development of tight oil reservoirs, hydraulic fracturing employing variable fluid viscosity and proppant density is essential for addressing the problems of uneven placement of proppants in fractures and low propping efficiency. However, the influence mechanisms of fracturing fluid viscosity and proppant density on proppant transport in fractures remain unclear. Based on computational fluid dynamics (CFD) and the discrete element method (DEM), a proppant transport model with fluid–particle two-phase coupling is established in this study. In addition, a novel large-scale visual fracture simulation device was developed to realize the online visual monitoring of proppant transport, and a proppant transport experiment under the condition of variable viscosity fracturing fluid and proppant density was conducted. By comparing the experimental results and the numerical simulation results, the accuracy of the proppant transport numerical model was verified. Subsequently, through a proppant transport numerical simulation, the effects of fracturing fluid viscosity and proppant density on proppant transport were analyzed. The results show that as the viscosity of the fracturing fluid increases, the length of the “no proppant zone” at the front end of the fracture increases, and proppant particles can be transported further. When alternately injecting fracturing fluids of different viscosities, the viscosity ratio of the fracturing fluids should be adjusted between 2 and 5 to form optimal proppant placement. During the process of variable proppant density fracturing, when high-density proppant was pumped after low-density proppant, proppants of different densities laid fractures evenly and vertically. Conversely, when low-density proppant was pumped after high-density proppant, the low-density proppant could be transported farther into the fracture to form a longer sandbank. Based on the abovementioned observations, a novel hydraulic fracturing method is proposed to optimize the placement of proppants in fractures by adjusting the fracturing fluid viscosity and proppant density. This method has been successfully applied to more than 10 oil wells of the Bohai Bay Basin in Eastern China, and the average daily oil production per well increased by 7.4 t, significantly improving the functioning of fracturing. The proppant settlement and transport laws of proppant in fractures during variable viscosity and density fracturing can be efficiently revealed through a visualized proppant transport experiment and numerical simulation study. The novel fracturing method proposed in this study can significantly improve the hydraulic fracturing effect in tight oil reservoirs.

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