Shale Fracturability Graphic Template Based onMixed Analytic Hierar-chy Process andMutation Theory

Due to the depletion of conventional energy reserves,there has been a global shift towards non-conventional energy sources.Shale oil and gas have emerged as key alternatives.These resources have dense and heterogeneous reservoirs,which require hydraulic fracturing to extract.This process depends on identifying optimal fracturing layers,also known as‘sweet spots’.However,there is currently no uniform standard for locating these sweet spots.This paper presents a new model for evaluating fracturability that aims to address the current gap in the field.The model utilizes a hierarchical analysis approach and a mutation model,and is distinct in its use of original logging data to generate a fracturability evaluation map.Using this paper’s shale fracturing sweet spot evaluation method based on a two-step mutation model,four wells in different blocks of Fuling and Nanchuan Districts in China were validated,and the results showed that the proportion of high-yielding wells on the sweet spot line could reach 97.6%,while the proportion of low-producing wells was only 78.67%.Meanwhile,the evaluation results of the model were compared with the microseismic data,and the matching results were consistent.

海上油田非均质性对聚合物驱开发效果的影响

海上某油田平面非均质性较强,基于生产数据分析发现不同注采方式间的聚合物驱效果存在一定的差异,该油藏的非均质性主要表现在油层砂体的渗透率、厚度和几何形态的平面分布上的差异。首先依据油田的平面非均质分布特征构建了三类概念模型,然后通过单因素分析和正交试验设计两种方法建立油藏单元地质模型,针对同一个地质模型,设计了两个对比研究的聚合物驱注采方案,采用油藏数值模拟技术分别建立了18个单因素和18个三因素三水平的多因素油藏数值模拟模型。首先基于单因素模拟计算的累计产油量指标可得出每一类平面非均质条件下最优的注采方式;然后以同一个非均质油藏单元不同聚合物驱注采方案间的累计产油量量差值为分析指标,通过单因素敏感性分析和正交设计直观分析得出了三类平面非均质对聚合物驱开发指标的影响程度,对聚合物驱注采方式的开发指标影响程度最大的是油藏单元砂体厚度平面非均质性,对聚合物驱注采方式的开发指标影响程度第二的是油藏单元砂体渗透率平面非均质性,对聚合物驱注采方式的开发指标影响程度最小的是油藏单元砂体几何形态平面非均质性。

Lignocellulosic biomass as sustainable feedstock and materials for power generation and energy storage

Lignocellulosic biomass has attracted great interest in recent years for energy production due to its renewability and carbon-neutral nature.There are various ways to convert lignocellulose to gaseous,liquid and solid fuels via thermochemical,chemical or biological approaches.Typical biomass derived fuels include syngas,bio-gas,bio-oil,bioethanol and biochar,all of which could be used as fuels for furnace,engine,turbine or fuel cells.Direct biomass fuel cells mediated by various electron carriers provide a new direction of lignocellulose conversion.Various metal and non-metal based carriers have been screened for mediating the electron transfer from biomass to oxygen thus generating electricity.The power density of direct biomass fuel cells can be over 100 mW cm^(-2),which shows promise for practical applications.Lignocellulose and its isolated components,primarily cellulose and lignin,have also been paid considerable attention as sustainable carbonaceous materials for preparation of electrodes for supercapacitors,lithium-ion batteries and lithium-sulfur batteries.In this paper,we have provided a state-of-the-art review on the research progress of lignocellulosic biomass as feedstock and materials for power generation and energy storage focusing on the chemistry aspects of the processes.It was recommended that process integration should be performed to reduce the cost for thermochemical and biological conversion of lignocellulose to biofuels,while efforts should be made to increase efficiency and improve the properties for biomass fuelled fuel cells and biomass derived electrodes for energy storage.

Production Capacity Evaluation of Horizontal Shale Gas Wells in Fuling District

One of the important indicators of shale gas reservoir excavation is capacity evaluation,which directly affects whether large-scale shale gas reservoirs can be excavated.Capacity evaluation is the basis of system analysis and dynamic prediction.Therefore,it is particularly important to conduct capacity evaluation studies on shale gas horizontal wells.In order to accurately evaluate the horizontal well productivity of shale gas staged fracturing,this paper uses a new method to evaluate the productivity of Fuling shale gas.The new method is aimed at the dynamic difference of horizontal wells and effectively analyzes the massive data,which are factors affecting the productivity of shale gas horizontal wells.According to the pressure system,production dynamic characteristics,well trajectory position,fracturing transformation mode and penetration depth,32 wells were divided into four types.Then,based on the classification,the principal component analysis methods can be used to evaluate the horizontal well productivity of shale gas.The new method of capacity evaluation has improved the accuracy by 10.25%compared with the traditional method,which provides a theoretical basis for guiding the efficient development of the horizontal wells of Fuling shale gas.

AModel for the Optimization of the Shale Gas HorizontalWell Section Based on the Combination of Different Weighting Methods in the Frame of the Game Theory

Existing“evaluation indicators”are selected and combined to build a model to support the optimization of shale gas horizontal wells.Towards this end,different“weighting methods”,including AHP and the so-called entropy method,are combined in the frame of the game theory.Using a relevant test case for the implementation of the model,it is shown that the horizontal section of the considered well is in the middle sweet spot area with good physical properties and fracturing ability.In comparison with the FSI(flow scanner Image)gas production profile,the new model seems to display better abilities for the optimization of horizontal wells.

Experimental Investigation on the Pressure Propagation Mechanism of Tight Reservoirs

Low permeability tight sandstone reservoirs have a high filtrational resistance and a very low fluid flow rate.As a result,the propagation speed of the formation pressure is low and fluid flow behaves as a non-Darcy flow,which typically displays a highly non-linear behavior.In this paper,the characteristics and mechanism of pressure propagation in this kind of reservoir are revealed through a laboratory pressure propagation experiment and through data from an actual tight reservoir development.The main performance mechanism is as follows:A new pressure cage concept is proposed based on the pressure variation characteristics of the laboratory experiments.There are two methods of energy propagation in the actual water injection process:one is that energy is transmitted to the deep reservoir by the fluid flowing through the reservoir,and the other is that energy is transmitted by the elasticity of the reservoir.For one injection well model and one production well model,the pressure distribution curve between the injection and production wells,as calculated by the theoretical method,has three section types,and they show an oblique“S”shape with a straight middle section.However,the actual pressure distribution curve is nonlinear,with an obvious pressure advance at the front.After the injection pressure increases to a certain level,the curve shape is an oblique and reversed“S”shape.Based on the research,this paper explains the deep-seated reasons for the difference in pressure distribution and proposes that it is an effective way to develop low permeability tight reservoirs using the water injection supplement energy method.

Experimental Study on the Influence of Fracturing Fluid Retention on Shale Gas Diffusion Law

Shale gas reservoirs have poor physical properties and a large number of micro-nano pores have been developed.Shale gas wells have no natural productivity and need fracturing reconstruction measures to put into production.However,the fracturing fluid will enter the reservoir space of shale matrix after fracturing and affect the production of shale gas.At present,there is no consensus on the influence of fracturing fluid retention on gas well production.Based on this,the paper adopts gas molecular transport analyzer to carry out experimental research on the influence of fracturing fluid on shale gas diffusion law after entering matrix pores.The results show that:(1)Compared with the diffusion capacity of single-phase shale gas,the diffusion capacity of shale gas decreases significantly when fracturing fluid is present in the reservoir;(2)In the process of fracturing fluid flowback,when the water saturation in the reservoir decreases from 50%to 0,the gas well productivity increases by about 60%.(3)When fracturing fluid exists in the reservoir,the pore diameter has an exponential relationship with the shale gas diffusion coefficient,and the diffusion coefficient increases exponentially with the increase of pore diameter.The research of this paper provides theoretical basis for guiding the efficient development of shale gas wells.

Prediction Model of Drilling Costs for Ultra-Deep Wells Based on GA-BP Neural Network

Drilling costs of ultra-deepwell is the significant part of development investment,and accurate prediction of drilling costs plays an important role in reasonable budgeting and overall control of development cost.In order to improve the prediction accuracy of ultra-deep well drilling costs,the item and the dominant factors of drilling costs in Tarim oilfield are analyzed.Then,those factors of drilling costs are separated into categorical variables and numerous variables.Finally,a BP neural networkmodel with drilling costs as the output is established,and hyper-parameters(initial weights and bias)of the BP neural network is optimized by genetic algorithm(GA).Through training and validation of themodel,a reliable prediction model of ultra-deep well drilling costs is achieved.The average relative error between prediction and actual values is 3.26%.Compared with other models,the root mean square error is reduced by 25.38%.The prediction results of the proposed model are reliable,and the model is efficient,which can provide supporting for the drilling costs control and budget planning of ultra-deep wells.

Coupling biomass pretreatment for enzymatic hydrolysis and direct biomass-to-electricity conversion with molybdovanadophosphoric heteropolyacids as anode electron transfer carriers

Owing to their acidity,oxidizing ability and redox reversibility,molybdovanadophosphoric heteropolyacids(H_(n+3)PMo_(12-n)VnO40,abbreviated as PMo_(12-n)Vn) were employed as electron transfer carriers for coupling biomass pretreatment for enzymatic hydrolysis and direct biomass-to-electricity conversion.In this novel coupled process,PMo_(12-n)Vn pretreatment that causes deconstruction of cell wall structure with PMo_(12-n)Vn being simultaneously reduced can be considered as the "charging" process.The reduced PMo_(12-n)Vn are further re-oxidized with release of electrons in a liquid flow fuel cell(LFFC) to generate electricity is the "discharging" process.Several Keggin-type PMo_(12-n)Vn with different degree of vanadium substitution(DSV, namely n) were prepared.Compared to Keggin-type phosphomolybdic acid(PMo_(12)),PMo_(12-n)Vn(n=1-6) showed higher oxidizing ability but poorer redox reversibility.The cellulose enzymatic digestibility of PMo_(12-n)Vn pretreated wheat straw generally decreased with increase in DSV, but xylan enzymatic digestibility generally increased with DSV.PMo_(12) pretreatment of wheat straw at 120℃ obtained the highest enzymatic glucan conversion(EGC) reaching 95%,followed by PMo11V1 pretreatment(85%).Discharging of the reduced heteropolyacids in LFFC showed that vanadium substitution could improve the maximum output power density(Pmax).The highest Pmax was obtained by PMo9 V3(44.7 mW/cm^(2)) when FeCl_(3) was used as a cathode electron carrier,while PMo_(12) achieved the lowest Pmax(27.4 mW/cm^(2)).All the heteropolyacids showed good electrode Faraday efficiency(>95%) and cell discharging efficiency(>93%).The energy efficiency of the coupled process based on the heat values of the products and generated electric energy was in the range of 18%-25% depending on DSV.PMo_(12) and PMo11V1 seem to be the most suitable heteropolyacids to mediate the coupled process.

A Software Defined Open Wi-Fi Platform

Wireless local area network(WLAN) is an indivisible part of the next generation wireless system. In this paper, an open Wi-Fi platform is designed and developed with special consideration of real-time signal processing. Such system can help accelerate research and development of future wireless network, especially in the case of cellular/Wi-Fi co-existing networks. This platform is based on the Intel general-purpose processor and the universal software radio peripheral(USRP) radio front end. The design including the physical layer implementations is purely software and is optimized for real-time signal processing on the general purpose processor. In the lab experiment, this platform supports baseband rate up to 700 Mbps with 2 transmitters in 80 MHz bandwidth. A cellular-Wi-Fi signaling interface between the Wi-Fi access point(AP) and the 5G core network is also developed and validated as an example for wireless resource allocation.

Quantum Brayton Refrigeration Cycle with Finite-Size Bose-Einstein Condensates

We consider a quantum Brayton refrigeration cycle consisting of two isobaric and two adiabatic processes,using an ideal Bose gas of finite particles confined in a harmonic trap as its working substance.Quite generally,such a machine falls into three different cases,classified as the condensed region,non-condensed phase,and regime across the critical point.When the refrigerator works near the critical region,both figure of merit and cooling load are significantly improved due to the singular behavior of the specific heat,and the coefficient of performance at maximum figure of merit is much larger than the Curzon-Ahlborn value.With the machine in the non-condensed regime,the coefficient of performance for maximum figure of merit agrees well with the Curzon-Ahlborn value.

Dynamic immune recovery process after liver transplantation revealed by single-cell multi-omics analysis

Elucidating the temporal process of immune remodeling under immunosuppressive treatment after liver transplantation(LT)is critical for precise clinical management strategies.Here,we performed a single-cell multi-omics analysis of peripheral blood mononuclear cells(PBMCs)collected from LT patients(with and without acute cellular rejection[ACR])at 13 time points.Validation was performed in two independent cohorts with additional LT patients and healthy controls.Our study revealed a four-phase recovery process after LT and delineated changes in immune cell composition,expression programs,and interactions along this process.The intensity of the immune response differs between the ACR and non-ACR patients.Notably,the newly identified inflamed NK cells,CD14+RNASE2+monocytes,and FOS-expressing monocytes emerged as predictive indicators of ACR.This study illuminates the longitudinal evolution of the immune cell landscape under tacrolimus-based immunosuppressive treatment during LT recovery,providing a four-phase framework that aids the clinical management of LT patients.

Enhanced high-temperature mechanical properties of laser-arc hybrid additive manufacturing of Al-Zn-Mg-Cu alloy via microstructure control

Recently,rapid and cost-effective additive manufacturing solutions for lightweight aluminum alloys with excellent high-temperature mechanical properties have been increasingly in demand.In this study,we combined laser-arc hybrid additive manufacturing with solution and artificial aging treatments to achieve Al-Zn-Mg-Cu alloy with favorable high-temperature strength via microstructure control.Hydrogen pores became the major defect in the as-deposited and heat-treated specimens.The continuous distribution of eutectics with hard-brittle characteristics at the grain boundaries was destructed following heat treat-ment.High-densityηprecipitates were uniformly dispersed in the heat-treated Al-Zn-Mg-Cu alloy,whereas appeared coarsened and dissolved at 473 K,owing to the rapid diffusion of Zn and Mg.The average 0.2%yield strength(318±16 MPa)and ultimate tensile strength(362±20 MPa)at 473 K af-ter heat treatment were enhanced by approximately 58%and 51%,respectively,compared to those of the as-deposited specimen.In addition,theηprecipitates contributed to lattice distortions and strain fields,which prevented dislocation motion and increased slip deformation resistance at high temper-atures.The as-deposited specimen exhibited intergranular fracture at 473 K,with cracks preferring to propagate along the aggregated eutectics.However,crack propagation proceeded in the sections with more pores in the heat-treated specimen.Our approach may provide a valid option for achieving alu-minum alloys with excellent high-temperature mechanical properties.

Strain and process engineering toward continuous industrial fermentation

Most current biotechnology industries are based on batch or fed-batch fermentation processes,which often show low productivity and high production costs compared to chemical processes.To increase the economic competitiveness of biological processes,continuous fermentation technologies are being developed that offer significant advantages in comparison with batch/fed-batch fermentation processes,including:(1)removal of potential substrates and product inhibition,(2)prolonging the microbial exponential growth phase and enhancing productivity,and(3)avoiding repeated fermentation preparation and lowering operation and installation costs.However,several key challenges should be addressed for the industrial application of continuous fermentation processes,including(1)contamination of the fermentation system,(2)degeneration of strains,and(3)relatively low product titer.In this study,we reviewed and discussed metabolic engineering and synthetic biology strategies to address these issues.