Aiming at the problem that a large number of microfractures are not fully and effectively supported during reservoir volume fracturing, a novel micropowder proppant with smaller particle size (7-75 μm), better suspension performance, and core chemical components, including SiO2 (65-70%), Al2O3 (20-25%), and epoxy resin binder (3-5%), was developed. Its migration and placement laws in complex fractures were studied using Fluent 2021 software, and the fracturing effects of 70/140 mesh ceramsite proppants and micropowder proppants were compared by FracMan software. The results show that the micropowder proppant is mainly placed in secondary fractures, presenting an overall "high front and low back" distribution pattern; in primary branch fractures, most micropowder proppant is in a suspended migration state, only 200 mesh micropowder proppant settles, with small equilibrium height and area of the sand dam, failing to form an effective sand dam; the placement law of micropowder proppant is greatly affected by particle size. When the proppant mesh increases from 200 to 600 mesh, the equilibrium height and area of the sand dam in secondary and tertiary branch fractures gradually increase. When the proppant mesh reaches 800 mesh, due to its excessively small particle size, a large number of proppant particles are in a suspended migration state and cannot settle to form an effective sand dam, which is likely to cause insufficient support of microfractures near the wellbore; compared with 70/140 mesh ceramsite proppant, the micropowder proppant has a longer migration distance and is easier to enter secondary fractures and microfractures; the micropowder proppant can make the fracture network more complex, and the stimulated reservoir volume (SRV) of shale reservoirs can be increased by 17.71%, with the calculation method: (5547.33-4712.61)/4712.61 × 100%, and the reservoir stimulation effect is significant. The research results further improve the relevant theories of the migration and placement laws of proppants and can provide certain theoretical guidance for the optimal design of field construction.
Li et al. (Mon,) studied this question.