Simulation Research on Coal-Water Slurry Gasification of Oil-Based Drill Cuttings Based on Fluent

In this paper,based on Fluent software,a five-nozzle gasifier reactor was established to simulate the gasification process of oil-based drill cuttings coal-water slurry.The influence of concentration and oxygen/carbon atomic ratio on the gasification process of oil-based drill cuttings coal-water slurry was investigated.The results show that when the oxygen flow is constant,the outlet temperature of gasifier decreases,the content of effective gas increases,and the carbon conversion rate decreases with the increase of concentration;When the ratio of oxygen to carbon atoms is constant,the effective gas content rises and the temperature rises with the increase of the concentration,and the carbon conversion rate reaches the maximum value when the concentration of oil-based drill cuttings coal-water slurry is 65%;When the concentration is constant,the effective gas content decreases and the outlet temperature rises with the increase of the oxygen/carbon atom ratio,and the carbon conversion rate reaches 99.80%when the oxygen/carbon atom ratio is 1.03.It shows that this method can effectively decompose the organic matter in oilbased drill cuttings and realize the efficient and cooperative treatment of oil-based drill cuttings.

Gas-hydrate formation,agglomeration and inhibition in oil-based drilling fluids for deep-water drilling

One of the main challenges in deep-water drilling is gas-hydrate plugs,which make the drilling unsafe.Some oil-based drilling fluids（OBDF） that would be used for deep-water drilling in the South China Sea were tested to investigate the characteristics of gas-hydrate formation,agglomeration and inhibition by an experimental system under the temperature of 4 ？C and pressure of 20 MPa,which would be similar to the case of 2000 m water depth.The results validate the hydrate shell formation model and show that the water cut can greatly influence hydrate formation and agglomeration behaviors in the OBDF.The oleophobic effect enhanced by hydrate shell formation which weakens or destroys the interfacial films effect and the hydrophilic effect are the dominant agglomeration mechanism of hydrate particles.The formation of gas hydrates in OBDF is easier and quicker than in water-based drilling fluids in deep-water conditions of low temperature and high pressure because the former is a W/O dispersive emulsion which means much more gas-water interfaces and nucleation sites than the later.Higher ethylene glycol concentrations can inhibit the formation of gas hydrates and to some extent also act as an anti-agglomerant to inhibit hydrates agglomeration in the OBDF.

Pyrolytic gas analysis and evaluation from thermal plasma pyrolysis of simulated oil-based drill cuttings

Oil-based drill cuttings(OBDCs)are hazardous wastes generated during shale gas exploration,and the rapid,efficient and safe disposal methods for OBDCs have attracted the attention of many researchers.Plasma pyrolysis technology is widely used in solid waste treatment due to its extremely high temperature and reaction activity.A laboratory-scale thermal plasma pyrolysis system was built to investigate the plasma pyrolysis mechanism of simulated OBDCs.The thermal decomposition characteristics of OBDCs were studied by thermogravimetric-derivative thermo gravimetric-differential scanning calorimetry(TG-DTG-DSC)analysis in the range of 50–1300℃.The thermal decomposition process of OBDCs was divided into the following four stages:evaporation of water and light oil,evaporation and decomposition of heavy oil,carbonate decomposition,and phase change reaction from solid to liquid.The effects of the oil ratio,water content,and water/oil(W/O)ratio of OBDCs on the composition and gas selectivity of pyrolytic gas were investigated.The results show that thermal plasma can crack the mineral oil in the OBDCs into clean gases such as H_(2),CO and C_(2)H_(2),while water can promote the decomposition of the heavy oil molecules and enhance the H_(2)production.The energy consumption model calculation for the pyrolysis and melting of OBDCs shows that the highest energy utilization and the lowest molar energy consumption of H_(2)were achieved at a W/O ratio of 1:4.Based on the thermal plasma pyrolysis system used in this study,the commercial application prospects and economic benefits of the plasma pyrolysis of OBDCs were discussed.

矿渣和粉煤灰对微生物-氧化镁协同固化钻屑性能的改良机理

钻屑作为一种固废,其主要处理方式为水泥固化,但加工水泥易产生大量二氧化碳,不利于环境保护。基于上述问题,提出了一种改良后微生物-氧化镁协同固化钻屑新方法。通过强度测试,研究了高炉矿渣和粉煤灰对微生物-氧化镁协同固化钻屑的改良,获得了钻屑固化体强度随高炉矿渣掺量增加而升高,随粉煤灰掺量增加而逐渐降低的规律,最高强度为5.4MPa。采用FTIR、XRD和SEM等测试手段,对固化体中产物类型和结构进行了分析,结果表明:产物由连续的水菱镁石(矿化产物)、云雾状水化硅酸镁和层状水滑石(水化产物)组成。钻屑颗粒由矿化产物和少量水化产物固化,揭示了矿渣和粉煤灰在微生物-氧化镁协同固化钻屑的作用机理。

高速机械粉磨对油基钻屑灰渣活性的影响

对油基钻屑灰渣进行了高速机械粉磨处理,研究了粉磨时间(0~7 min)对灰渣粒径分布和比表面积的影响,分析了掺灰渣胶砂试件的力学性能,并进行了XRD、SEM、FTIR微观分析。结果表明:与未粉磨处理的灰渣相比,粉磨3 min灰渣的粒径分布范围缩小至1.220~40.100μm,D50降低了60.9%,比表面积增大了27.6%;与其他粉磨时间的灰渣相比,用粉磨3 min的灰渣等质量取代30%水泥所制备的胶砂试件的28 d抗压强度最高,28 d抗折强度也较高;适宜的粉磨时间能够促进灰渣中的活性Si O2、Al2O3等与水泥水化产物Ca(OH)2发生二次水化反应,生成C-S-H凝胶和AFt,提高胶砂结构的密实度。

烧结温度对掺加二次铝灰及钻井岩屑制备陶粒支撑剂性能的影响

目的钻井岩屑作为油气开发过程中所产生的固体废物,产生量巨大且资源化利用途径单一。使用钻井岩屑及二次铝灰协同制备水力压裂用陶粒支撑剂,不仅可有效拓宽钻井岩屑资源化利用途径,而且还可降低油气开发生产成本。方法采用二级铝矾土为主要原料,添加质量分数分别为20%的钻井岩屑和10%的二次铝灰,甲基纤维素作为黏结剂,于不同烧结温度下制备了低密度高强度压裂用陶粒支撑剂,研究烧结温度对支撑剂结构、晶相组成及其产品性能的影响。结果钻井岩屑须经预处理,以降低岩屑中有机物对后续生胚烧结的影响。当烧结温度为1300℃时,其主晶相为刚玉,次晶相为钡长石,支撑剂的体积密度为1.45 g/cm^(3),52 MPa闭合压力下破碎率为5.26%,满足SY/T 5108-2014《水力压裂和砾石充填作业用支撑剂性能测试方法》对0.38 mm/0.25 mm支撑剂的质量要求。结论烧结温度是制备陶粒支撑剂的关键控制参数。随着烧结温度的增加,支撑剂内部产生的液相将逐渐增多,有利于加快扩散和增大传质速率,促进支撑剂的致密化,但过多的液相则会导致支撑剂膨胀变形,对抗破碎能力产生不利影响。以钻井岩屑、铝灰、铝矾土为原料,适宜的烧结温度建议为1260~1300℃。

黄河小浪底水利枢纽西霞院围堰粉煤灰混凝土防渗工程施工技术

西霞院反调节水库围堰工程地质条件复杂,由覆盖层和基岩层组成。地层含有大量块漂石,粒径大含量高。采用粉煤灰混凝土防渗墙垂直防渗,成槽难度极大。主要介绍采用"两钻一抓"快速成墙方法以及粉煤灰混凝成墙的经验。

水玻璃掺量对油基钻屑灰渣活性的影响与机理研究

为激发出油基钻屑灰渣的火山灰活性和阐明水玻璃掺量对其活性影响的作用机理,研究了灰渣在1.4模数水玻璃下根据不同碱掺比所制备的胶砂试件强度性能,并通过XRD、SEM和FTIR等测试技术分析试件的微观结构特征。结果表明:1.4模数水玻璃碱掺比在2%左右时,试件的3 d抗压强度和抗折强度较基准组分别提高了7.1%和16.7%,28 d龄期时的抗压强度提高了2.3%,碱掺比超过2%后,胶砂体系抗压与抗折强度均快速降低;微观测试结果表明2%的碱掺比能有效促进灰渣中的高聚态硅氧四面体解聚成低聚态,使得更多活性SiO_(2)、Al_(2)O_(3)参与二次水化反应,从而增加水化产物数量,提高整体结构密实性;过大碱掺比直接阻碍了水泥水化进程,体系内的Ca(OH)_(2)、AFt晶体和C-S-H凝胶数量大大减少,结构疏松多孔。