Identifying the geochemical fingerprints of fluids that return to the surface after high volume hydraulic fracturing of unconventional oil and gas reservoirs has important applications for assessing hydrocarbon resource recovery, environmental impacts, and wastewater treatment and disposal. Here, we report for the first time, novel diagnostic elemental and isotopic signatures (B/Cl, Li/Cl, δ11B...

The expansion of unconventional shale gas and hydraulic fracturing has increased the volume of the oil and gas wastewater (OGW) generated in the U.S. Here we demonstrate that OGW from Marcellus and Fayetteville hydraulic fracturing flowback fluids and Appalachian conventional produced waters is characterized by high chloride, bromide, iodide (up to 56 mg/L), and ammonium (up to 420 mg/L). Br/Cl...

BACKGROUND The economic value of unconventional natural gas resources has stimulated rapid globalization of horizontal drilling and hydraulic fracturing. However, natural radioactivity found in the large volumes of "produced fluids" generated by these technologies is emerging as an international environmental health concern. Current assessments of the radioactivity concentration in liquid waste...

It is common practice in industry to monitor hydraulic fracturing jobs by picking major, micro-earthquake events in seismograms whose source locations form a spatial pattern used for interpreting induced fractures. Surprisingly, controversy still surrounds the interpretation of these scattered, discrete events. Many authors conclude that hydraulic fractures are generated by shear failure events...

A carefully engineered stimulation that makes use of opening mode fractures is an effective way to reduce injection and production impedance and provide better access for the fluid to enter and promote shearing in the main reservoir volume. We present results from field experiments that mapped the fracture geometry for opening mode hydraulic fractures formed in naturally fractured crystalline r...

Induced seismicity has been recognized as a concern in subsurface industrial operation, and particularly at fluid-injection sites in major oil and gas exploitation plays, where hydraulic stimulations are conducted to increase rock permeability. Induced seismicity occurs also in Enhanced Geothermal Systems (EGS), where hydraulic fracturing is used to accelerate heat extraction from the rock. If ...

Multiple-factor analysis and optimization play a critical role in the the ability to maximizethe stimulated reservoir volume (SRV) and the success of economic shale gas production. In this paper, taking the typical continental naturally fractured silty laminae shale in China as anexample, response surface methodology (RSM) was employed to optimize multiple hydraulic fracturing parameters to max...

The potential hazards and risks associated with well-stimulation in unconventional oil and gas development (hydraulic fracturing, acid fracturing, and matrix acidizing) have been investigated and evaluated and federal and state regulations requiring chemical disclosure for well-stimulation have been implemented as part of an overall risk management strategy for unconventional oil and gas develo...

Flowback and produced wastewaters from unconventional hydraulic fracturing during oil and gas explorations typically brings to the surface Naturally Occurring Radioactive Materials (NORM), predominantly radioisotopes from the U238 and Th232 decay chains. Traditionally, radiological sampling are performed by sending collected small samples for laboratory tests either by radiochemical analysis or...

We introduce a discrete element simulation for the hydraulic fracture process in a petroleum well which takes into account the elastic behavior of the rock and the Mohr-Coulomb fracture criterium. The rock is modeled as an array of Voronoi polygons joined by elastic beams, which are submitted to tectonical stresses and the hydrostatic pressure of the fracturing fluid. The fluid pressure is trea...