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Analysis of bacterial diversity in two oil blocks from two low-permeability reservoirs with high salinities

Analysis of bacterial diversity in two oil blocks from two low-permeability reservoirs with high salinities

Abstract The community diversities of two oil reservoirs with low permeability of 1.81 × 10−3 and 2.29 × 10−3 μm2 in Changqing, China, were investigated using a high throughput sequencing technique to analyze the influence of biostimulation with a nutrient activator on the bacterial communities. These two blocks differed significantly in salinity (average 17,500 vs 40,900 mg/L).

Measurement and Visualization of Tight Rock Exposed to CO2 Using NMR Relaxometry and MRI

Understanding mechanisms of oil mobilization of tight matrix during CO2 injection is crucial for CO2 enhanced oil recovery (EOR) and sequestration engineering design. In this study exposure behavior between CO2 and tight rock of the Ordos Basin has been studied experimentally by using nuclear magnetic resonance transverse relaxation time (NMR T2) spectrum and magnetic resonance imaging (MRI) under the reservoir pressure and temperature.

Abstract Understanding mechanisms of oil mobilization of tight matrix during CO2 injection is crucial for CO2 enhanced oil recovery (EOR) and sequestration engineering design. In this study exposure behavior between CO2 and tight rock of the Ordos Basin has been studied experimentally by using nuclear magnetic resonance transverse relaxation time (NMR

Logging Evaluation Method for Pore Pressure of Shale Gas Reservoirs— Taking Fuling area, Sichuan Basin as an example

Logging Evaluation Method. Unconventional oil and gas resources, especially shale gas resources have great potential for exploration and development in China. In Shale gas exploration and development process, reservoir pore pressure is a very important parameter, and the pore pressure prediction can improve the appraisal accuracy of project dessert. This paper analyzes several formation pore pressure calculation methods based on logging data, and optimized the “Equivalent depth method”.

Abstract: Unconventional oil and gas resources, especially shale gas resources have great potential for exploration and development in China. In Shale gas exploration and development process, reservoir pore pressure is a very important parameter, and the pore pressure prediction can improve the appraisal accuracy of project dessert. This paper analyzes

A new nanocomposite forward osmosis membrane custom-designed for treating shale gas wastewater

Managing the wastewater discharged from oil and shale gas fields is a big challenge, because this kind of wastewater is normally polluted by high contents of both oils and salts. Conventional pressure-driven membranes experience little success for treating this wastewater because of either severe membrane fouling or incapability of desalination. In this study, we designed a new nanocomposite forward osmosis (FO) membrane for accomplishing simultaneous oil/water separation and desalination. This nanocomposite FO membrane is composed of an oil-repelling and salt-rejecting hydrogel selective layer on top of a graphene oxide (GO) nanosheets infused polymeric support layer.

Abstract   Managing the wastewater discharged from oil and shale gas fields is a big challenge, because this kind of wastewater is normally polluted by high contents of both oils and salts. Conventional pressure-driven membranes experience little success for treating this wastewater because of either severe membrane fouling or incapability of desalination.

Pre-stack basis pursuit seismic inversion for brittleness of shale

Brittleness of rock plays a significant role in exploration and development of shale gas reservoirs. Young’s modulus and Poisson’s ratio are the key parameters for evaluating the rock brittleness in shale gas exploration because their combination relationship can quantitatively characterize the rock brittleness. The high-value anomaly of Young’s modulus and the low-value anomaly of Poisson’s ratio represent high brittleness of shale. The technique of pre-stack amplitude variation with angle inversion allows geoscientists to estimate Young’s modulus and Poisson’s ratio from seismic data.

Pre-stack basis pursuit seismic inversion for brittleness of shale Abstract Brittleness of rock plays a significant role in exploration and development of shale gas reservoirs. Young’s modulus and Poisson’s ratio are the key parameters for evaluating the rock brittleness in shale gas exploration because their combination relationship can quantitatively characterize the rock

An Experimental Investigation of the Risk of Triggering Geological Disasters by Injection under Shear Stress

We developed a new direct shear test apparatus, coupled Hydro-Mechanical (HM), to investigate mechanical property variations when an intact rock experienced step drilling borehole, fluid injection, and fluid pressure acting on the borehole and fracture wall. We tested the peak shear stress of sandstone under different experimental conditions, which showed that drilling borehole, water injection, and increased pore pressure led to the decrease in peak shear stress.

An Experimental Investigation of the Risk of Triggering Geological Disasters by Injection under Shear Stress   Yixin Liu1,2, Jiang Xu1,2 & Shoujian Peng1,2 1State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China. 2State and Local Joint Engineering Laboratory of Methane Drainage in Complex Coal Gas Seam, Chongqing

Methane and the greenhouse-gas footprint of natural gas from shale formations

We evaluate the greenhouse gas footprint of natural gas obtained by high-volume hydraulic fracturing from shale formations, focusing on methane emissions. Natural gas is composed largely of methane, and 3.6% to 7.9% of the methane from shale-gas production escapes to the atmosphere in venting and leaks over the life- time of a well. These methane emissions are at least 30% more than and perhaps more than twice as great as those from conventional gas. The higher emissions from shale gas occur at the time wells are hydraulically fractured—as methane escapes from flow-back return fluids—and during drill out following the fracturing.

Methane and the greenhouse-gas footprint of natural gas from shale formations Robert W. Howarth1 • Renee Santoro • Anthony Ingraffea2 1Department of Ecology and Evolutionary Biology, Cornell  University, Ithaca,  NY 14853, USA. 2School of Civil and Environmental Engineering, Cornell  University, Ithaca,  NY 14853, USA  Abstract We evaluate the greenhouse gas footprint of natural gas

Nanostructural control of methane release in kerogen and its implications to wellbore production decline

Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases.

Nanostructural control of methane release in kerogen and its implications to wellbore production decline   Tuan Anh Ho1, Louise J. Criscenti1 & Yifeng Wang2 1Geochemistry Department, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA. 2Nuclear Waste Disposal Research and Analysis Department, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.   Abstract Despite massive success of shale

Confinement Correction to Mercury Intrusion Capillary Pressure of Shale Nanopores

We optimized potential parameters in a molecular dynamics model to reproduce the experimental contact angle of a macroscopic mercury droplet on graphite. With the tuned potential, we studied the effects of pore size, geometry, and temperature on the wetting of mercury droplets confined in organic-rich shale nanopores. The contact angle of mercury in a circular pore increases exponentially as pore size decreases. In conjunction with the curvature-dependent surface tension of liquid droplets predicted from a theoretical model, we proposed a technique to correct the common interpretation procedure of mercury intrusion capillary pressure (MICP) measurement for nanoporous material such as shale. Considering the variation of contact angle and surface tension with pore size improves the agreement between MICP and adsorption-derived pore size distribution, especially for pores having a radius smaller than 5 nm.

Confinement Correction to Mercury Intrusion Capillary Pressure of Shale Nanopores Sen Wang1,2, Farzam Javadpour1 & Qihong Feng2 1Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, United States. 2School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, China. Abstract We optimized potential parameters in

Flow visualization of CO2 in tight shale formations at reservoir conditions

Flow visualization of CO2 in tight shale formations at reservoir conditions. The flow of CO2 in porous media is fundamental to many engineering applications and geophysical processes. Yet detailed CO2 flow visualization remains challenging. We address this problem via positron emission tomography using11C nuclides and apply it to tight formations—a difficult but relevant rock type to investigate. The results represent an important technical advancement for visualization and quantification of flow properties in ultratight rocks and allowed us to observe that local rock structure in a layered, reservoir shale (K = 0.74 μdarcy) sample dictated the CO2 flow path by the presence of high-density layers.

Flow visualization of CO2 in tight shale formations at reservoir conditions   M. A. Fernø1, L. P. Hauge1, A. Uno Rognmo1, J. Gauteplass1, and  A. Graue1 1Department of Physics and Technology, University of Bergen, Bergen, Norway Abstract The flow of CO2 in porous media is fundamental to many engineering  applications and geophysical processes. Yet detailed

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