Experimental Research on Damage to Fracture Conductivity Caused by Fracturing Fluid Residues

Wang, Lei

doi:10.4028/www.scientific.net/amr.774-776.303

Cited by 1 publication

(1 citation statement)

References 2 publications

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“…In the process of fracturing, opening flow, and production, it is necessary to pay attention to the influence of pressure fluctuation on the conductivity of branch fractures and to accurately grasp the stress sensitivity of branch fractures [23,24]. After shale is soaked in water-based fracturing fluid, the damage caused by the leak off of gel-breaking fluid and the risk of shale hydration swelling especially need to be focused on to prevent excessive open flow pressure from causing shale particles on the wall of branch fractures to fall off and causing proppant to embed in the fractures, which will cause the fracture conductivity to decrease [25][26][27][28][29]. And the antiswelling effect of fracturing fluid on the stability of branch fractures needs to be clarified [30].…”

Section: Introductionmentioning

confidence: 99%

Experimental Evaluation on the Conductivity of Branch Fracture with Low Sand Laying Concentration and Its Influencing Factors in Shale Oil Reservoirs

et al. 2021

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The productivity of shale oil reservoirs is mainly determined by the hydraulic fractured reservoir volume. The branch fractures with low sand laying concentration are the main channels connecting the shale matrix and the main fractures. Maintaining the branch fracture conductivity is significant to the production of shale oil. In this study, a series of shale branch fracture conductivity and soaking experiments were conducted using a core flooding device and a small reactor, and the influences of different factors on the fracture conductivity were evaluated. The results show that when the sand laying concentration in fractures is less than 3 kg/m2, the branch fractures present a significant stress sensitivity. Particularly when the sand laying concentration is less than 1 kg/m2, and the closure pressure is greater than 15 MPa, there will be a risk of proppant embedded and fracture closed. The antiswelling agent has an inhibitory effect on the shale swelling. When the concentration of the antiswelling agent in the gel-breaking fluid is 2%, the swelling factor of shale powder is only 1.84%. Comparatively, the 0.5% of the antiswelling agent has a poor effect which can cause the shale rock to crack when the effective stress decreases. It can cause the fracture conductivity to decline by 70-90% when the gel-breaking fluid flows back associated with the shale oil. The probability of core breaking and proppant embedding will increase. The frequent shut-in and rapid open-flow for production can accelerate the damage of fracture conductivity. It is necessary to optimize the fracturing fluid and the open flow scheme to prevent the rapid decline of production in shale oil reservoirs.

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