Summary

Liquid loading is a key issue in shale gas reservoirs with hydraulic fractures. Field results show that only 15%–30% of the original fracturing fluid is recovered. Most liquid is trapped in the rock matrix near the fracture face and induced fractures. Significant efforts have been made to understand the impact of liquid loading on well performance and some models have been proposed to describe the liquid loading. However, these models ignore the effect of liquid drop size and its shape change with the size. The shape of falling liquid is nearly sphere when its diameter is less than 2 mm, otherwise, when larger than 2 mm, it will change to be half Hamburg. Hence, ignoring the liquid drop size and its shape change with size will lead to inaccurate calculation of the critical liquid loading flow rate.

In this work, we propose a new analytical model to describe the critical liquid loading by considering the size and shape of liquid drop. Also, we validate this model using field data of Marcellus Shale. Results of this work show that the ratio of the liquid drop height over width is a strong function of the liquid drop width. Both maximum and minimum rations are determined: the maximum is 1, representing the shape of sphere, and the minimum is 0.3765, and when less than 0.3765, the liquid drop is unstable.

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