High-conductance Channel Research Articles

OSCP subunit of mitochondrial ATP synthase: role in regulation of enzyme function and of its transition to a pore.

The permeability transition pore (PTP) is a latent, high-conductance channel of the inner mitochondrial membrane. When activated, it plays a key role in cell death and therefore in several diseases. The investigation of the PTP took an unexpected turn after the discovery that cyclophilin D (the target of the PTP inhibitory effect of cyclosporin A) binds to FO F1 (F)-ATP synthase, thus inhibiting its catalytic activity by about 30%. This observation was followed by the demonstration that binding occurs at a particular subunit of the enzyme, the oligomycin sensitivity conferral protein (OSCP), and that F-ATP synthase can form Ca2+ -activated, high-conductance channels with features matching those of the PTP, suggesting that the latter originates from a conformational change in F-ATP synthase. This review is specifically focused on the OSCP subunit of F-ATP synthase, whose unique features make it a potential pharmacological target both for modulation of F-ATP synthase and its transition to a pore. LINKED ARTICLES: This article is part of a themed section on Mitochondrial Pharmacology: Featured Mechanisms and Approaches for Therapy Translation. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.22/issuetoc.

Propagation, proppant transport and the evolution of transport properties of hydraulic fractures

Hydraulic fracturing is a widely used method for well stimulation to enhance hydrocarbon recovery. Permeability, or fluid conductivity, of the hydraulic fracture is a key parameter to determine the fluid production rate, and is principally conditioned by fracture geometry and the distribution of the encased proppant. A numerical model is developed to describe proppant transport within a propagating blade-shaped fracture towards defining the fracture conductivity and reservoir production after fracture closure. Fracture propagation is formulated based on the PKN-formalism coupled with advective transport of an equivalent slurry representing a proppant-laden fluid. Empirical constitutive relations are incorporated to define rheology of the slurry, proppant transport with bulk slurry flow, proppant gravitational settling, and finally the transition from Poiseuille (fracture) flow to Darcy (proppant pack) flow. At the maximum extent of the fluid-driven fracture, as driving pressure is released, a fracture closure model is employed to follow the evolution of fracture conductivity with the decreasing fluid pressure. This model is capable of accommodating the mechanical response of the proppant pack, fracture closure of potentially contacting rough surfaces, proppant embedment into fracture walls, and most importantly flexural displacement of the unsupported spans of the fracture. Results show that reduced fluid viscosity increases the length of the resulting fracture, while rapid leak-off decreases it, with both characteristics minimizing fracture width over converse conditions. Proppant density and size do not significantly influence fracture propagation. Proppant settling ensues throughout fracture advance, and is accelerated by a lower viscosity fluid or greater proppant density or size, resulting in accumulation of a proppant bed at the fracture base. ‘Screen-out’ of proppant at the fracture tip can occur where the fracture aperture is only several times the diameter of the individual proppant particles. After fracture closure, proppant packs comprising larger particles exhibit higher conductivity. More importantly, high-conductivity flow channels are necessarily formed around proppant banks due to the flexural displacement of the fracture walls, which offer preferential flow pathways and significantly influence the distribution of fluid transport. Higher compacting stresses are observed around the edge of proppant banks, resulting in greater depths of proppant embedment into the fracture walls and/or an increased potential for proppant crushing.

Constructal Optimization for Cooling a Non-Uniform Heat Generating Radial-Pattern Disc by Conduction.

A heat conduction model in a radial-pattern disc by considering non-uniform heat generation (NUHG) is established in this paper. A series of high conductivity channels (HCCs) are attached on the rim of the disc and extended to its center. Constructal optimizations of the discs with constant and variable cross-sectional HCCs are carried out, respectively, and their maximum temperature differences (MTDs) are minimized based on analytical method and finite element method. Besides, the influences of the NUHG coefficient, HCC number and width coefficient on the optimal results are studied. The results indicate that the deviation of the optimal constructs obtained from the analytical method and finite element method are comparatively slight. When the NUHG coefficient is equal to 10, the minimum MTD of the disc with 25 constant cross-sectional HCCs is specifically reduced by 48.8% compared to that with 10 HCCs. As a result, the heat conduction performance (HCP) of the disc can be efficiently improved by properly increasing the number of HCCs. The minimum MTD of the disc with variable cross-sectional HCC is decreased by 15.0% when the width coefficient is changed from 1 to 4. Therefore, the geometry of variable cross-sectional HCC can be applied in the constructal design of the disc to a better heat transfer performance. The constructal results obtained by investigating the non-uniform heat generating case in this paper can contribute to the design of practical electronic device to a better heat transfer performance.

Design and Development of Nitrogen Doped Nano Porous Activated Carbon As Electrode Active Material for Supercapacitors

Supercapacitors (SCs), which have been extensively applied in consumer electronics and energy management, are alternative energy storage devices for their high power densities. Electrochemical double layer capacitors (EDLCs) storing charge on the interface between electrode and electrolyte and pseudocapacitors associated with rapid surface redox reaction are the two categories of SCs. The former requires carbon materials with high specific surface area, high conductivity and suitable pore channels to achieve promising specific capacitance and long cycling life. N-doped activated carbon has been synthesized using cork, a biomass waste obtained from the bark of oak trees as carbon source by a two step thermal annealing process. The obtained carbon material possesses honey comb structure with microporous structure, high specific surface area (up to 1172 m2 /g) and large pore volume (0.12 cm3/g). Besides, N-doped carbon (CAC 1:1) with a nitrogen content of 5.17 wt.% exhibits a maximum specific capacitance of 185 F/g at a current density of 1 A/g in 6 M KOH aqueous electrolyte. It also displays a good rate performance, i.e., 176 F/g at 10 A/g and cycle stability, i.e., ~80.3% retention after 1175 charge-discharge cycles. The assembled CAC1:1 symmetric capacitor exhibits a maximum energy density of 20.2 Wh/kg at a power density of 448 W/kg within a voltage range of 0 - 1.8 V in 1M Na2SO4 aqueous electrolyte. The unique porous structure and N-doping characteristic endue the electrode material a potential candidate for high-performance supercapacitors.

Reverse-Blocking Normally-OFF GaN Double-Channel MOS-HEMT With Low Reverse Leakage Current and Low ON-State Resistance

An MOS field plate-protected Schottky-drain (gated Schottky-drain) is successfully integrated on a double-channel AlGaN/GaN MOS-HEMT to provide reverse blocking capability. The leakage suppression MOS field plate is deployed on the etched upper GaN channel layer after a barrier fully recess process, leading to a low reverse OFF-state leakage current of −20 nA/mm (at −100 V). The drain metal is deployed adjacent to the MOS field plate, contacting the upper MOS-channel and lower heterojunction channel from the sidewall. A metal-2DEG Schottky contact with a low turn-ON voltage of 0.5 V is achieved. Since the lower channel (below the MOS field plate) is separated from the etched surface of upper GaN channel layer, a high-conductivity MOS-gated channel with a sheet resistance of 806 $\Omega$ /Square is obtained. The device exhibits a threshold voltage of +0.6 V (at $10~\mu \text{A}$ /mm and +1.9 V from linear extrapolation) and an ON-resistance of ~18 $\Omega {\cdot} \text {mm}$ . Besides, a high forward (and reverse) breakdown voltage of 790 V (and −656 V, all at $10~\mu \text{A}$ /mm) is achieved.

Operating temperature and temperature gradient effects on the photovoltaic properties of dye sensitized solar cells assembled with thermoelectric–photoelectric coaxial nanofibers

In this work, the coaxial electrospinning technique was used to prepare coaxial nanofibers (CNFs) consisting of N-type thermoelectric Nb doped SrTiO3 (Nb/STO) coated with a thin layer of TiO2, which was referred to simply as TiO2–Nb/STO. Then a certain amount of TiO2–Nb/STO CNFs was added into the TiO2 nanocrystalline layer to obtain the composite photoanode of dye-sensitized solar cells (DSSCs). Owing to the high electrical conductivity and straightforward electron transport channels for TiO2-Nb/STO CNFs, the device assembled with 10 wt% TiO2-Nb/STO CNFs demonstrated the highest power conversion efficiency (PCE) of 7.25%, which was significantly higher than the reference one (6.45%). In order to investigate the temperature gradient (ΔT) on the photovoltaic performances of DSSCs assembled with TiO2-Nb/STO CNFs, a cold source (0 °C) and a heat source (75 °C) was placed on the Pt counter electrode to create a negative ΔT (−7 K) and a positive ΔT (+7 K), respectively. The mechanism model of thermoelectric effect on the charge transfer dynamic process of DSSCs under different ΔT is established and explained. Data showed that in response to temperature fluctuations, the performance of both reference device and 10% device could be affected. The cold source enable the reference device to obtain the highest PCE of 6.75% due to an increase in open-circuit voltage (Voc). This behavior is mainly ascribed to the reduced internal carrier recombination rates, caused by decreased carrier concentrations at low operating temperature. Herein, the operating temperature refers to an average value between the temperatures on both sides of each device. On the contrary, 10% device applying hot source results in an increase of short-circuit current density (Jsc) and fill factor (FF), yielding the highest PCE of 7.61% despite the negative effects of high operating temperature on Voc. It is found that the hot source benefits the fast electron transfer for 10% device under the synergistic effect of thermoelectromotive force and fast charge carrier diffusion. These results further confirm that the improved photovoltaic performance of 10% device under the condition of hot source was primarily attributed to the thermoelectric Seebeck effect of TiO2-Nb/STO CNFs.

Improved Electrochemical Performance Based on Nanostructured SnS2@CoS2\u2013rGO Composite Anode for Sodium-Ion Batteries

A promising anode material composed of SnS2@CoS2 flower-like spheres assembled from SnS2 nanosheets and CoS2 nanoparticles accompanied by reduced graphene oxide (rGO) was fabricated by a facile hydrothermal pathway. The presence of rGO and the combined merits of SnS2 and CoS2 endow the SnS2@CoS2–rGO composite with high conductivity pathways and channels for electrons and with excellent properties as an anode material for sodium-ion batteries (SIBs). A high capacity of 514.0 mAh g−1 at a current density of 200 mA g−1 after 100 cycles and a good rate capability can be delivered. The defined structure and good sodium-storage performance of the SnS2@CoS2–rGO composite demonstrate its promising application in high-performance SIBs.

Mobility Enhancement in Amorphous In-Ga-Zn-O Thin-Film Transistor by Induced Metallic in Nanoparticles and Cu Electrodes.

In this work, we fabricated a high-mobility amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) based on alumina oxide (AlO) passivation layer (PVL) and copper (Cu) source/drain electrodes (S/D). The mechanism of the high mobility for a-IGZO TFT was proposed and experimentally demonstrated. The conductivity of the channel layer was significantly improved due to the formation of metallic In nanoparticles on the back channel during AlO PVL sputtering. In addition, Ar atmosphere annealing induced the Schottky contact formation between the Cu S/D and the channel layer caused by Cu diffusion. In conjunction with high conductivity channel and Schottky contact, the a-IGZO TFT based on Cu S/D and AlO PVL exhibited remarkable mobility of 33.5–220.1 cm/Vs when channel length varies from 60 to 560 m. This work presents a feasible way to implement high mobility and Cu electrodes in a-IGZO TFT, simultaneously.

Constraint energy minimizing generalized multiscale finite element method in the mixed formulation

This paper presents a novel mass-conservative mixed multiscale method for solving flow equations in heterogeneous porous media. The media properties (the permeability) contain multiple scales and high contrast. The proposed method solves the flow equation in a mixed formulation on a coarse grid by constructing multiscale basis functions. The resulting velocity field is mass conservative on the fine grid. Our main goal is to obtain first-order convergence in terms of the mesh size which is independent of local contrast. This is achieved, first, by constructing some auxiliary spaces, which contain global information that can not be localized, in general. This is built on our previous work on the Generalized Multiscale Finite Element Method (GMsFEM). In the auxiliary space, multiscale basis functions corresponding to small (contrast-dependent) eigenvalues are selected. These basis functions represent the high-conductivity channels (which connect the boundaries of a coarse block). Next, we solve local problems to construct multiscale basis functions for the velocity field. These local problems are formulated in the oversampled domain taking into account some constraints with respect to auxiliary spaces. The latter allows fast spatial decay of local solutions and, thus, allows taking smaller oversampled regions. The number of basis functions depends on small eigenvalues of the local spectral problems. Moreover, multiscale pressure basis functions are needed in constructing the velocity space. Our multiscale spaces have a minimal dimension, which is needed to avoid contrast-dependence in the convergence. The method's convergence requires an oversampling of several layers. We present an analysis of our approach. Our numerical results confirm that the convergence rate is first order with respect to the mesh size and independent of the contrast.

Achieving of Flexible, Free‐Standing, Ultracompact Delaminated Titanium Carbide Films for High Volumetric Performance and Heat‐Resistant Symmetric Supercapacitors

AbstractThe volumetric performance of supercapacitors (SCs), besides the gravimetric performance, is attracting an increasing attention due to the fast development of electric vehicles and smart devices. Here, a unique design of symmetric supercapacitor material is reported with a tight face‐to‐face architecture by applying a high pressure to the delaminated Ti3C2 (d‐Ti3C2) films. The high pressure makes the d‐Ti3C2 films achieve an increased density, high electron conductivity, good wettability, and abundant interconnected mesopore channels to promote ion transport efficiently, that is, more cations can intercalate/deintercalate in the charging–discharging process. As a result, with the increase of the applying pressure, the d‐Ti3C2 film pressured at 40 MPa in 1 m Li2SO4 exhibits an ultrahigh capacitance of over 633 F cm−3, outstanding energy density, and cyclic stability. Especially, the corresponding SC in 1 m 1‐ethyl‐3‐methylimidazolium tetrafluoroborate/acetonitrile organic electrolyte shows a high volumetric energy density of 41 Wh L−1, which is the highest value reported for the SCs based on MXene materials in organic electrolytes. The outstanding volumetric electrochemical performance and thermal stability of the SCs based on the ultracompact d‐Ti3C2 film demonstrate their promising potential as forceful power sources for small electronic devices.

High-Conductance Channel Formation in Yeast Mitochondria is Mediated by F-ATP Synthase e and g Subunits

Background/Aims: The permeability transition pore (PTP) is an unselective, Ca²⁺-dependent high conductance channel of the inner mitochondrial membrane whose molecular identity has long remained a mystery. The most recent hypothesis is that pore formation involves the F-ATP synthase, which consistently generates Ca²⁺-activated channels. Available structures do not display obvious features that can accommodate a channel; thus, how the pore can form and whether its activity can be entirely assigned to F-ATP synthase is the matter of debate. In this study, we investigated the role of F-ATP synthase subunits e, g and b in PTP formation. Methods: Yeast null mutants for e, g and the first transmembrane (TM) α-helix of subunit b were generated and evaluated for mitochondrial morphology (electron microscopy), membrane potential (Rhodamine123 fluorescence) and respiration (Clark electrode). Homoplasmic C23S mutant of subunit a was generated by in vitro mutagenesis followed by biolistic transformation. F-ATP synthase assembly was evaluated by BN-PAGE analysis. Cu²⁺ treatment was used to induce the formation of F-ATP synthase dimers in the absence of e and g subunits. The electrophysiological properties of F-ATP synthase were assessed in planar lipid bilayers. Results: Null mutants for the subunits e and g display dimer formation upon Cu²⁺ treatment and show PTP-dependent mitochondrial Ca²⁺ release but not swelling. Cu²⁺ treatment causes formation of disulfide bridges between Cys23 of subunits a that stabilize dimers in absence of e and g subunits and favors the open state of wild-type F-ATP synthase channels. Absence of e and g subunits decreases conductance of the F-ATP synthase channel about tenfold. Ablation of the first TM of subunit b, which creates a distinct lateral domain with e and g, further affected channel activity. Conclusion: F-ATP synthase e, g and b subunits create a domain within the membrane that is critical for the generation of the high-conductance channel, thus is a prime candidate for PTP formation. Subunits e and g are only present in eukaryotes and may have evolved to confer this novel function to F-ATP synthase.

Evolution of a Diffusion Channel in an Inhomogeneous Electric Field of the KrF-Laser Pump Discharge

The results of studying the 2D-simulation of evolution of a diffusion channel in the KrF-laser pump discharge initiated by the pin on the cathode surface are presented. It is shown that during the pump pulse, the inhomogeneity passes successively through three stages: a plasma spot on the cathode surface, a diffuse channel, and a high-conductivity channel. From the analysis of the dynamics of spatial distribution of spontaneous emission on the B0-X transition of the KrF molecule in such a discharge, it is obtained that the channel can work as an amplifying medium while the volumetric form of its glow is maintained. Despite the contraction of the channel into a narrow cord at the end of the pump pulse, the distribution of the radiation energy over the entire pulse has the shape of a torch with the width at the anode of ~0.6 cm.

Constructal optimizations for “+” shaped high conductivity channels based on entransy dissipation rate minimization

Constructal optimizations of the elemental and first order “+” shaped high conductivity channels (HCCs) in the square bodies are carried out based on entransy dissipation rate (EDR) minimization. The optimal shapes of the HCCs and minimum EDRs of the bodies are derived. The results show that there exist optimal geometrical parameters of the first order “+” shaped HCC which lead to triple minimum dimensionless EDR of the body. The optimal shape of the first order “+” shaped HCC derived by EDR minimization makes the global heat conduction performance (GHCP) of the square body improve, and the temperature gradient more homogeneous. The optimal design scheme of the “+” shaped HCC with minimum EDR can be adopted in the heat dissipation problem of the electronic device to improve its GHCP.

Heat conduction constructal optimization for nonuniform heat generating area based on triangular element

A nonuniform heat generating model in a triangular area is built in this paper. Constructal optimizations of the models with constant and discrete variable cross-sectional high conductivity channels (HCCs) are performed by choosing minimum maximum temperature difference (MTD) as optimization objective. Optimal constructs of the triangular element and triangular first order assembly (TFOA) are obtained, respectively. The results indicate that for the TFOA with constant cross-sectional HCCs, the minimum MTD is reduced by increasing the nonuniform heat generating (NUHG) coefficient p, namely the heat conduction performance (HCP) is better when more heat generation is generated near the heat sink. The HCP of TFOA is also improved by increasing its complexity of internal structure. Furthermore, the minimum MTD of TFOA with discrete variable cross-sectional HCCs is reduced by 12.57% than that with constant cross-section. Therefore, the HCP of TFOA can be further improved by adopting discrete variable cross-sectional structures for the HCCs. The optimization results obtained from numerical calculations can provide some theoretical guidelines for the optimal heat dissipation designs of electronic devices.

A high-conductance chemo-optogenetic system based on the vertebrate channel Trpa1b

Optogenetics is a powerful research approach that allows localized optical modulation of selected cells within an animal via the expression of genetically encoded photo-excitable ion channels. Commonly used optogenetic techniques rely on the expression of microbial opsin variants, which have many excellent features but suffer from various degrees of blue spectral overlap and limited channel conductance. Here, we expand the optogenetics toolbox in the form of a tunable, high-conductance vertebrate cation channel, zTrpa1b, coupled with photo-activated channel ligands, such as optovin and 4g6. Our results demonstrate that zTrpa1b/ligand pairing offers high light sensitivity, millisecond-scale response latency in vivo, as well as adjustable channel off latency. Exogenous in vivo expression of zTrpa1b in sensory neurons allowed subcellular photo-activation, enabling light-dependent motor control. zTrpa1b/ligand was also suitable for cardiomyocyte pacing, as shown in experiments performed on zebrafish hearts in vivo as well as in human stem cell-derived cardiomyocytes in vitro. Therefore, zTrpa1b/optovin represents a novel tool for flexible, high-conductance optogenetics.

Mitochondrial permeability transition pore: sensitivity to opening and mechanistic dependence on substrate availability

Mitochondrial Ca2+ uptake has a key role in cellular Ca2+ homeostasis. Excessive matrix Ca2+ concentrations, especially when coincident with oxidative stress, precipitate opening of an inner mitochondrial membrane, high-conductance channel: the mitochondrial permeability transition pore (mPTP). mPTP opening has been implicated as a final cell death pathway in numerous diseases and therefore understanding conditions dictating mPTP opening is crucial for developing targeted therapies. Here, we have investigated the impact of mitochondrial metabolic state on the probability and consequences of mPTP opening. Isolated mitochondria were energised using NADH- or FADH2-linked substrates. The functional consequences of Ca2+-induced mPTP opening were assessed by Ca2+ retention capacity, using fluorescence-based analysis, and simultaneous measurements of mitochondrial Ca2+ handling, membrane potential, respiratory rate and production of reactive oxygen species (ROS). Succinate-induced, membrane potential-dependent reverse electron transfer sensitised mitochondria to mPTP opening. mPTP-induced depolarisation under succinate subsequently inhibited reverse electron transfer. Complex I-driven respiration was reduced after mPTP opening but sustained in the presence of complex II-linked substrates, consistent with inhibition of complex I-supported respiration by leakage of matrix NADH. Additionally, ROS generated at complex III did not sensitise mitochondria to mPTP opening. Thus, cellular metabolic fluxes and metabolic environment dictate mitochondrial functional response to Ca2+ overload.

Investigation of a Carbon Nanotube-Encapsulated Fe1−Xs Composite as Anode for Sodium-Ion Batteries

Owing to the long life span and high energy density, lithium-ion batteries (LIBs) have received worldwide application in our daily lives for powering portable devices and burdening electric vehicles (EVs) and hybrid EVs. A promising anode material consisting of Fe1−xS nanoparticles and bamboo-like carbon nanotubes (CNTs) has been designed and prepared by an effective in situ chemical transformation. The resultant Fe 1−xS@CNTs with a three-dimensional network not only provide high conductivity paths and channels for electrons and ions but also offer the combined merits of iron sulfide and CNTs in electrochemical energy storage applications, leading to outstanding performance as an anode material for sodium-ion batteries. When tested in a half-cell, a high capacity of 449.2 mAh g−1 can be retained after 200 cycles at 500 mA g−1, corresponding to a high retention of 97.4%. Even at 8000 mA g−1, a satisfactory capacity of 326.3 mAh g−1 can be delivered. When tested in the full cell, a capacity of 438.5 mAh g−1 with capacity retention of 85.0% is manifested after 80 cycles based on the mass of the anode. The appealing structure and electrochemical performance of this material demonstrate its great promise for applications in practical rechargeable batteries.

Geological heterogeneity: Goal-oriented simplification of structure and characterization needs

Abstract Geological heterogeneity, i.e. the spatial variability of discrete hydrogeological units, is investigated in an aquifer analog of glacio-fluvial sediments to determine how such a geological structure can be simplified for characterization needs. The aquifer analog consists of ten hydrofacies whereas the scarcity of measurements in typical field studies precludes such detailed spatial models of hydraulic properties. Of particular interest is the role of connectivity of the hydrofacies structure, along with its effect on the connectivity of mass transport, in site characterization for predicting early arrival times. Transport through three realizations of the aquifer analog is modeled with numerical particle tracking to ascertain the fast flow channel through which early arriving particles travel. Three simplification schemes of two-facies models are considered to represent the aquifer analogs, and the velocity within the fast flow channel is used to estimate the apparent hydraulic conductivity of the new facies. The facies models in which the discontinuous patches of high hydraulic conductivity are separated from the rest of the domain yield the closest match in early arrival times compared to the aquifer analog, but assuming a continuous high hydraulic conductivity channel connecting these patches yields underestimated early arrivals times within the range of variability between the realizations, which implies that the three simplification schemes could be advised but pose different implications for field measurement campaigns. Overall, the results suggest that the result of transport connectivity, i.e. early arrival times, within realistic geological heterogeneity can be conserved even when the underlying structural connectivity is modified.

Overview of Carbon Dioxide Injection and Water-Alternating-Gas Sensitivity

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 179569, “Overview of CO2 Injection and WAG Sensitivity in SACROC,” by Reza Barati Ghahfarokhi, SPE, The University of Kansas, and Steve Pennell, Michael Matson, SPE, and Mark Linroth, SPE, Kinder Morgan, prepared for the 2016 SPE Improved Oil Recovery Conference, Tulsa, 11–13 April. The paper has not been peer reviewed. This paper presents an overview of the SACROC Unit’s activity focusing on different carbon dioxide (CO2) injection and water-alternating-gas (WAG) projects that have made the SACROC unit one of the most successful CO2 injection projects in the world. The main objectives of this were was to review CO2 injection and injection-rate losses with respect to the CO2/WAG miscible displacement process in the SACROC Unit and recommend an injection strategy for WAG-sensitive patterns. Introduction The Kelly-Snyder field is the largest of a chain of fields along the Pennsylvanian Horseshoe atoll in the Midland Basin. Within this field, the Scurry Area Canyon Reef Operators Committee (SACROC) Unit covers approximately 56,000 acres with 2,800 million STB of original oil in place (OOIP). Limestone is the dominant mineral within the Canyon Reef formation, and less than 3% of the formation exists as thin sections of shale (1–10 ft in thickness) that are important stratigraphic markers. The formation is divided into four major zones: the Cisco, the Green Zone (GZ), the Upper Middle Canyon, and the Lower Middle Canyon (LMC). Of these, the GZ shows the highest matrix permeability, significant nonmatrix-flow features, and high-conductivity channels. Moreover, the transition zone (TZ) below the oil/water contact has recently been developed in parts of the SACROC Unit. Review Primary Production. Completed in November 1948, the Standard No. 1 Jessie Brown 2 was drilled to 6,700 ft and produced 530 B/D from the Canyon Reef Formation. Located 9 miles northwest of Snyder, Texas, this well was the discovery well of the North Snyder field. The Texas Railroad Commission eventually merged this field with the neighboring Kelly field upon recognizing that both fields produce from the same reservoir. The reservoir thickness varies from 10 ft on the flanks to 900 ft on the crest of the reef. A map of the unit’s 3D structure and thickness is shown in Fig. 1. By late 1950, 1,600 production wells had been drilled on the Kelly- Snyder field on irregular 40-acre spacing.

Modelling hydraulic fracturing process in one of the Iranian southwest oil reservoirs

ABSTRACTHydraulic fracturing creates a high conductivity channel within a large area of formation and bypasses any damage that may exist in the near wellbore region. Moreover, it has been one of the major well stimulation techniques to increase well production. In order to model and study the feasibility of implementing this technique in one of the Iranian Southwest oil reservoirs, an extensive literature survey was carried out. One-dimensional mechanical earth model was constructed. Stable mud window was determined and types of failures were diagnosed. Consequently, on these bases, geomechanical feasibility was confirmed and hydraulic fracturing treatment for the case study was designed. Different scenarios were defined and sensitivity analysis was conducted together with the confirmation of economic feasibility. Furthermore, channel fracturing technique was employed and it was found that using this technique can be more suitable and beneficial than conventional fracturing method.