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Deep natural gas is an important field and direction for oil and gas exploration and development in the Banqiao depression. The geochemical characteristics of the Paleogene Shahejie Formation source rocks in the Banqiao Sag were investigated based on pyrolysis, Total Organic Carbon (TOC), chloroform bitumen A, vitrinite reflectance, saturated hydrocarbon gas chromatography–mass spectrometry, and maceral determination. The results showed that the Es3source rocks of the Paleogene Shahejie Formation were generally of better quality than the Es1source rocks. Regarding the Es1source rocks, the abundance of organic matter was variable, with mixed types and low maturity. The source rocks were formed in a saline-water reductive environment. Regarding the Es3source rocks, the abundance of organic matter was relatively high, meaning that they were of medium–high quality, with mixed types of, yet highly mature, organic matter. The hydrocarbon generation environment was oxidative, and the source rocks were mainly deposited in fresh water with localized salinization. The main hydrocarbon-generating components of organic matter in the Shahejie Formation were amorphous humic components formed by intensive microbial modification of lower planktonic algae and terrestrial higher plants. Aquatic organisms were the main sources of organic matter, with localized mixing of higher-plant organic matter. The organic matter derived from these higher plant debris sources provided beneficial conditions for the generation of natural gas. At present, the Shasan source rock is at the peak of hydrocarbon generation. Under deep conditions, the maturity of organic matter increases, and organic matter rich in terrestrial higher plants can make a significant contribution to the generation of natural gas, especially shale gas.

The study of gas hydrate researched by the ice powder method is helpful for us to understand the storage, separation, transportation and transformation of gas on the solid surface. In this work, the change regulation has been studied that temperature, pressure, hydrate saturation, and conversion rate in the formation process of methane-ethylene mixed hydrate, which exploring the internal action mode of the methane-ethylene mixed hydrate. The experimental results show that under the condition of −4.0 °C and 4 MPa, the conversion rates of methane, methane-ethylene (with mole ratios 2, 1, and 0.5), and ethylene hydrate are 5.30%, 11.95%, 16.57%, 19.93%, and 26.84%, respectively. And more, the conversion efficiencies of hydrate are 0.36, 0.81, 0.96, 1.58, and 6.58, respectively. The above data show that with the increase of ethylene content, the formation of hydrate is easier, which proves that ethylene can promote the formation efficiency of methane hydrate. These results have reference value for understanding the formation of natural gas hydrates, so as to promote the development and application of gas hydrate.

The generalized seismic wavelets (GSWs) are defined by fractional derivatives of the Gaussian function, whose asymmetry allows them to represent seismic signals more accurately than the commonly used symmetrical Ricker wavelet. The latter is a particular case with a second derivative of the Gaussian function. To better obtain the GSW, which could be well-matched with seismic signals, this article proposes the $\boldsymbol {n}$ th power Fourier spectrum analysis method for GSWs. First, based on the $\boldsymbol {n}$ th power Fourier spectrum of GSWs, the proposed method builds the mathematical relationship between the frequency characteristics (e.g., central frequency and bandwidth) and the statistical properties (e.g., mean frequency and deviation). Second, according to the $\boldsymbol {n}$ th power Fourier spectrum, we propose a weighting calculation method for the derivative order $\boldsymbol {u}$ of the Gaussian function. This method could be used for estimating GSWs matched the seismic first-arrival record, which is conducive to improving the accuracy of seismic imaging, inversion, and $Q$ analysis. In theory, our proposed weighting method has better robustness and noise resistance than the traditional spectrum analysis method based on the power or amplitude spectrum. The experiment of synthetic noise, including first-arrival record and vertical seismic profiling (VSP) field data, shows the effectiveness of the proposed approach.

Hot Dry Rock (HDR) is a renewable energy source that has garnered attention due to its abundant reserves, widespread distribution, and consistent energy supply. However, the injection of cold water during the drilling and production process of HDR can alter the temperature of the rock in the HDR reservoir, leading to variations in its physical and mechanical properties near the wellbore. These changes can impact the stability and safety of the HDR wellbore. This study investigated the alterations in the physical and mechanical properties of HDR under different temperature conditions. The results revealed that there were negligible changes in the physical and mechanical properties when the temperature rose from 25 °C to 400 °C. However, noticeable changes occurred as the temperature increased from 400 °C to 800 °C, establishing 400 °C as the threshold for physical and mechanical property variations in the granite. Building upon these experimental findings, a segmented wellbore instability model was developed and validated. The model demonstrated that an increased temperature difference between the drilling fluid and the borehole corresponded to an expanded range of borehole failure. Furthermore, higher wellbore temperatures led to more pronounced disparities between the maximum and minimum principal stress of the borehole, rendering it more susceptible to instability. The research also uncovered that the optimal drilling position was influenced by temperature.

The pyroelectric effect and electron spin-state reconfiguration play a critical role in photocatalysis but are seldom investigated. This work is the first to exploit the fluctuating temperature (ΔT) between the cold-hot alternation in photocatalysis to drive the pyroelectric effect and electron spin-sate reconfiguration. FeS2/CuCo2O4(FS/CCO) hollow core-shell heterojunctions were prepared using hydrothermal and heating treatment methods. The FeS2(FS) can generate heat under near-infrared (NIR) light to provide the elevated temperature end required for the pyroelectric effect of CuCo2O4(CCO) under the influence of ΔT. With this thermoelectric and pyroelectric effect, CCO can release surface charges, generating spontaneous polarization, changing the electron (eg) filling number on Co surface sites, reversing the spin electron state, thus controlling the carriers' migration direction and enhancing their separation and migration rate, and finally prolonging their lifetime. As a result, the as-designed FS/CCO-15 composites yielded up to 19.5 mmol g−1h−1extraordinary photocatalytic performance, i.e., 10.2 and 6.45-fold of the pure FS (1.92 mmol g−1h−1) and CCO (3.02 mmol g−1h−1) under simulated sunlight, respectively. It also yielded up to 19.8% average apparent quantum yield. This work thoroughly explored the distinctive impact of the pyroelectric effect, electron spin-state reconfiguration, orbital coupling effect, and hydrogen evolution, guiding us and creating more possibilities for photocatalytic technology and efficiency using NIR light.

To optimize the conditions for the establishment of two-dimensional gel electrophoresis (2-DE) of soybean protein isolate (SPI), we investigated Ampholine mixture, anodic and cathodic electrolytes, loading amount of sample, acrylamide concentration, pH gradient and gel staining method in two-dimensional gel electrophoresis to optimize the protein imaging conditions in two-dimensional gel. The results of mixed-level design experiments showed that Ampholine, loading amount and gel staining method had significant effect (P < 0.05) on 2-DE of SPI. The optimal conditions were Ampholine mixture (pH 3–10 + pH 5–7 or pH 4–6 + pH 5–7), loading amount of 2 mg sample and silver staining. Although the acrylamide concentration of the gel, the pH gradient, the anodic and cathodic electrolyte solutions had significant statistical effects on the protein separation degree, the complexity of the protein composition and the visibility of the gel images were more inclined to the 12% gel, the 3–10 pH gradient and the H3PO4/NaOH electrolyte. According to the established conditions, the hydrolyzed products of SPI emulsion were determined by 2-DE, and the dynamic changes of protein in the process of enzymatic hydrolysis were described.

Shale reservoirs, characterized by their relatively low permeability and porosity, often employ hydraulic fracturing techniques to increase production during development. However, conventional large-scale hydraulic fracturing encounters challenges such as excessive water consumption, low flowback rates, and environmental concerns. Given the increasing scarcity of water resources and increased emphasis on sustainability environmental sustainability, hydraulic fracturing no longer meets the requirements for green and environmentally friendly extraction. The utilization of supercritical CO2fracturing technology emerges as a promising alternative, offering advantages such as reduced water usage and minimized environmental impact. Additionally, this technology allows for the sequestration of CO2underground, presenting an integrated approach to CO2geological storage and oil-gas extraction. Supercritical CO2possesses many unique physical and chemical properties. However, the micro-mechanisms governing its interaction with rock during fracturing, along with the mechanisms and propagation characteristics of fracture initiation, necessitate further in-depth investigation. This study aims to explore the development mechanisms of supercritical CO2fractures under the influence of single factor variables and natural fractures of different sizes (2 m, 4 m, and 6 m). To explore the interaction mechanisms between natural fractures and supercritical CO2fractures, single factor variable control experiments were conducted with natural fracture angles of 30 °, 45 °, and 60 °, and in-situ stress deviations of 3, 5, 7, and 9 MPa. Our research delves into the impact of natural fracture inclination angle, in-situ stress deviation, and natural fracture size on supercritical CO2fractures development. This comprehensive exploration unveils the intricate interaction mechanisms between natural fractures of different sizes and supercritical CO2fractures. Various control chart were studied, considering different natural fracture under diverse ground stresses and inclinations. The findings of this study bear theoretical significance and engineering application for enhancing efficiency in shale gas production.

The use of hydrothermal geothermal methods in Enhanced Geothermal Systems (EGS) presents challenges like reduced thermal storage life and high external energy consumption. Due to its stable heat production time and lower external energy demand, CO2has the potential to be substituted for H2O. The research zone for this study was chosen to be located in the HDR reservoir in the Gonghe Basin of Qinghai. A three-dimensional discrete fracture model based on a thermal-hydraulic-mechanical coupling method is established, where numerical simulations are conducted using COMSOL software. The discussion focuses on the comparison of heat production effects between H2O-EGS and CO2-EGS in different injection and extraction scenarios are discussed. The results indicate that by lowering the injection temperature and increasing the injection rate, the EGS net heat production rate can be increased, but it also accelerates the heat breakthrough time and shortens the reservoir life. Although CO2-EGS has a lower heat extraction rate in the early stage of thermal recovery than H2O-EGS, it has a longer stable heat production time and a more energy-efficient heat production process. Therefore, compared to H2O-EGS, CO2-EGS has more economic and social benefits.

The cyclic injection and production of fluids into and from underground gas storage (UGS) may lead to caprock failure, such as capillary sealing failure, hydraulic fracturing, shear failure, and fault slipping or dilation. The dynamic sealing capacity of a caprock-fault system is a critical constraint for safe operation, and is a key factor in determining the maximum operating pressure (MOP). This study proposed an efficient semi-analytical method for calculating changes in the in situ stress within the caprock. Next, the parameters of dynamic pore pressure, in situ stresses, and deformations obtained from reservoir simulations and geomechanical modeling were used for inputs for the analytical solution. Based on the calculated results, an experimental scheme for the coupled cyclic stress-permeability testing of caprock was designed. The stability analysis indicated that the caprock was not prone to fatigue shear failure under the current injection and production strategy, supported by the experimental results. The experimental results further reveal that the sealing capacity of caprock plugs may remain stable. This phenomenon is attributed to cyclic stress causing pore connectivity and microcrack initiation in certain plugs, while leading to pore compaction in others. A comparison between the dynamic pore pressure and the minimum principal stress suggests that the risk of tensile failure is extremely low. Furthermore, although the faults remain stable under the current injection and production strategies, the continuous increase in injection pressure may lead to an increased tendency for fault slip and dilation, which can cause fault slip ultimately. The MOPs corresponding to each failure mode were calculated. The minimum value of approximately 36.5 MPa at capillary sealing failure indicated that the gas breakthrough in the caprock occurred earlier than rock failure. Therefore, this minimum value can be used as the MOP for the target UGS.

Geologic structures such as faults and fractures play a vital role in reservoir development studies. Fault and fracture identification requires high-quality seismic amplitude data with good resolution and a high signal-to-noise ratio (SNR). An anticline fault-controlled carbonate structure in North China contains significant reserves of hydrocarbons. However, the heterogeneity of deeply buried carbonates (burial depth > 4000 m) results in poor resolution and low SNR of seismic amplitude data, making it challenging to distinguish fault edge characteristics under the buried structures. In this study, we apply an inverse Q-filtering method based on the Gabor transform and structure-oriented filtering to compensate for the weak signal of the seismic events and enhance the SNR under the deep buried carbonate rocks. We investigated fault and adjacent fracture zones in structurally complex deeply buried carbonate reservoirs by extracting seismic fracture attributes (fault likelihood, eigenvalue coherence, and curvature) and feedforward neural network spatial fracture distribution from high-resolution seismic amplitude data. Moreover, a fracture density prediction model based on seismic attributes, CNN (convolutional neural network), and LSTM (long short-term memory) is developed to predict spatial fracture density. The predicted fracture density results are verified with seismic fracture attributes, geological modeling, and FMI (formation micro-imager) logs. This integrated workflow can assist in identifying high-production zones in structurally complex and deeply buried carbonates reservoirs.

The Qingshankou Formation is the primary shale oil exploration and development target in the Songliao Basin, but controlling factors of shale oil enrichment, especially the role of faults and fractures, are still poorly understood. We identify fault geometry in the Qingshankou Formation based on seismic interpretation. We characterize natural fractures with outcrop and core observations, and thin-sections petrography. By integrating faults and fracture observations at various scales, tectonic history of the basin, and burial history of the studied reservoir formation, we explain the control of faults and fractures on shale oil enrichment. Results show that high-density fault systems, namely “T11″ and “T2″ fault systems, were developed at the top and bottom of Qingshankou Formation in the north of Songliao Basin. Both fault systems is characterized as a group of high-density, closely spaced small faults forming a fault belt, with evident multi-stage activities. Nature fracture categories identified including folding and faulting related fractures, bed-parallel fractures and overpressure fractures, while the former two are better developed. Tectonic movements have caused the structural uplift and subsidence to take place at different times in different parts of the basin. The structural uplift happened late in the study area, consequently the source rocks have gone through a long burial history and are well matured, which favors shale oil enrichment. Tectonic uplifts generated large numbers of fractures locally, effectively increase oil production by improving the migration pathways and storage space of shale oil. Fault systems of different scale also provided two-way channels for oil migration in Qingshankou Formation. Large-scale faults that cut through the full shale column allow the shale oil to migrate to the conventional reservoirs above and below the Qingshankou Formation. The smaller faults in the high-density fault belt within the Qingshankou Formation (Qing-1 Member) enhanced seepage capacity and connectivity of the shale reservoir. As a result, shale oil and conventional oil development in the study area can collaborate with one another. High-density, well connected natural fractures also played an important role by providing storage space and fluid flow conduit which is essential in shale oil reservoirs. However, these fractures along faults may migrate oil from shale reservoirs to neighboring conventional reservoirs.

Rock uniaxial compressive strength is a vital rock mechanics parameter, which accurate assessment is critical for high-efficiency unconventional reservoir development. However, its realization for standard cores is quite problematic due to difficulties and high costs related to the collection and preparation of samples. Unconventional fracturing treatment have evolved from single to composite lithology. This study collected shale and sandstone samples at different bedding angles (0°, 45°, 90°)to prepare the sandstone-shale composite samples at different interlayer ratios. It measured the prepared composites’ longitudinal wave and transverse wave velocities with ultrasonic velocity testing. The uniaxial compressive strength of the sandstone-shale composites with various bedding angles were tested via a servo rock triaxial testing machine. The anisotropic characteristics of the prepared sandstone-shale composites with various bedding angles were analyzed, and relation between the uniaxial compressive strength of the anisotropic sandstone-shale composite and P-wave velocity was derived and experimentally validated. The results show that: the wave velocity test results of the sandstone-shale combination show that with the increasing proportion of shale, the wave velocity of the longitudinal wave and the transverse wave both increase; The wave velocity results of different bedding planes in shale are as follows: Vp(0°)> Vp(45°)> Vp(90°). The average P-wave and S-wave velocities at 45° are 0.92, while the average P-wave and S-wave velocities at 90° are 0.85 compared to 0°; the P-wave and S-wave anisotropy of shale are both 0.14, and the shale shows significant anisotropy. In the sandstone-shale composite, the uniaxial compressive strength gradually decreases and the strain increases with the increase of shale proportion. The value of uniaxial compressive strength is UCS(0°) > UCS(90°) > UCS(45°). Based on the P-wave modulus, a fitting relationship formula for the uniaxial compressive strength of sandstone-shale composites with different bedding angles and interlayer ratios was established and verified. The anisotropic strength predictive formula established based on experimental data is simple, precise, and easy to obtain, with strong practicability. The present research results can provide proper technical support for sandstone-shale composite fracturing optimization and reservoir development.

Accurate prediction of CO2geological storage performance is of great guiding significance for oilfield development and management. The use of artificial neural networks is an effective method; however, insufficient data and certain errors caused by difficulties encountered during the measurement process make the traditional neural network fall into local optimization or overfitting. Therefore, in this study an optimized back propagation (BP) neural network based on the lion swarm optimization (LSO) algorithm was proposed. Firstly, the LSO algorithm was improved by combining a tent chaotic map and differential evolution to enhance its optimization capability. Secondly, the improved algorithm was used to obtain the optimal initial weights and thresholds of BP neural networks. Finally, by using the normalized sample data obtained by numerical simulation, five dimensionless variables were introduced to predict the CO2storage performance in reservoirs. Experimental results demonstrated that the proposed model yields a faster convergence speed and higher prediction accuracy compared with four existing neural networks. The root mean square errors on the training and test sets were 0.0234 and 0.0254, respectively, and the absolute error of more than 95% of the data was within 5%, which shows that the proposed method is feasible and effective in predicting the CO2storage performance and can serve as a good guide in oilfield development projects.

Non-contact sensors, intelligent electronics that interact with surrounding information with no physical contact, are highly desirable for human-machine interaction. Due to the increased sensing distance and expanded operation scope, it is anticipated the non-contact device exhibiting enhanced electrical output and detection range. Here, freeze-drying assisted 3D printing approach is employed to fabricate cellulose nanofiber (CNF)/MXene-based deep-trap hierarchical architecture for non-contact triboelectric nanogenerators, which exhibit excellent sensing performance for multi-direction motion monitoring. The intermolecular hydrogen bonding between CNF and MXene nanosheets facilitates the formation of a well-dispersed ink with suitable viscoelasticity for 3D printing. The incorporation of MXene nanosheets provides the printed scaffold with more open pores for increased charge generation. Meanwhile, the high electron trapping capability of MXene leads to a weakened electron escaping tendency and an increased decay time, which are beneficial for the device’s non-contact voltage output. Based on the as-prepared non-contact sensor, an all-printed sensing array and a 3D sensor are demonstrated for multi-site and multi-dimension motion trajectories monitoring, indicating its great potential in healthcare, safe navigation, and artificial intelligence.

The Ordos block experienced extension in the Mesoproterozoic, during which the Longshan–Kuanping and Haiyuan rifts developed on its southwest margin. The Jixian Group (1.6–1.4 Ga) is mainly exposed on the rimmed and ramp-type platforms at the Qishan County, southwest of the Ordos block. The deposition associated with the rimmed platform margin consists of platform facies, platform edge facies, and slope facies, which are characterized by small tidal creeks, mud cracks and scour troughs, rockfalls, respectively. The ramp-type platform is dominated by platform edge facies, shelf facies and slope facies and featured by intraclastic dolostones, tempestites and debris flow sediments respectively. The syndepositional normal faults were well developed at the early stage of the rifting. Fault-related cracks and folds present in the adjacent strata. The uplift of the footwall rimmed the platform. The drag structures determine the local sedimentary environment. In the final stage of the rifting, the fault movement stopped. The surrounding rocks were undeformed. The slope became less steep, resulting in the formation of ramp-type platform. The study area in the Jixian period, Mesoproterozoic is located at a palaeo-continental margin, which has already shown good petroleum prospectivity. A clear study on the type of carbonate platforms and the evolution of the platforms can help reduce exploration risks by improve the understanding of the presence of the source rocks.

The Hailar-Tamtsag Basin is a typical rift basin where two sets of regional caprocks are developed, i.e., mudstone caprocks (containing a small amount of tuff) developed in strong rifting stage and fault-depression stage, respectively. The caprocks have a cumulative thickness of 50–120 m in general, and a single-layer thickness of 20–50 m, interbedded with sandstone about 1–2 m thick. The large set of mudstone is distributed continuously, as pure mudstone caprock. Forty-three mudstone and tuff samples were taken to perform displacement pressure test with our independently developed displacement pressure tester. Test result shows that the displacement pressure is 0.04–10.00 MPa, which is equivalent to 0.09–20.01 MPa after being corrected to the actual burial depth. As the burial depth increases, the displacement pressure rises gradually, and is 1–10 times greater than that of oil-bearing sandstone or conglomerate reservoir at the same burial depth. The difference between displacement pressure of mudstone caprock and sandstone or conglomerate reservoir increases greatly if the burial depth exceeds 1000 m. Because of the displacement pressure difference between caprock and reservoir, the maximum height of hydrocarbon column sealed by the caprock ranges from 300 m to 2000 m, much higher than the height of the trap closure at the same burial depth. No hydrocarbons will leak through such caprocks. Analysis of the reservoir GOI, homogeneous temperature, and crude maturity of both deep and shallow reservoirs in Well Wu-20 in the Wuerxun Depression shows that Damoguaihe II Member reservoir is a secondary reservoir developed during adjustment of early reservoir. It is mainly distributed in inverted structures. Faulting is one of the main factors breaking the integrity of caprocks. Three kinds of faults are often related to the migration of hydrocarbons across regional caprocks: the first type refers to the positive inverted faults breaking the early sealing conditions and making the hydrocarbons accumulated in the early period re-migration; the second type refers to the faults with shear mudstone smear structures which lose their continuity and open vertically when the fault throws exceed 5 times of the mudstone thickness; the third type refers to the normal faults developed in the structural inversion stage, which have a typical cataclastic structure and are easy to cause vertical migration of hydrocarbons. Hydrocarbon enriched horizons of the rift basins are co-controlled by “fault-caprock”. Specifically, 95% of the geological reserve is controlled by regional caprocks, and only 5% is controlled by open faults, secondary oil/gas reservoirs are developed over regional caprocks.

Between the completion of the mesenchymal stem cell (MSCs) preparation and the transplantation into the patient, there is a time interval during which the quality control and transport of MSC products occur, which usually involves suspending the cells in normal saline in an oxygen–glucose deprivation (OGD) microenvironments. Thus, how to effectively maintain MSC viability during the abovementioned time interval is bound to play a significant role in the therapeutic effect of MSC-based therapies. Recently, menstrual blood–derived endometrial stem cells (MenSCs) have attracted extensive attention in regenerative medicine due to their superior biological characteristics, including noninvasive protocols for their collection, abundant source material, stable donation, and autotransplantation. Therefore, this study aimed to mainly determine the effect of storage temperature on the maintenance of MenSC viabilities in an OGD microenvironment, and to preliminarily explore its potential mechanism. Simultaneously, the effects of solvents commonly used in the clinic on MenSC viability were also examined to support the clinical application of MenSCs. Consequently, our results demonstrated that in the OGD microenvironment, a nonfreezing low temperature (4°C) was suitable and cost-effective for MenSC storage, and the maintenance of MenSC viability stored at 4°C was partly contributed by the sustained releases of autophagy-produced energy. Furthermore, the addition of human serum albumin effectively inhibited the cell sedimentations in the MenSC suspension. These results provide support and practical experience for the extensive application of MenSCs in the clinic.

•A novel biochar based MgO was synthesized via pyrolysis of MgCl2activated sludge.•The MgO-sludge biochar showed excellent adsorption ability for phosphate.•pH and ionic strength significantly impacted the sorption of phosphate.•Phosphate was mainly adsorbed by MgO particle on the surface of Mg-SB.

To investigate the effects of a slab edge and varying slab geometry on the mantle flow systems beneath south central Alaska, a total of 971 pairs of teleseismic shear wave (SKS, SKKS, and PKS) and 65 pairs of local S wave splitting parameters (fast orientations and splitting times) are measured using data from the USArray and other networks. The Pacific‐Yakutat slab edge separates two regions with different characteristics of the splitting measurements. The area to the west of the slab edge has greater splitting times and mostly trench parallel fast orientations, and the area to the east is dominated by smaller splitting times and spatially varying fast orientations. The spatial distribution of the splitting parameters and results of anisotropy layering and depth analyses can be explained by a model involving three flow systems. The sub‐slab flow initially entraining with the shallow‐dipping Yakutat slab deflects to a trench‐parallel direction due to slab retreat and an increase in slab dip, and flows northeastward toward the slab edge, where it splits into two branches. The first branch enters the mantle wedge as a toroidal flow and flows southwestward along the slab, and the second branch continues approximately eastward. The flowlines of the toroidal and continued flow systems are approximately orthogonal to each other in the vicinity of the slab edge, producing the observed small splitting times and spatially varying fast orientations. Alaska is home to some of the largest earthquakes and violent volcanic eruptions on Earth. These natural hazards are mostly caused by the subduction of the Pacific Plate beneath the North American Plate along the Aleutian Trench. Such subduction has not only led to the rising of the magnificent mountain belts seen on the surface, but also caused the mantle beneath the lithosphere to flow. By analyzing elastic waves produced by earthquakes that are at least 9,000 km away from the study area and recorded by seismographs deployed in south central Alaska, we have established a flow model that can adequately explain the observations. The model suggests that materials beneath the subducting Pacific‐Yakutat slab are driven northeastward by the southward retreat of the Aleutian Trench. At the eastern edge of the subducting slab, they split into two branches, with one continuing eastward and another going around the slab edge and entering the area above the slab. The observations and the new flow model can be used to better understand forces and processes inside the Earth, which are the ultimate reasons for the earthquakes and volcanoes in tectonically active areas such as south‐central Alaska. XKS and local S wave splitting analyses suggest splitting of sub‐slab flow into two branches after passing the eastern edge of the slabOne is a SE directed continuation of sub‐slab flow after passing the slab edge, the other enters the mantle wedge and flows to the SWThe two flow systems have nearly orthogonal directions, leading to weak azimuthal anisotropy in the vicinity of the slab edge XKS and local S wave splitting analyses suggest splitting of sub‐slab flow into two branches after passing the eastern edge of the slab One is a SE directed continuation of sub‐slab flow after passing the slab edge, the other enters the mantle wedge and flows to the SW The two flow systems have nearly orthogonal directions, leading to weak azimuthal anisotropy in the vicinity of the slab edge

To discern spatial and explore possible existence of temporal variations of upper crustal anisotropy in an ∼15 km section of the San Jacinto Fault Zone (SJFZ) that is composed of the Buck Ridge and Clark faults in southern California, we conduct a systematic shear wave splitting investigation using local S‐wave data recorded by three broadband seismic stations located near the surface expression of the SJFZ. An automatic data selection and splitting measurement procedure is first applied, and the resulting splitting measurements are then manually screened to ensure reliability of the results. Strong spatial variations in crustal anisotropy are revealed by 1,694 pairs of splitting parameters (fast polarization orientation and splitting delay time), as reflected by the dependence of the resulting splitting parameters on the location and geometry of the raypaths. For raypaths traveling through the fault zones, the fast orientations are dominantly WNW‐ESE which is parallel to the faults and may be attributed to fluid‐filled fractures in the fault zones. For non‐fault‐zone crossing raypaths, the fast orientations are dominantly N–S which are consistent with the orientation of the regional maximum compressive stress. A three‐dimensional model of upper crustal anisotropy is constructed based on the observations. An increase in the raypath length normalized splitting times is observed after the 03/11/2013 M4.7 earthquake, which is probably attributable to changes in the spatial distribution of earthquakes before and after the M4.7 earthquake rather than reflecting temporal changes of upper crustal anisotropy. A 3‐D model of upper crustal anisotropy in the vicinity of the SJFZ is proposed based on 1,694 pairs of splitting parameters at three stationsFast orientations are fault parallel for rays traversing the fault zones, and are parallel to regional stress for non‐fault‐crossing raysApparent temporal variations of the splitting parameters after an M4.7 earthquake are mostly caused by changes in source distribution A 3‐D model of upper crustal anisotropy in the vicinity of the SJFZ is proposed based on 1,694 pairs of splitting parameters at three stations Fast orientations are fault parallel for rays traversing the fault zones, and are parallel to regional stress for non‐fault‐crossing rays Apparent temporal variations of the splitting parameters after an M4.7 earthquake are mostly caused by changes in source distribution

Shale oil has become an important oil resource over the past decade. The oil storage behavior, including the adsorbed oil and free oil, is one of the most important controlling factors for shale oil production. Because the shale oil storage behavior is largely determined by the fluid and solid interactions, this review first evaluates the shale mineralogy, pore structure, and oil properties. Then, the experimental methods to characterize the free oil and adsorbed oil are reviewed. The relationship between the oil storage behavior and shale and oil properties are then discussed. It is concluded from the literature work that the organic matter has the highest adsorption capacity for oil, followed by clay minerals, quartz, and calcite. While it is well-known that heavier oil components are adsorbed more than the lighter components, a relationship between the ratio of pore size to oil molecular size and the ratio of free oil to adsorbed oil is suggested and plotted. Finally, it is found from the literature that accurate experimental methods and theoretical models on free oil and adsorbed oil characterization are still missing; therefore, these topics require attention in future researches on shale oil.

The mantle transition zone (MTZ) discontinuities beneath the Tanzania Craton and the Eastern and Western Branches of the East African Rift System are imaged by stacking over 7,100 receiver functions. The mean thickness of the MTZ beneath the Western Branch and Tanzania Craton is about 252 km, which is comparable to the global average and is inconsistent with the existence of present‐day thermal upwelling originating from the lower mantle. In contrast, beneath the Eastern Branch, an up to 30 km thinning of the MTZ is observed and is attributable to upwelling of higher temperature materials from either the upper MTZ or the lower mantle. The observations are in agreement with the hypothesis that rifting in Africa is primarily driven by gradients of gravitational potential energy and lateral variations of basal traction force along zones of significant changes of lithospheric thickness such as the edges of the Tanzania Craton. The 410 and 660 km discontinuities beneath the Tanzania Craton (TC) and the Eastern and Western Branches are imaged using receiver functionsNormal MTZ thickness is found beneath the Western Branch and the TC, implying the absence of significant thermal upwelling from lower mantleWhile the cause of a 30 km MTZ thinning beneath the Eastern Branch remains enigmatic, overall results are inconsistent with active rifting