scholarly journals Numerical Simulation Study on Waterflooding Heavy Oil Based on Variable Threshold Pressure Gradient

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Fan Liu ◽  
Qingdong Ni ◽  
Chunguang Zhang ◽  
Wensheng Zhou ◽  
Jingqi Lin ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Pressure Gradient ◽  
Simulation Study ◽  
Heavy Oil ◽  
Fluid Viscosity ◽  
Threshold Pressure ◽  
Threshold Pressure Gradient ◽  
Variable Threshold ◽  
Oil Flow ◽  
Phase Mobility

The heavy-oil flow in porous media is characterized by non-Darcy law with variable threshold pressure gradient (TPG) due to the large fluid viscosity. However, available analytical and numerical models hardly consider this effect, which can lead to erroneous results. This paper is aimed at presenting an innovative approach and establishing a numerical simulator to analyze the heavy-oil flow behavior with waterflooding. The apparent viscosity of the oil phase and flow correction coefficient characterized by the TPG were applied to describe the viscosity anomaly of heavy oil. Considering the formation heterogeneity, the TPG was processed into a variable related to mobility and the directionality. The discretization and linearization of the mathematical model were conducted to establish a fully implicit numerical model; the TPG value on each grid node was obtained through oil phase mobility interpolation, and then, the Jacobi matrix was reassembled and calculated to solve pressure and saturation equations. The corresponding simulator was thus developed. The pre-/postprocessing module of the simulator is connected to ECLIPSE; then, an efficient algorithm is introduced to realize a fast solution. Results show that considering the TPG will not only reduce the waterflooding area but also reduce the oil displacement efficiency because of aggravating the nonpiston phenomenon and interlayer conflict. The numerical simulation study on the TPG of heavy oil provides theoretical and technical support for the rational development and adjustment of water-driven heavy oil.

Effect of Asphaltene on Threshold Pressure Gradient of Heavy Oil in Porous Media

2021 ◽  
Vol 13 (2) ◽  
pp. 273-279
Author(s):  
Guishan Li ◽  
Xiankang Xin ◽  
Gaoming Yu ◽  
Yadi Gu ◽  
Qiong Wu ◽  
...  
Keyword(s):  
Porous Media ◽  
Pressure Gradient ◽  
Heavy Oil ◽  
High Viscosity ◽  
Threshold Pressure ◽  
Heavy Oils ◽  
Oil Viscosity ◽  
Threshold Pressure Gradient ◽  
Asphaltene Content ◽  
Effective Development

Many studies have shown that heavy oil with high asphaltene content has a yield stress. Coupled with the solid-liquid interaction between porous media and heavy oil, there is a threshold pressure gradient when heavy oil flows in porous media. Meanwhile, some previous research has indicated that the high viscosity of heavy oil is the decisive factor for its threshold pressure gradient. Hence, this concept needs more clarification, especially because its accuracy is questionable. In this research, different oil samples with the same viscosity and also different asphaltene contents heavy oil samples were prepared. The viscosity of the different heavy oil samples was measured. Threshold pressure gradient experiments under different permeabilities and temperatures were also conducted on heavy oils. The results proved that the viscosity was not directly related to threshold pressure gradient of heavy oil. They also suggested that the heavy oil viscosity increased with the increase of asphaltene content. Moreover, the formula of the factors affecting threshold pressure gradient was regressed, and also its applicability was verified. As the temperature and core permeability increase, the threshold pressure gradient was also proven to decrease significantly. Furthermore, it was found that the threshold pressure gradient increased significantly with the increase of asphaltene content. Therefore, the heavy oil threshold pressure gradient could be characterized as a function of temperature, permeability, and asphaltene content. This study provided some theoretical support for the research attempts on the reduction of threshold pressure gradient and also on the effective development of heavy oil reservoirs.

scholarly journals Numerical Simulation of Microemulsion Flooding in Low-Permeability Reservoir

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Dongqi Wang ◽  
Daiyin Yin ◽  
Xiangzhu Gong
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Moisture Content ◽  
Pressure Gradient ◽  
Laboratory Experiments ◽  
Flow Equation ◽  
Low Permeability ◽  
Threshold Pressure ◽  
Threshold Pressure Gradient ◽  
Relative Errors

Based on the features of microemulsion flooding in low-permeability reservoir, a three-dimension three-phase five-component mathematical model for microemulsion flooding is established in which the diffusion and adsorption characteristics of surfactant molecules are considered. The non-Darcy flow equation is used to describe the microemulsion flooding seepage law in which the changes of threshold pressure gradient can be taken into account, and the correlation coefficients in the non-Darcy flow equation are determined through the laboratory experiments. A new treatment for the changes of threshold pressure and the quantitative description of adsorption quantity of surfactant and relative permeability curves are presented, which enhance the coincidence between mathematical model and experiment results. The relative errors of main development indexes are within 4%. A software is programmed based on the model to execute a core-level small-scale numerical simulation in Chaoyanggou Oilfield. The fitting relative errors of the pressure, flow rate, and moisture content are 3.25%, 2.71%, and 2.54%, respectively. The results of laboratory experiments and numerical simulation showed that microemulsion system could reduce the threshold pressure gradient by 0.010 MPa/m and injection pressure by 0.6 MPa. The biggest decline in moisture content reaches 33%, and the oil recovery is enhanced by 10.8%.

Numerical Simulation of Pressure Distribution between Injection and Production Well in Low Permeability Reservoir

2013 ◽  
Vol 807-809 ◽  
pp. 2554-2557
Author(s):  
Qi Han Zhang ◽  
Zi Yi Guo ◽  
Ji Peng ◽  
Ting Song Xiong ◽  
Shi Feng Xue
Keyword(s):  
Numerical Simulation ◽  
Pressure Gradient ◽  
Pressure Distribution ◽  
Low Permeability ◽  
Threshold Pressure ◽  
Production Well ◽  
Pressure System ◽  
Threshold Pressure Gradient ◽  
Low Permeability Reservoir ◽  
Pressure Sensitive

Considering the pressure-sensitive effect and threshold pressure gradient in low permeability reservoirs, a new mathematical model of the variable permeability for reservoir between injection and production well is established. The Garlerkin method is used to set up the finite element computation equations, and corresponding numerical simulation program is developed. The influence of Injection-production pressure, well spacing and hydraulic fracture are quantitative evaluation. The simulation results show that the pressure-sensitive effect and threshold pressure gradient has a strong influence on pressure distribution between injection and production wells. Establishing the effective driving pressure system is the key to improve well production of low permeability reservoir.

Study on the Flow Characteristics of Shengli Oilfield Super Heavy Oil

2017 ◽  
Vol 10 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Wang Shou-long ◽  
Li Ai-fen ◽  
Peng Rui-gang ◽  
Yu Miao ◽  
Fu Shuai-shi
Keyword(s):  
Pressure Drop ◽  
Pressure Gradient ◽  
Heavy Oil ◽  
Flow Characteristics ◽  
Fluid Viscosity ◽  
Linear Flow ◽  
Start Up ◽  
Non Linear ◽  
Core Permeability ◽  
Velocity Pressure

Objective:The rheological properties of oil severely affect the determination of percolation theory, development program, production technology and oil-gathering and transferring process, especially for super heavy oil reservoirs. This paper illustrated the basic seepage morphology of super heavy oil in micro pores based on its rheological characteristics.Methods:The non-linear flow law and start-up pressure gradient of super heavy oil under irreducible water saturation at different temperatures were performed with different permeable sand packs. Meanwhile, the empirical formulas between start-up pressure gradient, the parameters describing the velocity-pressure drop curve and the ratio of gas permeability of a core to fluid viscosity were established.Results:The results demonstrate that temperature and core permeability have significant effect on the non-linear flow characteristics of super heavy oil. The relationship between start-up pressure gradient of oil, the parameters representing the velocity-pressure drop curve and the ratio of core permeability to fluid viscosity could be described as a power function.Conclusion:Above all, the quantitative description of the seepage law of super heavy oil reservoir was proposed in this paper, and finally the empirical diagram for determining the minimum and maximum start-up pressure of heavy oil with different viscosity in different permeable formations was obtained.

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