A stepwise sand adding method for shale gas fracturing

Abstract

The invention relates to a shale gas fracturing stepping sand-adding method which comprises the following steps: (1) pumping a prepared fluid into a shaft and causing the fluid enter into ground gaps; (2) pumping a first sand-adding section plug and performing the stepping sand adding; (3) pumping a first fluid section plug, and if the pressure shows as diagonal rising, confirming that the pressure change is mild and the sand ratio has a rising potential, and then skipping to the step (4), and if the pressure shows as the sand ratio rising unsuitable for the present stage, further pumping the fracturing fluid for forming gaps and then skipping to the step (1); (4) pumping a second sand-adding section plug and performing the stepping sand adding; (5) pumping a second fluid section plug and observing the pressure variation trend of the sand-adding section plug at different sand ratios after entering into the stratum; and (6) repeating the steps (4)-(5) for 15-20 times till meeting the requirement for designed fracturing sand-adding volume, completing the sand adding in each stage, and lastly, pumping the displacing liquid and completing the whole fracturing construction task. According to the invention, the stepping sand-adding method is adopted for effectively preventing reservoir sand blocking, reducing the construction risk and guaranteeing the smooth construction.

Description

technical field [0001] The invention relates to the technical field of shale gas exploration and development fracturing engineering, in particular to a stepwise sand adding method for shale gas fracturing. Background technique [0002] In the fracturing of shale gas reservoirs, the slug-type sand-adding process is often used, that is, pumping a sand-adding slug, and then pumping a liquid slug, so that the sand ratio gradually increases. The sand slug has a constant sand addition ratio, and the critical point of sand addition cannot be predicted, which may easily cause sand plugging, increase subsequent construction procedures and engineering costs, and affect the effect of reservoir stimulation. Contents of the invention [0003] In order to overcome the above-mentioned defects in the prior art, the object of the present invention is to provide a stepwise sanding method for shale gas fracturing, which can effectively prevent reservoir sand plugging and reduce construction ...

AI Technical Summary

Problems solved by technology

[0002] In the fracturing of shale gas reservoirs, the slug-type sand-adding process is often used, that is, pumping a sand-adding slug, and then pumping a liquid slug, so that the sand ratio gradually increases. The sand slug has a constant sand addition ratio, and the critical point of sand addition cannot be predicted, which may easily cause sand plugging, increase subsequent construction procedures and engineering costs, and affect the effect of reservoir stimulation

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