苏里格气田南区莲102井区盒8段储层微观孔隙结构及气-水渗流特征

苏里格气田南区莲102井区盒8段储层孔隙结构复杂,气-水渗流规律不清,因此,运用铸体薄片、图像孔隙、扫描电镜、高压压汞等测试方法对研究区储层孔隙结构进行分析,利用气-水相渗流及可视化渗流实验方法,研究了成藏过程中的气-水渗流特征。研究结果表明,研究区盒8段储层孔隙以岩屑溶孔为主,粒间孔次之,晶间孔及粒间溶孔发育较少,喉道类型以片状喉道和弯片状喉道为主,平均喉道半径0.3μm。根据孔隙度、渗透率、排驱压力及最大进汞饱和度,将盒8段储层孔隙结构分为3类,从Ⅰ类至Ⅲ类孔隙组合类型分别为粒间孔-溶孔、晶间孔-溶孔、溶孔-晶间孔;孔喉半径分布由单峰型或左高右低双峰型转变为左低右高双峰型,主流喉道半径逐渐变小;储层物性由好变差,孔隙连通性也逐渐变差。研究区目的层气驱水类型分为3类,分别为均匀驱替、网状驱替和指状驱替,不同气驱水类型的储层,气-水两相渗流束缚水饱和度及两相渗流区宽度差异较大。气-水渗流特征与物性和孔隙结构关系密切,从Ⅰ类至Ⅲ类气驱水由均匀驱替过渡为网状驱替再到指状驱替,两相共渗区域由宽变窄,等渗点由高变低,且束缚水饱和度逐渐增高,渗流能力由强变弱。基于储层渗流规律,预测研究区有利开发区域,为研究区勘探开发提供依据。

铁路路基降雨入渗过程中水-气两相渗流特性研究

降雨入渗过程中铁路路基填料内水、气两相渗流特性对路基填料的服役性能具有显著影响。在以往的研究中,通常假定孔隙气压力恒等于大气压力,而忽略了孔隙气压力变化对水流运动的影响。本文基于水-气两相渗流理论,考虑孔隙气压力的影响,建立路基降雨入渗过程中的水-气两相渗流数学模型。参照高速铁路典型路基横断面结构,针对路基各层填料水力特性,利用多物理场仿真软件COMSOL Multiphysics~?中的PDE模块对上述数学模型进行求解计算,结果表明:降雨入渗的主要影响区域是基床表层,特大暴雨持续9 h左右,基床表层基本全部处于饱和状态;而基床底层、路基本体、地基层填料由于渗透性较小,降雨过程中水分很难直接迅速地渗入,通常在基床表层与基床底层交界面处产生水分淤积。此时,若列车荷载反复作用,基床表层与基床底层交界面处填料中细颗粒易软化形成泥浆,产生翻浆冒泥病害。降雨入渗初期,由于渗入路基内部的水对原孔隙内气体的挤压作用,使得孔隙气压力逐渐增大,随着降雨时间的增加,受挤压的气体逐渐向下消散,孔隙气压力逐渐减小至接近大气压力值。孔隙气压力的增加会对路基内水流的运动产生阻滞作用,使得路基内孔隙水压力的增长变缓甚至孔隙水压力略有减小,因此,在求解路基降雨入渗的问题时,不能忽略土体内受压空气对水流运动的阻滞作用。

相间力对微孔通道内两相驱替渗流影响规律的LBM研究

为研究了相间力对微孔通道内水-气两相渗流规律的影响,利用格子-Boltzmann方法建立了孔隙尺度下微孔通道内的水-气两相渗流驱替的数学模型。采用C++语言编制的程序对微孔通道内水-气两相渗流驱替过程进行了数值模拟。通过对模拟结果的分析发现:两相驱替的总体效果与相间力有较大关系,流固作用力越大,多孔骨架的亲水性越强,两相渗流的总体驱替效果就越好,驱替速度越大,反之亦然。

高含硫气藏地层硫沉积研究进展及展望

地层硫沉积对高含硫气藏采收率及开发中后期稳产具有重要影响。文中通过梳理高含硫气藏天然气中硫溶解度、流体相态平衡、地层硫沉积伤害等方面的研究进展,提出了高含硫气藏地层硫沉积研究的重要手段,即开展不同温压条件下高含硫气体的相态及微观流动室内实验,并与分子模拟、数值模拟方法相结合,分析地层硫沉积机理及规律。未来应着重加强三方面的基础研究:结合硫溶解度实验,采用分子模拟方法开展分子尺度下的硫溶解行为研究,揭示硫溶解机理;进一步开展高温高压条件下多硫化氢和硫组分变化实验,建立考虑化学反应和热力学平衡的气-水-液态硫三相相平衡模型;加强固态硫伤害及气-水-液态硫三相渗流实验研究,采用分子模拟方法获取各流体组分间多相流动力学行为参数,联合介观尺度多相流模拟方法,模拟多孔介质中气-水-液态硫三相渗流规律。在此基础上,进一步开展储层硫沉积预测数值模拟和硫防治技术研究,为我国以普光、元坝为代表的高含硫气田防硫、控硫、治硫对策制订提供依据。

Pore-scale simulation of gas-water flow in low permeability gas reservoirs

A novel method was developed to establish a realistic three dimensional(3D) network model representing pore space in low permeability sandstone.Digital core of rock sample was established by the combination of micro-CT scanning and image processing,then 3D pore-throat network model was extracted from the digital core through analyzing pore space topology,calculating pore-throat parameters and simplifying the shapes of pores and throats.The good agreements between predicted and measured porosity and absolute permeability verified the validity of this new network model.Gas-water flow mechanism was studied by using pore-scale simulations,and the influence of pore structure parameters,including coordination number,aspect ratio and shape factor,on gas-water flow,was investigated.The present simulation results show that with the increment of coordination number,gas flow ability in network improves and the effect of invading water on blocking gas flow weakens.The smaller the aspect ratio is,the stronger the anisotropy of the network is,resulting in the increase of seepage resistance.It is found that the shape factor mainly affects the end points in relative permeability curves,and for a highly irregular pore or throat with a small shape factor,the irreducible water saturation(Swi) and residual gas saturation(Sgr) are relatively high.

Geo-Archeological Hazard in Ehnasi Site, Bani Souf, Egypt

Archaeological sites are most visible records of our cultural heritage, These sites are often constructed of stone threaten by geomorphological processing, pollution, urbanization, public access, groundwater seepage and geological hazards, such as rock falls. These archaeological sites suffered deterioration and failure of some parts. Environmental hazards are the main agent responsible for the monument degrading knowledge of intensity of environmental hazards together with their aggressiveness characteristics surrounding the monumentally area which is important during all phases restoration process （both previous and to be executed in situ）. The main geo-environmental hazards which affect the monuments under investigation; weathering, air pollution, seismic activity.

Coupled Seepage and Heat Transfer Intake Model

In the beach well intake system, heat is transferred from soil to fluid when seawater is filtered through the aquifer, providing higher temperature source water to the seawater source heat pump (SWHP) system in winter. A 3-D coupled seepage and heat transfer model for studying beach well intake system is established by adopting the computer code FLUENT. Numerical results of this model are compared with the experimental results under the same conditions. Based on the experiment-verified coupled model, numerical simulation of the supply water tem-perature is studied over a heating season. Results show that the minimum temperature of supply water is 275.2 K when this intake system continuously provides seawater with flow rate of 35 m3/h to SWHP. Results also indicate that the supply water temperature is higher than seawater, and that the minimum temperature of supply water lags behind seawater, ensuring effective and reliable operation of SWHP.

Modeling of coupled deformation,water flow and gas transport in soil slopes subjected to rain infiltration

Rain infiltration into a soil slope leads to propagation of the wetting front, transport of air in pores and deformation of the soils, in which coupled processes among the solid, liquid and gas phases are typically involved. Most previous studies on the unsaturated flow and its influence on slope stability were based on the singlephase water flow model (i.e., the Richards Equation) or the waterair two-phase flow model. The effects of gas transport and soil deformation on the movement of groundwater and the evolution of slope stability were less examined with a coupled solid-water-air model. In this paper, a numerical model was established based on the principles of the continuum mechanics and the averaging approach of the mixture theory and implemented in an FEM code for analysis of the coupled deformation, water flow and gas transport in porous media. The proposed model and the computer code were validated by the Liakopoulos drainage test over a sand column, and the significant effect of the lateral air boundary condition on the draining process of water was discussed. On this basis, the coupled processes of groundwater flow, gas transport and soil deformation in a homogeneous soil slope under a long heavy rainfall were simulated with the proposed three-phase model, and the numerical results revealed the remarkable delaying effects of gas transport and soil deformation on the propagation of the wetting front and the evolution of the slope stability. The results may provide a helpful reference for hazard assessment and control of rainfall-induced landslides.