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Imbibition of hydraulic fracturing fluids into partially saturated shale
Author(s) -
Birdsell Daniel T.,
Rajaram Harihar,
Lackey Greg
Publication year - 2015
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1002/2015wr017621
Subject(s) - imbibition , oil shale , hydraulic fracturing , petroleum engineering , saturation (graph theory) , fracturing fluid , porous medium , geology , porosity , permeability (electromagnetism) , geotechnical engineering , chemistry , biochemistry , mathematics , membrane , biology , paleontology , botany , germination , combinatorics
Recent studies suggest that imbibition of hydraulic fracturing fluids into partially saturated shale is an important mechanism that restricts their migration, thus reducing the risk of groundwater contamination. We present computations of imbibition based on an exact semianalytical solution for spontaneous imbibition. These computations lead to quantitative estimates of an imbibition rate parameter ( A ) with units of L T − 1 / 2for shale, which is related to porous medium and fluid properties, and the initial water saturation. Our calculations suggest that significant fractions of injected fluid volumes (15–95%) can be imbibed in shale gas systems, whereas imbibition volumes in shale oil systems is much lower (3–27%). We present a nondimensionalization of A , which provides insights into the critical factors controlling imbibition, and facilitates the estimation of A based on readily measured porous medium and fluid properties. For a given set of medium and fluid properties, A varies by less than factors of ∼1.8 (gas nonwetting phase) and ∼3.4 (oil nonwetting phase) over the range of initial water saturations reported for the Marcellus shale (0.05–0.6). However, for higher initial water saturations, A decreases significantly. The intrinsic permeability of the shale and the viscosity of the fluids are the most important properties controlling the imbibition rate.