三肇地区葡萄花油层微观孔隙结构及剩余油分布特征

为搞清微观剩余油分布,首次利用压汞资料、岩心薄片、扫描电镜、数字岩心、油水驱替实验等资料和技术,对三肇地区葡萄花油层微观孔隙结构及微观剩余油分布特征进行系统研究。构建数字岩心及孔隙网络模型,将孔隙结构类型划分为五种,其中以Ⅱ、Ⅲ、Ⅳ类孔隙结构为主,微观非均质性严重。研究不同孔隙结构二维和三维微观剩余油分布,平面上微观剩余油Ⅰ、Ⅱ类储层主要为簇状和角隅状,Ⅲ类储层以喉道状、角隅状为主;微观剩余油三维空间展布,初期以网络状为主,随着注水倍数增加向多孔状过渡,后期多孔状向孤立状和薄膜状转变,最终以多孔状和孤立状为主。剩余油分布受孔隙结构控制,微观孔隙结构发育直接影响储层含油饱和度。关于措施调整,建议Ⅰ、Ⅱ类储层以调堵、补孔、完善注采关系为主,Ⅲ、Ⅳ、Ⅴ类储层以压裂、细分、加强注水来提高驱油效率。     

CT扫描技术对岩石孔隙结构的研究

随着主力油田开发效果逐年变差,新发现油田开发难度不断加大,已探明的低渗透油田可采储量已经成为填补油田产量缺口的重要组成部分。但低渗透油田开发的难度同样不小,尤其在低渗透油田油层实际孔隙结构发育方面的研究较少,缺乏微观尺度的描述成果。利用SkyScan1172微焦点X射线计算机层析(CT)扫描仪,对天然岩心进行扫描,并进行三维重构和定量精细分析,通过对低渗透进行的成像实验,对直径2.0mm的岩心样品进行了微尺寸测量,在不损害样品内部结构的同时,扫描重构了岩心的孔隙结构,并结合室内流体实验,对不同压力下岩心样品孔隙结构变化规律进行了分析,空间分辨率能够达到0.8μm。实验结果表明:压力下降对岩心孔隙结构等参数的影响较压力上升更为明显。利用CT扫描技术,能够对低渗透岩心孔隙结构参数进行定量分析,并且三维重构技术能够对岩心内部孔隙结构进行无损研究。     

利用流动单元指数进行储层分类评价

南海深水某气田是由一系列线状的水道复合砂体组成,储层非均质性强,岩心孔隙度、渗透率关系比较分散,若给定岩石的任一孔隙度后,渗透率变化范围很大,孔隙度相近的不同地层,渗透率可以相差1～2个数量级,用传统的岩心样品孔隙度和渗透率建立关系式来估算储层渗透率很难得到理想的结果。采用取心井岩心,实验室分析孔隙度、渗透率、毛管压力等资料,采用聚类分析法和Winland孔喉半径(r35)分类法,将储层分为四级流动单元,将流动单元指数分类法推广到无取心井和储层段,计算出的储层渗透率与岩心分析比较接近,取得较满意的结果。同时,通过流动单元分类,搭建起储层岩性、物性与孔隙喉道半径之间的关系,为储层评价提供了一种途径,也在一定程度上提高了储层参数的解释精度。利用流动单元对储层进行分类评价,为地质建模提供了可靠的基础资料。     

鄂尔多斯盆地S区长6储层测井解释模型的建立及应用

鄂尔多斯盆地是我国典型的低渗透含油气盆地,受沉积、成岩以及构造作用的影响,具有孔隙结构复杂、非均质性严重和油、气、水分布规律不明显等特征,这导致了测井响应的复杂性,给测井参数的解释带来困难。以鄂尔多斯盆地S区长6储层为例,在大量文献调研基础上,基于搜集到的测井资料、岩心资料和地质资料等,首先开展了储层岩性特征、物性特征、电性特征和含油性特征的关系研究,得出储集层的岩性越好(泥质含量越低),则物性越好;其次对岩心数据进行了深度归位、插值滤波处理,在此基础上建立了相应的泥质含量、孔隙度、渗透率和含油饱和度等储层参数解释模型,并对所建模型进行精度检验;最后应用该模型对S区测井资料开展二次解释。研究表明,经过岩心深度归位及插值滤波处理后的岩心资料与测井资料相关性分析可靠,选用声波时差与岩心孔隙度回归建立的孔隙度模型、运用多元逐步回归法建立的渗透率模型精度较高。     

伊拉克S油田碳酸盐岩储层特征及裂缝孔隙度计算方法

伊拉克北部S油田位于扎格罗斯盆地,主力油层为侏罗系的海相碳酸盐岩,古近纪时阿拉伯板块与欧亚板块发生碰撞,受到剧烈造山运动的影响,储层裂缝非常发育。通过岩心、薄片观察、测井和测试数据分析,认为该油田储层裂缝既是渗流通道,也是重要的储集空间,总体上可以分为两类:裂缝-孔隙型储集空间和裂缝型储集空间。裂缝孔隙度是该类油藏储量计算的重要参数,针对裂缝孔隙度定量计算的难点,通过岩心观察分析和成像测井解释两种方法计算了该油田主力储层的平均裂缝孔隙度分别是0.15%和0.19%。数据分析表明,储层的裂缝孔隙度与裂缝段采油指数呈正相关,裂缝的发育明显改善了储层的渗流性,是该油田获得高产油气流的关键因素。另外,也发现泥质含量超过40%或者石膏含量超过50%的岩石,裂缝孔隙度几乎为零。     

砂岩气藏地层压力下降迂曲度变化规律探讨

通常在定量分析孔隙度、渗透率等物性参数变化规律时,往往假设迂曲度不发生变化。分析了在地层压力下降的情况下砂岩气藏岩石迂曲度的变化规律,以期对常规岩石渗透率变化规律定量研究结果进行修正。根据岩石孔隙结构毛管束简化模型对应的Kozney方程,推导建立了岩石比迂曲度变化理论关系式。结合模拟有效压力增加岩石变形实验,通过将地面实验数据转换为地层条件下孔隙度和渗透率变化数据,考虑储层岩石所承受初始有效压力,实例计算了地层压力下降岩石迂曲度变化规律。实例气藏6个岩心的计算结果表明,随着地层压力下降。岩石迂曲度逐渐增大,且岩石迂曲度的增幅已超过了可以忽略的程度,说明通常假设岩石迂曲度为常数是有局限的。因此。在研究砂岩气藏地层压力下降对岩石渗透率影响时,需要考虑岩石迂曲度的变化。     

喇嘛甸油田不同类型储层微观孔隙结构变化特征

储层微观孔隙结构参数是影响水驱开发效果的重要因素。喇嘛甸油田经过30多年的水驱开发调整,储层微观孔隙结构特征发生了一定的变化。通过天然岩心水驱实验及不同开发阶段检查井取心检测数据,研究了长期水驱后不同类型储层孔隙度、渗透率及孔喉半径等物性参数,分析了水驱前后储层微观孔隙结构特征参数的变化规律。统计资料表明,喇嘛甸油田各类油层,长期注水冲刷后,孔隙度值略有增加,但变化率不大,平均只有0.58%。物性好的储层,渗透率增加,但易形成无效循环通道;物性差的储层,渗透率增加幅度小,更差储层由于地层污染、堵塞,甚至存在渗透率降低现象。喇嘛甸油田经过长期注水冲刷,发育较好的厚油层,其孔喉半径、孔喉半径中值一般增加2μm左右;发育较差的薄油层,大喉道半径、喉道半径中值只降低1μm左右。     

开封地区砂岩孔隙热储回灌化学堵塞数值模拟研究

以开封圳宇花园的地热开发过程为研究对象,利用TOUGHREACT程序构建三维砂岩孔隙热储层的温度场-化学场-渗流场多场耦合模型,并对主要影响因素进行敏感性分析,探究地热回灌过程对热储层化学堵塞过程的影响。热储层中方解石、石英、伊利石、钙-蒙脱石、二氧化硅矿物沉淀,钾长石、钠长石和白云石矿物溶解,其中方解石矿物为主要沉淀矿物,堵塞回灌井热储层,导致孔隙度降低约10%。回灌过程中回灌水注入流速、温度、井间距的改变影响地热水回灌过程中方解石沉淀,从而导致热储层孔隙度变化。     

万花-劳山区长8油层组储层特征及有利区预测

延长组是鄂尔多斯盆地重要储油层系,而长8油层组为下组合最重要的含油层位,长8储层岩石类型主要为细粒长石砂岩,填系物以自生矿物为主,胶结物有方解石、绿泥石等,以泥质胶结为主。储层孔隙度平均值为8.6%,渗透率平均值为0.27mD,属于特低孔-超低渗储层。研究区不同沉积微相物性特征具有较大差异,高孔高渗主要集中在水下分流和河口坝优势微相。孔隙类型以粒间溶孔为主,这种孔隙对孔隙度的贡献较大,是研究区最主要的储集空间;粒内溶孔也是研究区孔隙类型之一,这种孔隙对提高储层孔隙度有限。微裂缝在研究区较常见,主要是由压实作用形成的,它们的存在改善了储层物性。依据层次分析方法 ,选取构造部位、微相部位、烃源岩厚度、砂体厚度、孔隙度和渗透率作为评价有利区指标,确定各评价指标的权重,采用模糊综合评判方法对研究区有利区进行了预测,其中长81预测Ⅰ类有利区2个,Ⅱ类有利区3个;长82预测Ⅰ类有利区3个,Ⅱ类有利区3个。     

应用流动带指数提高渗透率的处理精度

夏子街油田夏26-27-35井区的储层为砾岩骨架结构、中间填充砂岩与黏土矿物的复模态复杂储层,岩心分析数据的孔隙度和渗透率数值分散,如不经处理而直接进行回归计算,回归模型的相关系数很低,无法在实际工作中使用。流动带指数是一个把砾岩骨架结构、矿物地质特征、孔喉特征等因素结合起来判定孔隙几何形态的参数,可以准确描述油藏的非均质特征。使用流动带指数作为分类指标,将岩心分析的孔隙度-渗透率数据按照流动带指数进行分类(通常可以分为3类),再对每类中的孔隙度、渗透率数据分别进行回归计算,建立分类回归模型,可得到相关系数很高的渗透率预测模型。实际经验表明,流动性指数的分类数值区间可以选为小于3、大于6,以及3与6之间;流动性指数的数值越大,渗透性越好。使用这种分类回归模型,可大幅提高渗透率的处理精度,便于地质解释和分析。     

Quantitative evaluation of organic porosity and inorganic porosity in shale gas reservoirs using logging data

Reservoir pores space characterization is the core content of shale gas reservoir evaluation. The reservoir pore space of shale gas reservoir is complex, which can be divided into organic pore, clay pore, crack pore, and debris pore. A method for evaluating the four porosity of shale gas reservoir by using logging data is presented in this paper. First, according to the volume model, shale rock is equivalent to three parts: matrix, organic matter, and pore. On this basis, response equations of density logging and neutron logging are constructed. The total porosity of shale reservoirs can be solved by combining the two equations. Second, organic pore is nanopore that remains in organic matter during the conversion of kerogen to oil and gas, which is related to the content and maturity of organic matter. An equation for calculating organic porosity using total organic carbon content and density logging is presented. The scale factor in the equation is obtained from argon ion polishing scanning electron microscope experimental data. Third, based on the GRI porosity experimental data of 8 samples in the study area, the relationship among clay porosity, clay bound water saturation, and clay content was analyzed. It is considered that the clay bound water saturation has a certain correlation with the clay content, but the correlation coefficient is not high, has a positive correlation with the clay content. Based on this, a statistical model of clay porosity, clay content, and total porosity was established. Fourth, based on the dual laterolog response characteristics of microcracks, the fracture porosity of shale reservoirs is calculated by positive and negative simulation proposed by Li et al. In addition, the detrital porosity is equal to the difference between total porosity and organic porosity, clay porosity, crack porosity. The above techniques are applied to the calculation of four porosities of two wells in the Longmaxi Formation of Sichuan basin, China, and good effect has been achieved.     

Thermal conductivity modeling of micro- and nanoporous silicon

This study aims at developing an approximate model to predict the effective thermal conductivity of porous silicon at both micro- and nano- scales. The model accounts for different transport mechanisms and reduces to the Fourier’s law and phonon radiative transport expression in the diffusive and ballistic limits respectively. The effects of the pore size, the pore shape (square, rectangular, and triangular cylinders), and the porosity on the thermal conductivity are all taken into consideration. In particular, the geometrical effect is addressed by introducing the geometry-dependent view factor and porosity function. The accuracy of the proposed model is confirmed by comparing its predictions with the Monte Carlo simulations for two pore sizes, 100 nm and 500 nm, and a porosity ranging between 0.06 and 0.31. In addition, the geometric effect on the heat transport is also confirmed, which is found more conspicuous in the ballistic limit.     

Molecular dynamics study of the thermal conductivity of amorphous nanoporous silica

This study reports, for the first time, non-equilibrium molecular dynamics (MD) simulations predicting the thermal conductivity of amorphous nanoporous silica. The heat flux was imposed using the Müller-Plathe method and interatomic interactions were modeled using the widely used van Beest, Kramer and van Santen potential. Monodisperse spherical pores organized in a simple cubic lattice were introduced in an amorphous silica matrix by removing atoms within selected regions. The simulation cell length ranged from 17 to 189 Å, the pore diameter from 12 to 25 Å, and the porosity varied between 10% and 35%. Results establish that the thermal conductivity of nanoporous silica at room temperature was independent of pore size and depended only on porosity. This qualitatively confirms recent experimental measurements for cubic and hexagonal mesoporous silica films with pore diameter and porosity ranging from 3 to 18 nm and 20% to 48%, respectively. Moreover, predictions of MD simulations agreed well with predictions from the coherent potential model. By contrast, finite element analysis simulating the same nanoporous structures, but based on continuum theory of heat conduction, agreed with the well-known Maxwell Garnett model.     

基于分形理论预测砂岩储层岩性

根据分形几何学基本理论,探讨岩石孔隙及测井曲线分形维数的确定方法。求取岩石孔隙分形维数有3种方法:分子吸附法、扫描电镜法、压汞法。分子吸附法和扫描电镜法求取岩石孔隙分形维数,所需实验设备昂贵,且过程复杂。利用岩心压汞毛管压力资料,通过线性拟合lgs与lgpc的关系,可计算出岩石孔隙分形维数D。测井曲线反映了地层岩石物理性质。从测井曲线外形上看,对应同一地层的不同测井曲线之间,以及同一条测井曲线的不同部分,分别具有相似的特性。测井响应的这种相似性,可以利用分形理论进行定量描述。目前普遍采用关联维数计算法和测井曲线分形校正法,计算测井曲线的分形维数。实际应用中,根据某油田2口取心井近50块岩样的统计分析,利用岩心压汞资料得到lgs-lgpc散点图,由于分形现象只存在于无标度区范围内,因此一般选取双对数坐标系上线性范围最宽的一段为无标度区,然后再对该段内所有的点进行拟合,并做相关系数检验,从而得到砂砾岩、不等粒砂岩、细砂岩、粉砂岩4种岩性的lgs-lgpc散点图(无标度区)。计算结果表明,应用测井曲线关联维数法预测砂岩储层岩性,其精确度达到92%以上。     

Thermal conductivity of aluminum foam based on 3‐D stochastic sphere model

To accurately characterize the geometric structure of closed‐cell aluminum foam, a three‐dimensional stochastic sphere model with adjustable porosity and pore size was established, and its thermal conductivity was studied by numerical simulation. A closed‐cell aluminum foam heat conduction experiment was designed to verify the accuracy of the model. Using this model, the thermal conductivity of aluminum foam with different pore sizes and porosity was calculated, and the variation of thermal conductivity was studied. The results show that with the same porosity, the thermal conductivity increases linearly with the pore size. With the same pore size, the thermal conductivity decreases linearly with the porosity. The equivalent thermal conductivity decreases with the increase of porosity. According to the simulation results, the formula of equivalent thermal conductivity of aluminum foam is .     

Feasibility of preparing additive manufactured porous stainless steel felts with mathematical micro pore structure as novel catalyst support for hydrogen production via methanol steam reforming

In this paper, an additive manufacturing prepared porous stainless steel felt (AM-PSSF) is proposed as a novel catalyst support for hydrogen production via methanol steam reforming (MSR). In the method, 316 L stainless steel powder with diameter of 15–63 μm is processed by the additive manufacturing technology of selective laser melting (SLM). To accomplish the preparation, the reforming chamber where the AM-PSSF is embedded is firstly divided into an all-hexahedron mesh. Then, the triply periodic minimal surface (TPMS) unit with mathematical form, high interconnectivity and large specific surface area is mapped into the hexahedrons based on shape function, forming the fully connected three-dimensional (3D) micro pore structure of the AM-PSSF. By correlating the mathematical parameter and the porosity of the TPMS unit, and taking into account the SLM process, the porosity of the AM-PSSF is well controlled. Based on the designed 3D pore structure model, the AM-PSSF is produced using standard SLM process. The application of the AM-PSSF as catalyst support for hydrogen production through MSR indicates that: 1) both the naked and catalyst-coated AM-PSSF have the characteristics of high porosity, large specific surface area and high connectivity; 2) the MSR hydrogen production performance of the AM-PSSF is better than that of the commercial stainless steel fiber sintered felt. The feasibility of AM-PSSF as catalyst support for MSR hydrogen production may pave a better way to balance different requirements for catalyst support, thanks to the excellent controllability provided by AM on both the external shape and the internal pore structure, and to the produced rough surface morphology that benefits the catalyst adhesion strength. In addition, catalyst support with pore structures that are more accommodated with the flow field and the reaction rate of MSR reaction may be prepared in future, since the entire catalyst support structure, from macro scale to micro scale, is under control.     

Effect of compression on pore size distribution and porosity of PEM fuel cell catalyst layers

In this study, effects of compression (up to 5 MPa) on pore size distribution (PSD) and porosity of catalyst layers (CL) are investigated using a developed model for deformation of CL under compression. The model is based on effective medium theory and uses a representative geometry (unit cell) to simplify the complex and random porous structure of CL. In this model, different sizes are found for unit cells which are based on CL PSD measurement; this means that unit cell size has distribution since PSD is used as an input to the model. The model has been validated with experimental data in our previous publications. Effect of compression on four different CL samples is studied using the developed model and change of pore diameter is found as function of compression. The change of pore size is different for each sample and dependents on CL initial porosity, PSD, and ink properties. PSD and porosity, which are the indications of microstructure of CL, are found after compression up to 5 MPa. Larger pores show the most change, which causes the void volume percentage of smaller pores to increase, even though the number of pores remain the same. It is also found that the diameter of secondary pores can be decreased by up to 50% depending on CL microstructure, which is significant.     

多孔介质太阳能吸热器性能分析

采用4种多孔骨架中辐射传输模型,包括:忽略多孔骨架内部辐射模型(模型A)、Rosseland模型(模型B)、均匀内热源模型(模型C)与吸热器中辐射传输满足Beer定律的模型(模型D),推导得到了局部非热平衡条件下4种模型所对应的吸热器中多孔骨架温度、空气温度和吸热器热效率的解析解,分析了多孔骨架孔隙率、导热系数和孔隙直径对吸热器性能的影响。结果表明,对模型A和模型B,吸热器中最高温度位于吸热器进口处;对模型C,吸热器中最高温度位于吸热器出口处;而在模型D中,吸热器中吸热器内部或吸热器的出口处温度最高。吸热器效率取决于多孔骨架导热系数、孔隙率和孔隙直径等参数,当吸热器中内热源均匀分布时,吸热器效率是最高的。     

金属泡沫平板结构内对流换热的数值研究

基于Brinkman-Darcy模型和两方程模型,本文对流体在金属泡沫平板通道内的强制对流换热进行了自编程数值模拟,采用体积平均法对流体在金属泡沫内的流动和换热进行宏观处理。模拟结果表明：流体主流速度随孔密度增大而减小,随孔隙率增大而增大;流体相和固体相之间的局部对流换热系数随孔隙率和孔密度增加而增加,金属泡沫对流换热性能随孔隙率增大而减小,随孔密度增大而增大。金属泡沫强化换热的效果十分明显,可以应用于需要强化换热的紧凑式换热器和散热器。