地下水封洞库围岩气体渗透特性及滑脱效应研究

地下水封洞库的围岩是一种低渗透岩石,其气体渗透特性,以及气体渗透率随压力的变化是地下水封洞库工程非常关注的问题。该文对某石油储备地下水封洞库的风化花岗片麻岩进行了室内的气体渗透特性试验,滑脱效应试验以及扫描电镜试验。试验结果表明:该风化花岗片麻岩气体渗透在不同围压阶段,渗透率和孔隙度变化规律不同;存在一个围压拐点,小于拐点值时,渗透率随围压满足指数函数,大于拐点值时,满足二次函数关系;SEM试验表明,岩石内部不整合接触形成的微裂隙和微孔洞导致了围压加载过程中渗透率和孔隙度不同变化规律;气体在低渗透岩样渗流过程中存在滑脱效应,应对测试所得到的渗透率进行滑脱效应的修正;对于地下水封洞库,设计和运行时要考虑气体渗透的滑脱效应的影响;气体滑脱效应的影响与围压有关,当围压为8 MPa~9 MPa时,气体滑脱效应对气测渗透率影响最大。     

岩石渗透率节流毛细管气体流量计量测试方法研究

岩石气体渗透率是油田勘探开发最重要的基础数据之一。文章介绍了国内外岩石渗透率测试气体流量计量技术的现状，针对低渗透储层油气藏勘探开发过程中岩石渗透率测试存在的问题，开发研制了一套节流毛细管气体流量计量自动测定装置，建立了岩石渗透率节流毛细管p-g回归测试方法。该测试方法计量气体通过岩石的能力速度快，测试精度高，自动化程度高，是岩石渗透率测试技术的重大突破。     

一种应用于岩石渗透率测试的气体流量计量方法-节流毛细管法

本文介绍了国内外岩石渗透率测试气体流量计量技术的现状，针对低渗透储层油气藏勘探开发过程中岩石气体渗透率测试存在的问题，开发研制了一套节流毛细管气体流量计量自动测定装置，建立了岩石渗透率节流毛细管测试压力P-与测量气体流量Q回归的测试方法。该测试方法计量气体通过岩石的能力速度快，测试精度高，自动化程度高，是岩石气体渗透率测试技术的重大突破。     

激光共聚焦技术在岩芯图像分析中的应用

本文将激光共聚焦技术与岩芯图像相结合。使用激光共聚焦技术将采集到的岩芯进行切片,断层式的扫描,从而获得岩石孔隙分布的三维图像,并且对岩芯图像进行了定性和定量的分析(包括孔隙度、面孔率等)。使用该方法所获取孔隙度和面孔率能够更真实地反映岩芯宏观的孔洞特征,对油田的开发具有一定的积极作用。     

低渗透油藏流入动态分析

随着石油资源的不断开发与利用,低渗透油田在我国油田开发中所占的比例越来越大。低渗透油气田将是我国石油工业增产的资源基础。在低渗透油藏的开发中,即使渗透率和孔隙度下降值不是很大,但由于原始渗透率和孔隙度很低,其相对变化幅度对油藏开发产生的影响仍然较大,所以需要考虑介质变形的影响。目前对于渗流机理较为复杂的低渗透油藏的研究主要集中在单一因素对试井解释模型的影响,也将影响到后续工作的开展。因此研究考虑启动压力梯度和介质变形影响的低渗透油藏试井解释模型能够更加科学地指导低渗透油藏试井应用,具有重要的理论价值和实用价值。     

一种应用于岩石渗透率测试的气体流量计量方法-节流毛细管法

本文介绍了国内外岩石渗透率测试气体流量计量技术的现状,针对低渗透储层油气藏勘探开发过程中岩石气体渗透率测试存在的问题,开发研制了一套节流毛细管气体流量计量自动测定装置,建立了岩石渗透率节流毛细管测试压力P-与测量气体流量Q回归的测试方法。该测试方法计量气体通过岩石的能力速度快,测试精度高,自动化程度高,是岩石气体渗透率测试技术的重大突破。     

核磁共振测井基本理论研究与介绍

核磁共振测井是一门全新的技术，它直接测量地层流体中的氢原子信息，可直接得到地层中的孔隙度、渗透率等重要参数信息，不受岩石结构影响，因此一当它成功推出并应用于实际测井过程中，立即被誉为测井技术的神话。经过核磁共振测井已经应用了十多年，但是很多人对核磁共振测井理论还未弄清。文章主要从核磁共振测井基本理论入手，对核磁共振理论进行简要介绍，并对常用的核磁共振测井CPMG序列进行分析与说明。     

RTM中纤维渗透率预测的研究进展

对国内外在RTM 成型工艺中的渗透率预测方法进行了文献回顾。系统论述了理论分析法和数值模拟法, 评析了各方法中模型存在的问题, 比较了模型间的不足。理论分析法中详细介绍了毛细管模型和规则排列柱阵模型在单向纤维渗透率预测中的应用。数值模拟法中重点介绍了均匀化法、Boltzman 网格法和单胞法对单向纤维和平面机织纤维渗透率的预测。回顾了国内对渗透率预测的研究, 其方法主要以实验分析为基础, 分析了纤维结构与渗透率的关系, 讨论了渗透率特性对工艺过程的影响规律。提出了目前在渗透率预测研究中仍然存在的一些不足, 指出了该领域将来的研究方向。      

温度和损伤程度对砂岩渗透特性影响的试验研究

岩石的渗透特性与许多地下工程的稳定与安全有关,而深部岩石工程环境所处的温度、应力以及自身损伤情况对渗透特性也有较大的影响。因此,有必要开展损伤岩石在不同温度、应力情况下渗透特性研究。利用GCTS高温高压动态岩石三轴仪、岩石全自动气体渗透率测试系统,对不同损伤程度砂岩进行了不同围压和实时温度的渗透特性试验。试验结果表明:不同损伤程度砂岩的渗透率与围压之间呈现幂函数负增长关系,在低围压向高围压过渡过程中,高损伤试样渗透率出现较大的跌落;不同损伤程度砂岩渗透率与温度关系为负相关,高损伤试样渗透率随着温度增加下降得更加缓慢;随着损伤程度的增加,砂岩渗透率呈现出低围压情况下先略微下降再上升,高围压情况下逐渐上升的特征。低围压状况下,损伤程度较高的试样之间渗透率差异较大。     

岩石气体孔隙度测量不确定度分析

介绍了岩石气体孔隙度的测量方法原理以及仪器参数标定方法，对测量过程中的误差源进行了分析，给出了直接测量分量的A类和B类不确定度的计算公式以及不确定度的传递、合成和扩展算法。针对具体实验仪器和岩石样品的孔隙度测量实例进行了不确定度分析，给出孔隙度测量和不确定度分析结果。     

变形三重介质三渗模型的压力动态分析

在应力敏感油藏的试井分析中,常岩石特性的假设对于确定传导率和储存系数可能引起较大的误差。研究了应力敏感地层中三孔三渗流动模型的压力响应,不仅考虑了储层的三孔三渗特征,而且考虑了井筒储集效应和应力敏感地层中介质的变形,引入了渗透率模数,建立了应力敏感地层三孔三渗流动的数学模型,渗透率依赖于孔隙压力变化的流动方程是强非线性的,因而采用数值方法求解数学模型,并探讨了变形参数和三重介质参数变化时压力的变化规律,给出了典型的压力曲线图板,这些结果可用于试井分析。     

变形介质双渗模型非线性流动模拟

在碳酸盐油藏和低渗油藏的渗流问题研究中,传统的研究方法都是假设地层渗透率是常数,然而对于地层渗透率是压力敏感的,这样的假设,对压力的变化将导致较大的误差。研究了应力敏感地层中双渗流动模型的压力不稳定响应,不仅考虑了储层的双渗特征,而且考虑了应力敏感地层中介质的变形,建立了应力敏感地层双孔隙度、双渗透率流动的数学模型,渗透率依赖于孔隙压力变化的流动方程是强非线性的,采用Douglas-Jones预估-校正法获得了圆井定产量生产和定压生产时无限大地层情况下的数值解,并探讨了变形参数和双重介质参数变化时压力变化规律,给出了典型压力曲线图版和应用实例。     

Permeability and high temperature strength of porous mullite-alumina ceramics for hot gas filtration

The gas permeability and mechanical properties of mullite-alumina ceramics for potential use as filters in hot gas separation environments are examined. The mullite-alumina ceramics with different levels of induced porosity and pores sizes were fabricated by slip casting and characterised in terms of microstructure and strength properties at ambient and elevated temperatures. Permeability to nitrogen gas flow of the porous structures at ambient temperature was investigated over a range of flow velocities to quantify and assess the permeability. The strength at high temperatures is equivalent to ambient data signifying no discernible degradation. Nitrogen gas permeability tests reveal dramatic reductions in the pressure drop–gas velocity curves with increasing porosity. It is shown that the gas permeability increases with the level of porosity and pore size, with maximum Darcian permeability constant of k = 2.5×10⁻¹⁴ m² for a porosity of 71%.     

Preform permeability variation with porosity of fiberglass and carbon mats

An experimental investigation on fiber bed permeability variation with porosity for three types of reinforcement mats is performed. The reinforcements consist of plain-weave carbon, plain-weave fiberglass, and chopped fiberglass mats. Resin flow experiments are performed in a rectangular cavity with different fiber volume fractions. RL 440 epoxy resin is used as the working fluid in the experiments. Several layers of mats are laid inside the mold in each experiment and resin is injected at a constant pressure. The effects of reinforcement type and porosity on fiber bed permeability are investigated. Fiber mat permeability of woven mats show large degrees of anisotropy. Resin flow in chopped fiberglass mats is circular, suggesting an isotropic permeability tensor. In all the three cases, preform permeability increases with fiber bed porosity in a non-linear fashion. The results of this investigation could be employed in optimization of liquid composite molding manufacturing processes.     

考虑二次梯度项影响的双重介质流动分析

传统的试井模型与物质平衡方程都是不一致的。在非线性偏微分方程中根据弱可压缩液体的假设忽略了二次梯度项，对于混气石油和低渗透储层这种方法是有疑问的，我们已经知道在试井较长时间忽略二次梯度项将产生误差。本文对于双重介质流动系统建议了与物质平衡方程一致的方法，保留了非线性偏微分方程中所有项，建立了双重介质流动模型。采用Douglas-Jones预估-校正法获得了无限大地层定产量生产时和定压生产时双重介质模型的数值解，分别讨论了液体压缩系数和双重介质参数变化时压力变化规律，做出了典型压力曲线图版，这些结果可用于实际试井分析。     

Vacuum-bag-only co-bonding prepreg skins to aramid honeycomb core. Part II. In-situ core pressure response using embedded sensors

Miniature pressure sensors were embedded into the honeycomb core of sandwich panels featuring both tool-side and bag-side skins. The pressure response was measured throughout the vacuum hold and elevated temperature processing stages of both oven and autoclave manufacturing. The elevated temperature processing measurements validated the honeycomb core pressure model presented in Part I, confirming that gas flow primarily occurs through the bag-side skin in semi-infinite panels. Aramid core panels showed much higher honeycomb core pressures than aluminum cores during elevated temperature processing. Higher core pressures during processing led to more gas flow and as a result, cured skins with interconnected porosity. The best sealed aramid core honeycomb skins were processed under one atmosphere of positive pressure with a vented vacuum bag, avoiding the continuous extraction of gas through the skins by the vacuum pump while the resin was highly mobile.     

再生骨料影响混凝土渗透性的数值模拟

出于环境保护及经济方面的考虑,再生骨料在混凝土生产中得到越来越多的应用。混凝土可认为是由天然或再生骨料、多孔基体和界面过渡区三相组成的复合材料。基于随机骨料结构生成算法,建立了三相混凝土数值模型并应用于气体渗透性的分析。对于混凝土二维数值模型的稳态渗透问题,应用有限单元法求解压力场,并基于压力-流量的宏观等效关系计算混凝土材料的总体渗透率。数值分析结果表明:1) 总体渗透率随过渡区厚度及其相对渗透率的增加而非线性地增长;2) 由于骨料的存在而导致的稀释效应及曲折度效应是影响混凝土总体渗透性的两个重要因素;3) 再生骨料渗透率对混凝土宏观渗透率的影响呈“S”形曲线的关系。出于控制回收骨料混凝土渗透性能的考虑,回收骨料的渗透率最好比砂浆基体的渗透率低一个数量级,同时回收骨料的掺量也需要合理选择确定。     

In situ measurement and monitoring of whole-field permeability profile of fiber preform for liquid composite molding processes

For liquid composite molding (LCM) processes, such as resin transfer molding (RTM), the quality of final parts is heavily dependent on the uniformity of the fiber preform. However, the conventional permeability measurement method, which uses liquid (oil or resin) as its working fluid, only measures the average preform permeability in an off-line mode. This method cannot be used to create an in situ permeability profile because of fiber pollution. Further, the conventional method cannot be used to reveal preform's local permeability variations. This paper introduces a new permeability characterization method that uses gas flow to detect and measure preform permeability variations in a closed mold assembly before resin injection. This method is based upon two research findings: (1) resin permeability is highly correlated with air permeability for the same fiber preform with well-controlled gas flow, and (2) the whole-field air permeability profile of a preform can be obtained through measuring the pressure field of gas flow.In this study, first the validity of the gas-assisted, in situ permeability measurement technique was established. Then the technique was demonstrated as effective by qualitatively detecting non-uniformities and permeability variations in fiber performs. Finally, a two-dimensional flow model, based on the finite difference scheme, was developed to quantitatively estimate the whole-field preform permeability profile using predetermined pressure distribution. The efficacy of the new method was illustrated through experimental results.     

Experimental Study of Gas–Liquid Two-Phase Flow in Glass Micromodels

To estimate the most important flow variables in reservoir engineering, such as the relative permeability, it is required to know with high precision, other variables such as saturation, pressure drop of each phase, and porous media data such as porosity and absolute permeability. In this study, experimental tests were performed inside a glass micromodel using gas–liquid two-phase flow in steady-state conditions. The liquid-phase flow and the pressure drop of the porous media were determined. Additionally, the flow development inside the porous media was visualized using a high-speed video camera system. These pictures were recorded at 500 fps, and they were used to compute the phase saturation and the gas velocity in the glass micromodel. The visualization was performed in three regions of the glass micromodel demonstrating that saturation gradients were not present. The effect of the capillary number was studied over the gas–liquid relative permeability curves and on the flow mechanisms. It was concluded that high flow rates minimize edge effects, that the capillary number modifies the relative permeability values and the flow patterns inside the micromodel, and that the high-speed visualization is an efficient and accurate technique to determine saturation values and to study the flow patterns in transparent porous media such as glass micromodels.