A novel algorithm for evaluating cement azimuthal density based on perturbation theory in horizontal well

Cement density monitoring plays a vital role in evaluating the quality of cementing projects,which is of great significance to the development of oil and gas.However,the presence of inhomogeneous cement distribution and casing eccentricity in horizontal wells often complicates the accurate evaluation of cement azimuthal density.In this regard,this paper proposes an algorithm to calculate the cement azimuthal density in horizontal wells using a multi-detector gamma-ray detection system.The spatial dynamic response functions are simulated to obtain the influence of cement density on gamma-ray counts by the perturbation theory,and the contribution of cement density in six sectors to the gamma-ray recorded by different detectors is obtained by integrating the spatial dynamic response functions.Combined with the relationship between gamma-ray counts and cement density,a multi-parameter calculation equation system is established,and the regularized Newton iteration method is employed to invert casing eccentricity and cement azimuthal density.This approach ensures the stability of the inversion process while simultaneously achieving an accuracy of 0.05 g/cm^(3) for the cement azimuthal density.This accuracy level is ten times higher compared to density accuracy calculated using calibration equations.Overall,this algorithm enhances the accuracy of cement azimuthal density evaluation,provides valuable technical support for the monitoring of cement azimuthal density in the oil and gas industry.

Change in relative density of WC-Co cemented carbides in spark plasma sintering process

The relative density of WC-Co cemented carbides during spark plasma sintering（SPS） was analyzed.Based on the change in displacement of the ram in the SPS system,the relative densities in the sintering process can be achieved at different temperatures.The results indicated that densification of the samples started at near 900°C,the density rapidly reached its maximum at the increasing temperature stage,in which the temperature was lower than the sintering temperature of 1200°C,and most of the densification took place in the stage.Besides,the theoretical values were consistent with the experimental results.

Packing Density Improvement through Addition of Limestone Fines, Superfine Cement and Condensed Silica Fume

Adoption of a low water/powder (W/P) ratio is the key to improve the strength and durability of concrete, which relies on a high packing density because fresh concrete requires excess water to offer flowability. To obtain a high packing density, powders with different particle sizes, including limestone fines (LSF), superfine cement (SFC), condensed silica fume (CSF), were added to the cement paste and the resulting packing densities were measured directly by a newly-developed wet packing test. Results demonstrated that addition of powders with a finer size would more significantly improve the packing density but the powders should be at least as fine as 1/4 of the OPC to effectively improve the packing density. Packing density and voids ratio relationship showed that a small increase in packing density can significantly decrease the voids ratio, which could allow the W/P ratio to be reduced to improve the strength and durability of the concrete without compromising the flowability.

Preparation and Properties of Alkali Activated Foam Cement Reinforced with Polypropylene Fibers

A new form of foam cement was produced by mixing alkali-activated slag,clay,a small amount of polypropylene fibers with prepared foam during stirring.The preparation of the material is quite different from the normal one,which is produced just at room temperature and without baking.The fabrication of this energy-saving and low-price material can be favorable for lowering carbon emission by using recycled industrial wastes.Thermal conductivity of 0.116 W/（m·k）,compressive strength of 3.30 MPa,flexural strength of 0.8 MPa and density of 453 kg/m3 can be achieved after 28 days aging.The hydration product is C-S-H with less Ca（OH）2,calcium aluminum and zeolite,which was characterized by X-ray diffraction（XRD） measurement.This prospective foam cement may be expected to be an excellent economical energy-saving building material.

Colloidal gas aphron(CGA) based foam cement system

To solve the problems such as high denstiy,foam instability,low compressive strength,high porosity and poor durability associated with conventional foam cements,a novel colloidal gas aphron(CGA)based foam cement system was investigated and tested for properties.CGA is used in a base slurry as the foam component and the recipe was optimized with hollow sphere and micro-silica in terms of particle size distribution(PSD).Porosity,permeability,strength,brittleness,elasticity,free water content,foam stability and density tests on the CGA based foam cement system were carried out to evaluate the performance of the system.According to the experiment results,at the foam proportion of 10%,the cement density was reduced to 1040 kg/m3,and stable microfoam net structure not significantly affected by high temperature and high pressure was formed in the cement system.The optimal CGA based foam cement has a free water content of 0%,porosity of 24%,permeability of 0.7×10-3μm2,low elasticity modulus,high Poisson’s ratio,and reasonable compressive strength,and is more elastic and flexible with capability to tolerate regional stresses.

Microstructure and Properties of Cement Foams Prepared by Magnesium Oxychloride Cement

Microstructural features including pore size distribution, cell walls and phase compositions of magnesium oxychloride cement foams（MOCF） with various MgO powders and water mixture ratios were studied. Their infl uences on compressive strength, water absorption and resistance of MOCF were also discussed in detail. The experimental results indicated that moderate and slight excess MgO powders（MgO/MgCl2 molar ratios from 5.1 to 7） were beneficial to the formation of excellent microstructure of MOCF, but increasing water contents（H2O/MgO mass ratios from 0.9 to 1.29） might result in opposite conclusions. The microstructure of MOCF produced with moderate and slight excess MgO powders could enhance the compressive strength, while serious excess MgO powders addition（MgO/MgCl2 molar ratios = 9） would destroy the cell wall structures, and therefore decrease the strength of the system. Although MOCF produced with excess MgO powders could decrease the water absorption, its softening coefficient was lower than that of the material produced with moderate MgO powders. This might be due to the instability of phase 5, the volume expansion and cracking of cell walls as immersed the sample into water.

Functional Acrylic Polymer as Corrosion Inhibitor of Carbon Steel in Autoclaved Air-Foamed Sodium Silicate-Activated Calcium Aluminate/Class F Fly Ash Cement

The study focused on investigating the effectiveness of functional acrylic polymer (AP) in improving the ability of airfoamed sodium silicate-activated calcium aluminate/Class F fly ash cement (slurry density of ￡1.3 g/cm3) to mitigate the corrosion of carbon steel (CS) after exposure to hydrothermal environment at 200?C or 300?C. Hydrothermally-initiated interactions between the AP and cement generated the formation of Ca-, Al-, or Na-complexed carboxylate derivatives that improved the AP’s hydrothermal stability. A porous microstructure comprising numerous defect-free, evenly distributed, discrete voids formed in the presence of this hydrothermally stable AP, resulting in the increase in compresive strength of cement. The foamed cement with advanced properties conferred by AP greatly protected the CS against brine-caused corrosion. Four major factors governed this protection by AP-incorporated foamed cements: 1) Reducing the extents of infiltration and transportation of corrosive electrolytes through the cement layer deposited on the underlying CS surface;2) Inhibiting the cathodic reactions at the corrosion site of CS;3) Extending the coverage of CS by the cement;and 4) Improving the adherence of the cement to CS surface.

疏松砂岩多层气藏钻井难点及优化对策

涩北气田是典型的疏松砂岩气藏,具有纵向气层多、储层疏松非均质性强、敏感性矿物多等地质特征。利用大量的气藏地质、动态监测和钻录测资料,剖析钻井施工中存在的问题和技术难点,开展优化对策研究。结果表明:1)储层疏松、薄互层多、矿化度高和开发后期纵向压力系统紊乱是影响优快钻井施工的主要因素;2)针对钻井施工中井控风险大、井身结构确定困难的问题,通过优化研究确定了不同气藏、不同深度、不同部位井的井身结构;3)针对比较突出的井漏问题,研发适宜的低伤害、能有效抑制黏土膨胀的MEG (甲基葡萄糖苷)钻井液体系;4)针对固井质量难以保证的问题,采用纳米基低密度水泥浆、工艺改进和精细施工等措施得以解决。认为,优化技术对策应用效果明显,解决了钻井技术难点,实现了疏松砂岩多层气藏快速安全钻井。

发泡水泥板的应用背景、现状及前景概述

为深层次、全面了解发泡水泥板诞生背景、应用现状和发展前景,本文对发泡水泥板应用背景、市场需求、技术标准沿变、整体性能、综合成本、应用现状、发展前景进行全方位、多角度、深层次剖析。综合认为:尽管发泡水泥板具有隔热、防火(A1级)、环保、抗老化、强度高等优点,但其研发技术壁垒低,加上劣质产品挡道、厂家恶性竞争等恶劣现象,致使其市场容纳空间已非常狭小。本文将为建筑从业人员全面了解发泡水泥板的“来龙去脉”和实时动态提供最新现实科学依据,为科研工作者研发新型建筑保温材料提供更多理论科学依据。

经皮椎体成形后邻近椎体压缩骨折的危险因素

背景:经皮椎体成形术是治疗骨质疏松性椎体压缩骨折应用最广泛的方法,多数研究认为经皮椎体成形术会增加继发性邻近椎体压缩骨折的概率。然而,对于经皮椎体成形术后引起的邻椎再骨折相关危险因素仍然存在争议。目的:归纳并总结骨质疏松性椎体压缩骨折患者行经皮椎体成形术后邻近椎体再发骨折的影响因素,为降低其发生风险以及制定相应治疗方案提供一定的参考。方法:以“骨质疏松症,骨折,经皮椎体成形术,邻近椎体压缩骨折,危险因素”为中文检索词,以“osteoporosis,osteoporotic vertebral compression fractures,percutaneous vertebroplasty,adjacent vertebral compression fractures,risk factors”为英文检索词,应用计算机检索中国知网、万方医学网、维普、PubMed、Springer、ScienceDirect及Elsevier数据库收录的相关文献。检索时限重点为2018年1月至2023年9月,同时纳入少数经典远期文献。通过阅读文题和摘要进行筛选,最终纳入83篇文献进行综述。结果与结论:(1)骨质疏松性椎体压缩骨折是骨质疏松症最常见的并发症之一,使老年患者致残和死亡的风险显著增加。经皮椎体成形术是治疗骨质疏松性椎体压缩骨折切实有效的方法。(2)随着经皮椎体成形术的普及,继发椎体压缩性骨折也逐渐增多,以邻近椎体压缩骨折最为常见。(3)以往的研究仅讨论了骨密度、多发椎体骨折、身体质量指数、年龄、性别、骨水泥的用量、骨水泥渗漏及抗骨质疏松治疗等因素对经皮椎体成形术后继发邻近椎体压缩骨折的影响,而对于椎体骨折数量、手术时机、手术方式、骨水泥材料、骨水泥弥散分布、伤椎恢复高度和术后佩戴支具等方面总结的尚不全面,并且对危险因素引起邻椎骨折的具体机制分析也较为少见。(4)文章结果表明,骨密度过低、高龄、围绝经期女性、多发椎体骨折、伤椎高度的过度恢复、骨水泥渗漏、合并基础疾病及不良的生活习惯是经皮椎体成形术后继发邻近椎体压缩骨折的危险因素,保持正常的身体质量指数、早期手术、双侧经皮椎体成形术、使用新型骨水泥材料、适宜的骨水泥注射体积、均匀的骨水泥弥散分布、规律抗骨质疏松治疗和术后佩戴支具是经皮椎体成形术后继发邻近椎体压缩骨折的保护因素。

基于紧密堆积理论的深水低密度三元固相水泥浆体系

深水浅表层固井作业过程中由于海底低温导致水泥环早期力学强度发展缓慢、内部密实度不高,易引发水气窜流,进而导致固井质量低劣甚至密封失效等复杂情况。为此,采用分形特征方程对G级油井水泥、纳米CaCO_(3)(NC)和漂珠(CS)进行紧密堆积,然后结合室内实验评价,优选出了一套密度为1.50 g/cm^(3)的具有低温早强性能的三元固相水泥浆体系,并利用抗压强度测试、XCT、SEM等方法对紧密堆积体系的增强机理进行了表征和分析。研究结果表明:(1)三元紧密堆积体系早期力学强度发展快速,在10℃的低温条件下,24 h抗压强度可达3.5 MPa以上;(2)相比于相同密度的NC二元体系和CS二元体系,孔隙率降低了19.10%~33.05%,抗压强度提高了7.0%~21.1%;(3) NC可以为水泥水化提供成核位点、填充细化孔隙,CS可以部分替代水而提高体系致密性,在两种材料的协同作用和紧密堆积效应下可实现早期力学强度的快速发展。结论认为,三元固相级配水泥浆体系利用紧密堆积理论发挥了3种材料的各自优势,进而实现了早期力学强度的快速发展,对于深水井表层套管固井作业防止水气窜流具有很好的理论指导意义和应用推广价值。

超低密度水泥浆固井质量改进方法研究

随着油气田勘探和开发的不断深入,对于一些极低压力地层条件,有时低密度水泥浆也无法满足安全固井施工的需求,只能采用超低密度水泥浆解决平衡压力固井问题。由于现有低密度固井质量评价标准不能客观准确地反映超低密度水泥浆的真实胶结质量,因此,对超低密度水泥浆在不同养护条件下的水泥石的声学特性、力学参数等进行了实验检测,分析了影响超低密度水泥石力学及声学特性的因素及规律。研究结果表明:密度、温度、养护时间均会对超低密度水泥石的声速和抗压强度发展产生影响,其中,温度对水泥石早期影响较大,后期影响小;水泥石密度越高,声阻抗与抗压强度越高,声阻抗与弹性模量存在线性关系,与抗压强度呈指数关系;建立了超低密度水泥浆固井套管波相对声幅计算公式,研究结果为制定超低密度水泥浆固井质量评价指标提供了基础。

外加剂对硫氧镁水泥泡沫混凝土性能影响

该文研究磷酸三钠、葡萄糖、有机酸C、有机酸盐D四种外加剂复掺对硫氧镁水泥泡沫混凝土抗压强度和耐水性的影响。并采用XRD、SEM表征硫氧镁水泥泡沫混凝土试样的物相组成和微观结构。结果表明,适当掺量的四种外加剂都能提高硫氧镁水泥泡沫混凝土抗压强度及耐水性,有机酸C对硫氧镁水泥泡沫混凝土抗压强度影响较大,有机酸C掺量为0.6%时,试块28 d抗压强度达到1.91 MPa;磷酸三钠可以有效改善硫氧镁水泥泡沫混凝土耐水性,当磷酸三钠掺量0.6%时,试块软化系数达0.8;复掺外加剂试样强度与耐水性得到提升,其28 d抗压强度达到2.1 MPa,是不掺外加剂试样的1.58倍,其软化系数达0.92。

轻钢骨架水泥粉煤灰发泡墙板的抗震性能

针对轻钢轻混凝土组合墙板抗震性能的研究相对缺乏,同时为研究不同填料对轻钢骨架水泥粉煤灰发泡墙板抗震性能的影响规律,设计了3个不同填料的墙板进行低周往复水平荷载试验,探究了不同填料对墙板的抗震性能的影响。结果表明:不同填料配比墙板的破坏模式大致相同,墙板的整体性和抗震性能较好;在轻钢骨架水泥粉煤灰发泡墙板中掺入聚丙烯纤维和增加水泥用量可以有效地提高墙体的抗震性能和抗侧刚度,增强墙体的承载力和延性,同时还可以明显提高墙体的变形能力以及耗能能力。与对照组相比,掺加0.4%聚丙烯纤维或增加水泥用量至50.0%的墙板受剪承载力均提高了约54.0%,抗侧刚度分别提高了26.0%和15.0%,累计耗能分别提高了172.0%和86.0%。

硬质合金刀具皮秒激光加工表面形貌及成分变化研究

聚焦于硬质合金皮秒激光加工表面成分变化特性,研究了不同激光能流密度对硬质合金表面形貌、粗糙度、材料去除特性和化学成分的影响,重点讨论了烧结WC-Co硬质合金在皮秒激光加工前后的表面特性,获得不同能流密度激光与WC-Co材料的作用机制,结果表明,在低能流密度下,激光与WC-Co的作用机制主要是浅表层熔化机制,属于激光抛光,在WC-Co刀具激光加工中可用作精加工工序;在高能流密度下,激光与WC-Co的作用机制主要在材料深度方向稳定去除,在WC-Co刀具激光加工中可用作粗加工工序。本研究为WC-Co刀具的激光加工提供了理论参考和数据支持。

抗高温低密度水泥浆体系研究与应用

为解决低密度水泥浆高温强度低、减轻材料承压能力不高、低密度水泥浆配浆困难等难题,研制了低密度增强材料DRA-2S、优选了耐压105 MPa的高性能空心玻璃微珠、聚羧酸分散剂DRS-2S及其他配套抗高温水泥外加剂,开发了抗高温低密度固井水泥浆体系。研究结果表明,该水泥浆能够满足循环温度150℃、井底静止温度180℃、耐压105 MPa的固井要求,顶部127℃静胶凝13.3 h起强度,24 h抗压强度12.4 MPa。开发的抗高温低密度水泥浆在西南油气田高温探井ZJ2井Ф127 mm尾管固井成功应用,固井质量合格率96.7%,为西南油气田高温易漏失复杂深井勘探开发提供了固井技术支撑。

冻融循环作用下不同路基材料力学特性对比研究

为探究寒区路基新型材料泡沫轻质土强度特性,完成了不同湿密度下的泡沫轻质土路基的冻融强度损伤试验。并将新型路基材料泡沫轻质土和传统路基材料水泥改良土进行对比发现:水泥改良土在冻融前期强度会大幅下降,但是在冻融循环5次左右,抗压强度会有回升趋势;而泡沫土从冻融开始到结束始终随冻融循环次数增加抗压强度缓慢下降。强度损失方面,2种路基材料的强度损失速率不同,水泥改良土抗压强度下降速率比泡沫轻质土更快。泡沫轻质土损失率随循环次数变化波动较小,相较为稳定。冻融循环对水泥改良土损失率影响离散型较大。

废弃泥浆制作水泥泡沫轻质土室内试验研究

为处理废弃泥浆,利用水泥协同泥浆制作泥浆水泥泡沫轻质土来修筑高速公路路基。制作了相同重度、不同水固比以及相同水固比、不同重度的泥浆水泥泡沫轻质土试块,测试在标准养护条件下28 d抗压强度,探究泥浆水泥泡沫轻质土水固比、水泥比例与重度对28 d抗压强度的影响。结果表明:泥浆泡沫轻质土的28 d抗压强度与水固比成负相关,与重度和水泥比例成正相关;配制合适的废弃泥浆水泥泡沫轻质土可用于高速公路路基修筑。此外,1 m3泡沫轻质土中,各掺量分别为水泥397 kg、干泥浆193 kg、水383.5 kg、发泡液27.1 kg时,流值为187.3 mm,试块28 d抗压强度可达2.62 MPa,且早期强度较高、水泥用量较少,可作为泥浆水泥泡沫轻质土的推荐配比。

水泥基气泡轻质土冻融耐久性的研究

气泡轻质土作为一种新型材料因其具有轻质性、自密实、保温等优良特性,在寒区路基工程中有更加广泛的应用趋势。为了降低气泡轻质土的工程造价、充分利用当地资源,分别采用0%、20%、30%、40%粉质黏土和10%的粉煤灰替代部分水泥制备水泥基气泡轻质土,并开展了500 kg/m~3、600 kg/m~3、700 kg/m~3、800 kg/m~3湿密度下水泥基气泡轻质土的冻融耐久性试验。评价了不同粉质黏土掺量和湿密度对水泥基气泡轻质土冻融耐久性的影响。结果表明:(1)从质量损失率分析,掺量为20%、30%试件的质量损失率相对较小,冻融耐久性较好。(2)通过相对动弹模损失量分析,粉质黏土掺量40%和湿密度为500 kg/m~3试件的冻融耐久性较差,不宜使用。因为粉质黏土消耗了水泥水化作用需要的水分,且泡沫越多,试件内部越稀疏。(3)建立了以冻融循环次数、粉质黏土掺量为因子的相对动弹性模量预测模型公式,该模型验证结果较好且公式结构简洁,便于应用到实际工程中。

碳化再生微粉泡沫混凝土的工作和力学性能研究

选取碳化或未碳化再生水泥混凝土粉作为辅助胶凝材料,考察不同水泥替代量(0、20%、40%、60%)对泡沫混凝土和易性和力学性能的影响。结果表明,碳化处理改善了新拌泡沫混凝土浆体和易性,改善幅度在1.08%~5.61%之间。机械强度与基体密度呈正相关,相比于未碳化再生微粉泡沫混凝土,碳化处理能显著提升泡沫混凝土的密度并降低吸水率,进而提升泡沫混凝土的抗压强度。随着碳化微粉掺量增加,对泡沫混凝土抗压强度的影响表现为先升高后降低,在掺量为20%时达到最大值。