Fracture development during disposal of hazardous drilling cuttings by deep underground injection: A review

Drilling fluids with complicated compositions are becoming more common as the oil and gas industry develops. The production of hazardous cuttings is increasing, which not only stifles the oil and gas industry's development but also poses a severe environmental threat. Deep underground re-injection is a cost-effective and efficient method for dealing with hazardous cuttings. Numerous experiments and numerical studies on cuttings re-injection have been conducted in the past thirty years. However, there is still a divergence of views on the fracture development in the process of cuttings re-injection. A comprehensive review of existing studies is necessary to help researchers advance this technology. This paper provides a review of the fundamental studies on fracture behaviors during the deep underground re-injection of drilling cuttings. The limitations of the existing studies are also discussed to inspire new research endeavors.     

可重构并行嵌入式系统

摘要：针对目前应用于军事、航天特殊环境的嵌入式系统存在功能单一、灵活性差、可靠性有限等问题,构建高性能高可靠嵌入式系统RPES,采用SMP并行机制、多种容错策略、硬件支持的软件重注入机制和算法部件动态重构机制,支持系统容错策略以及性能和灵活性的提升。‘测试结果表明,该系统能适应大范围的特殊应用。     

砂岩储层清水和污水混注对储层损害的实验评价

注入水中乳化油含量和悬浮颗粒含量及粒径一直是控制砂岩油藏注入水水质的重要指标。利用正交试验原理,通过实验系统评价了乳化油和悬浮颗粒共存时乳化油滴浓度、固相颗粒含量及粒径、渗透率及注入孔隙体积的相互作用及其对中高渗储层吸水能力的影响。结果表明,对于污水回注或清水、污水混注的砂岩地层,乳化油和悬浮颗粒共存比其单一存在时对地层吸水能力的损害要严重。当油滴粒径小于10μm时,岩心损害程度大于70%,油滴粒径大于30μm时,岩心损害程度低于50%。对于给定孔喉的岩心,有一个临界颗粒粒径。临界固相颗粒粒径随渗透率(即孔喉大小)的变化而变化,而临界油滴粒径基本不随渗透率变化,粒径约为15μm。     

海上油田污水处理技术研究进展

阐述了国内外海上油田污水处理新技术的研究进展和应用情况,包括海上油田注水水源及水质处理技术、海水中硫酸盐去除技术及海底海水处理和就地注入工艺技术等。同时阐述了采出水回注和达标排放处理技术,重点论述了气浮技术、旋流分离技术、萃取技术、过滤技术、氧化技术及生化处理技术等在海上油田的研究进展及应用现状。最后展望了海上油田污水处理技术发展趋势,其重点是对现有技术的优化改进以及工艺的优化组合,以提高处理效率。     

长庆气田污水回注井井筒腐蚀现状及对策

长庆气田污水回注井主要用来将天然气生产过程中产生的污水回流至地下遮挡层,回注水主要来自气井产水以及天然气净化处理过程中产生的污水,其矿化度较高,含有大量硫化物、Ca、Mg等物质,水质复杂,腐蚀性较强。先后对5口污水回注井井下管柱起出分析和腐蚀检测,发现4口井井下管柱腐蚀严重。套管腐蚀会导致回注污水窜层,甚至威胁到饮用淡水层。对回注污水水质分析显示,回注污水水型为CaCl2型,pH值较低,在5.65～6.52之间,呈酸性,污水中含有大量的H2S、CO2等酸性气体,4口严重腐蚀井单井平均H2S含量为820mg/m3,CO2含量为5%,这些酸性气体在污水中溶解,导致套管腐蚀。提出优化回注井井身结构,下入双层套管;使用非金属套管,加强套管涂层防腐技术研究;下封隔器,封隔油套环空,打入缓蚀剂以保护套管;对井下管柱定期检测、维护等防护措施。     

Produced water re-injection with seawater treated by sulphate reduction plant: Injectivity decline, analytical model

Commingled injection of seawater with produced water is an option for offshore fields submitted to waterflooding. It resolves the problems of produced water disposal and of the reservoir pressure maintenance.The presence of barium (strontium) in the formation water and consequent sulphate scaling with seawater flooding is a wide spread phenomenon. In this case, the produced water also contains some barium, which results in sulphate scaling in injection well during commingled injection with seawater.One of the ways around to avoid injectivity damage during the commingled injection of incompatible waters is using a sulphate reduction plant. Being mounted on sea platform, the plant significantly reduces sulphate concentration in seawater and allows using it for commingled produced water re-injection (PWRI). Low sulphate seawater injection together with PWRI causes low injectivity decline and makes it feasible to apply in offshore waterflood projects.Planning and design of commingled PWRI with low sulphate seawater injection includes choice of the ratio “produced water:seawater”, determination of maximum allowed sulphate concentration in seawater after treatment, and injectivity decline prediction. The reliable design and plan is based on mathematical modelling with well-known model coefficients.In the current paper we derive an analytical model for the co-injection of low sulphate seawater with barium-containing produced water. Reagent and deposit concentrations along with the injectivity index are expressed by explicit formulae. It was found out that bulk sulphate deposition occurs in the 10–20 well radius neighbourhood. The injectivity decline is one order of magnitude higher than the productivity decline under similar reservoir conditions. Calculations for sulphate reduction plant have been performed for six fields of Campos Basin (Brazil).     

西安市城区地热水人工加压回灌试验研究

为研究西安市地热水回灌的可行性及适合的回灌模式,本文以陕西宾馆地热井加压回灌试验为例进行了试验研究,结果表明:在西安城区地热水中开展单井加压回灌是可行的,通过分析加压前后回灌能力的变化、压力与回灌量之间的关系以及回灌量与出水量之间的联系,对回灌过程中的堵塞机理进行了分析,结果说明加压回灌可以有效提高回灌能力,增大回灌量。     

制盐废水回注岩盐卤井采区选择分析

通过对我公司制盐冷凝水向不同采区回注岩盐卤井运行费用以及所形成的不同卤水输送结果和投资差异比较，提出就近回注的看法，供搬迁矿山设计和同行参考。     

采油污水处理现状及其深度处理技术

我国多数油田采油污水的处理工艺是以传统的“老三套”工艺(混凝-沉降-过滤)为基础的初级处理技术，主要去除对象是以浮油、分散油形式存在的石油类和悬浮固体物质。采油污水深度处理技术是以去除以乳化油、有机物和降低水硬度为目的，在原有工艺基础上进行深度处理可以使出水水质达到外排标准和回用要求。     

油田注水系统腐蚀因素的分析

油田注水系统管网的腐蚀是油田生产过程中一直难以有效解决的难题。引起腐蚀的因素有物理因素、化学因素和生物因素等。为了揭示油田污水诸多影响因素与腐蚀的相关性,本研究对胜利油田55个不同的污水站污水理化性质进行全面系统的分析,并应用SPSS程序分析了污水中物理、化学和生物因素与腐蚀的相关性。结果表明:污水矿化度(20 g/L)、溶解氧、悬浮物与腐蚀速率的相关系数分别为0.345、0.440、0.305,概率(P)分别为0.039、0.001、0.044,与腐蚀均呈显著正相关;p H值、温度与腐蚀速率的相关系数分别为0.127、0.185,P分别为0.356、0.177,与腐蚀存在相关性,但影响有限;含油量与腐蚀速率的相关系数为-0.295,P为0.029,与腐蚀呈显著负相关。由于各水站都添加杀菌剂,导致细菌与腐蚀速率之间的相关性减弱。