Abstract:Pulse hydraulic fracturing (PHF) is a key technique for reservoir stimulation. PHF can well accelerate the rupture of rock. However, the supercharging mechanism of PHF is not fully understood. The main reason is that the pressure distribution and its variation, especially the peak pressure characteristics, are unclear inside the pipe and fissure. The present research focuses on the sine pulse applied at the inlet of a pipe or fracture to reveal the variation regularity of peak pressure with the pulse frequency… Show more
“…Compared with previous research in the field, the present study's findings reveal several similarities and differences and provide further insights into the effectiveness of rectangular pulse hydraulic fracturing compared to conventional hydraulic fracturing. Our findings align with previous studies demonstrating the advantages of rectangular pulse hydraulic fracturing regarding water management and overall efficiency in shale gas extraction [38]. A similar investigation reported a reduction in total fluid volume of 15% when using rectangular pulse hydraulic fracturing compared to conventional hydraulic fracturing [10].…”
Although conventional hydraulic fracturing techniques have revolutionized shale gas development, they have raised concerns regarding water management and environmental impacts. This research introduces an innovative step-rectangular pulse hydraulic fracturing method to optimize water usage and reduce environmental hazards in shale gas extraction. The method involves the application of lower-energy fluid in a step-rectangular pulse pattern, which results in higher pressures, more intricate fractures, and improved water management. A comprehensive analysis of the propagation and attenuation characteristics of this technique is conducted using a combination of a two-dimensional pulse transient flow equation with damping, software numerical simulations, and theoretical analysis. The study reveals that the step rectangular pulse hydraulic fracturing method offers superior pressurization and more complex fracture networks in shale reservoirs while lowering water consumption by 20% less than conventional methods and increasing shale gas production by 12%. Through identifying optimal pulse parameters, this research provides valuable guidance for field implementation, promoting efficient water management and environmental sustainability in hydraulic fracturing operations. This novel approach to hydraulic fracturing has the potential to significantly advance the industry’s efforts to address water management challenges and mitigate environmental risks associated with shale gas extraction.
“…Compared with previous research in the field, the present study's findings reveal several similarities and differences and provide further insights into the effectiveness of rectangular pulse hydraulic fracturing compared to conventional hydraulic fracturing. Our findings align with previous studies demonstrating the advantages of rectangular pulse hydraulic fracturing regarding water management and overall efficiency in shale gas extraction [38]. A similar investigation reported a reduction in total fluid volume of 15% when using rectangular pulse hydraulic fracturing compared to conventional hydraulic fracturing [10].…”
Although conventional hydraulic fracturing techniques have revolutionized shale gas development, they have raised concerns regarding water management and environmental impacts. This research introduces an innovative step-rectangular pulse hydraulic fracturing method to optimize water usage and reduce environmental hazards in shale gas extraction. The method involves the application of lower-energy fluid in a step-rectangular pulse pattern, which results in higher pressures, more intricate fractures, and improved water management. A comprehensive analysis of the propagation and attenuation characteristics of this technique is conducted using a combination of a two-dimensional pulse transient flow equation with damping, software numerical simulations, and theoretical analysis. The study reveals that the step rectangular pulse hydraulic fracturing method offers superior pressurization and more complex fracture networks in shale reservoirs while lowering water consumption by 20% less than conventional methods and increasing shale gas production by 12%. Through identifying optimal pulse parameters, this research provides valuable guidance for field implementation, promoting efficient water management and environmental sustainability in hydraulic fracturing operations. This novel approach to hydraulic fracturing has the potential to significantly advance the industry’s efforts to address water management challenges and mitigate environmental risks associated with shale gas extraction.
“…The detailed temporal evolution of the pressure is given in Fig. 6 k. Figure 6 Normalized pressure-position curves alone pipe axes direction during 2.5 pulsating periods where the pipe length is 250 m and the pulsating frequency is 1 Hz 25 . …”
Section: Discussion On the Supercharging Mechanismmentioning
confidence: 99%
“… Normalized pressure-position curves alone pipe axes direction during 2.5 pulsating periods where the pipe length is 250 m and the pulsating frequency is 1 Hz 25 . …”
Section: Discussion On the Supercharging Mechanismmentioning
Considering the discontinuous square pulse wave and continuous sine pulsating wave, we report a distinctive supercharging phenomenon of fluid in a water-filled semi-enclosed pipe and reveal the supercharging regularity. We demonstrate that there can be significant supercharging phenomena at the pipe end-face if the water is periodically injected at the pipe inlet with certain frequency. Compared to the traditional pulsating injection method, the present injection strategy can remarkably enhance the peak pressure of the water at the end face of the pipe. We explained this phenomenon by numerical simulations based on the computational fluid dynamic method. It’s found that there is a quantitative relationship between the optimal pulse frequency, pipe length and wave speed. The proposed frequency model is suitable for the multi-waveform, such as sine wave, square wave and arcuate wave. The fluid pressure at the pipe end-face intermittently increases and the end-face peak pressure is largest when the inlet injection frequency equals to the optimal frequency.
“…Clearly, this wave speed derived from above model is consistent with the existing experimental value. The FVS method introduced in Section 2.2 is based on the linear model (7).…”
Section: Weakly Compressible Water N-s Equationmentioning
confidence: 99%
“…These methods include the upwind scheme and MacCormack (MAC) method, etc. [2][3][4][5][6][7]. Most of these methods are based on the idea of explicit scheme.…”
Water is a weakly compressible fluid medium. Due to its low compressibility, it is usually assumed that water is an incompressible fluid. However, if there are high-pressure pulse waves in water, the compressibility of the water medium needs to be considered. Typical engineering applications include water hammer protection and pulse fracturing, both of which involve the problem of discontinuous pulse waves. Traditional calculation and simulation often use first-order or second-order precision finite difference methods, such as the MacCormark method. However, these methods have serious numerical dissipation or numerical dispersion, which hinders the accurate evaluation of the pulse peak pressure. In view of this, starting from the weakly compressible Navier–Stokes (N-S) equation, this paper establishes the control equations in the form of flux, derives the expressions of eigenvalues, eigenvectors, and flux vectors, and gives a new flux vector splitting (FVS) formula by considering the water equation of state. On this basis, the above flux vector formula is solved using the fifth-order weighted essentially non-oscillatory (WENO) method. Finally, the proposed FVS formula is verified by combining the typical engineering examples of water hammer and pulse fracturing. Compared with the traditional methods, it is proved that the FVS formula proposed in this paper is reliable and robust. As far as we know, the original work in this paper extends the flux vector splitting method commonly used in aerodynamics to hydrodynamics, and the developed model equation and method are expected to play a positive role in the simulation field of water hammer protection, pulse fracturing, and underwater explosion.
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