A Bingham-Plastic Model for Fluid Mud Transport Under Waves and Currents

Simplified equations of fluid mud motion, which is described as Bingham-Plastic model under waves and currents, are presented by order analysis. The simplified equations are non-linear ordinary differential equations which are solved by hybrid numerical-analytical technique. As the computational cost is very low, the effects of wave current parameters and fluid mud properties on the transportation velocity of the fluid mud are studied systematically. It is found that the fluid mud can move toward one direction even if the shear stress acting on the fluid mud bed is much smaller than the fluid mud yield stress under the condition of wave and current coexistence. Experiments of the fluid mud motion under current with fluctuation water surface are carried out. The fluid mud transportation velocity predicted by the presented mathematical model can roughly match that measured in experiments.

In-Situ Observation of Fluid Mud in the North Passage of Yangtze Estuary, China

Observations of fluid mud were made in the lower North Passage of the Yangtze Estuary in February 2000, on 10～11 August 2000, on 30～31 August 2000 (after two strong typhoons), on 21～24 August 2000 (neap tide) and on 3～6 September 2000 (mean tide) respectively. In situ data show that the fluid mud in this area consists of fine cohesive sediment (median size 7.23 μm). The formation and movement of fluid mud varied during the neap-spring and flood-ebb tidal cycle. Observations suggest that fluid mud phenomena in this area may be categorised in a three-fold manner as slack water, storm and saltwedge features. The thickness of the fluid mud layer of slack water during the neap tide ranged from 0.2 to 0.96 m, whereas during the mean tide, the thickness ranged from 0.17 to 0.73 m, and the thickness of the fluid mud layer was larger during slack water than at the flood peak. Shoals cover an area of 800 km2 with a water depth smaller than 5 m. Erosion of these extensive intertidal mudflats due to storm action provides an abundant sediment source. This is particularly significant in this estuary when the tidal level is lower than 5 m. The lower North Passage is a typical zone of saltwater wedging, so the saltwedge fluid mud has the most extensive spatial range in the estuary.

Fluid Mud Measurement and Siltation Analysis in A Trial Excavated Channel in the Approach Channel of the Xiangshan Port

In order to clarify the distribution and variation of silt and fluid mud in the Waiganmen shallow section of the 50000-ton intake channel of the Xiangshan Port,and to understand the influence of the channel excavation on the surrounding flow conditions and the strength of the backsilting,especially the impact of typhoon on the sudden silting of the channel,so as to demonstrate the feasibility and stability of the channel excavation.The fluid mud,hydraulic,sediment and topographic measurements were carried out in the study area,and the thickness of the fluid mud layers,tidal current,sediment and topographic data were obtained.Dual-frequency sounder,gamma-ray densitometer and SILAS navigational fluid mud measurement system were used to monitor the fluid mud,and the results were compared and verified.The adaptability and accuracy of the three methods were analyzed.The SILAS navigational continuous density measurement system and gamma-ray fixed-point fluid mud measurement are used to detect the density,thickness and variation of the fluid mud accurately.Based on the hydrological observation data,the process of erosion and deposition in excavation channel and its influence mechanism are analyzed,and the distribution characteristics and evolution law of siltation in engineering area are given in the form of empirical formula.The research shows that the super typhoon can produce large siltation,which results in sudden siltation of the channel.The tidal current is the main dynamic factor of the change of erosion and siltation of the excavation trench.Under the influence of reciprocating tidal current and excavation topography,the trial excavation trench is silted on the whole.There is fluid mud in the monitoring area of the trench,and the distribution of fluid mud is different in space.The thickness of the fluid mud at the bottom of the trench is generally larger than that outside the trench and the slope of the trench,and the siltation of the trench tends to be slow.The research results can provide scientific evaluation for channel excavation and maintenance,and support for the implementation of the project.

Geoacoustic model and acoustic reflection properties of fluid mud layer in Changjiang Estuary and Hangzhou Bay

A generalized geoacoustic model of fluid mud layer in Chanaiiang Estuary and Hangzhou Bay has been derived from a large amount of in-situ measurements of bulk density (p) profiles of the lay6rs and of lab measurements of acoustic velocities (c) and attenuation coefficients (o) of the fluid mud samples with different values of p for four frequencies of 100 kHz, 150 kHz, 500 kHz, 1500 kHz. The main features of the geoacoustic model can be expressed as follows: from the upper boundary, the bulk density of the fiuid mud increases linearly with depth z, however there is a gradient change (knee) when p is about 12.5 kN/m', then p increases linearly to a value about 15.0 kN/m'. After p more than 15.0, the fluid mud layer quickly transform into an ooze layer. In the fluid mud layer, the acoustic velocity c can be regarded as constant since its variation with z less than 1.5%, and a minimum vaue of c ekists when p is about 13.5 kN/m'. The variations of β with p and with frequency f are linear. Based on the geo-acoustic model and the ray theory, simulations of sound refiection from the fluid mud layers have been made, and some significallt results obtained, from which the bulk density profiles of fluld mud layers can be derived inversely.

Fluid mud transportation at water wedge in the Changjiang Estuary

In situ data show that fluid mud of the Changjiang Estuary consists of fine sediment ranging from 8 to 11.5 μm (median grain-size) including 28.8%-36.4% of clay. The composition of the clay is illite, chlorite, kaolinite and montmoillonite. The FM is a layer of high sediment concentration near the bed and results from flocculation under the environment of salt and fresh water mixing. Three kinds of FM have been identified under typical dynamic conditions: the first one is formed at slack water of ebb tide during the flood season, with the characteristics of extended area and low thickness; the second one is formed following a storm, characterized by large area and larger thickness; the third one is formed around the front of the saltwater wedge, characterized by small area but large thickness. In the dredged channel, the FM can be accumulated up to 1 m thick. In general, FM will change with the alternation from spring to neap tides, flood and dry seasons. Drastic change can happen during storms. At the same time, the change of FM is closely related to the erosion and growth of the mouth bar.

库区浮泥层纵向流速垂线分布特性研究

水库浮泥是存在于水库底部的一层高含沙水体,流动性较强,直接影响水库淤积形态和水库排沙,研究其运动规律对水库减淤优化调度具有重要意义。根据三峡库区实测泥沙矿物组成和级配资料,配置沙样进行流变试验,以幂律流变模型描述浮泥的本构关系。构建了浮泥运动的速度分布理论模型,通过水槽试验对模型进行了验证,计算结果与试验结果吻合较好。结果表明,浮泥运动速度随浮泥厚度、上层水流流速、床面坡度增大而增大,随浮泥密度增大而减少。沿水深方向浮泥纵向流速分布始终呈抛物线型,表层的浮泥流速要远大于底层浮泥,浮泥纵向流速沿垂向方向不断减少,最底部的浮泥几乎处于静止状态。

负压振动筛原理及在油基钻井液钻屑减量中的应用

经过几十年的发展,振动筛性能有很大提高,但其对钻屑的脱液能力已达极限。40年来,应用于钻井固控,效果不明显。十多年前,经过尝试与高频低幅振动相结合的真空过滤技术应用于钻井固控时,钻屑的脱液能力显著提高,排放钻屑体积大幅减小。近年来,多种负压振动筛在国内钻井中开展了应用试验。经过对常规振动筛复合负压过滤的负压振动筛的原理、主要技术参数、现场应用与国内外类似技术的对比分析及现场应用表明,所使用的负压振动筛的处理量、钻屑含液率、钻屑排放减少量、筛网寿命、能效、设备成本、使用经济效益等都均有明显优势。负压振动筛的应用对节能减排和实现“碳中和”具有重要作用,其逐渐替代常规振动筛,将是钻井固控技术发展的必然趋势。

一种油基钻开液用延时泥饼解除液体系性能评价

针对常规强酸对油基钻开液泥饼解除不彻底等问题,自研一种温度相应型生酸材料,该材料在常温条件下几乎不反应,当达到储层温度后,会与淡水或盐水反应释放出H+,并以此材料为主剂,优选抑制剂,控制H+在储层下的释放速度,优选表面活性剂及加重材料,形成一种新型油基钻开液用延时泥饼解除液体系,可延时并解除可酸溶固相所形成泥饼,含10%生酸材料解除液体系综合性能评价结果表明:该延时泥饼解除液体系延时作用效果及泥饼解除效果明显,表面活性剂加量可影响该体系泥饼延迟时间及泥饼解除时间,可通过调节不同成分加量对泥饼解除时间进行调控,延时泥饼解除液体系处理后岩心渗透率恢复值可达到90%以上,具有良好的储层保护性能。

高性能密胺降滤失剂的研究

用多聚甲醛与三聚氰胺合成了密胺树脂,对经黏土改性后的丙烯酰胺类聚合物进行包覆,制备了一种抗温抗盐的钻井液降滤失剂。采用单因素实验对样品的加量及耐温耐盐性能进行了评价,实验结果表明,2号样品的性能最佳。在盐浓度为8%的钻井液中,加量为1.5%时,经100℃老化后,2号样品的加量比对照样品减少3%,滤失率为77.7%,性能更优良。

The instability of water-mud interface in viscous two-layer flow with large viscosity contrast

The temporal instability of parallel viscous two-phase mixing layers is extended to current-fluid mud by considering a composite error function velocity profile. The influence of viscosity ratio, Reynolds number, and Froude number on the instability of the system are discussed and a new phenomenon never discussed is investigated based on our numerical results. It is shown that viscosity can enlarge the unstable wave number range, cause new instability modes, and certainly reduce the growth rate of Kelvin-Helmholtz （K-H） instability.

变含水量泥流本构及泥流-桥墩冲刷的流固耦合分析

泥石流是山区主要的地质灾害之一,对山区桥梁破坏严重.在流动过程中,泥石流受到含水量的影响较大,其本构模型会发生变化.本文对泥石流的一种特殊形式——泥流的质量含水量进行分析,将含水量引入泥浆的Herschel-Bulkley模型中,提出质量含水量及剪切速率同时变化下的泥流材料本构模型,并与成都黏土泥浆流变实验对比,验证该模型的正确性.而后基于两相流体的Navier-Stokes方程,将该本构模型应用于三维泥流-桥墩立柱冲击的流固耦合分析中,通过与相关规范及文献冲击压力经验公式计算结果对比,证实了模型的实用性.

北部湾深层深井油基钻井液研究及现场应用

为了缩短钻井周期以及提高井壁稳定,油基钻井液的护壁防塌性能可通过加入封堵剂来优化。本文以纳米SiO_(2)、N-氨乙基-3-氨丙基三乙氧基硅烷和全氟辛基三甲氧基硅烷为原料制备一种纳米封堵剂,其粒径主要分布在10~200nm之间,其粒径较为集中,应用于钻井液中可降低泥饼渗透率,显著提高油基钻井液的封堵性能,降低滤失量,对储层渗透率影响较小。纳米封堵剂与油基钻井液具有良好的配伍性,提高油基钻井液的稳定性。本文研究的高性能油基钻井液成功应用于现场钻井,钻井过程中,纳米封堵剂的加入显著提高了起钻速度,缩短了现场钻井周期,封堵性能的提高使钻井液泥饼在裂缝和孔隙中进行有效封堵,井壁未出现掉块及剥落片。

低孔隙度低渗透率储层复杂流体综合评价方法

渤海LD油田目的层东三段发育低孔隙度低渗透率储层,其孔隙结构复杂,且储层流体地露压差小、溶解气油比高,导致油、气、水层的测井响应特征差异小。对比和分析经测试、测压、取样证实的油、气、水层的测井资料及录井资料,认为体积压缩系数与泊松比的交会幅度、视地层水电阻率、气测异常倍数及热解气相色谱对流体性质的响应较为敏感。基于上述4类参数,以经过测试、测压、取样等证实的70个油、气、水层为数据样本,其中51个作为训练样本,19个作为检验样本,采用支持向量机算法,建立了油、气、水层的流体判别模型。该方法在LD油田流体识别中取得较好的应用效果,流体性质识别符合率达89.4%,为该油田的储量评价奠定了基础,该方法对同类型储层的流体性质判别具有借鉴意义。

复兴地区页岩气井油基钻井液井壁稳定和防漏堵漏技术

针对复兴地区凉高山组地层漏失严重,自流井组东岳庙段溢漏同存,地层垮塌掉块,频繁憋泵蹩顶驱的问题。采用XRD衍射法对兴页L2HF井、兴页1002HF井凉高山组和自流井组东岳庙段地层的岩石进行矿物组成分析,使用微观SEM扫描电镜对该地层岩石进行了微观形貌分析,再结合现场情况总结了复兴地区井壁失稳和地层漏失机理。通过提高钻井液的乳化稳定性、降摩减阻和多重封堵性能,形成复兴地区页岩气井油基钻井液井壁稳定技术,该钻井液体系满足封堵性PPA小于2 mL,填砂管侵入深度小于2 cm;基于压裂砂堵效应,通过优选和研制了复合堵漏剂、诱导剂、悬浮剂,形成复兴地区程序法“控滤失”模拟砂堵防漏堵漏技术,堵漏浆体系可承压能力高达7 MPa,更适合应用于多裂缝地层。油基钻井液井壁稳定和防漏堵漏技术在兴页某-1井进行现场应用,相对于使用高密度柴油基钻井液体系的兴页某-2井,优化后钻井液体系的黏度和切力更低,润滑减阻性能更强,漏失和地层失稳等复杂情况明显减少。

盾构排浆管道内块石流速分析与沉积临界泥浆流速公式推导

为了明晰排浆管道内各种块石的流速情况,探讨块石沉积形成的管道堵塞和泥浆流速的关系,首先,根据流体力学基本方程推导出泥浆液动力计算式;然后,从运动力学角度对水平、斜向上、斜向下、垂直向上管道内的石块取最难排出的状态进行受力分析;最后,对不同形状、不同粒径石块,在不同倾斜角度的泥浆通道内随泥浆流动,达到受力平衡时和泥浆流速差值计算公式进行推导,进而分析推导出各种块石沉积临界泥浆流速计算公式,并设定工程数据试算。得出以下结论:1)不同尺寸、不同形状、不同密度的块石在不同倾角排浆管道内差速流动、流动速度自动分级、沉积临界泥浆流速不同;2)密度小、体积小的块石运动速度快、沉积临界泥浆流速小;3)相同重量、密度的块石,球形的运动速度最快、沉积临界泥浆流速最小,正方体形的次之,长条形的运动速度最慢、沉积临界泥浆流速最大,长径比越大流速越慢、沉积临界泥浆流速越大;4)同一块石,在向下管道流速最快、沉积临界泥浆流速最小,水平管道次之,在垂直上升管道流速最小、沉积临界泥浆流速最大。重点控制始发井和地面垂直向上管道内的泥浆流速至关重要。通过计算以适用经济的泥浆流速来预防排泥管道堵塞。

内蒙古某矿山开采主要污染物治理与环境保护研究

内蒙古某大型铀矿床采用CO_(2)+O_(2)地浸开采技术,以CO_(2)+O_(2)作为溶浸剂配制溶浸液,与矿层中的铀络合生成离子,在井场浸出和浸出液水冶处理过程中产生废井液和工艺废水污染物。在治理污染物的过程中,通过固井、地表固化和回收方式对废井液进行处理;对树脂转型废水进行反渗透处理,将反渗透浓水、树脂反冲废水等排至蒸发池蒸发。研究结果显示,废井液放射性较低,U天然平均浓度为38 mg/L,226Ra活度浓度平均为79 Bq/L。树脂转型水反渗透处理后U天然浓度<0.05 mg/L,226Ra活度浓度<1.1 Bq/L。蒸发池残渣中U天然平均比活度为426.90 Bq/L,226Ra平均比活度696.67 Bq/kg。通过对污染物进行治理,固井、地表固化均符合环保要求,工艺废水和蒸发池残渣符合相关标准要求,为该类型矿山污染物治理提供了方法和思路。通过采用本文方法可以达到污染物治理的目的,保护当地生态环境,产生积极的企业效益和社会效益,为企业高质量发展提供保障。

高海拔排水巷断层突水突泥前兆信息演化规律数值模拟

目的:以西藏巨龙铜矿穿破碎带排水巷道施工为工程背景,分析断层突水突泥前兆信息演化规律。方法:通过数值模拟,探究了流固耦合作用下排水巷道施工至破碎带过程中围岩位移、应力、塑性区以及渗流场的变化规律,分析了巷道穿断层破碎带突水突泥前兆信息演化规律。结果:结果表明:巷道掘进至破碎带时,掌子面位移发生突变性增大。同时破碎带发生应力扰动。围岩塑性区向破碎带方向扩展,破碎带内岩体发生塑性变形,与掌子面塑性区贯通。巷道掘进至破碎带时,围岩内渗流场发生明显变化,被揭露的破碎带形成排水口,围岩水压骤然减小,巷道内容易发生突水突泥事故。意义:本文研究结果为巨龙排水巷穿破碎带施工提供了理论参考。

钻井液罐液面抗波动装置的研发与应用

钻井液池体积参数变化是钻井液液量增加或减少的直接显示,也是判断和预防溢流、井漏的关键参数。由于钻井液液面受搅拌器搅拌的影响,波动剧烈,给综合录井仪钻井液池体积参数准确监测造成一定的干扰,影响到溢流和井漏等工程异常的判断,也是录井作业的一个难点。为此,研发了钻井液罐液面抗波动装置,该装置由镂空式抗波动管、安装卡箍、传感器安装支架3部分构成,可大幅减少钻井液搅拌器的影响。通过现场在同一窗口安装两个同型号传感器进行监测对比得知,钻井液罐液面抗波动装置有效地降低了液面波动干扰,提高了溢漏等关键井控异常监测的精确性,为钻井工程实时决策提供了科学依据,为确保井控安全发挥了重要作用。

A novel oil-in-water drilling mud formulated with extracts from Indian mango seed oil

Drilling muds with less environmental impact are highly desired over conventional diesel-based mud systems,especially in light of the emerging strict environmental laws.In this article,a novel oil-in-water(O/W)emulsion drilling fluid formulated with a methyl ester extracted from Indian mango seed oil was evaluated.The effect of the weight percent of different constituents of the emulsion/suspension including the oil phase,bentonite,and polyanionic cellulose polymer on the rheology and the fluid loss was examined.The methyl ester oil phase/mud system displayed superior physical,chemical,rheological and filtration properties relative to the diesel and the mango seed oil.Eco-toxicity of the methyl ester and diesel(O/W)emulsion mud systems was assessed using the acute lethal concentration test.The Indian mango methyl ester(O/W)emulsion mud displayed much less impact on fish population.Flow characteristics collected from the flow model at 85°C suggested excellent shear thinning behavior of the Indian mango methyl ester(IMME)(O/W)emulsion mud.Moreover,the IMME(O/W)emulsion displayed strong pseudoplastic behavior,an attractive feature in a drilling mud,with increasing clay content and polymer concentration.The methyl ester mud was thermally stable over a wide range of the constituent concentrations.Furthermore,a particle size analysis revealed that engineered drilling muds targeting suspension of particles with certain size range can be formulated by changing the volume fraction of the methyl ester in the mud system.

Experimental Investigation of Drilling Fluid Performance as Nanoparticles

In this work, a drilling fluid recipe has been developed by using nanoparticles, to increase the efficiency of drilling operations for maximum accessibility to new & matured oil reserves and suited to various drilling conditions. The solution to severe drilling problems like pipe sticking, lost circulation, formation damage, erosion of borehole, thermal instability of drilling fluids and insufficient gel properties of the drilling fluids, lies in controlling and optimizing the rheology of the drilling fluid. The inefficiency of the drilling fluid in performing certain functions is mainly due to a lack in a particular rheological property. The performance of the clay composites water-based bentonite drilling mud in terms of its rheological behavior in drilling systems was investigated at various pressures and temperatures. It was found that temperature had a detrimental effect on the rheological properties. The behavior was investigated using synthesized nano bentonite water based drilling fluid. The fluid retained all the desired rheological properties at elevated temperatures and pressures, thus enhanced the possibility of its application in deep wells, where elevated temperatures and pressures were quite common.