Remaining oil distribution characteristics in an oil reservoir with ultra-high water-cut

An accurate mapping and understanding of remaining oil distribution is very important for water control and stabilize oil production of mature oilfields in ultra-high water-cut stage.Currently,the Tuo-21 Fault Block of the Shengtuo Oilfield has entered the stage of ultra-high water cut(97.2%).Poor adaptability of the well pattern,ineffective water injection cycle and low efficiency of engineering measures(such as workover,re-perforation and utilization of high-capacity pumps)are the significant problems in the ultra-high water-cut reservoir.In order to accurately describe the oil and water flow characteristics,relative permeability curves at high water injection multiple(injected pore volume)and a semiquantitative method is applied to perform fine reservoir simulation of the Sand group 3e7 in the Block.An accurate reservoir model is built and history matching is performed.The distribution characteristics of remaining oil in lateral and vertical directions are quantitatively simulated and analyzed.The results show that the numerical simulation considering relative permeability at high injection multiple can reflect truly the remaining oil distribution characteristics after water flooding in an ultrahigh water-cut stage.The distribution of remaining oil saturation can be mapped more accurately and quantitatively by using the‘four-points and five-types’classification method,providing a basis for potential tapping of various remaining oil types of oil reservoirs in late-stage of development with high water-cut.

Enhancing fly ash utilization in backfill materials treated with CO_(2)carbonation under ambient conditions

The environmental concerns resulting from coal-fired power generation that produces large amounts of CO_(2)and fly ash are of great interest.To mitigate,this study aims to develop a novel carbonated CO_(2)-fly ash-based backfill(CFBF)material under ambient conditions.The performance of CFBF was investigated for different fly ash-cement ratios and compared with non-CO_(2)reacted samples.The fresh CFBF slurry conformed to the Herschel-Bulkley model with shear thinning characteristics.After carbonation,the yield stress of the fresh slurry increased significantly by lowering fly ash ratio due to gel formation.The setting times were accelerated,resulting in approximately 40.6%of increased early strength.The final strength decreased when incorporating a lower fly ash ratio(50%and 60%),which was related to the existing heterogeneous pores caused by rapid fluid loss.The strength increased with fly ash content above 70%because additional C-S(A)-H and silica gels were characterized to precipitate on the grain surface,so the binding between particles increased.The C-S(A)-H gel was developed through the pozzolanic reaction,where CaCO_(3)was the prerequisite calcium source obtained in the CO_(2)-fly ash reaction.Furthermore,the maximum CO_(2)uptake efficiency was 1.39 mg-CO_(2)/g-CFBF.The CFBF material is feasible to co-dispose CO_(2)and fly ash in the mine goaf as negative carbon backfill materials,and simultaneously mitigates the strata movement and water lost in post-subsurface mining.

Calculation method of first collapse span with superhigh water material backfill mining

It is critical for the material to be of active supporting capacity before initial collapse ot mare root wltn supermgn water material backfill mining, and the maximum bending moment should be first calculated in order to determine the initial collapse span. In the light of principal of virtual work, the simple expression of deflection, bending moment of elastic clamped plate were deduced under the condition of vertical uniform distributed load, horizontal pressure and supporting by elastic foundation, and then, the maximal bending moment expression was derived too. At the same time, the influence degree on square clamped plate by adding horizontal pressure and elastic foundation were analyzed. The results show that the effect of horizontal pressure on maximal bending moment can be ignored when the value of horizontal pressure is two orders of magni- tude less than that of coeificient of elastic stiffness existing elastic foundation.

REQUIREMENT OF FLUIDITY OFHIGH WATER CONTENT MATERIALS FOR THE GETWAY-SIDE BACKFILLING TECHNIQUE

Through analyzing the effects of water consumption, diameter of solid particle, and flow vefority on the fluidity of high water content material slurry, the relatinnship among the fluidity, the isotropy of the slurry, and the pumping facilities applied in getway-side backfilling has been found. And the requirment of fluidity of high water content material for the design of getway-side back filling technique is put forward in the paper.

Study on Fracture Characteristic of Artificial Roof of Downward Drift with High-Water Solidifying Backfill

On the basis of analysis of the structure aud loading characteristic of downward drift with high-water solidifying backfill, the fracture characteristics of the artiricial roof of "hard-support weak-plate" drift and "soft-support weak-plate" drift are demonstrated rrom theory. The location and the maximum tensile stress of destruction point are given.This paper aims at providing some theoretical basis and practical reference for designing the artificlal roof structure parameter in downward drirt backfill mining.

Creep Property of Solidifying Backfill Body of High-Water Material

On the basis of the creep test of bigh-water materisl solidifying backfill body(abb. HW body), This paper discusses its creep properties- The visco-elasto-plastic model, which shows the creep properties of HW body, is developed, and the creep contitutive equations are deduced. The visco-elastoplastic model is proved by the experiments and practice.

Coupled effect of cement hydration and temperature on hydraulic behavior of cemented tailings backfill

Cemented tailings backfill(CTB) is made by mixing cement, tailings and water together, thus cement hydration and water seepage flow are the two crucial factors affecting the quality of CTB. Cement hydration process can release significant amount of heat to raise the temperature of CTB and in turn increase the rate of cement hydration. Meanwhile, the progress of cement hydration consumes water and produces hydration products to change the pore structures within CTB, which further influences the hydraulic behavior of CTB. In order to understand the hydraulic behavior of CTB, a numerical model was developed by coupling the hydraulic,thermal and hydration equations. This model was then implemented into COMSOL Multiphysics to simulate the evolutions of temperature and water seepage flow within CTB versus curing time. The predicted outcomes were compared with correspondent experimental results, proving the validity and availability of this model. By taking advantage of the validated model, effects of various initial CTB and curing temperatures, cement content, and CTB's geometric shapes on the hydraulic behavior of CTB were demonstrated numerically. The presented conclusions can contribute to preparing more environmentally friendly CTB structures.

Correlative Mechanism of Hydraulic-mechanical Property in Cemented Paste Backfill

Hydraulic characteristic is a good indication of binder hydration, which determines the strength development of cemented paste backfill（CPB）. Therefore, the hydraulic characteristic should be communicated with the mechanical property to provide an advanced knowledge that can help mine workers make a rational strategy and reduce the mining cycle. An experimental program was performed to obtain the hydraulic（monitored by suction and volumetric water content） and mechanical properties（unconfined compressive strength（UCS） test） of CPB at the 28 days curing age. According to the monitoring and testing results, the relationships between the hydration reaction rate and volumetric water content（VWC）, suction and VWC, suction and UCS were established. The hydration degree showed a liner rise as the VWC decreased. Curves of the VWC and UCS were featured with a nonlinear reduction and nonlinear growth（both are exponential functions） as the suction rising, respectively. These established relationships validated the strong correlative mechanism of hydraulic and mechanics behavior for CPB. Also, the results of the present research indicated that the hydraulic characteristics and mechanical property were strongly coupled. These correlations and couplings will be of great importance to understand the hardening process of CPB and bring to a safe CPB field operation.

Production prediction at ultra-high water cut stage via Recurrent Neural Network

A deep learning method for predicting oil field production at ultra-high water cut stage from the existing oil field production data was presented,and the experimental verification and application effect analysis were carried out.Since the traditional Fully Connected Neural Network(FCNN)is incapable of preserving the correlation of time series data,the Long Short-Term Memory(LSTM)network,which is a kind of Recurrent Neural Network(RNN),was utilized to establish a model for oil field production prediction.By this model,oil field production can be predicted from the relationship between oil production index and its influencing factors and the trend and correlation of oil production over time.Production data of a medium and high permeability sandstone oilfield in China developed by water flooding was used to predict its production at ultra-high water cut stage,and the results were compared with the results from the traditional FCNN and water drive characteristic curves.The LSTM based on deep learning has higher precision,and gives more accurate production prediction for complex time series in oil field production.The LSTM model was used to predict the monthly oil production of another two oil fields.The prediction results are good,which verifies the versatility of the method.

建筑物下特厚煤层镁渣基全固废连采连充开采技术与实践

我国建筑物下压煤量巨大,同时煤矸石、粉煤灰等煤基工业固体废弃物排放量日益增加,严重制约地方经济社会发展。以榆林麻黄梁煤矿为试验矿井,针对其特厚煤层、建筑物下压煤、充填成本高等问题,提出了特厚煤层全固废连采连充开采技术。采用四阶段工序并将特厚煤层分为上、下2部分二次回采压覆煤炭,最大程度控制地面沉降。为降低充填原材料成本,采用化学优化剂对镁渣进行源头改性,抑制镁渣冷却粉化,稳定水化活性,协同粉煤灰、脱硫石膏等煤基固废,研发了改性镁−煤渣基胶凝材料。采用改性镁−煤渣基胶凝材料胶结煤矸石、粉煤灰制备了全固废充填材料。针对麻黄梁煤矿四阶段强、弱充填强度要求,设计不同配比的改性镁渣基充填材料试验,优选配比并应用于井下充填。论述了膏体充填系统与充填接顶方法。麻黄梁煤矿全固废胶结充填工艺试验显示,井下28 d龄期充填体钻芯平均单轴抗压强度超设计强度27%,钻芯浸出毒性满足相关国家标准要求,成功回收了建筑物下压覆煤炭资源,社会经济效益显著。麻黄梁煤矿特厚煤层全固废胶结充填开采实践为国内类似矿井提供了有益借鉴,同时为我国大型煤炭基地的“煤−电−化−冶”固废大规模资源化利用提供了新的思路。

道路生态滤沟回填黄土毛细持水特性试验研究

市政道路生态滤沟雨季积水渗透、旱季保墒是基本功能,而黄土生态滤沟回填土的设计无据可依,常导致景观植被雨季渍害或旱季枯死。为此,通过对重塑黄土进行小尺寸毛细水上升高度试验、大尺寸持水特性模型试验以及非饱和数值分析研究。结果表明:当干密度分别为1.3 g/cm^(3)、1.4 g/cm^(3)时,土柱的最终毛细水上升高度均可达到100 cm。土柱高度超过20 cm后,其含水率基本保持稳定,稳定含水率分别为30.0%、28.0%;在重塑黄土毛细水上升过程中,存在一个暂态饱和区,其中干密度越小,孔隙比越大,大孔隙数量增多,毛细吸力减弱,导致水分迁移速率较慢,同时被湿桥封闭的大气泡数量也较多,因此暂态饱和区的持续时间较长。对于1.3 g/cm^(3)的土柱,其湿润锋时程曲线的模拟值与实测值基本吻合。综合考虑黄土地层稳定的天然平均干密度、毛细水上升高度及其持水特性以及生态滤沟回填土在后期将经历反复的渗透固结与毛细作用,采用1.2 g/cm^(3)作为回填控制干密度,以确保市政道路生态滤沟中的植土在旱季仍能维持植被生长所需的土壤湿度。

低场核磁共振技术在充填体材料的应用优势

低场核磁共振技术近年来应用发展迅速,具有精准高效低价无损的特点,通过检测多孔结构中氢质子的核磁共振弛豫信号,来反映孔隙及其内部流体信息。研究矿山充填体材料的孔隙结构、水化进程和水分迁移,对于维护矿山与工程稳定具有重大意义。本文主要介绍了近年来低场核磁共振技术在矿山充填材料中的应用,如孔隙度、孔径分布、水化进程、水分迁移等;阐述了低场核磁相应设备的发展,对其前景的展望。

酒精湿化法调配压实膨润土缓冲回填材料含水率研究

压实膨润土砌块在我国高放射性废物处置中发挥着缓冲回填工程屏障的作用。然而,膨润土材料塑性极强,水分极易拌和不均,易导致压实砌块干缩开裂,显著降低了砌块质量。提出一种采用酒精代替纯水来湿化膨润土的新方法,以提高压实膨润土质量。对比喷水法,酒精湿化法中酒精浓度设计在5%~35%间。通过分析膨润土与酒精混合物的混合效率、黏附质量损失率、混合物中团聚体的含量、压实样干缩前后强度、干缩裂纹规律、干燥效率、膨胀性等指标综合评价酒精湿化压实膨润土样的适用性。试验结果表明:在相同含液率情况下,随酒精浓度增大,所得膨润土样的混合效率明显提高,黏附质量损失率及团聚体含量明显降低;压实样内团聚体与干缩裂纹及试样质量间具有较好对应关系。此外,酒精湿化法所得压实样在压实方向密度分布更均匀,干缩裂纹数量及宽度明显变小,风干试样剪切强度及膨胀性均与加纯水试样较为接近,压实样均匀性与完整性明显提高。新方法及相关成果可供我国高放废物缓冲回填砌块制备参考。

基于低标硫铝酸盐水泥熟料的高水材料物理力学性能及应用

为解决高水材料充填成本高、物理力学性能差等问题,选用低标硫铝酸盐水泥熟料为主要原料,通过物理试验探究了低标硫铝酸盐水泥熟料高水材料在不同外加剂剂量、水灰比、水温下的物理力学性能,并通过工艺性试验测试了实际应用效果。研究结果表明:(1)不同条件下高水材料物理力学性能不同的主要原因在于其钙矾石的生成速率及生成量受到影响;(2)以低标型硫铝酸盐水泥熟料作为高水材料原料时,使用一定量外加剂能够改善其样貌并显著提升其强度;(3)降低水灰比能够显著提升高水材料的早期强度及峰值强度,且每提高0.1的水灰比,平均各龄期强度下降约11%;(4)水温对于高水材料初凝时间的影响高于终凝时间,对早期强度起促进作用,水温每上升2℃, 1d强度增加约6.8%;(5)影响高水材料强度的各项因素排序为:外加剂>水灰比>水温;(6)现场应用低标型硫铝酸盐水泥熟料高水材料后,巷道变形量较小,取得较好的留巷效果。

尾砂粒级组成对胶结充填料流变特性与强度的影响

为探究尾砂粒级组成与充填料流变特性及强度之间的关系,采用全尾砂、旋流器分级溢流和底流尾砂经人工配制成5种尾砂充填料,开展了不同粒级组成尾砂充填料流变与强度试验。结果表明:随着尾砂中-38μm细粒级含量的增加,充填料浆屈服应力和塑性黏度增加,且-38μm细粒级含量越高充填料浆屈服应力和塑性黏度增加幅度越大;随着细粒级尾砂含量的增加,水化膜厚度呈先增加后降低的变化趋势;充填料浆初始屈服应力和塑性黏度受水化膜厚度和固体颗粒比表面积的双重影响;当细粒级尾砂含量超过44.37%时,水化膜厚度与充填料浆初始屈服应力和塑性黏度之间存在负指数关系。随着细粒级尾砂含量的增加,尾砂充填体强度先增加后减小,细粒级含量为44.37%时为尾砂最佳粒级组成,此时充填体中尾砂堆积所形成的骨架结构最密实,充填体总孔隙率、平均孔径和大于0.2μm有害孔占比最小。

浅埋强富水区下绿色高效保水开采技术

西部地区煤层资源丰富,开采强度大,传统开采方式容易导致含水层水资源流失,产生严重的缺水问题,因此,研究浅埋强富水区的保水开采技术,通过控制岩层移动保持含水层的稳定性,研发低成本、广适用的保水开采技术和材料,形成浅埋强富水区煤层的绿色高效保水开采体系,实现煤炭开采与水资源保护的双重目标,对保障水资源安全、维护生态平衡和促进经济发展具有重要意义。本文首先分析了保水开采现状与难题,从技术先进性和安全性等方面对现有技术进行了对比,从材料、设备和工艺等方面进行了深入研究,总结并分析了不同技术的适用条件。接着以锦界煤矿为例,依据保水采煤方案和导水裂隙带实测高度,对井田进行区域划分,提出“分区分类治理”的原则,并创新性地提出了采前第四系松散含水层底部隔水层再造技术,形成了有效隔离,实现了煤炭开采与水资源保护的协调发展,保护了自然地貌和地表植被。同时,针对现有综采架后膏体充填不高效,且支架无法做到充填非充填灵活转换的问题,设计提出了一种新型充填非充填两用支架,既可作为同一工作面分段充填、非充填支架两种模式交替使用,又可进行后部支架拆解,安装掩护梁侧护板,满足普通支架使用需求,提高了设备使用效率。最后对采后导水裂隙带裂隙顶部注浆修复改造技术和注浆效果评价进行了总结,以锦界煤矿的应用为例进行了说明,对鄂尔多斯盆地类似条件煤层开采具有广泛指导意义,为煤炭行业的绿色开采提供了重要支持。

特厚煤层限厚与充填协同分层开采覆岩导水裂隙发育规律研究

由于技术装备问题导致前期一些矿井的特厚煤层开采仅限厚开采造成了大量优质煤炭资源的浪费,本研究基于榆树湾煤矿20111限厚开采工作面,综合运用现场实测,UDEC数值模拟、实验室试验、理论分析研究了特厚煤层工作面限厚与充填协同分层开采覆岩导水裂隙发育规律。数值模拟表明,当下分层充填开采充实率达到70%及以上时,导水裂隙带发育高度为177.4 m,下分层开采对第四系萨拉乌苏组含水层无影响;下分层70%充实率充填开采物理模型相互验试验表明,下分层70%充实率充填开采时,覆岩裂隙发育明显减缓,导水裂隙带发育高度明显降低,仅为179.7 m,导水裂隙带未发育至最小隔水保护层,可实现第四系萨拉乌苏组含水层下的特厚煤层安全、高效开采。

特大断面导流隧洞施工技术在水利枢纽工程中的应用

该文以某水利枢纽工程为例,探究特大断面导流隧洞施工中爆破开挖与锚喷挂网联合支护技术的应用。经前期地质勘察可知,隧洞围岩为Ⅱ~Ⅲ级,围岩稳定性较好,采取先进行光面爆破再进行洞身开挖的作业方案。在清运碴石、清除危石后,在开挖面上初喷混凝土形成稳定工作面。然后打入锚杆、挂钢筋网并进行二次衬砌,对导流隧洞支护,营造安全的施工环境。拱顶沉降监测数据表明,在导流隧洞开挖后的30 d内,每日平均沉降速率为2.09 mm,在允许范围之内,本次特大断面导流隧洞施工效果符合预期。

酸性矿井水环境中矸石胶结充填体的强度演化及劣化规律

矸石胶结充填开采是一种重要的充填开采方法,然而,酸性矿井水会严重影响矸石胶结充填体的强度。在本研究中,将矸石胶结充填体试件分别置于不同环境(空气、水、硫酸溶液、硫酸与荷载耦合)中,测试了不同龄期试件的抗压强度、电阻率及超声波波速,监测了加载过程中试件的声发射能量数值,同时结合扫描电镜和X衍射分析不同龄期充填体的微观结构。结果表明,1)空气中与水中养护的充填体抗压强度的增长趋势随龄期的增加而逐渐减缓。硫酸溶液中的充填体强度在前90天大于空气及水中养护的充填体强度。硫酸溶液与荷载耦合作用下充填体的强度随龄期的下降速率比单一硫酸溶液作用的较为缓慢;2)不同龄期矸石胶结充填体电阻率与超声波波速与强度有较好的对应关系。受侵蚀后矸石胶结充填体的破坏形式较为多样,且在加载不同阶段表现出不同的声发射能量特征,可以将声发射能量激增作为充填体的破坏前兆;3)侵蚀产物前期填充充填体内部孔隙,提高了其强度,后期会导致充填体膨胀开裂,强度降低。施加40%应力强度比的荷载会抵抗硫酸溶液的侵蚀。本文研究结果可以为充填体的耐侵蚀设计提供参考。

水压-氯盐侵蚀耦合作用下膏体充填材料力学性能实验研究

在膏体充填开采中,煤矸石-粉煤灰胶结充填材料(CGFB)可有效控制地表沉降。CGFB在被注入采空区后会受到水压影响和氯离子侵蚀。因此,研究水压和氯离子侵蚀对CGFB性能的影响对于实现有效的绿色开采至关重要。将CGFB试样在0、0.5、1.5或3.0 MPa的氯化钠溶液中浸泡15天,通过单轴压缩试验、声发射信号监测、数字散斑应变测量、扫描电子显微镜和X射线衍射研究了试样的力学性能和劣化机理。结果表明,随着浸泡压力的增加,试样单轴抗压强度先增大后减小。当浸泡压力从0 MPa增加到1.5 MPa时,平均单轴抗压强度增加了43.5%。当浸泡压力从1.5 MPa增加到3.0 MPa时,平均单轴抗压强度下降18.9%。此外,水压会促进氯离子进入CGFB内部并产生弗里德尔盐。较高的水压-氯盐耦合作用增加了CGFB的孔隙率,与0 MPa样品相比,3.0 MPa样品的孔隙率增加8.2%。高水压作用下,膏体充填体内部孔隙裂纹发育贯通,力学性能劣化,其密实度与抗压强度下降。