Water/Rock Interaction for Eagle Ford, Marcellus, Green River, and Barnett Shale Samples and Implications for Hydraulic-Fracturing-Fluid Engineering

Abstract

Summary Knowledge of water/rock interactions on the surface of fractures is important to develop an understanding of the geological structures and changes within the formation, and to determine hydraulic-fracturing (HF) performance. To obtain this knowledge, this study investigates water/shale interactions in carbonate-rich (Eagle Ford), organic-rich (Green River), clay-rich (Barnett), and other-minerals-rich (Marcellus) shale samples. Crushed shale samples were exposed to water for 3 weeks at reservoir conditions. The water and rock samples before and after each static experiment were subjected to several analyses. The change in the rock mineralogy was defined by X-ray diffraction (XRD), the elemental composition of rock was determined by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy energy dispersive spectroscopy (SEM-EDS), and the organic content of rock samples was estimated by thermogravimetric analysis (TGA). The water was analyzed for its anions and cations, total dissolved solids (TDS), conductivity, pH, total organic carbon (TOC), and average particle sizes of colloids. The stability of the colloids was characterized by zeta-potential. We show that Barnett rock is high in illite content, and the greatest calcite concentration is determined for Eagle Ford. The sulfate content of water correlates with the atomic percent of the sulfur and oxygen elements determined through XPS analyses. The magnesium content of water correlates mainly with the illite amount in the rock, and calcium concentration associates with the calcite and gypsum content of the rock samples. The greatest dissolution rate belongs to the minerals that yield sulfate in the water; then, gypsum and calcite that yield calcium cation in the water come second; and the lowest dissolution rates are obtained from the magnesium-containing minerals (mainly, dolomite). TDS of the water samples shows that Green River has the least tendency to interact with water, and Barnett has the greatest tendency. Zeta-potential values indicate that particles in the water that interacted with Eagle Ford have the highest tendency for precipitation. The results of this study are used to make suggestions on the engineering of hydraulic-fracturing fluids (HFFs) in the context of water/rock interactions by considering the type and the concentration of ions along with colloidal stability determined through zeta-potential measurements.

WITHDRAWN: Impact of Hydraulic fracturing on Mineralogy on Change in Micro and Nano Porosity and Permeability of Shales

“…All test samples were first dried in a vacuum for 12 hours under a constant temperature of 150°C before BET tests. The pore volume was determined using the Density Functional Theory (DFT) model [32,33,34].…”

Water–rock interaction and the concentrations of major, trace, and rare earth elements in hydrocarbon-associated produced waters of the United States

“…Many other studies have presented results from a variety of water-rock interaction experiments for the Marcellus shale, and these were also compared to present data, particularly the brine leachates. 22,23,[30][31][32][33]45,56 In general, concentrations from leaching experiments overlapped with produced waters for Al, As, Mo, Pb, Sb, and Zn (Fig. 11) and additionally for Cu, P, and Ti based on the other studies.…”

“…Such studies focus on the waterrock interaction component of produced waters compositions, or how hydraulic fracturing uids can mobilize or precipitate elements from the rock matrix, but oen fail to reproduce concentrations observed in actual produced waters. [22][23][24][25][26][27][28] Broad studies of produced waters encompassing multiple energy-producing basins have generally focused on patterns in a few, oen major, elements because of data availability. 21,29 In contrast, studies examining suites of trace elements and waterrock interaction experiments have typically focused on shales from one or two basins.…”

Experimental Investigation into the Effects of Fracturing Fluid-Shale Interaction on Pore Structure and Wettability

“…The interaction between slick water and shale may have a great impact on the storage and flow of shale gas [15,[17][18][19]. Therefore, an in-depth understanding of the interaction between the fracking fluid and shale is essential to deepen our understanding of changes in the pore structure in the reservoir and the long-term productivity of shale gas [17,19,20]. In addition to organic matter, shale also contains clay minerals, carbonate, and brittle minerals [21].…”