Prediction of wax precipitation region in wellbore during deep water oil well testing

During deep water oil well testing, the low temperature environment is easy to cause wax precipitation, which affects the normal operation of the test and increases operating costs and risks. Therefore, a numerical method for predicting the wax precipitation region in oil strings was proposed based on the temperature and pressure fields of deep water test string and the wax precipitation calculation model. And the factors affecting the wax precipitation region were analyzed. The results show that: the wax precipitation region decreases with the increase of production rate, and increases with the decrease of geothermal gradient, increase of water depth and drop of water-cut of produced fluid, and increases slightly with the increase of formation pressure. Due to the effect of temperature and pressure fields, wax precipitation region is large in test strings at the beginning of well production. Wax precipitation region gradually increases with the increase of shut-in time. These conclusions can guide wax prevention during the testing of deep water oil well, to ensure the success of the test.

Survey-Based Analysis of Water Consumption Law in High-Rise Public Buildings and Water-Saving Performance of Pressure-Reducing Measures

Facing the contradiction of water scarcity and water wastage in most cities of China, this study aims at probing into the factors influencing water-use efficiency and assessing water-saving potential by adopting pressure control measures based on field survey conducted in 23 high-rise buildings in Suqian, China and laboratory tests. Results showed that per capita water consumption (PCWC) exceeding water consumption norms is common in these buildings. The hourly water consumption variation law is quite different among different types of buildings. These differences should be considered in designing building water supply systems to lower water and energy consumption. On the basis of correlation analysis, the order of factors influencing the PCWC follows average tap water pressure, percapita building area, and building age, suggesting pressure management in high-rise buildings is a key water-saving measure. Field tests of outflow characteristics under different water pressures indicated that over-pressure outflow (OPO) is a common cause of water wastage in buildings, however, no branch pipe pressure control measures were found in all the surveyed buildings. Laboratory tests showed that branch pipe pressure-reducing measures can lower water consumption and improve the comfortability of use as well. Therefore, in addition to applying high efficiency water-saving devices, we strongly recommend that branch pipe pressure-reducing measures should be strictly implemented in designing new building water supply systems and reconstruction of existing old building water supply systems, thereby, promoting water, energy saving and development of green building.

Outflow of Pacific water from the Chukchi Sea to the Arctic Ocean

Pacific water exits the Chukchi Sea shelf through Barrow Canyon in the east and Herald Canyon in the west, forming an eastward-directed shelfbreak boundary current that flows into the Beaufort Sea. Here we summarize the transformation that the Pacific water undergoes in the two canyons, and describe the characteristics and variability of the resulting shelfbreak jet, using recently collected summertime hydrographic data and a year-long mooting data set. In both canyons the northward-flowing Pacific winter water switches from the western to the eastern flank of the canyon, interacting with the northward-flowing summer water. In Barrow canyon the vorticity structure of the current is altered, while in Herald canyon a new water mass mode is created. In both instances hydraulic effects are believed to be partly responsible for the observed changes. The shelfl）reak jet that forms from the canyon outflows has distinct seasonal configurations, from a bottom-intensified flow carrying cold, dense Pacific water in spring, to a surface-intensified current advecting warm, buoyant water in summer. The current also varies significantly on short timescales, from less than a day to a week. In fall and winter much of this mesoscale variability is driven by storm events, whose easterly winds reverse the current and cause upwelling. Different types of eddies are spawned from the current, which are characterized here using hydrographic and satellite data.

Assessment of Water Losses from Badovc Lake, Kosovo： Hydrochemical Implications

This paper aims to quantitatively assess water losses of Badovc Lake-Kosovo based on both water balance of the lake and water hydrochemistry. This attempt was strongly prompt by both the importance of this lake for water supply of Prishtina city and the lack of water. According to lake water balance, a water loss of 3,738,905 m^3 and 1,722,552 m^3 for the hydrologic year 2014 and the period January-May （2015） was evaluated. These consistent data favour the opinion that a continuous groundwater outflow from the lake is present and it is conditioned by the intensively developed fracture system in the lake basement formations. This was also supported by the chemical data （chloride, sulphate, hardness and electric conductivity etc.） of the water. Water from the leakages on the right side of the dam shows the same chemical signature as the water from the lake. Whereas, water from the piezometer, monitoring well and the gallery of Hajvalia mine show similar values with those of the water from the lake. The calculations of the chloride mass balance showed that the fractions of lake and rainfall waters in the water mixture of Hajvalia mine were 67% and 33% respectively.

Dynamic modelling and engineering simulation of fluid mechanics in water injectors

To study the fluid dynamic response mechanism under the working condition of water injection well borehole,based on the microelement analysis of fluid mechanics and the classical theory of hydrodynamics,a fluid microelement pressure-flow rate relationship model is built to derive and solve the dynamic distribution of fluid pressure and flow rate in the space of well borehole.Combined with the production data of a typical deviated well in China,numerical simulations and analyses are carried out to analyze the dynamic distribution of wellbore pressure at different injection pressures and injection volumes,the delayed and attenuated characteristics of fluid transmission in tube,and the dynamic distribution of wellbore pressure amplitude under the fluctuation of wellhead pressure.The pressure loss along the wellbore has nothing to do with the absolute pressure,and the design of the coding and decoding scheme for wave code communication doesn’t need to consider the absolute pressure during injecting.When the injection pressure is constant,the higher the injection flow rate at the wellhead,the larger the pressure loss along the wellbore.The fluid wave signal delay amplitude mainly depends on the length of the wellbore.The smaller the tubing diameter,the larger the fluid wave signal attenuation amplitude.The higher the target wave code amplitude(differential pressure identification root mean square)generated at the same well depth,the greater the wellhead pressure wave amplitude required to overcome the wellbore pressure loss.

Key Technology of Ground Grouting Treatment for Inclined Shaft under Condition of Super Thick Water-Rich Loose Layer

Shaft is one of the important links of mine production. In recent years, wellbore deviation has occurred many times in various regions of China, especially under the condition of thick water-rich loose layer, wellbore deviation has become an important factor that seriously affects the safety of mine production and miners’ life. Taking the serious deviation of shaft in Guotun Coal Mine in Shandong Province as an example, this paper analyzes the causes of wellbore deviation from the aspects of wellbore geological conditions and wellbore construction methods, and grouting treatment engineering carried out on the deviated shaft under the condition of mine production. Through on-site grouting construction, repair and treatment are remarkable, which provides reference for the subsequent surface grouting treatment engineering of wellbore deviation.

井筒举升工艺在稠油冷采开发中的应用

针对草古1潜山稠油油藏注汽热采效果不佳的状况,根据不同区域地质、油藏特点,先后应用井筒电加热、电喷泵及阀式泵泵上掺水等以井筒降粘为主要目的的新工艺开展了冷采试验,取得了较好的生产效果,实现了该区块的高效规模开发,同时也形成了适合油藏特点的草古1冷采系列技术,为制定企业相关生产工艺标准,奠定了必要的基础。

Research progress and application prospect of functional adhesive materials in the field of oil and gas drilling and production

By summarizing the composition,classification,and performance characterization of functional adhesive materials,the adhesion mechanisms of functional adhesive materials,such as adsorption/surface reaction,diffusion,mechanical interlocking,and electrostatic adsorption,are expounded.The research status of these materials in oil and gas drilling and production engineering field such as lost circulation prevention/control,wellbore stabilization,hydraulic fracturing,and profile control and water plugging,and their application challenges and prospects in oil and gas drilling and production are introduced comprehensively.According to the applications of functional adhesive materials in the field of oil and gas drilling and production at this stage,the key research directions of functional adhesive materials in the area of oil and gas drilling and production are proposed:(1)blending and modifying thermoplastic resins or designing curable thermoplastic resins to improve the bonding performance and pressure bearing capacity of adhesive lost circulation materials;(2)introducing low-cost adhesive groups and positive charge structures into polymers to reduce the cost of wellbore strengthening agents and improve their adhesion performance on the wellbore;(3)introducing thermally reversible covalent bond into thermosetting resin to prevent backflow of proppant and improve the compressive strength of adhesive proppant;(4)introducing thermally reversible covalent bonds into thermoplastic polymers to improve the temperature resistance,salt-resistance and water shutoff performance of adhesive water shutoff agents.

Effects of instantaneous shut-in of high production gas well on fluid flow in tubing

As the classical transient flow model cannot simulate the water hammer effect of gas well, a transient flow mathematical model of multiphase flow gas well is established based on the mechanism of water hammer effect and the theory of multiphase flow. With this model, the transient flow of gas well can be simulated by segmenting the curved part of tubing and calculating numerical solution with the method of characteristic curve. The results show that the higher the opening coefficient of the valve when closed, the larger the peak value of the wellhead pressure, the more gentle the pressure fluctuation, and the less obvious the pressure mutation area will be. On the premise of not exceeding the maximum shut-in pressure of the tubing, adopting large opening coefficient can reduce the impact of the pressure wave. The higher the cross-section liquid holdup, the greater the pressure wave speed, and the shorter the propagation period will be. The larger the liquid holdup, the larger the variation range of pressure, and the greater the pressure will be. In actual production, the production parameters can be adjusted to get the appropriate liquid holdup, control the magnitude and range of fluctuation pressure, and reduce the impact of water hammer effect. When the valve closing time increases, the maximum fluctuating pressure value of the wellhead decreases, the time of pressure peak delays, and the pressure mutation area gradually disappears. The shorter the valve closing time, the faster the pressure wave propagates. Case simulation proves that the transient flow model of gas well can optimize the reasonable valve opening coefficient and valve closing time, reduce the harm of water hammer impact on the wellhead device and tubing, and ensure the integrity of the wellbore.

超深层断控碳酸盐岩油藏地质力学建模及其在开发中的应用

为提高超深断控碳酸盐岩油藏的开发效益,通过开展大尺寸岩样力学实验,揭示高角度—近直立断裂面变形与连通机理;基于高压注水提采的力学与流动耦合原理,通过地质力学建模,明确了断控碳酸盐岩油藏现今地应力场和断裂活动性分布规律;发现不同方位的断裂活动性以及不同部位的缝洞体连通性有明显差异,进而分析了不同井眼轨迹的开发效果,提出了地质工程一体化工作方法,科学指导井眼轨迹设计和注水方案优化。结果表明:①走滑断裂变形中的大尺度破碎体和高角度裂缝系统是影响储层品质的关键因素,高压注水一方面能够激活先存裂缝,一方面还能在先存裂缝基础上发生延伸扩展,甚至可以产生新的裂缝,促进了断控缝洞体在纵横向上的互相连通;②高压注水过程中断裂体内部发生力学与流动之间的耦合变化,渗流环境得到改善,通过循环举升,从而提高油气采收率;③根据断裂体形态、产状以及断裂面动态剪切变形连通性,可优选定向井最佳井点和井眼轨迹,并优化注水方案;④塔里木盆地断控油藏试验区通过高压注水,采收率提高5个百分点,该方法为超深断控型油藏高效开发提供了较好的理论依据和技术支撑。

吐哈油田胜北区块地层特性及钻井液技术对策

吐哈油田胜北区块钻井过程中遇到井壁失稳引起的下钻遇阻、划眼、卡钻等井下复杂情况,制约了钻井提速提效。以胜北508H为代表井,对不同层位岩屑样品的矿物组成及理化性能进行了测定,进而分析了上部地层和下部地层的主要特性和井壁失稳机理。研究表明,地层中普遍存在泥岩,泥岩中粘土矿物含量较高且其组成主要以伊蒙混层和伊利石为主,同时也含有蒙脱石,这些是导致井下发生复杂情况的地层因素。针对上部地层泥岩易水化分散造浆、缩径,提出了采取聚合物强化包被性能以及复合盐强化抑制性能的钻井液技术措施,优化后钻井液的滚动回收率高达88.40%,膨胀率为1.17%。针对下部地层泥岩易剥落掉块、坍塌,提出了通过微-纳米全尺寸封堵并结合复合盐的活度控制及聚胺强化抑制性能的钻井液技术措施,优化后钻井液的平衡压力时间大幅延长,达160 h。钻井液活度低于0.76,钻井液72 h浸泡泥岩岩心的强度降幅减小。优化后的钻井液在胜北区块SH5s21-2和SH5s13-2两口井应用中取得了良好的效果,钻井过程中未发生复杂事故,实现了维持井壁稳定、提高钻井时效的目的。

Limit analysis of extended reach drilling in South China Sea

Extended reach wells （ERWs）, especially horizontal extended reach well with a high HD （horizontal displacement） to TVD （true vertical depth） ratio, represent a frontier technology and challenge the drilling limitations. Oil and gas reservoir in beaches or lakes and offshore can be effectively exploited by using extended reach drilling （ERD） technology. This paper focuses on the difficult technological problems encountered during exploiting the Liuhua 11-1 oil field in the South China Sea, China. Emphasis is on investigating the key subjects including prediction and control of open hole limit extension in offshore ERD, prediction of casing wear and its prevention and torque reduction, φ244.5mm casing running with floating collars to control drag force, and steerable drilling modes. The basic concept of limit extension in ERD is presented and the prediction method for open hole limit extension is given in this paper. A set of advanced drilling mechanics and control technology has been established and its practical results are verified by field cases. All those efforts may be significant for further investigating and practicing ERD limit theory and control technology in the future.

流域水资源配置方法研究

流域水资源配置解决的主要问题是确定不同天然来水情况下的省际规划出境水量,以及平原地下水规划开采量和入海水量。省际规划出境水量是流域水资源管理的基础指标,平原地下水规划开采量和入海水量是反映生态状况的指标。结合严重缺水的海河流域,研究并提出采用典型年法进行水资源配置的技术路线,提出2010规划水平年满足各项控制指标条件下省际配置分区经济社会发展的可利用水量。

灰色聚类协调分析模型及其应用

以灰色聚类方法为基础,利用协调优先指标与非协调优先指标的性质,建立了一种新的综合评判模型。实例分析结果表明,该模型具有科学合理、计算简便、分辨率高等特点。

近井地带高含水饱和度对火驱开发效果影响的实验

火驱技术是注蒸汽开发后的有效接替技术,然而注蒸汽后近井地带储层形成的高含水饱和度对火驱的点火、火线推进和开采效果的影响尚未明确。利用燃烧管实验装置将高含水饱和度的油砂填充到注气端附近,以模拟近井地带储层的高含水饱和度,并研究了近井地带储层的高含水饱和度对火驱的点火、火线推进特征及开发效果的影响。结果表明:近井地带储层的含水饱和度高达91.7%时,依然可以实现成功点火,形成有效驱替。近井地带储层的水能起到蒸汽驱油作用,加快火线的推进速度,缩短油墙的形成时间,从而导致火驱受效时间提前,但也会降低火驱过程中的燃料消耗量和氧气利用率,导致火线前缘的燃烧效果变差和原油采收率的降低。研究成果可为蒸汽吞吐后转火驱技术的现场应用提供理论参考。

海陆过渡相页岩储层液岩作用机理及钻井液体系构建

我国海陆过渡相页岩地质储量大、资源丰度高,开发前景广阔。但钻井过程中井壁极易发生掉块、坍塌,导致井壁失稳影响钻井安全。本文通过钻井岩心观察、电镜和CT扫描、X射线衍射分析等相关实验,得到储层岩样矿物组分及微观结构等特征,结果表明:页岩气储层全岩主要含石英和黏土矿物,地层黏土矿物含量高达45.7%,且黏土矿物中不含蒙脱石,高岭石含量为35%,伊/蒙混层含量为26%;岩样表面纳微米孔隙和微裂缝发育,裂缝宽度在微米级并连通多条窄裂缝;通过岩液作用后晶层间距、表面张力、线性膨胀率和裂缝扩展变化分析,海陆过渡相页岩仅发生表面水化,揭示了海陆过渡相页岩气储层岩液作用机理。优选了水基钻井液抑制剂、封堵剂与润滑剂,构建了一套海陆过渡相页岩气储层的高性能水基钻井液体系,并对其展开了室内评价。钻井液常规性能、抑制性、封堵性、润滑性评价实验结果表明,该钻井液体系抗温100℃,高温高压失水6 mL,泥页岩膨胀率为1.03%,钻井液润滑系数整体小于0.15,体系30 min的API滤失量较基浆降低40%,可对地层微裂缝实现有效封堵,且生物毒性EC50值为37260 mg/L,属于无毒级别,能够满足海陆过渡相页岩气钻井作业施工对钻井液性能的要求并进行了现场应用,封堵防塌效果良好,可有效解决海陆过渡相泥页岩井壁失稳的技术难题。

考虑产水量变化的气井井筒结垢堵塞预测

为提高气井解堵措施的针对性,综合考虑气井井筒无机物结垢的热力学和动力学影响,特别是考虑气井产水量变化与垢在井筒内壁的黏附系数,建立了气井井筒结垢堵塞预测模型,并应用于靖边气田。结果表明:基于平滑指数法预测了气井日产水量,预测时间越长,累积产水量的误差越小。加权系数α越小,预测结果越精准,模型中α取0.2;通过现场生产资料拟合,垢在井筒内壁的黏附系数取0.001时,能够取得较为满意的预测结果;现场应用结果表明该模型预测的结垢堵塞物组成和堵塞程度与现场相符,对气井井筒除垢解堵措施具有指导意义。

基于PIPEPHASE的苏南采出水外输系统模拟研究

采出水外输是各大气田生产过程中保证气田产量和完善气田开发效果的重要途径。苏南气田采出水外输系统是一个复杂的流体网络系统,系统需要在不同状态下对外输方式进行调整。基于集气站、输水阀室、输水管线、处理厂的空间分布和拓扑结构关系,利用PIPEPHASE稳态多相流模拟计算软件,建立包含管网设施和参数的气田采出水外输系统模型;通过黏密度检测分析、阴阳离子色谱实验等明确了外输系统中的介质组分,进而开展仿真模拟;通过误差修正后的模型开展模拟计算,得出不同状态下各节点单元的压力和流量。结果表明:外部气温变化造成的介质温度改变会对外输系统产生小幅影响,通过对比不同分配分输方式的模拟计算结果与现场生产数据,验证了模型的合理性。研究结果可以为苏南气田现场生产提供参考。

环空水泥浆顶替界面稳定性数值模拟研究

借助计算流体力学(CFD)软件FLUENT6.0,利用流体体积法(VOF)对环空内水泥浆顶替进行了数值模拟,模拟环空井筒长为10m,外径为0.112m,内径为0.089m。在不同流态、不同流动雷诺数和不同环空无量纲偏心度的条件下进行了计算,得到了顶替速度及偏心度对顶替效率以及界面稳定性的影响规律。与实验数据对比表明,数值模拟得到的结果与实验结果相吻合。模拟结果表明,降低套管偏心度及进行湍流顶替或低速下的层流顶替有助于界面稳定和提高顶替效率。

复合盐层多元协同稳定井壁钻井液技术

复合盐层性质复杂,钻井过程中易发生井壁失稳.通过分析多个地区复合盐层的矿物组成、微观结构、理化性质及界面力学特性,探讨了井壁失稳机理.结果表明,地层孔隙和微裂缝发育、盐岩蠕变及溶解、膏泥岩水化是造成复合盐层井壁失稳的关键原因.提出了强化钻井液封固井壁作用-抑制盐膏溶解与膏泥水化-水活度平衡-有效应力支撑“多元协同”稳定井壁钻井液技术对策.依据水活度对泥岩水化膨胀和分散的影响规律,明确了钻井液水活度安全窗口的设计依据.针对中东地区M油田、乌兹别克斯坦H-S油田以及中国新疆地区复合盐层井壁失稳问题,采用“多元协同”稳定井壁技术对策,设计了相应的防塌钻井液体系.现场应用表明,该技术可有效提高复合盐层井壁稳定性,大幅减少井下复杂事故,提高钻井作业效率.