川东北元坝地区须家河组钙质交代-胶结致密层分布与成因

方解石是须家河组砂岩中常见的成岩矿物之一，可在局部层段富集形成钙质交代-胶结致密层，对砂岩的物性有明显的破坏作用。基于岩心观察和薄片鉴定，对川东北元坝地区钙质交代-胶结致密砂岩的岩石学特征开展了分析，刻画了致密砂岩的分布规律；结合全岩X射线衍射、稳定碳氧同位素和微量元素等测试资料，分析了钙质交代-胶结致密砂岩的形成期和物质来源，阐明了钙质胶结物和交代物的形成机制。钙质交代-胶结致密层主要发育在元坝地区西部与须家河组三段（须三段）源岩层相邻的须家河组二段和须家河组四段的砂岩中，在东部须三段源岩层附近的砂岩中则较少；通常出现在厚层砂体的中部，厚度为1~2 m；长石含量或白云岩岩屑含量较高，杂基含量较低；经历的主要成岩作用包括压实作用、方解石的胶结作用和交代作用。方解石的胶结物和交代物主要形成于早成岩阶段B期，此时的地层温度为60~80℃，烃源岩处于有机酸生成的高峰期。由于元坝地区西部须三段烃源岩中含有较高的碳酸盐矿物组分，其排出的富有机酸流体可携带较多的Ca²⁺和HCO₃^-离子进入砂岩层，当砂岩富含长石和白云岩岩屑等碱性矿物时，富Ca²⁺的有机酸流体能被有效缓冲，形成有利于方解石胶结物和交代物沉淀的微环境，从而导致方解石大量沉淀。     

EFFECT OF MICRITE CONTENT ON CALCITE CEMENTATION IN AN UPPER JURASSIC CARBONATE RESERVOIR,EASTERN SAUDI ARABIA

Cementation is a primary factor reducing the porosity of carbonate rocks. It is a challenge to accurately model cementation for reservoir quality prediction because cementation is often a syndepositional process. In addition, cementation requires fluid flow to transport chemical species for precipitation within the pore spaces in a sediment. The development of fully‐coupled depositional‐hydrogeochemical models for cementation prediction is desirable, but the parameters which control the extent of cementation need to be identified and evaluated. This study uses petrographic data from 583 carbonate samples from 15 wells in an Upper Jurassic (Kimmeridgian) reservoir at a giant oilfield in eastern Saudi Arabia to investigate the controlling effects of micrite content on cementation in carbonate rocks. The results indicate that the amount of cement decreases with increasing micrite content in the carbonate rocks analysed. In addition, a modified Houseknecht method has been developed to assess the relative fractions of porosity reduction in carbonate sediments due to compaction and cementation. The method highlights variations in depositional porosity for different rock textures and distinguishes microporosity from interparticle porosity. In the studied samples, the total porosity loss due to compaction and cementation is generally less than 45%, and samples lose more porosity due to compaction than cementation. The relative importance of compaction and cementation in reducing porosity is different for different rock textures: wackestones and mudstones lose porosity mostly as a result of compaction, while grainstones, mud‐lean packstones and packstones lose porosity due to both compaction and cementation.     

A novel ultra-high-temperature oxidation protective MoSi2-TaSi2 ceramic coating for tantalum substrate

To protect refractory metal against oxidation at ultra-high temperatures, a MoSi₂-TaSi₂ ceramic coating was prepared on a pure tantalum (Ta) substrate using a novel three-step process, which included dip-coating with a molybdenum slurry, vacuum sintering, and halide-activated pack cementation (HAPC). The original coating had a MoSi₂-TaSi₂ double-layer structure from the surface to the substrate. After oxidation at 1700°C for 8 h in air, the coating exhibited a complex multi-layer structure composed of SiO₂-Mo₅Si₃-MoSi₂-(Mo,Ta)₅Si₃-TaSi₂-Ta₅Si₃ from the outer layer to the inner layer, due to the high-temperature phase transition and diffusion of Si and O. The coating effectively protected the Ta substrate at 1700°C for 12 h without failure, thereby demonstrating great improvement to its service life in an ultra-high-temperature aerobic environment. The protective effect was attributed to the integrity of the ceramic coating and the formation of a dense, uniform SiO₂ film that effectively lowered the inward oxygen diffusion rate.     

胶凝态水泥浆渗透率测试装置研制及应用

为解决胶凝态水泥浆渗透率性能测试需求,满足水泥凝结过程中的早期窜流风险预测和水泥浆防窜工程性能评价,基于胶凝态水泥浆渗透率预测模型,研究了胶凝态水泥浆渗透率试验测试方法。提出了气侵危险时间内平均渗透率的概念,并研制了对应的胶凝态水泥浆渗透率测试仪。该装置具有结构简单、易于操作,试验测试集成化、简单化和自动化,能有效测试胶凝态水泥浆渗透率在凝固过程中的时变关系曲线等技术参数。可对水泥浆本体防气窜能力的研究提供参考,有助于提高固井质量。     

CONTROLS ON FRACTURE FLOW POTENTIAL IN A TIGHT CARBONATE RESERVOIR: SAYINDERE FORMATION (CAMPANIAN), WEST ADIYAMAN BASIN,SE TURKEY

Identifying controls on the permeability of fluid‐conductive fractures is critical in tight reservoirs, but this is challenging in tectonically complex regions such as foothills belts where there may have been multiple stages of deformation and fracturing. Fracture permeability depends on fracture aperture and connectivity, both of which are affected by tectonism and cementation. Among the many factors that control the cementation history, oil charging may play an important role. Important challenges in studies of fractured reservoirs in tectonically complex regions include determining the timing (and intensity) of fracturing events relative to that of the oil charge, verifying the presence of matrix storage, and establishing the fracture cementation history. This paper reports on a comparative fracture study of four small‐scale oilfields in the west Ad?yaman Basin, located within the foothills belt of the Tauride suture zone in SE Turkey. Here the tight reservoir carbonates of the Say?ndere Formation (Campanian) were subjected to repeated phases of structural deformation. Major deformation phases took place in Campanian and Maastrichtian times, before oil charging into the reservoir began in the Eocene; and in the Late Eocene – Oligocene and Late Miocene, after the oil charge. Fractures that were generated before oil emplacement appear to have been cemented or partially cemented by calcite as indicated by cross‐cutting cemented fractures on borehole images. Partially‐cemented fractures in cores are oil‐stained with cement‐lined walls, suggesting cementation began before oil emplacement but was not completed. Image logs and cores also show the presence of clean, open fractures with no cement present on the walls. These open fractures cut across the cemented or partially‐cemented fractures, and are in general related to Late Miocene compressional folding. Open fracture density is correlated to Late Miocene fold curvature and asymmetry in the four oilfields studied. Of these fields, the ?ambayat structure is the tightest and most asymmetric anticline and hence has the maximum open fracture density; this field also has the highest oil potential. Although the available data is not sufficient to evaluate the effects of oil charging on fracture cementation definitively, the observations are consistent with a model that oil charge into the fractured Say?ndere Formation carbonates inhibited or slowed calcite cementation. Hence fracturing of a carbonate reservoir after oil emplacement may significantly enhance the fracture permeability, and may even render a tight reservoir prospective.     

台头焦煤7202运输顺槽弱胶结围岩支护技术研究

台头焦煤7202运输顺槽进过程中存在弱胶结膨胀软岩地层,支护难度大。为解决该问题,进行耦合模拟研究,结果表明,普通锚杆支护在90 d左右时会出现巷道垮塌现象,结合顶板离层仪观测数据,表明模拟结果真实可靠。对巷道支护优化方案,采用工字钢结合管棚锚喷技术,实施完成进行效果考察,考察结果显示优化方案有效解决了弱胶结软岩支护难度大的问题。     

Application of the pack cementation process on SiC/SiC ceramic matrix composites

The potentials and limitations of a halide-activated pack cementation process on SiC/SiC Ceramic Matrix Composites for the development of bond coats as part of environmental barrier coating (EBCs) systems were investigated. Different pack compositions using chromium, aluminum and alloys of these elements were tested and the kinetics of coating formation were examined in addition to their microstructure. The results and their analogy to diffusion couples were discussed and it was shown that coating elements which form silicides and carbides are promising candidates for coatings deposited on SiC/SiC via pack cementation. Based on such considerations a two-step pack cementation was proposed, which used chromium, one of the suitable elements, in a first step, to finally achieve an alumina-forming coating. The oxidation resistance of the developed coating was tested via thermogravimetric analysis and compared to the uncoated material. The coating protected the fiber-matrix interface of the SiC/SiC Ceramic Matrix Composites from oxidation.     

氧化钇对TC4钛合金表面包埋渗硼的影响

目的 加快TC4钛合金表面固体渗硼时渗层的生长,研究渗剂中添加Y2O3对渗硼的影响。方法 采用固体粉末包埋渗法对TC4基材进行1 050 ℃/8 h渗硼,包括渗剂中不添加Y2O3以及渗剂中分别添加质量分数为1%、3%、5%、7%Y2O3的试验研究。通过扫描电子显微镜、能谱仪、波谱仪和X射线衍射仪分析渗硼样品的截面形貌、元素含量和表面物相,并测量渗硼样品的表面硬度和摩擦系数。结果 在渗剂中加入1%~7%的Y2O3,渗硼层结构与未添加氧化钇渗剂形成的相同,由致密连续的TiB2层和TiB晶须扩散层组成。Y2O3促进渗层生长的作用与其添加量密切相关。渗剂中加入1%~3%的Y2O3有促进渗硼层生长的作用,且加入3%的Y2O3时,催渗效果最佳,可使渗硼层厚度增加40.24%,但加入5%~7%的Y2O3时反而会抑制渗硼层的生长。能谱分析表明,Y原子能够扩散到渗硼层内,且渗硼层中存在原子数分数为0.01%~0.34%的微量Y元素,其随渗剂中Y2O3含量的增加而增加。热力学分析发现,Y2O3参与渗剂反应形成活性Y原子而渗入基体。向渗硼试剂中加入3%的Y2O3,样品的表面硬度较未添加Y2O3时提高35.54%,摩擦系数较未添加Y2O3时降低28.57%。结论 向渗硼试剂中加入适量氧化钇,是获得TC4合金表面高渗速、高硬度和低摩擦系数渗硼层的一种有效方法。     

DZD型高效双相分散冲洗液的室内研究

改善钻井液-冲洗液-水泥浆这三液两界面的相容性,减少彼此絮凝和结构的破坏,可以有效提高注水泥顶替效率和界面胶结强度,保证较好的固井质量。通过大量的室内研究,优选出一种高效双相分散剂,确定冲洗液配方。性能评价结果表明,该冲洗液具有良好的流变性,与低固相钻井液和水泥浆均具有良好的相容分散性;对低固相泥浆冲洗效率达到了90%以上,界面胶结强度平均提高50%以上。此外,通过电镜、原子力显微镜等现代分析手段,对胶结强度提高原因进行了微观分析。     

一个非饱和结构性黄土三维胶结接触模型

对非饱和结构性黄土进行离散元模拟需要合理的三维胶结接触模型。在含抗转动和抗扭转模型基础上引入了颗粒间吸引力以考虑范德华力和毛细力作用;提出了考虑胶结尺寸影响的胶结刚度和强度公式,考虑了不可恢复的化学胶结作用;建立了可以全面考虑含水率-孔隙比-吸力耦合作用的黄土接触模型。通过开展常规三轴压缩以及在不同偏应力水平下湿陷试验的三维离散元模拟,表明该三维接触模型可以较好地反映室内试验中非饱和结构性黄土的主要力学特性。