Modeling of Subsidence and Reservoir Compaction under Waterflood Operations

A full-field, three-dimensional (3D) computer model has been developed to numerically simulate reservoir compaction and surface subsidence for a weak, water-sensitive, hydrocarbon reservoir during field-wide water-injection operations. The developed model was used for modeling the compaction and subsidence processes under waterflood operations at the Ekofisk Field in the North Sea. The model was thoroughly validated through the comparison of model results to extensive field measurements with good agreement being achieved. The validated model has been successfully employed as a tool to forecast subsidence and to assist in the development of a subsidence risk assessment. For practical field applications, important quantitative information, that includes reservoir compaction, seafloor subsidence, and seafloor horizontal movement, may be generated from the full-field, 3D model and is presented in this paper.     

Casing Influence in Reservoir Compaction Measurement by Radioactive Markers in the Northern Adriatic, Italy

The reliability of in situ compaction measurements made in producing gas/oil reservoirs with the aid of the radioactive marker technique (RMT) is a very important issue as an essential parameter controlling the geomechanical response of fluid extraction from the subsurface, i.e., the rock vertical compressibility cM, is obtained from RMT data. The validity of cM as provided by RMT has recently been questioned on the basis of the possible disturbance that a fully cased hole can induce on the actual reservoir compaction. By the use of a numerical approach and real casing information, the present paper addresses and discusses the reliability of RMT measurements performed in hole casings of the Northern Adriatic gas fields, Italy. The results show that the casing stiffness affects the RMT measurements only marginally, and especially so at a larger depth (i.e., 3,000?m), and does not significantly impact on the estimate of cM derived from RMT data.     

3D Analytic Model for Testing Numerical Tidal Models

A 3D analytic solution is presented for tides in channels with arbitrary lateral depth variation. The solution is valid for narrow channels in which the lateral variation of the amplitude of tidal elevation is small. The error introduced by the solution is on the order of a few percent in a tidal channel of a few kilometers in width. The solution allows an arbitrary lateral depth variation and thus provides a wide choice of depth functions, especially those with large bottom slopes. The largest amplitude of the along-estuary velocity appears on the surface in the deepest water. The depth-averaged velocity is the largest in the deepest water. The time of flood (ebb) in deep water lags that in shallow water. The time of flood (ebb) on the surface lags that at the bottom. Since this solution is simple and allows arbitrary lateral depth variations, it can be used to demonstrate the first-order tidal flow in narrow tidal channels of variable depth, and to test high-resolution numerical models with large depth gradients.     

Radioactive Marker Measurements in Heterogeneous Reservoirs: Numerical Study

A numerical study is performed to simulate the vertical deformation of a depth interval representing a marker spacing (10.5 m) located in a deep heterogeneous sedimentary reservoir. Realistic lithostratigraphic sequences typical of the Northern Adriatic basin are used. A number of scenarios are addressed consistent with the available data. In particular two basic geologic scenarios at the marker scale are simulated, one where sands prevail within the marker spacing (SD), and another where thin sandy and clayey layers alternate (CL). The sensitivity of the marker response is investigated in relation to clay and sand permeability and compressibility contrast, Biot’s coefficient, and respective position of monitoring and fluid pumping wells. The modeling results show that rock may indeed expand above and below depleted layers. Depending on the marker position the expansion may partially offset the compaction, especially in the CL scenario with a very low permeable clay. To obtain a representative field compaction the markers should span a depth interval made mostly by sand and entirely depleted, and should be installed in a test hole far from producing wells. Compressibility contrast and the Biot coefficient play a secondary role. Very critical measurements are provided by two markers which incorporate a thin (≈1 m) depleted level overlain and underlain by almost impermeable clay layers.     

台南凹陷三叠系油气有效输导层特征分析

有效输导层是油气运移过程中实际经过的那部分输导通道。在常规储层物性研究的基础上,分析有效输导层宏观影响因素,结合油气显示数据,研究油气运移过程中流体在储层中的通道优选规律。研究工作显示:吐哈盆地台南凹陷三叠纪储层油气经历了由西向东的长距离运移过程,砂体是主要运移通道。埋藏压实作用是影响输导层物性最重要的因素,同等压实程度下,细砂岩物性最佳,三角洲内前缘和辫状三角洲平原是有利的储层形成环境。应用滑动砂地比连续计算地层砂泥岩分布,85%的油气显示小层分布在滑动砂地比大于60%的地层段内。台南凹陷有效输导层分布于研究区中部和南部,累加有效储层孔隙空间厚度在20~40 m范围。     

深插入浸罩CAS钢包流场混合特性的水模型研究

按照110t CAS钢包1/6的水模型,研究了浸罩深度(熔池液面深度0～20%)和直径(钢包底部直径的0.4～0.7)对熔池混匀时间的影响。结果表明,随着浸罩深度和直径的增加,罩内的循环流增强,在深插入浸罩(熔池液面深度的20%)条件下,钢包内流场发生显著变化,浸罩内形成了明显的循环流。通过无因次分析,得出底吹气量Q和浸罩深度H对混匀时间T影响程度的经验公式(T-T0)/T=3.13Q^-0.66(H/HL)^1.56。     

Mathematical Simulation of Flow Field for Molten Steel in an 80–ton Single Snorkel Vacuum Refining Furnace

The three–dimensional flow field of molten steel in an 80–ton single snorkel vacuum refining furnace has been mathematically simulated to attain the optimal configuration and operation parameters, such as the bottom blowing Ar flow rate, the eccentric position of bottom blowing Ar port at ladle bottom, the single snorkel inner diameter, and the single snorkel immersion depth into molten steel. The mathematical simulation results show that a stable flow field of molten steel can be achieved in 70–second; meanwhile, the maximal circulation intensity of molten steel in the 80–ton single snorkel vacuum refining furnace can be found on a cross–section with y as 0 mm based on the middle of ladle bottom as circular point of the Cartesian space coordinate under the condition of injecting Ar gas on x coordinate considering the asymmetry of flow field for molten steel in the single snorkel vacuum refining furnace. The recommended parameters of the 80–ton single snorkel vacuum refining furnace with ideal circulation intensity as 970.1 kg/s are the bottom blowing Ar flow rate as 450–500 Nl/min, the eccentric position of bottom blowing Ar port as 250 mm, the single snorkel inner diameter as 1000 mm, and the single snorkel immersion depth as 500 mm.     

Extension of Poroelastic Analysis to Double-Porosity Materials: New Technique in Microgeomechanics

Double-porosity materials were introduced as models for oil and gas reservoirs having both storage and transport porosities, and were at first usually treated as static mechanical systems in order to study the flow patterns of fluids during reservoir pump down. Because fluid withdrawal normally increases the effective stress acting on the reservoir, it also turns out to be important to study the geomechanics of the reservoir and how changing fluid pressure affects the solid compaction and fluid permeability of these systems. At the microscale, the mechanical properties of the solid constituents and their distribution in space determine the overall macromechanics of the reservoir system. For systems containing two porosities and two types of solid constituents, exact results for all but one (which may be taken as the overall drained bulk modulus of the system) of the mechanical constants can be derived when the constitutents’ properties are known using methods developed in this paper. For multiporosity systems, closure of the system of equations remains an open question, although it is clear that the system can always be closed by the addition of further macroscale measurements.     

电弧炉底吹搅拌熔池表面突起高度的模拟研究

模拟实验测定了气体搅拌能、喷嘴孔径及孔数、液体深度对液体表面突起高度的影响，回归得到各因素间的关系式，并由此推算了电弧炉底吹的条件。     

插入浸渍圆筒底吹氩钢包内钢液搅拌行为的水模型研究

以150 t钢包为原型,采用几何相似比1:7的水模型,研究插入钢包的浸渍圆筒直径(50~130 mm) , 插入深度(30~150 mm)和底吹气体流量(0.03~0.48 m³/h)对钢液混匀时间和液面振幅的影响。结果表明,随浸渍圆筒直径和插入深度的增加,液面振幅减小;随底吹气量增加,液面振幅增大;不插入浸渍圆筒时不发生卷渣的临界底吹气量为0.09 m~³/h,混匀时间为10 s;插入直径130 mm、深度90 mm的浸渍圆筒时,不发生卷渣的临界底吹气量为0.30 m³/h,最短混匀时间为4 s。实验数据回归分析得出150 t钢包内钢液均混时间-t’与底吹气量-Q’、浸渍圆筒直径-d’和插入深度h’的关系为t’=2.69+0.017 9 d’+0.011 2h’-0.425 Q’。     

120 t钢包底吹氩气物理模拟

为了优化国内某钢厂钢包的底吹位置和气体流量等工艺参数,更好地提高钢水洁净度,对120 t钢包建立1∶3水模型,模拟研究了底吹位置和气体流量对钢液混匀时间和钢渣覆盖情况的影响。结果表明,底吹位置不同时,混匀时间存在明显差异;随着气体流量增大,钢包混匀时间整体呈下降趋势,但减小幅度越来越小,吹气流量有最佳值;底吹位置为0.4R-0.6R,气体流量为500~700 L/min时,混匀时间由大到小的双孔角度为双孔135°＞双孔90°≥双孔120°;相同吹气量条件下单孔透气砖布置比双孔透气砖引起的钢渣卷入深度更大,深度差距基本为20~70 mm,而引起的渣眼面积大小则为双孔大于单孔。综合考虑混匀时间和钢渣覆盖情况,最优的透气砖布置和工况参数为双孔120°-0.4R-0.6R、气体流量500~600 L/min。     

One-Dimensional Gas Flow Model for Horizontal Gas Collection Systems at Municipal Solid Waste Landfills

Extraction of biogas from horizontal layers above, below, and within municipal solid waste landfills is becoming more commonplace. A steady-state one-dimensional analytical landfill gas model was developed to assist in the assessment and design of such collection systems. The model simulates the distribution of gas pressure within a layer of landfill waste under a variety of operating conditions that include upper and lower boundaries specified at given fluxes or pressures. The model can be used to predict where maximum pressures will build up within the landfill and what vacuum pressures must be applied to achieve specific gas collection efficiency in a horizontal collection layer. The utility of the model was illustrated for several scenarios of interest. In the absence of gas collection from a landfill’s leachate collection system, considerable gas pressures can build up at the bottom of the landfill. The design of leachate collection systems for landfill gas removal should be considered from the outset. An evaluation of the parameters that impact vacuum requirements—waste depth, gas generation rate, and waste permeability—suggests that it may not be feasible to rely solely upon the leachate collection system for the removal of landfill gas. The model was thus used to illustrate cases where a horizontal collection layer underneath the landfill cap is used in conjunction with gas extraction from the bottom of the landfill. Several recommendations are proposed to improve the gas collection efficiencies for landfills utilizing horizontal gas collection layers.     

Relationships between In Situ and Roller-Integrated Compaction Measurements for Granular Soils

To evaluate compaction meter value and machine drive power roller-integrated compaction technologies, a field study was conducted with 30-m test strips using five granular materials. The test strips were compacted using a prototype CS-533E vibratory smooth drum roller and tested for various compaction parameters using in situ test methods (e.g., nuclear moisture density, dynamic cone penetrometer, plate load tests, etc.). To characterize the roller machine-ground interaction, soil testing focused on measuring soil compaction parameters of the compaction layer, to a depth not exceeding 300?mm. The experimental testing of five test strips provided roller data and in situ measurements for several stages of compaction that were used in performing statistical regression analyses. The relationships between data from the roller-integrated compaction technologies were investigated with special consideration for the relative variation that was observed for each measurement system. Statistical averaging mitigated measurement variability and revealed statistically significant (R2>0.9) relationships between in situ and roller-integrated compaction measurements. This research demonstrates statistical analysis techniques for which calibration procedures using roller-integrated compaction technologies may be developed.     

RH喷吹参数对循环流量和均混时间影响的物理模拟

以某厂300tRH真空精炼装置为研究原型,建立1∶6.5的水力模型对RH喷吹精炼工艺进行物理模拟。研究了喷吹位置、喷吹气量及驱动气体流量对循环流量和均混时间的影响。结果表明:不同喷吹气量、驱动气体流量条件下,获得大循环流量和短均混时间的最优喷吹位置不同。较小的喷吹气量(2.98~3.53m3/h)或者较小的驱动气体流量(0.93~1.02m3/h)时,宜采用低顶枪枪位(153.8mm)喷吹;喷吹气量大于3.91m3/h或者驱动气体流量大于1.12m3/h时,宜采用真空槽底部喷吹角度120°的侧喷嘴喷吹。顶枪与侧喷嘴复合喷吹有利于提高RH喷吹工艺的适应性及循环效率。     

300 t复吹转炉底吹系统优化模拟

 顶底复合吹炼转炉炼钢法是当下主流的炼钢方法,底部供气元件的种类、支数、排布方式和底吹供气强度直接影响着转炉熔池的混匀效果,合理的流场不仅可以降低生产成本,更能缩短冶炼周期,增加企业效益。基于冷态水模拟以及CFD数值模拟手段各自的研究特点,以某钢厂300 t转炉为原型,将不同底吹条件下熔池的混匀时间、死区以及弱流区体积作为评判依据,对300 t转炉的底枪排布方式、底吹供气模式(非均匀供气和均匀供气)以及底吹供气强度进行了系统研究,研究结果表明,当底枪排布位置由0.3D(D为炉底直径)到0.5D,底吹系统对炉壁处钢液的搅拌能力明显增强,但熔池内死区以及弱流区体积却会明显增加,使得整个熔池混匀时间增长;在对适宜底吹强度研究发现,当熔池底吹强度的临界值为0.28 m3/(t·min),此底吹强度下对熔池的搅拌效果最好;底吹系统对熔池的搅拌效果会随着供气模式的不同而改变,当底吹流量分配为2:1时,底吹系统对熔池的搅拌效果最佳,均匀供气模式(1:1)次之,而当分配比为3:1和4:1时,由于熔池的大流量侧供气强度相对较大,会极大影响底吹系统对熔池的搅拌效果。     

基于D-InSAR雷达检测技术的矿区周边地表沉降变形研究

针对河北省内的多个地区矿山展开地面沉降监测研究,研究发现,通过D-InSAR技术的应用可以有效监测出矿山开采区周边地面沉陷状况,从而为地面沉降提供风险预警,保障矿区周边地面的安全发展。     

PIV measurements on physical models of bottom blown oxygen copper smelting furnace

A 1/5 scaled physical slice model of a bottom blown oxygen copper smelting furnace was established to investigate the flow field characteristics in the pool and in the freeboard above the pool. Particle image velocimetry technique was applied to measure the flow field in different depths of the pool, installation angle of the nozzle and gas flow rate. It was found that two circulations were divided by the jet zone above the nozzle. Above the nominal liquid surface level, there is a fountain zone where splash and liquid droplets occur. With the growth of pool depth, the distribution of velocity tended to become uniform. The area of dead zone decreased and mean velocity became larger. Different installation angles of nozzle will cause very different flow patterns. As the increase of gas flow rate, the area of dead zone decreased and the mean velocity increased.     

钢包底吹液面产生液峰高度的水模型研究

对钢包底吹过程中液峰的高度变化规律朱力学模型实验研究的结果表明，底吹气体流量对液高度影响很大，不同底吹透气砖其产生的液峰高度，随包内渣层厚度的增加面降低；随包内浸罩深度的增加亦提高。     

Numerical Study of Gas‐Solid Flow in the Raceway of a Blast Furnace

This paper presents a numerical study of gas‐solid flow in a blast furnace raceway using a 2D slot cold model. Numerical experiments are conducted by combining the discrete element method for the solid phase with computational fluid dynamics for the gas phase. The motion of particles caused by lateral gas blasting under conditions similar to that in the blast furnace process is examined at a particle scale. Combustion and associated solids movement around the raceway are simulated by extraction of particles from the bottom of the bed. The effect of bed height or solid pressure is considered by imposing a downward force on the top layers of particles in the bed. It is shown that depending on the gas velocity, the bed can transit from a fixed bed to a fluidized bed or vice versa. Two zones can be identified in such a bed: a stagnant zone in which the particles remain at their initial positions, and a moving zone in which particles can move in various flow patterns. In particular, if the gas velocity is in a certain range, the moving zone is formed just in front of the gas inlet, giving the so‐called raceway in which the particles can circulate. The effects of gas velocity, solid pressure and solid extraction are quantified. The fundamentals governing the gas‐solid flow and the formation mechanisms of a raceway are discussed in terms of particle‐particle and particle‐fluid interaction forces.     

气幕挡墙对中间包内钢液流场影响的数值模拟

根据实际中间包的操作工艺参数,采用欧拉-欧拉两流体模型,用数值模拟法模拟计算了中间包底吹对钢液流动的影响.结果表明,底吹改变了中间包内钢液的流动状态,在气幕挡墙的两侧分别形成了方向相反的回流区.底吹气体流量对钢液流动状态、气泡分布影响显著,底吹气体流量太大或太小都不利于改善钢液的流动状态.