Water shutoff and conformance improvement: an introduction

This paper provides an introduction to the topic of water shutoff and conformance improvement. After indicating the volumes of water produced during oilfield operations, a strategy is provided for attacking excess water production problems. Problem types are categorized, typical methods of problem diagnosis are mentioned, and the range of solutions is introduced for each problem type. In the third section of the paper, the concept of disproportionate permeability reduction is introduced—where polymers and gels may reduce permeability to water more than to oil or gas. When and where this property is of value is discussed. The fourth section describes the properties of formed gels as they extrude through fractures and how those properties can be of value when treating conformance problems caused by fractures. Section 5 covers the efficiency with which gels block fractures after gel placement—especially, the impact of fluids injected subsequent to the gel treatment.

High-strength and self-degradable sodium alginate/polyacrylamide preformed particle gels for conformance control to enhance oil recovery

Excess water production has become an important issue in the oil and gas extraction process.Preformed particle gels(PPGs),show the capability to control the conformance and reduce excess water cut.However,conventional PPGs have poor mechanical properties and their swollen particles are easily damaged by shearing force when passing through the fractures in formations,meanwhile PPGs can be also degraded into various byproducts,leading to permanent damage to the reservoir permeability after temporary plugging.Herein,a novel type of dual cross-linked PPGs(dPPGs)was designed and synthesized using sodium alginate(SA)and acrylamide(AAm),cross-linked with N,N’-methylenebisacrylamide(MBA)and Fe^(3+).Results show that dPPGs have excellent mechanical properties with a storage modulus up to 86,445 Pa,which is almost 20 times higher than other reported PPGs.Meanwhile,dPPGs can be completely degraded into liquid without any solid residues or byproducts and the viscosity of dPPGs degraded liquid was found to be lower than 5 mPa·s.A laboratory coreflooding test showed that the plugging efficiency of dPPGs was up to 99.83%on open fractures.The obtained results demonstrated that dPPGs could be used as economical and environment-friendly temporary plugging agent with high-strength,self-degradation,thermal stability,and salt stability,thus making it applicable to a wide range of conformance control to enhance oil recovery.

Conformance control by a microgel in a multi-layered heterogeneous reservoir during CO_(2) enhanced oil recovery process

Injecting CO_(2)into the underground for oil displacement and shortage is an important technique for carbon capture,utilization and storage(CCUS).One of the main problems during the CO_(2)injection is the channeling plugging.Finding an effective method for the gas channeling plugging is a critical issue in the CO_(2)EOR process.In this work,an acid-resistance microgel named dispersed particle gel(DPG)was characterized and its stability was tested in the CO_(2)environment.The microgel size selection strategies for the homogeneous and heterogeneous reservoirs were respectively investigated using the single core flooding and three parallel core flooding experiments.Moreover,the comparison of microgel alternate CO_(2)(MAC)injection and water alternate CO_(2)(WAC)injection in the dual core flooding experiments were presented for the investigation of the role of microgel on the conformance control in CO_(2)flooding process.The results have shown that the microgel featured with ANH and CAN groups can keep its morphology after aging 7 days in the CO_(2)environment.Where,the small microgel with unobstructed migration and large microgel with good plugging efficiency for the high permeability zone were respectively featured with the higher recovery factor in homogeneous and heterogeneous conditions,which indicate they are preferred used for the oil displacement and conformance control.Compared to WAC injection,MAC injection had a higher incremental recovery factor of 12.4%.It suggests the acid-resistance microgel would be a good candidate for the conformance control during CO_(2)flooding process.

Importance of conformance control in reinforcing synergy of CO_(2) EOR and sequestration

Injecting CO2into hydrocarbon reservoirs can enhance the recovery of hydrocarbon resources,and simultaneously,CO2can be stored in the rese rvoirs,reducing considerable amount of carbon emissions in the atmosphere.However,injected CO_(2)tends to go through fractures,high-permeability channels and streaks present in reservoirs,resulting in inefficient hydrocarbon recovery coupled with low CO_(2)storage performance.Conformance treatments with CO_(2)-resistant crosslinked polymer gels were performed in this study to mitigate the CO_(2)channeling issue and promote the synergy between enhanced oil recovery(EOR) and subsurface sequestration of CO_(2).Based on a typical low-permeability CO_(2)-flooding reservoir in China,studies were performed to investigate the EOR and CO_(2)storage performance with and without conformance treatment.The effect of permeability contrast between the channels and rese rvoir matrices,treatment size,and plugging strength on the efficiency of oil recovery and CO_(2)storage was systematically investigated.The results indicated that after conformance treatments,the CO_(2)channeling problem was mitigated during CO_(2)flooding and storage.The injected CO_(2)was more effectively utilized to recover the hydrocarbons,and entered wider spectrum of pore spaces.Consequently,more CO_(2)was trapped underground.Pronounced factors on the synergy of EOR and CO_(2)storage were figured out.Compared with the treatment size,the CO_(2)storage efficiency was more sensitive to the plugging strength of the conformance treatment materials.This observation was important for conformance treatment design in CCUS-EOR projects.According to this study,the materials should reduce the channel permeability to make the channel/matrix permeability ratio below 30.The results demonstrate the importance of conformance treatment in maximizing the performance of CCUS-EOR process to achieve both oil recovery improvement and efficient carbon storage.This study provides guidelines for successful field applications of CO_(2)transport control in CO_(2)geo-utilization and storage.

A review of nuclear magnetic resonance(NMR) technology applied in the characterization of polymer gels for petroleum reservoir conformance control

Polymer gel systems have been widely applied to control excessive water and improve oil recovery(IOR)in petroleum reservoirs.They are usually divided into two main types,in-situ cross-linked polymer gels,and pre-formed polymer gels.In recent years,nuclear magnetic resonance(NMR) technology has been gradually applied to the research of polymer gel systems due to its unique analysis advantages.This paper is intent to review these works systematically.For in-situ cross-linked polymer gel systems,NMR can be used to characterize the chemical structure changes of the polymer,the cross-linker,and the auxiliary agent in the formulation of the polymer gel systems.Moreover,the gelation time and the gel strength of the in-situ cross-linked polymer gel systems can also be measured by NMR.For pre-formed polymer gels,NMR can be employed to detect the chemical structure of the designed products.Last,the NMR method can evaluate the plugging,water control,and oil improvement performance of the polymer gels in porous media without using dopants.This review can help readers build a more systematic understanding of the application of NMR technology in polymer gel systems for IOR and help re searchers to more deeply study the performance of polymer gel systems.

Development of a Model Driven ACSI Conformance Testing for IEC 61850-Based IED

Globally, traditional power systems are rapidly transforming towards the adoption of smart grid platforms. Substations which are at the center of the electric power transformation from the power plant are changing to IEC 61850 based digital substations. Therefore, within substation, there is a growing demand for the IEC 61850 based Intelligent Electronic Devices (IEDs). The operation of multiple manufacturers of IEDs in a single digital substation network increases the need for IEC 61850 communications specification conformance diagnosis to ensure interoperability for efficient data exchange between IEDs. The IEC 61850-10 presents test items for diagnosing communication specification conformance. There are many test tools available in the market today to test the compliance of the IEC 61850 communications specifications to the IED. In this paper, we propose a model-based diagnostic method for IED communication conformance testing. The proposed model-based software therefore uses the “drag and drop” technique to select the various IEC 61850 communication services (objects) required to design the test case in a user friendly Graphical User Interface (GUI). This makes the service conformance testing more flexible for test engineers and system integrators especially in situations that require test case modifications. Also, the proposed software tool makes it easy to understand the various IEC 61850 services using the friendly GUI.

A novel polymer gel with high-temperature and high-salinity resistance for conformance control in carbonate reservoirs

Plugging agents have been widely used to enhance oil recovery in fractured-vuggy carbonate reservoirs.However,the harsh conditions of fractured-vuggy carbonate reservoirs yield a significant challenge in maintaining a long-term stabilization of plugging agents.In this work,we developed an anti-hightemperature and high-salinity polymer gel(APG)with excellent resistance to high temperature(140℃)and ultra-high salinity(240000 mg/L).The rheology and microstructure of APG were characterized before and after gelation.Core plugging tests on fractured cubic cores were conducted to quantify the plugging performance of the gel system.Experimental results showed that the Sclerglucan and Cobalt(Ⅱ)Chloride Hexahydrate filled the three-dimensional(3-D)network with various morphologies,providing extra protection to the cross-linking points of the 3D network structure of APG and thus,leading to a prolongation of the dehydration time.The dehydration rate of APG was only 5%within 30days,and the strength of APG could be maintained at a rigid or near-rigid level over 150 days.Moreover,APG exhibited satisfactory shear and scour resistance.Core plugging tests showed that APG could achieve a plugging rate of 90%and demonstrate ignorable minor damage to the substrate.Our results indicate that APG can serve as a great candidate in channel plugging in fractured-vuggy carbonate reservoirs where fractures are fully developed.

Development of re-crosslinkable dispersed particle gels for conformance improvement in extremely high-temperature reservoirs

Micro-scale and nano-scale dispersed gel particles(DPG)are capable of deep migration in oil reservoirs due to their deformability,viscoelasticity,and suitable particle size.Therefore,it has been widely studied and applied in reservoir conformance control in recent years.However,for highly permeable channels,their plugging performance is still limited.In addition,conventional in situ cross-linked polymer gels(ISCPGs)have fast gelation time under extremely high-temperature conditions,which often causes problems such as difficulty in pumping.Therefore,a re-cross linkable dispersed particle gel(RDPG)system applied for conformance control in highly permeable channels of extremely high-temperature petroleum reservoirs was investigated.The particle size distribution,gelation time,gel strength,injection performance,and perfo rmance strength in po rous media were investigated using a laser particle size meter,the Sydansk bottle test method,rheometer,and core displacement experiments,respectively.Results show that the RDPG suspension can be stable for more than 6 months at room temperature with storage modulus G’much lower than 10 Pa.It can pass through the pore throat by elastic deformation effect and does not cause strong blockage.Moreover,it can undergo re-crosslinking reaction at 150℃to form a strong bulk gel.The gel strength G’of re-crosslinked RDPG can be as high as 69.3 Pa,which meets the strength requirement of conformance control.The RDPG suspension has the properties of easy injection,and it also has strong plugging,and high-temperature resistance after re-crosslinked in the core,which can be a very promising material for conformance improvement in extremely high-temperature reservoirs.

Pore-scale investigation on occurrence characteristics and conformance control mechanisms of emulsion in porous media

Microscopic computed tomography(Micro-CT)is used to visualize microscopic flow in sandstone core samples during emulsion flooding.The images obtained during the experiment are processed quantitatively with a series of methods to evaluate the occurrence characteristics and oil recovery enhancement mechanisms of emulsion.(1)The emulsion is distributed in the cores in spherical shape,and its sphericity is significantly different from that of the remaining oil.Sphericity can be taken as a characteristic parameter to identify emulsion.(2)The emulsion with specific size prefers to stay in pores with matching sizes;when the emulsion volume is smaller than the product of the lower limit of pore occupancy and the corresponding pore vol-ume,it will not be able to effectively trap in the pore to achieve conformance control.In the process of emulsion displacement designing,we need to design emulsion with suitable particle size according to the pore distribution of the reservoir.(3)Mobi-lization ratio of the pores can be increased from 23.1%to 59.3%by emulsion flooding after subsequent water flooding,and the average oil displacement efficiency at the pore-scale can be increased from 22.9%to 75.8%under the test conditions;(4)After emulsion flooding,the clustered remaining oil and the oil phase in the trapped emulsion are the main targets for further EOR.

The Protocol Conformance Testing of CCSS7 ISUP

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Conformance Test for IEDs Based on IEC 61850 Communication Protocol

In this paper, a conformance test platform is built for intelligent electronic devices (IEDs) from different manufacturers based on IEC 61850 communication protocol. A conformance test of time delay of message transmission between two IEDs, made by the same or different manufacturers, is performed. The conformance test platform, as well as the test results provide a helpful reference for IEC 61850 implementation.

ZTE Achieves TM Forum's Frameworx 12.0 Conformance Certification

19 November 2013,Shenzhen-ZTE Corporation has announced that ZTE＇s ZSmart BSS/OSS V8 has successfully achieved TM Forum＇s Frameworx 12.0 Conformance Certification.TM Forum＇s Frameworx Conformance Certification is an independent verification of how a solution＇s business processes and information models align with the industry standards found in Frameworx,including the Business Process Framework（eTOM）and Information Framework（SID）.

Effects of synthesis parameters on the performance of crosslinked Co-polymers with clays for conformance control

Conformance control or water shut-off is a technique used to improve oil recovery.During conformance control,polymers block high permeability water areas and redistribute water drive toward unswept oil zones.In this study,co-polymers(denoted ATP-PGV/AM-co-AMPS)were synthesized using acrylamide(AM)and 2-acrylamide-2-methylpropane sulfonic acid(AMPS)as the monomers,polyethylene glycol(PEG)-200 and methylenebisacrylamide(MBA)as the crosslinkers,attapulgite(ATP)and bentonite(PGV)as the clay types,and ammonium persulfate(APS)as the initiator,in addition to paraffin oil and surfactants.Samples were synthesized using inverse emulsion polymerization with different concentrations of monomers,crosslinkers,and clays,and they were characterized using Fourier-transform infrared(FTIR)spectroscopy and scanning electron microscopy(SEM)with energy dispersive X-ray spectroscopy(EDX).FTIR spectra of the samples confirmed the existence of sulfonate and hydroxyl groups,which are important for polymer swelling.SEM-EDX images indicated that the morphology and elemental composition were different before and after swelling,confirming the occurrence of swelling.Moreover,samples were placed in sodium chloride solution(20,000 ppm)for 7 days to evaluate swelling at both room temperature and 90°C.Thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC)were used to determine the thermal characteristics of the microparticles.Finally,rheological measurements were used to assess the deformation and rheological behavior of the hydrogels.The results showed that after 1 day,good swelling without loss of mechanical strength was achieved with the composite synthesized using 10%AM,15%AMPS,6%PGV,and 10%ATP.

基于层次化Conformer的语音合成

语音合成需要将输入语句的文本转换为包含音素、单词和语句的语音信号。现有语音合成方法将语句看作一个整体,难以准确地合成出不同长度的语音信号。通过分析语音信号中蕴含的层次化关系,分别设计基于Conformer的层次化文本编码器和基于Conformer的层次化语音编码器,并提出了一种基于层次化文本-语音Conformer的语音合成模型。首先,该模型根据输入文本信号的长度,构建层次化文本编码器,包括音素级、单词级、语句级文本编码器3个层次,不同层次的文本编码器描述不同长度的文本信息;并使用Conformer的注意力机制来学习该长度信号中不同时间特征之间的关系。利用层次化的文本编码器,能够找出语句中不同长度需要强调的信息,有效实现不同长度的文本特征提取,缓解合成的语音信号持续时间长度不确定的问题。其次,层次化语音编码器包括音素级、单词级、语句级语音编码器3个层次。每个层次的语音编码器将文本特征作为Conformer的查询向量,将语音特征作为Conformer的关键字向量和值向量,来提取文本特征和语音特征的匹配关系。利用层次化的语音编码器和文本语音匹配关系,可以缓解不同长度语音信号合成不准确的问题。所提模型的层次化文本-语音编码器可以灵活地嵌入现有的多种解码器中,通过文本和语音之间的互补,提供更为可靠的语音合成结果。在LJSpeech和LibriTTS两个数据集上进行实验验证,实验结果表明,所提方法的梅尔倒谱失真小于现有语音合成方法。

基于改进Conformer的新闻领域端到端语音识别

目前,开源的中文语音识别数据集大多面向通用领域,缺少面向新闻领域的开源语音识别语料库,因此该文构建了面向新闻领域的中文语音识别数据集CH_NEWS_ASR,并使用ESPNET-0.9.6框架的RNN、Transformer和Conformer等模型对数据集的有效性进行了验证,实验表明,该文所构建的语料在最好的模型上CER为4.8%,SER为39.4%。由于新闻联播主持人说话语速相对较快,该文构建的数据集文本平均长度为28个字符,是Aishell_1数据集文本平均长度的2倍;且以往的研究中训练目标函数通常为基于字或词水平,缺乏明确的句子水平关系,因此该文提出了一个句子层级的一致性模块,与Conformer模型结合,直接减少源语音和目标文本的表示差异,在开源的Aishell_1数据集上其CER降低0.4%,SER降低2%;在CH_NEWS_ASR数据集上其CER降低0.9%,SER降低3%,实验结果表明,该方法在不增加模型参数量的前提下能有效提升语音识别的质量。

基于时频感知双路径Conformer的语音增强

近年来,Conformer在语音领域的应用表现较为突出。该模块通过结合多头自注意力机制和卷积神经网络,能够同时关注短时和长时序列信息,从而在语音处理任务中表现出卓越的性能。在此基础上提出了一种基于时频感知双路径Conformer的语音增强网络(TFDPCNet)。首先,该网络将改进的Conformer结构作为核心,采用双路径结构,构成时频感知的双路径Conformer模块(TFDP-Conformer),增强了整体网络的时频提取能力;同时,为了减小时频特征融合的难度,提出了注意力门控交叉融合模块(AGCF),通过额外的注意力门进一步增强了网络训练过程中时频特征的交互,提高了时频特征的利用率;最后,引用度量鉴别器,并对其进行适当剪枝,使得增强后的音频和原始音频在量化评价指标上保持更高的一致性。实验结果表明,相比于TSTNN算法,TFDPCNet在主观和客观指标上都有明显提高。

低资源非自回归壮语语音合成

基于FastSpeech2模型,文章提出了非自回归的壮语语音合成模型Zhuang-TTS。为了提升模型合成壮语语音的韵律,根据壮语特点及实地调查提出了一套新的壮语音系(声调、声母或辅音、韵母或元音),同时针对壮语声学特点进行了改进:(1)使用壮语音素序列表征壮语发音信息;(2)使用音素级的声学调节器(与FastPitch类似),使合成结果更加稳定;(3)使用Conformer代替FastSpeech2模型中的Transformer,同时构建了一个壮语语音合成语料库。实验结果表明,Zhuang-TTS在韵律方面的意见评分(Mean Opinion Score, MOS)达到3.90,合成实时率达8.65×10^(-2)。该模型在合成壮语语音的质量和速度方面获得了较大提升,优于Tacotron2和FastSpeech2基线模型,研究推动了壮语语音合成领域的发展。

Laccase/caffeic acid-catalyzed crosslinking coupled with galactomannan alters the conformational structure of ovalbumin and alleviates Th2-mediated allergic asthma

Ovalbumin(OVA)is the major allergenic protein that can induce T helper 2(Th2)-allergic reactions,for which current treatment options are inadequate.In this study,we developed a polymerized hypoallergenic OVA product via laccase/caffeic acid(Lac/CA)-catalyzed crosslinking in conjunction with galactomannan(Man).The formation of high molecular weight crosslinked polymers and the Ig G-binding were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)and Western blotting.The study indicated that Lac/CA-catalyzed crosslinking plus Man conjugation substantially altered secondary and tertiary structures of OVA along with the variation in surface hydrophobicity.Gastrointestinal digestion stability assay indicated that crosslinked OVA exhibited less resistance in simulated gastric fluid(SGF)and simulated intestinal fluid(SIF).Mouse model study indicated that Lac-Man/OVA ameliorated eosinophilic airway inflammatory response and efficiently downregulated the expression of Th2-related cytokines(interleukin(IL)-4,IL-5,and IL-13),and upregulated IFN-γand IL-10 expression.Stimulation of bone marrow-derived dendritic cells with Lac-Man/OVA suppressed the expression of phenotypic maturation markers(CD80 and CD86)and MHC class II molecules,and suppressed the expression levels of proinflammatory cytokines.The knowledge obtained in the present study offers an effective way to acquire a hypoallergenic OVA product that can have a therapeutic effect in alleviating OVA-induced allergic asthma.

Classifying rockburst with confidence:A novel conformal prediction approach

The scientific community recognizes the seriousness of rockbursts and the need for effective mitigation measures.The literature reports various successful applications of machine learning(ML)models for rockburst assessment;however,a significant question remains unanswered:How reliable are these models,and at what confidence level are classifications made?Typically,ML models output single rockburst grade even in the face of intricate and out-of-distribution samples,without any associated confidence value.Given the susceptibility of ML models to errors,it becomes imperative to quantify their uncertainty to prevent consequential failures.To address this issue,we propose a conformal prediction(CP)framework built on traditional ML models(extreme gradient boosting and random forest)to generate valid classifications of rockburst while producing a measure of confidence for its output.The proposed framework guarantees marginal coverage and,in most cases,conditional coverage on the test dataset.The CP was evaluated on a rockburst case in the Sanshandao Gold Mine in China,where it achieved high coverage and efficiency at applicable confidence levels.Significantly,the CP identified several“confident”classifications from the traditional ML model as unreliable,necessitating expert verification for informed decision-making.The proposed framework improves the reliability and accuracy of rockburst assessments,with the potential to bolster user confidence.