Pressure Analysis for Volume Fracturing Vertical Well considering Low-Velocity Non-Darcy Flow and Stress Sensitivity

Wu, Zhongwei; Cui, Chuanzhi; Trivedi, Japan; Ai, Ning; Tang, Wen-Hao

doi:10.1155/2019/2046061

Cited by 11 publications

(4 citation statements)

References 31 publications

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“…During the crack formation process, some of the original cementation between the sandstone particles and some of the dead pores rupture under the shear stress and connect with the original pores to form microcracks, which greatly improves the seepage capacity of the core. This part of the microcracks will be closed under pressure [3,[40][41][42].…”

Section: Discussionmentioning

confidence: 99%

Influence of Microcracks on Stress Sensitivity in Tight Sandstone

Zhang

et al. 2021

Lithosphere

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Stress sensitivity occurs throughout the reservoir development process, especially in the study of low permeability tight reservoir, considering the influence of stress sensitivity is particularly important. When studying stress sensitivity, the current main experimental methods are variable confining pressure and variable fluid pressure methods, but they cannot simulate the stress sensitivity during water injection development. Therefore, in this paper, an experimental stress sensitivity method that can be used to study the depletion mining and water injection development processes is established. In addition, the influence of different degrees of microcrack development on the stress sensitivity of the reservoir is investigated. The results of this study show that under the experimental conditions described in this article, the loading of axial compression plays a role of preloading stress and realizes the whole process of stress sensitivity under the condition that the fluid pressure is lower than the confining pressure. In the experiment, the permeability growth rate of matrix cores does not exceed 20%. For cores containing microcracks, when the axial pressure was less than 30 MPa, the permeability slowly increased with increasing fluid pressure. When the axial pressure was 30 MPa, the permeability changes are mainly divided into two stages. In the first stage, the microcracks are closed under compressive stress. At this time, the microcracks have a limited impact on the seepage capacity. The permeability increases slowly with increasing fluid pressure. In the second stage, the permeability rapidly increases after the microcracks open. These two stages can be described by two straight lines. The slope of the first line has nothing to do with the development of microcracks; the higher the degree of microcrack development, the greater the slope of the straight line of the second stage. For all of the cores, the permeability decreases as the axial pressure increases.

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Section: Discussionmentioning

confidence: 99%

Influence of Microcracks on Stress Sensitivity in Tight Sandstone

Zhang

et al. 2021

Lithosphere

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“…MB problems usually have a strong nonlinearity. In order to linearize the mathematical models for simplifying the model computation, MB conditions that describe the effect of TPG are not always taken into account in the relevant mathematical modeling in the previously published literature (Guo et al, 2012;Zeng et al, 2018;Wu et al, 2019). The TPG effect is just described through continuity equations or inner boundary conditions.…”

Section: Effect Of Considering Moving Boundary Conditions or Notmentioning

confidence: 99%

“…However, this kind of linearization may introduce a lot of errors (Yao et al, 2013;Liu et al, 2019a). Here, without considering MB conditions (Guo et al, 2012;Zeng et al, 2018;Wu et al, 2019), a dimensionless mathematical model for this 1D commingled preferential Darcian flow and non-Darcian flow problem is presented, and its EAS is also presented. Please see Appendix A for the details of the mathematical model and its EAS process.…”

Section: Effect Of Considering Moving Boundary Conditions or Notmentioning

confidence: 99%

A Fundamental Moving Boundary Problem of 1D Commingled Preferential Darcian Flow and Non-Darcian Flow Through Dual-Layered Porous Media

Wang

Ding

et al. 2022

Front. Energy Res.

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In consideration of vertical formation heterogeneity, a basic nonlinear model of 1D commingled preferential Darcian flow and non-Darcian flow with the threshold pressure gradient (TPG) in a dual-layered formation is presented. Non-Darcian flow in consideration of the TPG happens in the low-permeability tight layer, and the Darcian kinematic equation holds in the other high-permeability layer. The similarity transformation method is applied to analytically solve the model. Moreover, the existence and uniqueness of the analytical solution are proved strictly. Through analytical solution results, some significant conclusions are obtained. The existence of the TPG in the low-permeability tight layer can intensify the preferential Darcian flow in the high-permeability layer, and the intensity of the preferential Darcian flow is very sensitive to the dimensionless layer thickness ratio. The effect of the layer permeability ratio and layer elastic storage ratio on the production sub-rate is more sensitive than that of the layer thickness ratio. In addition, it is strictly demonstrated that moving boundary conditions caused by the TPG should be incorporated into the model. When the moving boundary is neglected, the preferential Darcian flow in the high-permeability layer will be exaggerated. Eventually, solid theoretical foundations are provided here, which are very significant for solving non-Darcian seepage flow problems in engineering by numerical simulation validation and physical experiment design. Furthermore, they are very helpful for better understanding the preferential flow behavior through the high-permeability paths (such as fractures) in the water flooding development of heterogeneous low-permeability reservoirs; then, the efficient profile control technology can be further developed to improve oil recovery.

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“…Moreover, Zhao et al and Ding et al proposed new well productivity models of tight gas reservoirs, respectively, using numerical simulation and experimental methods [5,32]. Wu et al conducted a transient model for volume fracturing vertical well, simultaneously considering the low-velocity non-Darcy flow and stress sensitivity [33]. Xu et al conducted an investigation into the pressure behavior of multi-stage fractured horizontal wells, considering stress sensitivity and dual permeability within fractured gas reservoirs [22].…”

Section: Introductionmentioning

confidence: 99%

A Composite Framework Model for Transient Pressure Dynamics in Tight Gas Reservoirs Incorporating Stress Sensitivity

Cao,

Wang,

Jiang

et al. 2023

Energies

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Natural gas is an eco-friendly energy source with low carbon emissions, making it attractive globally. Understanding gas reservoirs is crucial for sustainable extraction and optimizing potential. However, the complicated fluid flow and production dynamics within intricate gas reservoirs, particularly those characterized by abnormally high pressures and tight porous media, remain partially understood and demand further investigation. In a tight porous medium subjected to high pressure, the assumption of constant permeability is no longer valid. Consequently, a novel composite seepage model has been developed in this study, which considers the responsiveness of permeability to stress. Perturbation theory is employed to address the inherent non-linearity demonstrated by the permeability modulus. The solution of dimensionless pressure responses under constant production conditions is accomplished in the Laplace domain by implementing integral transformation methods. Overall, a comprehensive model is provided to understand the production behaviors of tight gas reservoirs. Moreover, in order to comprehend the transient flow characteristics of tight gas reservoirs, log–log plots are generated through the Stehfest numerical inversion approach, with the flow regimes categorized based on the normalized time phases of the pressure curves. Parametric investigations reveal that stress sensitivity detrimentally affects permeability, resulting in more pronounced pressure declines during the intermediate and late flow phases. The transient seepage model elaborated in this study is able to consider the pertinent formation and well parameters. These interpreted parameters bear significance in designing hydraulic fracturing operations, assessing the potential of tight gas reservoirs, and ultimately enhancing gas production. The presented model not only enhances our understanding of the behavior of horizontal wells in stress-sensitive tight gas reservoirs but also makes a valuable contribution to the broader discussion on transient flow phenomena in petroleum engineering.

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Pressure Analysis for Volume Fracturing Vertical Well considering Low-Velocity Non-Darcy Flow and Stress Sensitivity

Cited by 11 publications

References 31 publications

Influence of Microcracks on Stress Sensitivity in Tight Sandstone

Influence of Microcracks on Stress Sensitivity in Tight Sandstone

A Fundamental Moving Boundary Problem of 1D Commingled Preferential Darcian Flow and Non-Darcian Flow Through Dual-Layered Porous Media

A Composite Framework Model for Transient Pressure Dynamics in Tight Gas Reservoirs Incorporating Stress Sensitivity

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