A critical review of water uptake by shales

Fast mass transport of oil and supercritical carbon dioxide through organic nanopores in shale

The effect of microstructure and rock mineralogy on water imbibition characteristics in tight reservoirs

A model for gas transport in microfractures of shale and tight gas reservoirs is established. Slip flow and Knudsen diffusion are coupled together to describe general gas transport mechanisms, which include continuous flow, slip flow, transitional flow, and Knudsen diffusion. The ratios of the intermolecular collision frequency and the molecule-wall collision frequency to the total collision frequency are defined as the weight coefficients of slip flow and Knudsen diffusion, respectively. The model is validated by molecular simulation results. The results show that: (1) the model can reasonably describe the process of the mass transform of different gas transport mechanisms; (2) fracture geometry significantly impacts gas transport. Under the same fracture aperture, the higher the aspect ratio is, the stronger the gas transport capacity, and this phenomenon is more pronounced in the cases with higher gas pressure and larger fracture aperture. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2079–2088, 2015

A model for gas transport in microfractures of shale and tight gas reservoirs

An analytical model for relative permeability in water-wet nanoporous media

During and after hydraulic fracturing, fluid–shale interaction has a prominent impact on liquid retention and thus on gas phase permeability and gas productivity. By providing a low surface tension or wettability alteration, surfactants are widely used to decrease liquid retention after fracturing. To evaluate the liquid intake of a rock sample, an imbibition experiment is commonly used, especially when it is treated by a surfactant. However, conventional imbibition experiments with gas shale could not quantitate the imbibition behaviors as it does with conventional rocks because of the low porosity and extremely low permeability of gas shale. In this paper, a comprehensive experimental method was successfully developed to study the liquid imbibition in shale samples. Bulk shale easily fell apart during imbibition experiments. However, samples prepared with the coating method decribed herein remained intact except for fractures generated in them during the first imbibition. On each imbibition curve with i...

Microfracture and Surfactant Impact on Linear Cocurrent Brine Imbibition in Gas-Saturated Shale

Microfluidic and nanofluidic devices have undergone rapid development in recent years. Functions integrated onto such devices provide lab-on-a-chip solutions for many biomedical, chemical, and engineering applications. In this paper, a lab-on-a-chip technique for direct visualization of the single- and two-phase pressure-driven flows in nano-scale channels was developed. The nanofluidic chip was designed and fabricated; concentration dependent fluorescence signal correlation was developed for the determination of flow rate. Experiments of single and two-phase flow in nano-scale channels with 100 nm depth were conducted. The linearity correlation between flow rate and pressure drop in nanochannels was obtained and fit closely into Poiseuille's Law. Meanwhile, three different flow patterns, single, annular, and stratified, were observed from the two-phase flow in the nanochannel experiments and their special features were described. A two-phase flow regime map for nanochannels is presented. Results are of critical importance to both fundamental study and many applications.

Optic imaging of single and two-phase pressure-driven flows in nano-scale channels

Crude oil is found in underground porous sandstone or carbonate rock formations. In the first (primary) stage of oil recovery, oil is displaced from the reservoir into the wellbore and up to the surface under its own reservoir energy, such as gas drive, water drive, or gravity drainage. In the second stage, an external fluid such as water or gas is injected into the reservoir through injection wells located in the formation that have fluid communication with production wells. The purpose of secondary oil recovery is to maintain reservoir pressure and displace hydrocarbons towards the wellbore. The most common secondary recovery technique is waterflooding. Once the secondary oil recovery process has been exhausted, about two thirds of the original oil in place (OOIP) is left behind. Enhanced oil recovery (EOR) methods aim to recover the remaining OOIP. Enhanced oil production is critical today when many analysts are predicting that world oil peak production is either imminent or has already passed while demand for oil is growing faster than supply. For example, the United States has a total of 649 billion barrels original oil in place, and only about 220 billion barrels are recoverable by primary and secondary recovery methods. EOR methods offer the prospect of recovering as much as 200 billion barrels of more oil from existing U.S. reservoirs, a quantity of oil equivalent to the cumulative oil production to date.

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Measurement and Impact Factors of Polymer Rheology in Porous Media

Experimental study of friction reducer flows in microfracture

Microfluidic and nanofluidic devices have undergone rapid development in recent years. Functions integrated onto such devices provide lab-on-a-chip solutions for many biomedical, chemical, and engineering applications. In this paper, a lab-on-a-chip technique for direct visualization of the single- and two-phase pressure-driven flows in nano-scale channels was developed. The nanofluidic chip was designed and fabricated; concentration dependent fluorescence signal correlation was developed for the determination of flow rate. Experiments of single and two-phase flow in nano-scale channels with 100 nm depth were conducted. The linearity correlation between flow rate and pressure drop in nanochannels was obtained and fit closely into Poiseuille’s Law. Meanwhile, three different flow patterns, single, annular, and stratified, were observed from the two-phase flow in the nanochannel experiments and their special features were described. A two-phase flow regime map for nanochannels is presented. Results are of critical importance to both fundamental study and many applications.

Yongpeng Sun

Papers

Microfracture and Surfactant Impact on Linear Cocurrent Brine Imbibition in Gas-Saturated Shale

Optic imaging of single and two-phase pressure-driven flows in nano-scale channels

Measurement and Impact Factors of Polymer Rheology in Porous Media

Experimental study of friction reducer flows in microfracture

Optic imaging of single and two-phase pressure-driven