Performance Analysis of a Profile Control Agent for Waste Drilling Fluid Treatment

A method for the treatment of hazardous waste drilling fluids,potentially leading to environmental pollution,is considered.The waste drilling fluid is treated with an inorganic flocculant,an organic flocculant,and a pH regulator.The profile control agent consists of partially hydrolyzed polyacrylamide,formaldehyde,hexamethylenetetramine,resorcinol,phenol,and the treated waste drilling fluid itself.For a waste drilling fluid concentration of 2500 mg/L,the gelling time of the profile control agent is 25 h,and the gelling strength is 32,000 mPa.s.Compared with the profile control agent prepared by recirculated water under the same conditions,the present profile control agent displays better stability,salt-resistance,and performance.

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.

Rheological properties of oil-based drilling fluids at high temperature and high pressure

The rheological properties of two kinds of oil-based drilling fluids with typically composition were studied at pressures up to 138 MPa and temperatures up to 204 ℃ using the RheoChan 7400 Rheometer.The experimental results show that the apparent viscosity,plastic viscosity and yield point decrease with the increase of temperature,and increase with the increase of pressure.The effect of pressure on the apparent viscosity,plastic viscosity and yield point is considerable at ambient temperature.However,this effect gradually reduces with the increase of temperature.The major factor influencing the rheological properties of oil-based drilling fluids is temperature instead of pressure in the deep sections of oil wells.On the basis of numerous experiments,the model for predict the apparent viscosity,plastic viscosity and yield point of oil-based drilling fluids at high temperature and pressure was established using the method of regressive analysis.It is confirmed that the calculated data are in good agreement with the measured data,and the correlation coefficients are more than 0.98.The model is convenient for use and suitable for the application in drilling operations.

Comparison and application of different empirical correlations for estimating the hydrate safety margin of oil-based drilling fluids containing ethylene glycol

As the oil and gas industries continue to increase their activity in deep water, gas hydrate hazards will become more serious and challenging, both at present and in the future. Accurate predictions of the hydrate-free zone and the suitable addition of salts and/or alcohols in preparing drilling fluids are particularly important both in preventing hydrate problems and decreasing the cost of drilling operations. In this paper, we compared several empirical correlations commonly used to estimate the hydrate inhibition effect of aqueous organic and electrolyte solutions using experiments with ethylene glycol （EG） as a hydrate inhibitor. The results show that the Najibi et al. correlation （for single and mixed thermodynamic inhibitors） and the Ostergaard et al. empirical correlation （for single thermodynamic inhibitors） are suitable for estimating the hydrate safety margin of oil-based drilling fluids （OBDFs） in the presence of thermodynamic hydrate inhibitors. According to the two correlations, the OBDF, composed of 1.6 L vaporizing oil, 2% emulsifying agent, 1% organobentonite, 0.5% SP-1, 1% LP-1, 10% water and 40% EG, can be safely used at a water depth of up to 1900 m. However, for more accurate predictions for drilling fluids, the effects of the solid phase, especially bentonite, on hydrate inhibition need to be considered and included in the application of these two empirical correlations.

Development of a High Temperature and High Pressure Oil-Based Drilling Fluid Emulsion Stability Tester

When drilling deep wells and ultra-deep wells, the downhole high temperature and high pressure environment will affect the emulsion stability of oil-based drilling fluids. Moreover, neither the demulsification voltage method nor the centrifugal method currently used to evaluate the stability of oil-based drilling fluids can reflect the emulsification stability of drilling fluids under high temperature and high pressure on site. Therefore, a high-temperature and high-pressure oil-based drilling fluid emulsion stability evaluation instrument is studied, which is mainly composed of a high-temperature autoclave body, a test electrode, a temperature control system, a pressure control system, and a test system. The stability test results of the instrument show that the instrument can achieve stable testing and the test data has high reliability. This instrument is used to analyze the factors affecting the emulsion stability of oil-based drilling fluids. The experimental results show that under the same conditions, the higher the stirring speed, the better the emulsion stability of the drilling fluid;the longer the stirring time, the better the emulsion stability of the drilling fluid;the greater the oil-water ratio, the better the emulsion stability of the drilling fluid. And the test results of the emulsification stability of oil-based drilling fluids at high temperature and high pressure show that under the same pressure, as the temperature rises, the emulsion stability of oil-based drilling fluids is significantly reduced;at the same temperature, the With the increase in pressure, the emulsion stability of oil-based drilling fluids is in a downward trend, but the decline is not large. Relatively speaking, the influence of temperature on the emulsion stability of oil-based drilling fluids is greater than that of pressure.

Development of key additives for organoclay-free oil-based drilling mud and system performance evaluation

Traditional oil-based drilling muds(OBMs) have a relatively high solid content, which is detrimental to penetration rate increase and reservoir protection. Aimed at solving this problem, an organoclay-free OBM system was studied, the synthesis methods and functioning mechanism of key additives were introduced, and performance evaluation of the system was performed. The rheology modifier was prepared by reacting a dimer fatty acid with diethanolamine, the primary emulsifier was made by oxidation and addition reaction of fatty acids, the secondary emulsifier was made by amidation of a fatty acid, and finally the fluid loss additive of water-soluble acrylic resin was synthesized by introducing acrylic acid into styrene/butyl acrylate polymerization. The rheology modifier could enhance the attraction between droplets, particles in the emulsion via intermolecular hydrogen bonding and improve the shear stress by forming a three-dimensional network structure in the emulsion. Lab experimental results show that the organoclay-free OBM could tolerate temperatures up to 220 ?C and HTHP filtration is less than 5 m L. Compared with the traditional OBMs, the organoclay-free OBM has low plastic viscosity, high shear stress, high ratio of dynamic shear force to plastic viscosity and high permeability recovery, which are beneficial to penetration rate increase, hole cleaning and reservoir protection.

Research on High Temperature and High Density White Oil Based Drilling Fluid and Its Application in Well 201H7-6

As the depth and horizontal length of shale gas development wells increase,the requirement for the temperature resistance and the ability of the drilling fluids to stabilize the shale formation becomes higher.A new type of high temperature and high density white oil based drilling fluid system has been developed in laboratory.Research shows that the drilling fluid system has good rheological property,low filtration loss,strong anti-debris pollution capability and good plugging performance at high temperature and high density.The system has been successfully applied in the 201H7-6 well.Application results show that the drilling fluid rheology,high temperature and high pressure fluid loss and demulsification voltage meet the field requirements.The drilling fluid performance is stable in drilling an 1800 m horizontal section,and no stuck or shale swelling and wellbore collapsing are induced.It is the first well drilled successfully with domestic white oil-based drilling fluid in Zigong Region.It also sets several new records including the deepest well,the shortest drilling cycle,and the fastest drilling speed in that region,which provides valuable experience for the future drilling activities.

Calculation and application of partition coefficients of light hydrocarbons in oil-based mud system

To find out the relationship between the oil-based mud,the formation fluid and the extracted gas,we use a thermodynamic approach based on static headspace gas chromatography technique to calculate the partition coefficients of 47 kinds of light hydrocarbons compounds between nC5 and nC8 in two kinds of oil-based mud-air systems,and reconstruct the original formation fluid composition under thermodynamic equilibrium.The oil-based drilling mud has little effect on the formation fluid compositions in the range of nC5-nC8(less than 1%for low-toxicity oil-based mud and less than 10%for oil-based mud).For most light hydrocarbon compositions,the partition coefficients obtained by vapor phase calibration and the direct quantitative methods have errors of less than 10%,and the partition coefficients obtained by direct quantitative method are more accurate.The reconstructed compositions of the two kinds of crude oil have match degrees of 91%and 89%with their real compositions,proving the feasibility and accuracy of reconstructing the composition of original formation fluid by using partition coefficients of light hydrocarbon compositions between nC5 and nC8.

Soil microbial response to waste potassium silicate drilling fluid

Potassium silicate drilling fluids （PSDF） are a waste product of the oil and gas industry with potential for use in land reclamation. Few studies have examined the influence of PSDF on abundance and composition of soil bacteria and fungi. Soils from three representative locations for PSDF application in Alberta, Canada, with clay loam, loam and sand textures were studied with applications of unused, used once and used twice PSDF. For all three soils, applying ≥40 m^3/ha of used PSDF significantly affected the existing soil microbial flora. No microbiota was detected in unused PSDF without soil. Adding used PSDF to soil significantly increased total fungal and aerobic bacterial colony forming units in dilution plate counts, and anaerobic denitrifying bacteria numbers in serial growth experiments. Used PSDF altered bacterial and fungal colony forming unit ratios of all three soils.

利用响应面法优化废弃钻井液破胶

针对废弃水基钻井液破胶难、回用难且存在二次污染等问题,开展废弃水基钻井液破胶过程的优化。基于对废弃水基钻井液的性能分析,采用单因素试验对复合破胶剂破胶过程中各因素的影响规律进行研究,借助响应面法对破胶过程的显著性影响因素进行深度优化。结果表明:废弃水基钻井液的工作性能无法满足油田作业区规定的指标要求,必须对其进行破胶回用处理;当破胶剂加入量为3.97 kg/m^(3)废弃水基钻井液,反应温度为51℃,搅拌速度为419 r/min时,废弃水基钻井液破胶出水率的预测最优值(体积分数)可达62.37%,经t检验,预测最优值和实验验证值之间不存在显著差异。该研究可为深层复杂钻井液的无害化处理提供准确可靠的理论依据和数据来源。

胜利油田钻井液环保处理技术研究与应用

在胜利油田钻井过程中,废弃物总量大、污染物含量高,废弃物污染控制集中于末端治理,资源化利用程度低、成本高,无法实现钻井过程中的污染控制,严重影响油田生态环境。针对该油田钻井过程中的环保关键技术难题,以“减量化、无害化、资源化”为目标,进行了理论研究、装备研发、技术攻关和集成应用,形成了钻井污染物源头控制、全井段钻井废弃物随钻过程减量化和钻井废弃物末端无害化处理与资源化利用等3项核心技术,创新了覆盖“源头控制、过程减量、末端治理”的钻井液环保处理技术。“十三五”期间,该钻井液环保处理技术在胜利油区及新疆、四川等地的中国石化工区实现规模化应用,建成了胜利油田滨105、盐222、桩146等绿色低碳钻井示范工程,为保障胜利油田绿色低碳开发提供了技术支撑,也为我国陆上油气田绿色低碳开发提供了有益借鉴。

陕西榆林废弃钻井液固液分离技术研究

采用稀硫酸作为破胶剂,通过室内抽滤实验对各种常用絮凝剂进行了优选,优化了废弃钻井液固液分离配方,即采用酸化破胶后加入3.09 g/L硫酸铝和3.09 g/L硫酸铁,能够将废弃钻井液进行脱稳分离。经陕西榆林现场应用表明,废弃钻井液应用此技术脱稳后,一次压滤成功,滤饼中平均含水量为31.79%。与前期固液分离效果相比,滤饼平均含水量降低了17.90%,废弃钻井液处理成本降低了10.21%。

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。

海上钻井废弃物负压抽吸减量技术研究

针对“零排放”背景下海上钻井废弃物回收总量大、转运成本高、甲板空间受限等难题,常规钻屑减量工艺是将减量设备置于螺旋输送器末端,由于螺旋体的搅拌混合导致钻屑黏度增大,加剧固液分离难度,造成减量效果不理想。基于负压抽吸技术,对常规减量工艺进行优化改进,开发出一种小型化源头减量分离技术及装置,将设备工艺前置,通过在振动筛下方增设小型固液分离装置,形成了一种“零排放”钻屑随钻减量处理工艺,并在渤海油田C平台应用测试2井次,取得了较好的效果,基本具备了现场随钻处理能力,验证了负压抽吸减量技术的可行性。该装置占用空间小,利于安装,能够大幅降低钻井液损耗,提升钻屑干燥程度,为“零排放”背景下海上钻井废弃物处置提供了技术思路,具有一定的推广价值和借鉴意义。

水基钻井液废弃固液处置及配套技术

为满足环保要求,长庆区域实行钻井废弃物“不落地”政策,但在施工中存在水基钻井液净化困难、岩屑废弃物含水率高且处理量大、固体废弃物无法重复使用、钻井施工占地面积大幅增加等技术难点,通过研制新型固控设备、“钻屑不落地”装置,优化钻井液循环净化工艺,研发阳离子型聚合物水基钻井液净化剂,优选废弃钻屑处理技术,形成了水基钻井液废弃固液处置及配套技术。该技术已在长庆钻井区域全面推广应用,岩屑减量29.82%,岩屑含水率≤35%,钻井废液循环利用率≥94%,钻井占地面积降低23.7%,现场应用效果显著。通过技术的集成及配套应用,大幅降低了钻井液废弃固液总量,实现绿色、安全、环保钻井,助力我国早日实现“碳达峰”和“碳中和”。

页岩气聚磺钻井废液循环利用优化技术研究

非常规能源页岩气开发将有助于改善我国的能源结构,国家能源局将其纳入国家战略性新兴产业,是四川省五大高端新成长产业规划之一。钻井废液是钻井过程中最具有代表性的废弃物之一,其产生量大、成分复杂、处理成本较高,研究钻井废液的处理对钻井作业现场周边环境的可持续发展意义重大。研究结论表明:以钻井液表观粘度、塑性粘度、动切力和中压滤失量为主要指标,通过不同浓度影响因子对钻井液的性能影响研究,结合Design Expert中Box-Behnken模块数值模拟,确定聚磺钻井废液循环利用配制钻井液指标体系要求。

油田废弃钻井液处置技术研究

随着石油钻采工业化生产进程的迅速发展,油田废弃钻井液量逐年增加,油田废弃钻井液含有多种有毒有害化学物质,实现油田废弃钻井液的无害化处置对环境保护有重要的意义。文章分析了目前油田废弃钻井液处置技术存在的问题,如成本问题、环保问题等,介绍了目前常见地处置油田废弃钻井液的技术,主要包括:回注技术、循环使用技术、固化技术、生物降解技术、回填技术、钻井液转化固井液技术及固液分离技术等,指出了废弃钻井液各种处置技术的适用范围及存在的局限性,提出了油田废弃钻井液处置技术及今后的研究方向,应从源头上进行管控,加强处理剂和技术研发,加强发掘高效菌种,以实现废弃钻井液的无害化处置。

海上水基钻井液废弃物压滤液回用技术研究与应用

海上油田环保项目水基钻井液废弃物压滤液如果能够实现资源化利用,那将大大降低海上环保项目钻井过程中产生的废弃物终端处理费用,实现降本增效。从滤液回用技术难点出发,通过室内实验,研究压滤液回收利用配置的钻井液性能是否稳定和对储层保护的效果方面进行分析,证实了其可行性。以海上某调整井项目为依托,将压滤液配置的钻井液应用到该项目5口井的钻井中,钻井全过程中的钻井液性能稳定,储层配伍性强,无污染,进一步验证了压滤液回用的可行性,实现了水基钻井液废弃物压滤液的重新利用。该项技术的成功应用,对后续海陆油田环保钻井项目的成本控制、资源化利用均具有重要的指导意义。

Novel Eco-friendly Additives for Aqueous and Non-aqueous Fluid Design

The global oil and gas industry has a long standing initiative to develop and use the most environment friendly solutions in the exploration and exploitation of oil and gas resources to prevent any damage or degradation of other marine and terrestrial resources. This is reflected by increasing research in academics, research institutes and organizations around the globe to develop better and more environment friendly base fluids, viscosifiers, fluid loss additives, emulsifiers, lubricants, etc. to protect the local, regional and global environments, eco-systems, habitats and also the OHS of workers and professionals working in the oil and gas industry. This paper describes the development, testing and evaluation of several novel additives to demonstrate their suitability for oil and gas field applications to avoid any negative impact to the surrounding environment. Experimental results indicate that the newly developed additives provide desirable, similar or better performance with respect to conventional additives used by the industry and thus demonstrate their suitability for application in aqueous and non-aqueous fluid design. The plant-based organic additive identified to use as an ecofriendly viscosifier for aqueous mud system can also control the fluid loss behavior of clay free system and thus can act as a bi-functional additive. Several waste vegetable oil-based eco-friendly additives have been developed for their application as spotting fluids, base oil and emulsifiers for invert emulsion oil based mud. These additives have similar or better technical performance than the equivalents and the eco-friendly nature of the mud additives demonstrates their ability to perform the functional tasks with better protection of the surrounding environments.

四川盆地南部地区页岩气开发及其减污降碳再认识

为助推中国页岩气持续高质量发展,在溯源页岩气环境争议的基础上,结合四川盆地南部地区(以下简称川南)十余年来页岩气开发实践,总结了国内对页岩气开发生态环境影响的新认识,系统介绍了中国自主创新形成的页岩气清洁开采技术,并指明了下一步技术发展的方向。研究结果表明:①页岩气环境问题的广泛关注始于2009—2011年,经过激烈讨论,美国学术界主流意见认为,页岩气开发存在生态环境风险,但通过合理取水、确保井筒质量、妥善贮存和处置压裂返排液及钻井固体废物等措施可有效防范;②页岩气开发对中国温室气体排放量贡献有限,不会必然污染地下水环境,绿色开发应重点关注低碳钻井和压裂、废弃物处置、地下水保护等方向;③“电代油”钻井和压裂实现了施工过程无直接温室气体排放,川南页岩气压裂返排液在处理回用基础上已实现处理外排,油基岩屑处置对规模开发的制约也因热脱附技术的进步而突破;④页岩气清洁开采技术仍应在深度降碳、稳定减污、持续增效等方面开展技术创新和管理创新工作。结论认为,基于10余年来对中国页岩气开发生态环境保护的探索与再认识,可为中国未来页岩气绿色高效开发提供有益参考和借鉴。