下寺湾油田柳洛峪区长8油层组裂缝特征与开发效果关联评价

利用构造应力场的研究结果,结合岩心薄片观测和测井解释资料,本文对下寺湾油田柳洛峪区长8油层组裂缝特征进行了综合研究。结果表明：研究区长8储层微裂缝以构造缝为主,占微裂缝总数的70%;大部分为全充填缝（即闭合缝）;充填物成分主要为泥质,少数为方解石和铁质及其它充填物;压裂施工过程中当油井不存在过井天然缝时,压裂过程中破压明显,产生新人工缝。当存在过井天然缝时,压裂过程中破压不明显,人工缝沿天然裂缝延伸。长8层的裂缝方位与构造最大主应力方向一致,均为为北偏东70°左右。     

东濮凹陷沙三上盐间泥页岩储集空间发育特征

东濮凹陷沙三上盐间泥页岩厚度大、埋深浅、有机质含量高,热演化程度适中,既是常规油气的主力烃源岩,也是非常规页岩油气的赋存的有利场所。研究结果表明沙三上盐间泥页岩储集空间可划分为宏观裂缝、微裂缝和微孔隙三大类;裂缝类型为高角度构造缝、成岩缝、超压破裂缝和微裂缝,均以全充填为主,储集空间发育较差;微孔隙主要为粒间溶蚀孔、晶间孔、生物体腔溶蚀孔、铸模孔、有机质溶蚀孔、有机质收缩孔;微孔隙孔径以未充填和半充填为主,整体上呈孔隙类型多、孔隙数量多、孔径小、充填程度低、连通性较差的特征,是沙三上盐间泥页岩的主要储集空间,有利于页岩油气的赋存。     

束鹿凹陷沙三下段孔隙空间类型及其发育特征研究

通过岩芯观察、薄片鉴定、全井眼微电阻率扫描成像(FMI)测井分析等手段,对束鹿地区古近系沙三下段砾岩,泥灰岩〔1〕储层进行了研究分析。结果认为,研究区储集空间类型以裂缝和次生孔洞为主。对储层孔渗特征起作用的又以构造裂缝和孔隙——溶蚀孔洞为主。构造裂缝中以高角度斜交缝和垂直缝为主,部分充填或未充填,填充物以方解石为主,其发育经历了先期张裂、后期压扭和充填三个世代。     

体积压裂应力干扰现场应用的规律

通过室内岩心地应力测试,利用多缝应力干扰理论分析应力场变化特征,结合现场压力测试诊断和微地震裂缝监测结果,验证不同缝间距下的应力干扰对裂缝延伸的影响规律.结果表明:裂缝一旦转向延伸后,随缝间距的缩小,应力干扰导致裂缝转向的程度增加,提高了体积缝的复杂程度,但抑制了缝长方向的延伸,影响裂缝对砂体控制范围.因此,对于既定应力差的地层,尤其对于水平应力差异小的地层,须合理设计缝间距,在利用应力干扰提高体积缝复杂程度同时,要考虑裂缝方向正常延伸,保证裂缝长度上对砂体的整体控制.     

克拉玛依油田砂砾岩储层裂缝识别与评价

断裂是控制克拉玛依油田八区下乌尔禾组砂砾岩油藏裂缝发育的重要因素。根据岩心观察、薄片鉴定和成像测井资料分析,将裂缝分为三大类型,即成岩裂缝、构造裂缝和溶蚀缝洞,构造缝又分为微裂缝、斜交缝、直劈缝和网状缝,八区下乌尔禾组油藏以直劈缝为主。根据不同类型裂缝的成像特征,标定出常规曲线的响应特征,总结出不同类型裂缝对应的不同测井响应规律,建立了定性识别砂砾岩储层裂缝的模式。根据这一模式,以T85006井为例,用成像测井裂缝解释结果验证了模糊识别方法的合理性,并对全区所有井的裂缝进行解释。应用生产动态资料对解释结果进行了评价,说明目前开发中遇到的水淹和水窜问题受裂缝发育影响比较大。     

浅层砂岩垂直井分段压裂起裂压力研究

浅层砂岩垂直井分段压裂,初次裂缝压裂的产生会对后续缝的起裂压力产生影响.在综合考虑了原始井筒周围地应力场的基础上,结合叠加原理和弹性力学理论,建立了浅层砂岩诱导应力场中井筒周围应力场应力分布模型和起裂压力的计算模型.研究结果表明:诱导应力场的分布受裂缝缝长、裂缝间距和原始地应力场的影响.在初次裂缝缝长一定的前提下,裂缝间距越小对诱导应力的影响越大.在裂缝间距一定的前提下,裂缝缝长越长对诱导应力场的影响越大.     

重庆西部地区二叠系长兴组裂缝特征研究

重庆市西部地区二叠系长兴组裂缝发育且普遍充填方解石脉,通过野外露头的观察,结合该区域的构造演化分析,长兴组主要以高角度NW走向张性裂缝为主,该组裂缝形成于喜山期,近NE方向的侧向挤压作用形成;另一组共轭X型高角度剪切缝形成时间较晚,为燕山期,构造主应力为SE方向挤压。本次研究对重庆西部地区长兴组地层典型的岩样进行声发射Kaiser效应实验,样品一般都有3个明显的Kaiser效应点,其中一个是现今构造应力作用的结果,其他两个Kaiser效应点反映了地质历史时期中岩石经历了2次微破裂事件,喜山期岩石所受的构造应力值明显大于燕山期,所以该区发育大量的高角度张性裂缝。     

徐家围子断陷营四段砂砾岩裂缝特征分析

营四段砂砾岩储层成岩作用强,物性差,微裂缝或其它裂缝的发育是改善砂砾岩储层物性的主要因素。裂缝以砾内裂缝和砾间裂缝为主,砾岩储层的孔隙组合主要为孔缝型组合。裂缝的发育主要受岩性、构造和溶蚀作用控制。     

坪北油田长6储层裂缝特征

坪北油田长6储层属于湖相三角洲前缘砂体,是坪北油田的主力产层。通过用倾角测井及微地震波裂缝监测、几何变形分析和相对地压力分析等方法点、面结合分析了坪北长6储层裂缝特征,按成因总结了三种类型,即剪切构造裂缝、层间缝和压裂缝。构造裂缝、层间裂缝不发育,作为渗流通道对坪北长6储层意义不大。压裂缝中的粒间缝与一般的孔喉所起作用相当,而超微压裂缝在原始状态下对渗流没有意义。     

庄X区块不同地应力差下裂缝延伸模拟

体积压裂是非常规油气开采的关键技术,然而体积压裂形成缝网的机理极为复杂,裂缝之间的相互关系仍是目前研究的重点。本文采用边界元理论建立的数值模拟法,对庄X区块不同地应力差下裂缝的延伸情况进行模拟分析。研究结果表明:人工压裂缝及天然微裂缝的延伸受裂缝周围地应力影响明显。地应力差越小,裂缝越容易开裂延伸;压裂缝之间间距越小,诱导应力对裂缝的延伸影响就越明显。文章为预测和人为控制裂缝走向,以及区块后续压裂参数设计提供了参考。     

鄂尔多斯盆地劳山油田长4+5、长6油层组储层特征研究

采用物性分析、压汞、铸体薄片、扫描电镜等方法,对劳山油田长4+5、长6油层组储层特征进行了研究。结果表明:劳山油田长4+5、长6储层岩石成分以长石砂岩为主,孔隙类型主要有原生粒间孔、溶蚀孔及微裂缝3种,孔隙结构有中孔-细喉型和中小孔-微喉型,对孔隙度影响较大的主要成岩作用是压实压溶、胶结和溶蚀作用。根据岩性、物性及孔隙结构特征参数,将研究区储层划分为特低渗储层Ⅱa和超低渗储层Ⅲb两类。     

A Practical Technique for Investigating the Fracture Properties of Clay-Based Ceramics by Diamond Indentation

A method is described for investigating the fracture properties of vitreous clay-based ceramics. It involves indenting the specimen with a Vickers diamond in-denter under paraffin oil and revealing the radial cracks so formed with the aid of insoluble dye particles. Typical results are quoted for soda-lime glass and two electrical porcelains. It is suggested that differences in behavior of the porcelains can be attributed to the toughening effect of microcracks.     

橡胶磨耗及表面形貌的研究

通过改变温度和转数来研究它们对橡胶磨耗性能的影响。采用扫描电子显微镜和固体核磁共振研究了磨耗表面形貌的演变过程和结构变化的属性。研究表明,转数与磨耗体积几乎呈线性增大的关系;随着温度的升高,磨耗体积有加剧变大的趋势。扫描电镜的图像表明,磨耗花纹起始于硫化胶表面的微裂纹,在应力作用下,裂纹不断增大、加深,最终形成了山脊状的磨耗花纹。固体核磁共振谱图表明阿克隆磨耗主要是物理性结构变化,并没有明显的化学性变化。     

The theory of thermal shock in heterogeneous refractory materials

Conclusions Increases in the thermal shock resistance with the addition of high-molecular organic liquids to the grog, proven experimentally, is confirmed by calculations of the factors for thermal-shock resistance of fireclay articles according to the theory of maximum stresses.The established reduction of thermal resistance with the addition of organic liquids in the bond is not reflected by the calculations. Hence, the theory of maximum stresses, although it can in certain cases be applied to bodies which are heterogeneous, it is not universal.On account of the growth in microcracks, the experimentally determined thermal-shock resistance for firebrick increases with chaotic orientation of the microcracks, and with their distribution over the grog grains, but diminishes when the microcracks are located in the bond parallel to each other.In this and other cases, the coefficient of homogeneity of the material diminishes, and the associated probability of destruction (calculated by Weibull) increases. Thus, the statistical theory of strength evolved by Weibull cannot be used to account for the effect of the orientation of microcracks in the structure on the distribution of cracks developed in the material during thermal shock.Calculation of the developed thermal stresses, as a function of the Biot and Fourier criteria, established that with the addition to the grog grains in the fireclay mass of organic liquids, these stresses diminish by a factor of 3–4; there is an increase in the time period and difference in temperature at which the cracks develop, and also the depth of the development of the latter. However, the distribution of the developing thermal cracks is limited when the microcracks are arranged chaotically and around the grog grains. This also increases the thermal resistance of the fireclay refractories when the high-molecular organic liquids are added to the grog grains.     

Effect of Grain Thermal Expansion Mismatch on Thermal Conductivity of Porous Ceramics

Many ceramics contain microcracks, which are often situated between sintered grains. These microcracks constitute thermal resistances, which may affect heat transfer through the material and its effective thermophysical properties. The thicknesses and the contact areas of the microcracks change with temperature as a result of the thermal expansion mismatch between the grains on opposite sides of the microcracks. This physical mechanism affects changes of the material's thermal conductivity, k , with temperature. The above mechanism usually plays a minor role at atmospheric pressure, where heat may flow via the gas filling the cracks. Hence, the temperature-induced changes of the crack geometry have little effect on heat transfer. However, at low gas pressures, where the heat flow between the grains occurs mainly via the contact areas, the grains' thermal expansion mismatch causes unusual temperature behavior of the material's thermal conductivity observed for several industrial refractories. In this paper, the influence of the above physical mechanism is discussed relative to other heat transfer mechanisms described in the literature. A simple physical model of the thermal expansion of grains bonded by an agent, having different thermal expansion coefficients, is developed. This model allows calculation of the contact area and the average microcrack opening between the grains as functions of the temperature, the characteristic grains sizes and their thermal expansion coefficients, and the permanent crack area. These parameters are evaluated and used to calculate the effective thermal conductivity of ceramic materials containing microcracks that appear as a result of thermal contraction of grains. The calculated thermal conductivity satisfactorily correlates with the experimental data collected for several chrome-magnesite refractories over a wide range of temperatures and gas pressures.     

纳米复合陶瓷增韧机理分析

分析研究了纳米复合陶瓷材料的断裂模式和和场情况,提出纳米复合陶瓷韧性增加是主晶界强化和晶粒分化共同作用的结果。晶界纳米相能和基质形成高和谐主晶界,从面对沿晶裂纹起强“钉扎”作用;晶内纳米相的增韧作用在于形成有利于穿晶断裂的应力场,再加上微纹和次界面,使晶界得以强化,而基质晶粒趋向脆化。若纳米相过多,基体得到细化,但晶内纳米颗粒的应力作用更加突出,不利于断裂韧性的提高。     

Indentation Deformation and Fracture of Sapphire

Relatively little is known about the fundamental deformation processes in intrinsically hard, brittle materials, and even less about how these processes lead to the initiation of cracks. In this paper, transmission electron microscopy is used to study the deformation structure within Vickers indentation zones of single-crystal sapphire with {     } surface orientation. The relative misorientation of regions within these zones, as mapped by convergent-beam kikuchi patterns, is found to be severe, indicative of shear processes operating close to the cohesive limit. Two principal types of deformation are identified, basal twinning and pyramidal slip. Incipient microcracks are observed at both the twin interfaces and the slip planes. These incipient "flaws" act as nucleation sites for the ensuing radial and lateral cracks.     

Self-healing of TiSiN/Ag coatings induced by Ag

Ceramic coatings often suffer from the formation and expansion of microcracks, which leads to a failure of the protective function. In this work, we observed self-healing of the microcracks in the TiSiN/Ag multilayer coating upon heating. This behavior can be attributed to diffusion of the Ag atoms to the cracks in the multilayer coating, while similar cracks in the TiSiN monolayer coating remain unchanged after the same treatment. Furthermore, the TiSiN/Ag coating with healed cracks possesses similar electrochemical corrosion and biofouling properties to the as-deposited one, suggesting that TiSiN/Ag is a promising system in marine engineering applications. The mechanism of self-healing was explained by kinetic simulations based on ab initio molecular dynamics and the diffusion activation energies of Ag in irregular ceramic structures have been calculated. The here adopted theoretical method also provides a new pathway for exploring new coating systems with a potential self-healing function.     

Statistics of Flaw Interaction in Brittle Materials

The problem of elastic interaction of an array of microcracks is considered. The solution is based on an efficient surface integral method using distribution of edge dislocations to represent the microcracks in the mathematical model. From the analysis of the interaction between two identical cracks, it is seen that interaction is most likely to produce a slight enhancement in the stress intensity factor. By performing computer experiments on a random array of microcracks, the effect of crack interaction is studied statistically as a function of the density of the microcracks. The significance of the interaction effects for fracture in ceramics is discussed.