The cementing industry is increasingly exploring the replacement of conventional silica flour (SF) with high-silicon industrial solid wastes (ISWs) to improve the thermal stability of oil well cement (OWC). Quartz tailings (QT)-a byproduct of quartz mining and processing-have attracted attention owing to their high silicon dioxide content. Driven by rising global demand for high-purity silicon flour, substantial QT accumulation causes land occupation and environmental pollution, making its recycling and reuse critically important. This study investigates the novel use of QT as an anti-strength retrogression additive for OWC under high-temperature and high-pressure (HTHP) conditions (230 °C/20.7 MPa). The hydration behaviour, microstructural evolution, and mechanical performance of pure OWC (Class G OWC (GOWC)), SF-blended pastes (SF30), and QT-blended pastes (QT30) were systematically investigated. Results showed that QT significantly enhanced the compressive strength and thermal stability of GOWC. After 28 d of HTHP curing, GOWC exhibited severe strength retrogression (8.9 MPa), while QT30 reached 23.5 MPa-a 164.0 % improvement. Under HTHP conditions, both SF30 and QT30 followed similar hydration pathways, forming thermally stable, silicon-rich xonotlite (Ca/Si ~ 1.0) instead of high Ca/Si ratio phases such as reinhardbraunsite (Ca/Si ~ 2.5) and jaffeite (Ca/Si ~ 3.0). The formation of xonotlite refined the pore structure and densified the matrix microstructure. Compared to GOWC, QT30 reduced large capillary pores by 33.28 % after 28 d. This work not only introduces a sustainable and environmentally friendly additive for high-temperature resistant cementing applications but also provides valuable insights into the resource utilisation of QT.

The accumulation or landfill of lithium slag will contaminate the surrounding soil and water quality with residual sulfides and harmful elements, causing serious environmental hazards. This study aims to use Lithium slag (LS) as a sustainable alternative for silica flour (SF) in high-temperature cementing and examines the effects of this substitution on the microstructural and mechanical properties of cement pastes. The results show that an appropriate amount of LS can reduce the permeability of oil well cement and increase its high temperature compressive strength. Compared with pure paste (RS), the compressive strength of the sample replaced by 30 % LS increased by 87.8 % and the permeability decreased by 57.1 % after 28 days of high temperature curing. From the phase point of view, the samples supplemented with LS can form Xonotlite and Katoite with dense structure and high temperature stability. These hydration products can reduce the matrix porosity and permeability, increase the matrix density, and effectively improve the compressive strength of the cement pastes. In addition, the environmental effect analysis showed that the leaching toxicity and radioactivity of the sample did not exceed the standard requirements. This study provides a new direction for the sustainable utilization of LS resources, which not only combats the environmental pollution caused by LS accumulation, but also reduces the cost of cementing materials.

The fourth member of the Shahejie Formation in the Leijia area of the western depression of the Liaohe Oilfield represents a typical shale oil reservoir. However, post-hydraulic fracturing operations in this region are often hindered by significant discrepancies in well productivity, low fracturing fluid flowback efficiency, and an unclear understanding of reservoir damage mechanisms during fracturing. These challenges have become major bottlenecks restricting the efficient exploration and development of shale oil in this block. In this study, a series of laboratory-simulated experiments were conducted to investigate the primary mechanisms of formation damage induced by fracturing fluids in shale oil reservoirs. An experimental methodology for evaluating reservoir damage caused by fracturing fluids was developed accordingly. Results indicate that guar gum-based fracturing fluids exhibit good compatibility with formation-sensitive minerals, resulting in relatively minor damage. In contrast, capillary trapping of the aqueous phase leads to moderate damage, while polymer adsorption and retention cause low to moderate impairment. The damage associated with fracturing fluid invasion into fractures is found to be moderately high. Overall, the dominant damage mechanisms of guar gum fracturing fluids in the Shahejie Member 4 shale oil reservoir are identified as aqueous phase trapping and polymer adsorption. Based on the identified damage mechanisms, corresponding optimization strategies for fracturing fluid formulations are proposed. The findings of this research provide critical insights for improving shale oil development strategies in the Leijia area.

The solid phase produced during the development of shale gas oil and gas wells is largely composed of drilling cuttings. Calcination these cuttings can generate valuable supplementary cementitious materials (SCMs). This study examines the effect of curing temperature (30 or 60 degrees C) in the production of calcined drilling cuttings (600-900 degrees C) (CDC) as an effective route to SCMs. The hydration of the residual solid thermally treated drilling cuttings has been examined, focusing on mechanical strength, degree of hydration, ion dissolution in pore solutions, heat of hydration, hydration products, and microstructure. The results have demonstrated a maximum pozzolanic activity (83.3 %) for CDC at 800 degrees C, achieving high paste strength following 28 d curing. The mechanical properties showed a marked improvement after curing at 60 degrees C, with a 71.22 % increase in 3 d. The CDC hydration exhibited two exothermic peaks due to the dissolution of active minerals and the hydration reaction. After 28 d, an amorphous needle-shaped C-S-H gel and flaky Ca(OH)2 were detected in the CDC hardened paste. The hydration products calcined at 800 degrees C exhibited a higher C-S-H gel component with improved size and structure. The Ca/(Al+Si), and particularly the Ca/Si, ratios increased with increasing calcination temperature in the range of 700-800 degrees C. An increase in the curing temperature significantly increased the Ca/Si ratio in C-S-H. The initial CDC hydration increased the pH and conductivity of the pore solutions, facilitating chemical bond cleavage in the active aluminosilicate phase, promoting pozzolanic reactions and consuming higher levels of Al3 + and Si4+ than observed during dissolution. Enhanced CDC hydration results in the formation of hydration products that fill the pore structure and contribute to improved material hardening.

Abstract Temporary Plugging fracturing technology is an effective method to increase fracture complexity in shale oil and gas development. During the temporary plugging process, the gradual increment of net pressure within the fracture leads to a progressive increase of the fracture width, ultimately rendering the temporary plugging zone ineffectual. Therefore, it is crucial to understand the plugging behavior of the temporary plugging zone as the fracture width increases. In this paper, we establish a novel plugging evaluation device capable of dynamically altering the fracture width in real time, while monitoring the plugging pressure within the fracture. The pressure response characteristics of temporary plugging zones with different particle diameters in the process of dynamic fracture width increase were understood. Finally, the influence of injection rate and viscosity on re-plugging of temporary plugging zone is studied. The findings indicate that when the fracture width reaches the critical fracture width, a distinct dominant channel forms between the temporary plugging zone and the fracture wall, causing a significant drop in plugging pressure. The critical fracture width is determined as one-third of the particle diameter, and smaller particle sizes correspond to smaller critical fracture widths. When the fracture width is below the critical fracture width, effective particle rearrangement can be achieved by increasing the injection rate and viscosity to prevent the formation of dominant channels. However, when the fracture width exceeds the critical fracture width, re-plugging the temporary plugging zone through increased injection rate or viscosity is not feasible. In such cases, the dominant channels can only be filled by pumping additional particles. This paper provides the study on the plugging characteristics of the temporary plugging zone under dynamic changes in fracture width for the first time. It proposes the critical fracture width conditions for re-plugging, which serve as a basis for selecting particle size, optimizing injection rate, and viscosity in temporary plugging and diverting fracturing.

川东南盆缘复杂构造区龙马溪组页岩总有机碳(total organic carbon,TOC)含量高、热演化成熟度高,但构造条件复杂,其微观孔隙结构特征及分形特征相关研究较少且与四川盆内页岩存在差异,亟需进一步深入研究.为更好地表征页岩孔隙结构非均质性及其对页岩气富集的影响,综合运用核磁共振、高压压汞及扫描电镜等技术,定量表征复杂构造区页岩微观孔隙结构特征.基于分形理论,利用高压压汞、核磁共振方法获得不同尺度孔隙的分形维数,并探讨分形维数与孔喉结构参数、TOC含量、矿物组分含量的关系及其地质意义.结果表明:川东南盆缘复杂构造区页岩主要发育有机孔、粒间孔和微裂缝.孔隙结构具有多重分形特征,不同尺度孔喉分形维数存在差异,大孔喉复杂程度高于小孔喉,孔隙总分形维数为2.470 2～2.819 1,均值为2.625 6,反映复杂构造区页岩发育更为复杂的孔隙结构,为页岩气提供大量吸附点位,对页岩气聚集具有积极作用.TOC含量和石英含量等因素的共同影响,造成研究区页岩的强非均质性和复杂的孔隙结构特征.与四川盆内页岩相比,研究区页岩孔径分布较广、分形维数偏低.综合分析页岩孔隙结构及分形特征可为昭通示范区、整个川渝盆缘山地页岩有利储集层段优选提供重要参考.

Tight sand is an important unconventional reservoir. Aiming at the problem of large unused reserves and the poor development effect of Chang 6(3) reservoir, this paper researches reunderstanding reservoir and evaluating unused reserves. Employing rock slice and scanning electron microscope (SEM), the experiment of low-field nuclear magnetic resonance (NMR), water-oil relative permeability experiment, reservoir space, movable fluid, and oil-water seepage characteristics was studied. The factors affecting NMR T-2 cutoff, controlling factors of movable fluids, and controlling factors of displacing efficiency in tight sandstone reservoirs are discussed. The study demonstrates that (1) the mean pore volume and permeability are 4.4% and 0.068 mD, respectively. The reservoir pertains to tight sandstone, mainly intergranular pore and dissolution pore, and the intercalated materials are mainly chlorite and illite. (2) The characteristic of the NMR T-2 spectrum has bimodal characteristics and can be subdivided into two classes: left peak dominant and right peak dominant. The mean value of mobile fluid saturation was 17.9%. (3) According to the relative permeability curve pattern, it is divided into four categories, and the mean bound water saturation is 29.9%. The average irreducible oil saturation was 40.6%. The mean oil flooding efficiency was 40.2%. (4) The better the pore-throat relationship, the lower the T-2 cutoff, the stronger ability of the fluid migration ability, and the higher of a percentage of active fluid. The percentage of active fluid in a low-permeability reservoir is affected by the reservoir's physical property and pore structure.

为了抑制水泥石高温下强度衰退现象,研究硅粉加量,以及赤泥与硅粉在高温下的协同作用对G级油井水泥石抗压强度的影响,并借助X射线衍射、热重分析高温下水泥水化产物的变化,通过扫描电镜观察水泥石的微观形貌.结果表明:225℃高温养护7 d后,35％硅粉(质量分数)可以提高水泥石高温力学性能,5％赤泥(质量分数)可以协助硅粉进一步提高水泥石高温下的强度,同对照组相比抗压强度提高11.3％.赤泥掺入促进水泥石内部生成纤维状硬硅钙石(Ca6Si6O17(OH)2,C6S6H)物相,水泥石内部孔结构减少,水泥石内部结构致密.

"晶体光学"课程具有很强的理论性、抽象性和空间性特点,需要在显微镜下反复操作及实践才能掌握.在有限的学时内,既保证课程理论教学的深度和广度,强化显微镜下鉴定的实践能力,又培养学生的综合分析能力与创新精神,课程团队对该课程按照"金课"的标准进行一系列的建设、改革、创新与实践.精选优质教学素材,精心凝练教学内容,建设了优质的视频资源库和兼具基础性与高阶性的习题库,启发学生的创新思维和创新能力;引入"慕课堂"等智慧教学工具,构建了多种先进教学方法相结合的线上线下混合式教学模式,建立了线上单元知识点测验、线下显微

针对致密砂岩储层,采用API裂缝导流能力测试仪,进行不同类型、粒径、组合的支撑剂裂缝导流能力测试实验,研究支撑剂不同粒径组合对导流能力的影响.实验结果发现:当石英砂与两种不同粒径陶粒组合比例为1:2:2和1:2:7时,在较高的闭合应力下,仍然保持较高的导流能力,而且随着闭合应力增加,导流能力下降幅度较小.因此在致密砂岩储层压裂中,可以选择石英与两种不同粒径陶粒组合,保证裂缝在长时间和较高地层压力下,保持较高的导流能力,从而提高致密砂岩气藏的采收率.

At present, evaluation on reservoir damage induced by fracturing fluid mainly refers to The Evaluation Measurement for Properties of Water-based Fracturing Fluid: SY/T5107-2016 (referred to as the industry standard below). However, the fracturing fluid displacing core process stipulated in the industry standard is not consistent with the fast invading process of fracturing fluid into the reservoir under high pressure during the actual fracturing construction. Besides, the influences of fracturing fluid residues, gel breaking mode, original water saturation and other factors are not taken into consideration in the experiments to evaluate the damage of fracturing fluids. Thus, the accuracy of evaluation results is influenced. In this paper, tight sandstone cores of the Lower Jurassic Ahe Formation (J1a) in Dibei area of Kuqa Depression of the Tarim Basin were selected as samples. The invading process of fracturing fluid into a tight sandstone reservoir was simulated by modifying experimental process and method. Then, the damage degree of fracturing fluid to gas reservoir was evaluated and the damage mechanisms of fracturing fluid were analyzed systematically. And the following research results were obtained. First, the modified evaluation method takes into account the influences of several factors, such as the original water saturation of gas reservoir, the instantaneous “breakdown” effect of high-pressure during fracturing and the fracturing fluid residues, so it can evaluate the damage degree of fracturing fluid to tight sandstone gas reservoirs more objectively. Second, the evaluation results based on the industry standard show that the damage degree of fracturing fluid to the permeability of tight sandstone gas reservoirs is medium to strong, whereas the damage degree evaluated by the modified method is medium to weak. Third, the retention of fracturing fluid residues in fractures is the main cause of permeability damage. The residues can easily block fractures and fracture surface pores. Most of them retain in the pores in the surface layer of matrix cores (invasion depth less than 3 cm), so residues are filtered by matrix pores. Fourth, when fracturing fluid migrates inwards from the core surface, high molecular polymers retain in the form of thin-film lamellar, local flaky nodular and crystal inclusion in turn in the reservoir pores. Fifth, under the experimental conditions, salting-out crystals appear and are unevenly distributed in the cores. In fractures, salting-out crystals and high molecules are polymerized to form composite inclusions. In matrix pores, salting-out crystals and a small number of fragments (e.g. illite) are enclosed to form a complex. Sixth, migratory particles caused by speed sensitivity are usually combined with residues and high molecular polymers to form composite inclusions, thus blocking pores and fractures.

Due to the diversity of pore types, it is challenging to characterize the Middle East’s Cretaceous carbonate reservoir or accurately predict its petrophysical properties. In this paper, pore structure in the reservoir is first classified using a comprehensive method. Then, based on the identified pore structure types, a new permeability model with high prediction precision is established. The reservoir is dominated by 6 pore types, such as intergrain pores and moldic pores, and 6 rock types. Grainstone, algal packstone, algal wackestone, and foraminifera wackestone are porous rock types, and echinoderm wackestone and mudstone are nonporous rock types. The types of pore structure in the study area can be divided into four types. Type I has midhigh porosity and medium-high permeability due to its large throat, while type II has a fine throat type with midhigh porosity and midpermeability. Due to their isolated pores, the permeability is low in types III and IV, and out of these two, type III has better storage capacity. Movable fluid saturation calculated by the spectral coefficient method and rapex can characterize the boundary between the connected pores and unconnected pores very well in the research area. It is not accurate enough to simply classify the pore structure by permeability and porosity. The combination of porosity, permeability, rapex , flow zone indicator, and the reservoir quality index can effectively distinguish and classify pore structure types in noncoring wells. The characteristics of each pore structure type are consistent with those of the fractal dimension, which thereby proves the effectiveness of the pore structure classification. New permeability prediction models are proposed for different pore structure types, and good prediction results have been obtained. This study is of great significance for enhancing oil recovery.

在地质类专业基础课中进行引导式教学模式的探索与实践,是适应当代大学生自主学习能力培养的重要方式,也是新工科背景下培养创新型人才的有益尝试.讨论引导式教学模式在地质类专业基础课教学中的构建原则,并举例展现具体的教学设计,结合实际教学效果提出建议.

碱激活矿渣地聚物(AASGP)在早期水化和碳化的耦合作用下其物相和微观结构变化尚不明确.因此围绕在早期水化和碳化耦合作用下AASGP的物相和微观结构的演变过程采用X射线衍射仪(XRD)、孔结构和环境扫描电子显微镜(ESEM)进行分析.结果表明:AASGP的抗压强度在耦合反应开始后的前3d损失最为显著,损失率为89.75％.AASGP试样在耦合反应开始7d后累积孔隙体积从2.71mL/g增加到5.03mL/g,内部孔隙急剧增加,结构被完全破坏,抗压强度消失,无法满足实际应用.耦合作用对孔结构的影响和C-S-H与CO2反应而导致的脱钙解释了AASGP试样抗压强度衰退的原因.

雷家地区沙四段致密油的开采和研究刚刚起步,在地质认识方面尚不够深刻.本文通过对雷家地区沙四段岩芯观察、XRD衍射、铸体薄片、场发射扫描电镜、氩离子抛光扫描电镜、CT扫描及氮气吸附等方法对沙四段储层地质特征展开系统分析,结果发现:该区主要发育白云岩,根据组成矿物含量的不同可分为白云岩类、方沸石岩类和泥岩类3大类15种岩;孔隙度分布范围1.68％～11.65％,渗透率介于0.01～6.35 mD,属于特低孔特低渗型储层;储集空间类型多样,主要发育溶蚀孔、晶间孔、有机质孔裂缝,该区孔隙结构较复杂,存在少量大孔,但主要由纳米孔组成,孔隙分布较为分散,喉道数量少,连通性差;根据该段储层孔隙结构及储集空间分布特征,将该段储层分为孔隙型、裂缝型和裂缝-孔隙型3类,其中孔隙型储层孔隙分布较为分散、连通性较差,裂缝型储层岩性主要为泥岩类,裂缝-孔隙型储层物性相对较好且主要发育在杜家台段.

研究区储层为文昌组低渗储层,文昌组储层埋深,面孔率<10％,孔隙分布不均,孔喉结构复杂,黏土矿物附着岩石颗粒表面,当与外界流体接触时,容易发生颗粒膨胀、运移、离子沉淀等一系列反应伤害储层,导致生产效率降低.在岩石颗粒表面附着大量的黏土矿物,容易受到外来流体的影响,发生颗粒膨胀、迁移、离子沉淀等反应伤害储层,从而影响生产效率.本文以陆丰14-4油田延长组油层为例,通过储层岩心的XRD、SEM、薄片分析获得储层矿物组成、产状和孔隙结构,初步判断储层潜在损害因素;按照有关的最新标准进行岩心流动速敏、水敏、盐敏、碱敏、酸敏及应力敏感性的实验,结合矿物产状及孔隙结构给出储层的敏感性评价结论及应分别采取的储层保护措施.岩心分析实验表明,储层黏土矿物中比例最大的为伊利石,其次是伊利石、高岭石,还有少量的伊蒙混层.影响储层滲透性的敏感性伤害由弱至强为速敏、水敏、盐敏、酸敏、碱敏.

PL19-9油田是典型的疏松砂岩稠油油藏,其正式投入开发不久后,与PL19-3设计注水量相比,暴露出注入压力高、油井欠注等一系列问题,原油产量明显下降.本文在深化研究该油田储层地质特征的基础上,利用储层敏感性矿物分析、配伍性实验、电镜能谱、X射线衍射、红外光谱分析、室内岩芯驱替、平台水质调研等手段,明确了注水过程中储层损害机理.研究结果表明:PL19-9油田岩石胶结疏松、黏土矿物含量高、层间非均质性强是注水困难的客观因素;储层具有强速敏,注入强度过大是影响注水效果的重要原因;注入水与地层水存在轻度不配伍,不配伍比例在3∶1-1∶3之间;注入40 PV时损害程度为中等偏弱;水质不达标是注水困难的关键外因,注入水中对储层造成伤害的物质主要为油污、腐蚀产物,其次为少量垢和地层颗粒.针对上述损害机理采取相应的措施,提高注水井的吸水能力,保证注采平衡,促进高效稳产.

以东方1-1气田低渗疏松砂岩气藏为研究对象,针对气藏自身特点并结合现场实际开采情况,建立了储层在不同含水饱合度下的速敏评价实验,提出了石油天然气行业标准对疏松砂岩气藏流速敏感性伤害评价改进方法,结果表明,改进后方法的评价结果更加符合现场生产实际.