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.

Development of Film Forming Agent HN-1 and Its Application in Drilling Fluid

Borehole instability and reservoir damage had become the international technical problems of petroleum exploration and development of complicated area, and the water of drilling fluid invading borehole wall and petroleum reservoir was the main cause of borehole instability and reservoir damage. In order to prevent the water of drilling fluid invading borehole wall and petroleum reservoir, domestic and foreign scholars recently put forward the technology of ultra-low permeable drilling fluid. Film forming agent was the key treating agent of ultra-low permeable drilling fluid, the film forming agent (HN-1) was developed, which did not affect properties of the drilling fluid and could decrease the filter loss of drilling fluid applied in Enping 24-2 oil field. Based on this research, ultra-low permeable drilling fluid could be applied to Enping 24-2 oil field. By the methods of testing ultra-low permeable drilling fluid properties, the drilling fluid invasion sand-bed depth, drilling fluid high temperature/high pressure (HTHP) sand-bed filter loss, the pressure-bearing ability of rock core and the ability of reservoir protection were studied. By synergistic effect, HN-1 containing the organic silicate and natural fiber polymer modified by organic amine prevented the liquid and solids in drilling fluid invading reservoir, decreased drilling fluid invasion sand-bed depth and drilling fluid HTHP sand-bed filter loss, improved the pressure-bearing ability of rock core and the ability of reservoir protection. The drilling fluid could decrease reservoir damage to the maximal degree, and it offered efficiency guarantee for exploitation Enping 24-2 oil field.

Thermo-sensitive polymer nanospheres as a smart plugging agent for shale gas drilling operations

Emulsifier-free poly（methyl methacrylate-styrene） [P（MMA-St）] nanospheres with an average particle size of 100 nm were synthesized in an isopropyl alcoholwater medium by a solvothermal method. Then, through radical graft copolymerization of thermo-sensitive mono- mer N-isopropylacrylamide （NIPAm） and hydrophilic monomer acrylic acid （AA） onto the surface of P（MMA- St） nanospheres at 80 ℃, a series of thermo-sensitive polymer nanospheres, named SD-SEAL with different lower critical solution temperatures （LCST）, were prepared by adjusting the mole ratio of NIPAm to AA. The products were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, particle size distribution, and specific surface area analysis. The temperature-sensitive behavior was studied by light transmittance tests, while the sealing performance was investigated by pressure transmission tests with Lungmachi Formation shales. The experimental results showed that the synthesized nanoparticles are sensitive to temperature and had apparent LCST values which increased with an increase in hydrophilic monomer AA. When the temperature was higher than its LCST value, SD- SEAL played a dual role of physical plugging and chemical inhibition, slowed down pressure transmission, and reduced shale permeability remarkably. The plugged layer of shale was changed to being hydrophobic, which greatly improved the shale stability

Experimental study of low-damage drilling fluid to minimize waterblocking of low-permeability gas reservoirs

This paper discusses the systematic design and development of low-damage drilling fluid to protect the low-permeability gas reservoir of the Sulige block in the Ordos Basin, Inner Mongolia Autonomous Region, China. Based on investigation of the geological characteristics and the potential formation damage of the Permian formation of the reservoir, waterblocking due to invasion of drilling or completion fluids was identified one of the most severe causes of damage to gas well deliverability. By adopting the phase trap prevention method, ideal packing theory, and film-forming technology, a lowdamage drilling fluid, sodium formate brine containing efficient waterblocking preventing surfactants, optimized temporary bridging agents （TBAs）, and film-forming agents has been developed. The performance of the new drilling fluid was evaluated by using a variety of techniques. The results show that the fluid has good rheological properties, good strong shale-swelling inhibition, good temporary plugging effect, ultra-low filtration, and good lubricity. It can efficiently minimize waterblocking and can be used to drill horizontal wells with minimal intervention of the reservoir in the Sulige Gas Field.

Rheological property of low-damage,ideal packing,film-forming amphoteric/sulfonation polymer drilling fluids

Low-permeability dense reservoirs,including micro-fractured reservoirs,are commonly characterized by high content of clay substances,high original water saturation,high sensitivity to invasive fluids,high capillary pressure,complicated structure and anisotropic,high flow-resistance and micro pore throats etc,.Generally they also have lots of natural micro fractures,probably leading to stress sensibility.Main damaging factors in such reservoirs are water-sensibility and water-blocking caused by invasive fluids during drilling and production operations.Once damaged,formation permeability can rarely recovered.Numerous studies have shown that damaging extent of water-blocking ranges from 70% to 90%.Main damaging mechanisms and influencing factors of water-blocking were systematically analyzed.Also some feasible precaution or treating approaches of water-blocking were put forward.In a laboratory setting,a new multi-functional drilling fluid composed mainly of amphion polymer,sulfonation polymer,high effectively preventive water-blocking surfactants,ideal packing temporary bridging agents(TBA) and film-forming agents,etc.,were developed.New low-damage drilling fluids has many advantages,such as good rheological properties,excellent effectiveness of water-blocking prevention,good temporary plugging effect,low filtration and ultra-low permeability(API filtration≤5 mL,HTHP filtration≤10 mL,mud cake frictional coefficient≤0.14,permeability recovery>81%),can efficiently prevent or minimize damage,preserve natural formation and enhance comprehensive development-investment effect in TUHA Jurassic dense sandstone reservoir formation with low-permeability,the only one developing integrated condense gas field.Some references can be provided to similar reservoir formations.

Super-amphiphobic, strong self-cleaning and high-efficiency water-based drilling fluids

Based on the amphiphobic theory on underground rock surface, a super-amphiphobic agent is developed and evaluated which can form nano-micro papilla structure on rock, filter cake and metal surface, reduce surface free energy, prevent collapse, protect reservoir, lubricate and increase drilling speed. With this super-amphiphobic agent as the core agent, a super-amphiphobic, strong self-cleaning and high-performance water-based drilling fluid system has been developed by combining with other agents based on drilled formation, and compared with high-performance water-based drilling fluid and typical oil based drilling fluid commonly used in oilfields. The results show that the super-amphiphobic, strong self-cleaning and high-performance water-based drilling fluid has better rheology, and high temperature and high pressure filtration similar with that of oil-based drilling fluid, inhibiting and lubricating properties close to oil based drilling fluid. Besides, the super-amphiphobic system is non-toxic, safe and environmentally friendly. Field tests show this newly developed drilling fluid system can prevent wellbore collapse, reservoir damage and pipe-sticking, increase drilling speed and lower drilling cost, meeting the requirement of safe, high efficient, economic and environmentally friendly drilling. Compared with other drilling fluids, this new drilling fluid system can reduce downhole complexities by 82.9%, enhance the drilling speed by about 18.5%, lower drilling fluid cost by 39.3%, and increase the daily oil output by more than 1.5 times in the same block.

RESEARCH ON CATIONIC POLYMER WATER BASE DRILLING FLUIDS

Cationic polymer drilling fluid (CPDF) is a new water base drilling fluid in which high molecular weight (HMW) cationic polymer (CPAM) is an encapsulating and flocculating agent and organic quaternary ammonium compound (NW-1) acts as shale inhibitor. This paper describes the experimental results of cuttings recovery, particle size distribution layer spacing and Zeta potential, and discusses the inhibition of CPDF system and its major additives. The advantages of CPDF will be proved by its application in well LX-2.

Development and Performance Evaluation of a Deep Water Synthetic Based Drilling Fluid System

With the enhancement of environmental protection awareness, the requirements on drilling fluid are increasingly strict, and the use of ordinary oil-based drilling fluid has been strictly restricted. In order to solve the environmental protection and oil-gas reservoir protection problems of offshore oil drilling, a new synthetic basic drilling fluid system is developed. The basic formula is as follows: a basic fluid (80% Linear a-olefin + 20% Simulated seawater) + 2.5% nano organobentonite + 3.5% emulsifier RHJ-5# + 2.5% fluid loss agent SDJ-1 + 1.5% CaO + the right amount of oil wetting barite to adjust the density, and a multifunctional oil and gas formation protective agent YRZ has been developed. The performance was evaluated using a high-low-high-temperature rheometer, a high-temperature and high-pressure demulsification voltage tester, and a high-temperature and high-pressure dynamic fluid loss meter. The results show that the developed synthetic based drilling fluid has good rheological property, demulsification voltage ≥ 500 V, temperature resistance up to 160°C, high temperature and high pressure filtration loss < 3.5 mL. After adding 2% - 5% YRZ into the basic formula of synthetic based drilling fluid, the permeability recovery value exceeds 90% and the reservoir protection effect is excellent. The new synthetic deepwater drilling fluid is expected to have a good application prospect in offshore deepwater drilling.

复杂泥页岩地层井壁稳定钻井液材料研究现状

针对复杂泥页岩地层钻井过程中频繁出现的井壁失稳问题,目前国内外已形成了用于稳定井壁的钻井液技术,包括泥页岩水化抑制技术、地层孔隙封堵技术和化学固壁技术。但以上多种技术均无法抑制泥页岩的表面水化作用,高温条件下快速封堵和化学固壁剂的效果也相当有限,因此井壁失稳问题仍难以解决。系统总结了复杂泥页岩地层井壁稳定钻井液材料的研究工作,通过对井壁稳定钻井液材料研究现状进行分析,阐述了不同钻井液材料包括泥页岩水化抑制剂、封堵剂、化学固壁剂的作用机理,探讨了不同种类井壁稳定材料的优势和缺陷。据此指出开展泥页岩水化基础理论研究、开发高温高盐条件下稳定有效的新型纳米材料、建立能够模拟井下条件的化学固壁剂的评价方法将成为未来复杂泥页岩地层井壁稳定钻井液材料和技术研究的热点和难点。最后对复杂泥页岩地层井壁稳定钻井液技术和材料的发展方向进行了展望。

煤层气储层保护钻井液技术研究进展

中国煤层气储层具有物性复杂、非均质性强、易发生损害等特征,因此增加了煤层气钻完井过程中储层保护的难度,在一定程度上影响煤层气产能的发挥及采收率的提高。为系统总结煤层气钻井液储层保护技术的发展现状,从敏感性损害、固相侵入损害、表面活性剂损害3个方面对煤层气井储层损害原因进行了分析,总结了近年来煤层气储层保护钻井液技术的研究进展及适用性,最后从深层煤岩储层应力敏感损害防治、长水平段固相堵塞防治、多类型可降解处理剂研发、钻井液参数优化与维护工艺4个方面对储层保护钻井液及处理剂的发展进行了展望。研究结果表明:①中国煤岩储层具有“三低”特性,主要存在敏感性损害(应力敏感、水敏)、固相侵入损害和表面活性剂损害;②为减少煤层气储层敏感性造成的损伤,可采用增强钻井液的封堵能力、优化钻井液的抑制能力、调节钻井液密度等方式;③固相侵入损害可通过减少钻井液中固相颗粒含量、阻止固相颗粒进入地层、增强钻井液的携带能力、应用可降解处理剂等方式解决;④表面活性剂对储层的伤害不容忽视,可以使用阳离子/非离子表面活性剂防止损害发生。结论认为,钻井液储层保护技术是深层煤岩气长水平井储层损害防治的关键技术,对煤层气经济化、清洁化开发及全流程绿色高效开发具有重要意义。

海上某盆地胶结型防漏堵漏钻井液技术

分析了我国海上某盆地地质特征和历史井漏情况,明确了该盆地钻井防漏堵漏难点:地层裂缝发育且存在微米级至毫米级的多尺度裂缝,甚至裂缝和孔、洞并存,导致堵漏材料选配难、一次堵漏成功率低;地层发育大段风化壳、部分地层破碎严重、钻井中裂缝极易二次发育等,导致恶性漏失甚至失返性漏失等复杂情况。针对上述难点,以聚乙烯醇、聚丙烯酸以及含邻苯二酚结构的有机物为原料,合成了一种胶结型堵漏剂BFD-1。实验结果表明,人造疏松岩心在加有4%BFD-1的水溶液中浸泡后,岩心抗压强度提高率达19.34%。以BFD-1为核心,复配现场常用堵漏材料,构建了适用于不同尺寸范围漏失通道的防漏堵漏钻井液体系,具良好的防漏堵漏性、胶结性,并可有效阻止压力传递。研究成果可为该地区钻井井漏防治提供有力技术支撑。

改性二氧化硅封堵剂的制备及性能评价

为了降低水基钻井液滤液对储层的扰动,以丙烯酰胺、苯乙烯、乙烯基三甲氧基硅烷对纳米SiO_(2)进行表面改性,将柔性链聚合物接枝在纳米刚性SiO_(2)粒子表面,形成一种新型的有机-无机复合封堵剂。实验结果发现:该封堵剂提高了泥饼的致密性和封堵性能,并对岩心孔隙进行了有效封堵,有效抑制岩屑水化现象,为水基钻井液在低渗-致密储层开发过程中的应用提供技术支持。

深井超深井钻井液技术应用现状及发展展望

深井超深井最主要的难点是深部高温以及钻进距离长,成为限制其安全快速钻井最主要因素。文章根据深井超深井安全快速钻井对钻井液的核心需求,从抗高温钻井液技术的流变性调控、井壁稳定、防漏堵漏、降摩减阻4个方面分析了钻井液研发与应用中面临的难点,并对国内外抗高温钻井液技术、高温流变稳定技术、井壁强化钻井液技术、深井超深井防漏堵漏技术和抗高温钻井液润滑技术的现场应用及研究成果进行了综述。最后对国内钻井液技术研究领域存在的问题进行分析,并从基础理论研究、新型抗高温钻井液处理剂研发、油基钻井液防漏治漏等方面对深井超深井钻井液技术发展进行展望。

塔河稠油高黏特性及其侵入钻井液治理探索

为了解决塔河高黏稠油侵害钻井液的问题,研究对比了塔河稠油与典型劣质重油的关键性质及塔河稠油沥青质-甲苯溶液黏度随浓度的变化规律,发现塔河稠油的高黏特性主要原因是沥青质含量高与芳香度高,以此为基础,设计2种实验方案。一是针对钻井初期稠油侵入量少的情况,通过在钻井液中添加适宜的分散剂和芳香馏分的复配体系,将稠油进行分散,结果为5#钻井液体系效果最好,TH121155X井稠油在无固钻井液中的分散度超过99%。二是针对稠油侵入量大的情况,对稠油进行包裹,使稠油失去黏附性,降低稠油在钻具上黏附,确保地面振动筛能够顺利筛分。研究数据表明,BGJ-2-4复配的包裹剂对塔河TH12471H井稠油具有良好的包裹效果,罐黏附率仅为0.3%。

基于改性壳聚糖螯合的新型除钙技术

目的以长庆油田某区块钻井污水为例,解决钻井污水产量大、组分复杂和Ca^(2+)等多价离子含量高,且经常规工艺处理后污水仍难以满足压裂液回配性能要求的问题。方法基于以上难解工艺特征,提出多官能团壳聚糖改性螯合Ca^(2+)新型除钙工艺,并对其除钙效果、除钙机理、适用条件(温度、pH)、环境影响(产泥量)及回配性能进行了评价。结果以高脱乙酰度壳聚糖为原料,过硫酸钾作引发剂接枝丙烯酸,在温度为70℃,m(壳聚糖)∶m(过硫酸钾)∶m(丙烯酸)=1.0∶1.2∶25.0的条件下反应2 h可制得高水溶性多官能团SZ-1螯合剂,采用质量浓度为600 mg/L的SZ-1可将Ca^(2+)质量浓度螯合去除至500 mg/L以下;SZ-1在10~40℃、pH为6~14条件下均适用,产泥量低(0.016 g/L),回配压裂液基液黏度较优(30.9~31.2 mPa·s),满足SY/T 7627—2021《水基压裂液技术要求》的基液黏度范围要求(10~40 mPa∙s)。结论该药剂绿色清洁、性能优异、制备简单,有望为油气田高含钙钻井污水处理提供新方法。

微米刚性氧化石墨烯颗粒的制备及协同堵漏性能评价

泸州区块深层页岩气地层微米级裂缝发育,且偶有天然裂缝存在,结构面节理特征弱,钻井过程中,容易造成滤液侵入地层,引起井壁坍塌,亟待研制一款能抗压抗高温的微米尺度刚性封堵剂,既能应对微米裂缝带来的威胁,又可以与大片径堵漏剂有很好的协同堵漏作用。采用改进Hummers法制备氧化石墨烯(GO)水凝胶,经超长时间高温真空干燥之后,将其粉碎,获得了一种刚性氧化石墨烯颗粒(GO-RP)。这种颗粒属于氧化石墨烯纳米片的多重叠加,用超声波无法使之分散,单体能够承受215℃以下的温度。采用可驱替式堵漏仪评价这种颗粒的协同堵漏性能,实验结果表明,GO-RP可在压力作用下不断地冲进裂缝孔隙进行填充,搭配混合堵漏剂,尤其是带有柔性纤维的材料,能够形成更致密的承压封堵层,承压能力高达9 MPa,降漏失率提升了约70百分点。将封堵剂GO-RP加入水基钻井液中,可使钻井液漏失量显著降低,同时,在高温下仍能保持较好的摩擦性能和抗压能力。这种刚性氧化石墨烯颗粒封堵剂在钻井堵漏领域有良好的应用前景。

一种适用于油基钻井液堵漏水泥浆体系研发

水泥浆堵漏是解决恶性漏失的有效措施之一,但是水泥浆在油基钻井液中难以凝结固化,致使其使用受限。从油基钻井液污染水泥浆机理出发,开发油水置换剂,并对胶凝体系和配套降失水剂和缓凝剂进行研选,开发油基钻井液堵漏水泥浆体系,并对水泥浆体系性能进行评价。研究表明:通过微乳液共聚法(即油相和水相同时引发聚合)制备了油水置换剂,在油井水泥中加入油水置换剂后,钻井液与水泥浆的相容性良好,水泥浆与油基钻井液体积比为50∶50的混浆体系在50℃条件下养护时间24 h,强度可达2 MPa左右,且油水置换剂具有很好的广谱性能,现场不同区域取的不同类型的油基钻井液,均发展强度;研选了配套降失水剂BXF-200LL和缓凝剂GH-9,开发出了适用于油基钻井液堵漏的水泥浆体系,油水置换剂对水泥浆稠化没有不良影响,且抗温达120℃。

PGA可降解材料作为钻完井液暂堵剂实验研究

聚乙醇酸(PGA)具有良好的环保特性,通过高温浸泡前后PGA力学性能、颗粒粒径、分子热稳定性和晶体致密度等参数分析,研究了PGA在水相及油相环境中的热稳定性,评价了PGA作钻完井液暂堵剂的应用潜力。结果表明PGA理化性质受钻井液液相环境和温度的影响较大。对水基钻井液而言,100℃高温水相环境下PGA分子受pH值影响降解生成低聚物,分子热稳定性降低、力学强度下降,表现为强酸(pH<5)及强碱(pH>9)环境加速降解,且强碱条件下降解快于强酸环境。高温油相环境导致PGA颗粒先溶胀后出现剥落、破碎现象,本体由塑性向脆性转变,抗拉及抗压强度出现一定程度下降,PPA封堵实验显示油相环境中8 d内具有良好的封堵效果。与水基钻井液相比,暂堵剂PGA更适合在油基钻井液中使用。

深层煤层气防塌钻井液优化研究

辽河油田宜川-黄龙地区井壁失稳、阻卡等问题严重制约了开发进程。针对该地区深层煤层气A井井壁失稳问题,对煤岩矿物组成、微观结构进行了分析并揭示了井壁失稳机理。发现:钻井过程中滤液侵入,易发生水化膨胀和裂缝扩展等情况,导致井壁失稳。构建了适用于该地区的防塌钻井液体系,特征为强封堵、强抑制性,以及较好的流变性和耐高温性,且在现场应用中表现出良好的性能。为深层煤层气井的高效开发提供了有效的技术支持。

水基钻井液复合纳米成膜封堵剂的制备及性能

以改性纳米SiO_(2)为刚性粒子,丙烯酰胺、2-丙烯酰胺基-2-甲基丙磺酸、苯乙烯和醋酸乙烯酯为聚合单体,壬基酚聚氧乙烯醚(10)和十二烷基磺酸钠为乳化剂,过硫酸铵和亚硫酸氢钠为引发剂,合成了一种有机/无机复合纳米成膜封堵剂。采用FTIR、SEM、动态光散射(DLS)和TGA对产物进行了表征和测试。考察了不同质量分数复合纳米成膜封堵剂对水基钻井液的流变性、滤失性及封堵性能的影响。结果表明,复合纳米成膜封堵剂呈球形,并保持纳米级分布,中值粒径为325 nm;340℃时的质量损失率为14%;120℃、16 h老化后较老化前表观黏度和塑性黏度均明显增加。当复合纳米成膜封堵剂质量分数为3%时,水基钻井液的静滤失量为10 mL;当质量分数≥2%后,砂床滤失量为0;当质量分数从0增至4%时,高温高压滤失量从104 mL减至29 mL,渗透性为1.56×10^(–2)mD,封堵率为90.7%。