Laponite:a promising nanomaterial to formulate high-performance water-based drilling fluids

High-performance water-based drilling fluids(HPWBFs)are essential to wellbore stability in shale gas exploration and development.Laponite is a synthetic hectorite clay composed of disk-shaped nanoparticles.This paper analyzed the application potential of laponite in HPWBFs by evaluating its shale inhibition,plugging and lubrication performances.Shale inhibition performance was studied by linear swelling test and shale recovery test.Plugging performance was analyzed by nitrogen adsorption experiment and scanning electron microscope(SEM)observation.Extreme pressure lubricity test was used to evaluate the lubrication property.Experimental results show that laponite has good shale inhibition property,which is better than commonly used shale inhibitors,such as polyamine and KCl.Laponite can effectively plug shale pores.It considerably decreases the surface area and pore volume of shale,and SEM results show that it can reduce the porosity of shale and form a seamless nanofilm.Laponite is beneficial to increase lubricating property of drilling fluid by enhancing the drill pipes/wellbore interface smoothness and isolating the direct contact between wellbore and drill string.Besides,laponite can reduce the fluid loss volume.According to mechanism analysis,the good performance of laponite nanoparticles is mainly attributed to the disk-like nanostructure and the charged surfaces.

High temperature and high pressure rheological properties of high-density water-based drilling fluids for deep wells

To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines temperature effects on the rheological properties of two types of high-density water-based drilling fluids （fresh water-based and brine-based） under high temperature and high pressure （HTHP） with a Fann 50SL rheometer. On the basis of the water-based drilling fluid systems formulated in laboratory, this paper mainly describes the influences of different types and concentration of clay, the content of a colloid stabilizer named GHJ-1 and fluid density on the rheological parameters such as viscosity and shear stress. In addition, the effects of aging temperature and aging time of the drilling fluid on these parameters were also examined. Clay content and proportions for different densities of brine-based fluids were recommended to effectively regulate the rheological properties. Four theological models, the Bingham, power law, Casson and H-B models, were employed to fit the rheological parameters. It turns out that the H-B model was the best one to describe the rheological properties of the high-density drilling fluid under HTHP conditions and power law model produced the worst fit. In addition, a new mathematical model that describes the apparent viscosity as a function of temperature and pressure was established and has been applied on site.

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.

Preparation and Performance of the Hyperbranched Polyamine as an Effective Shale Inhibitor for Water-Based Drilling Fluid

Seeking effective solutions to control and mitigate the interaction between drilling fluids and clay formations has been a challenge for many years, and various shale inhibitors have shown excellent results in problematic shale formations around the world. Herein, the hyperbranched polyamine (HBPA) inhibitor with a higher ratio of amine groups and obvious tendentiousness in protonation was successfully synthesized from ethylenediamine, acryloyl chloride and aziridine by five steps, in which the metal-organic framework (MOF) was employed as a catalyst for ring-open polycondensation (ROP). The structure and purity were confirmed by nuclear magnetic resonance hydrogen spectroscopy and high-performance liquid chromatography (HPLC) respectively. The HBPA displays more excellent performance than EDA and KCl widely applied in the oil field. After aging at 80°C and 180°C, the YP of a slurry system containing 25 wt.% bentonite and 2 wt.% HBPA are just 8.5 Pa and 5.5 Pa (wt.%: percentage of mass), respectively. The swelling lengths of 2 wt.% HBPA are estimated to be 1.78 mm, which falls by 70% compared with that of freshwater. Under a hot rolling aging temperature of 180°C, the HBPA system demonstrates a significant inhibition with more than 85% shale cuttings recovery rate and is superior to conventional EDA and KCl. Mechanism analysis further validates that the HBPA can help to increase the zeta potential.

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.

Influence of monoethanolamine on thermal stability of starch in water based drilling fluid system

To improve the thermal stability of starch in water-based drilling fluid,monoethanolamine(MEA)was added,and the effect was investigated by laboratory experiment.The experimental results show that the addition of monoethanolamine(MEA)increases the apparent viscosity,plastic viscosity,dynamic shear force,and static shear force of the drilling fluid,and reduces the filtration rate of drilling fluid and thickness of mud cake apparently.By creating hydrogen bonds with starch polymer,the monoethanolamine can prevent hydrolysis of starch at high temperature.Starch,as a natural polymer,is able to improve the rheological properties and reduce filtration of drilling fluid,but it works only below 121℃.The MEA will increase the thermal stability of starch up to 160℃.There is a optimum concentration of MEA,when higher than this concentration,its effect declines.

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.

Laboratory Study on 210°C High Temperature and Salt Resistant Drilling Fluid

Combined with the current research status in this area at home and abroad, with the improvement of salt and high temperature resistance as the research goal, the laboratory research of salt and high temperature resistant drilling fluid system has been carried out, and lubricants, inhibitors and stabilizers have been optimized. The final drilling fluid formula is: water + 3% sepiolite + 0.3% Na2CO3 + 3% RH-225 + 3% KCOOH + 3% G-SPH + 3% CQA-10 + 1.5% ZX-1 + Xinjiang barite, density 2.2 g/cm3, using hot-rolling furnace, environmental scanning electron microscope, high temperature and high pressure plugging instrument and Zeiss microscopes and other instruments use core immersion experiments, permeability recovery value experiments, and static stratification index methods to perform temperature resistance, reservoir protection, plugging performance, and static settlement stability performance of the configured drilling fluid., Inhibition performance, biological toxicity, salt resistance, anti-pollution performance have been tested, and it is concluded that the temperature resistance is good under the condition of 210°C, and the salt resistance can meet the requirements of 20% NaCl + 0.5% CaCl2 concentration. It has a good reservoir protection effect, the permeability recovery value can reach more than 90%, the performance of restraining water dispersion and cuttings expansion is good, the heat roll recovery rate can reach more than 85%, and the SSSI value shows that its settlement stability performance is good;Its plugging performance is good under high temperature and high pressure. It laid the foundation for the next step to promote the field application of the drilling fluid system.

Study on a Polyamine-Based Anti-Collapse Drilling Fluid System

In complex strata, oil-based drilling fluid is the preferred drilling fluid system, but its preparation cost is high, and there are hidden safety risks. Therefore, the new progress of high-performance anti-collapse water-based drilling fluid at home and abroad is analyzed. It is difficult to prevent and control the well collapse. Once the well wall instability problem occurs, it will often bring huge economic losses to the enterprises, and the underground safety accidents will occur. In order to ensure the stability of the well wall and improve the downhole safety, the key treatment agent of water-based collapse drilling fluid is selected, the anti-collapse drilling fluid system is formulated, the evaluation method of drilling fluid prevention performance is established, and a set of water-based drilling fluid system suitable for easy to collapse strata in China is selected to ensure the downhole safety. The development trend of high performance anti-collapse water-based drilling fluid is expected to provide a reference for the research of high performance anti-collapse water-based drilling fluid system and key treatment agent.

Numerical analysis on coal-breaking process under high pressure water jet

Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was established;the fluid-structure couplingof water jet and coal was implemented by penalty function and convection calculation.The dynamic process of coal breaking under a water jet was simulated and analyzed bycombining the united fracture criteria of the maximum tensile strain and the maximal shearstrain in the two cases of damage to coal and damage failure to coal.

纳米流体和两性表面活性剂改善钻井液性能实验研究

本文研究了碳化硅纳米流体和表面活性剂对水基钻井液物理和化学性质(热稳定性、黏度、表面张力和滤失特性)的影响。将碳化硅纳米流体、表面活性剂溶液和水基钻井液混合形成表面活性剂——碳化硅(Si C)钻井液,分别用流变仪、张力仪和压滤机对混合钻井液的黏度、表面张力和滤失性等性质进行了研究。实验结果表明,与常规表面活性剂相比,两性表面活性剂对钻井液黏度的增量最大,此外,混合钻井液具有更好的热稳定性,随着温度的升高,黏度平均变化率为9%,表面张力和滤失性分别下降了31.0%和22.2%。

一种抗超高温配位键合型低聚物降黏剂

针对高密度水基钻井液高温增稠引发的滤失量大、ECD与内耗高、流动性下降甚至完全丧失难题,在AAAMPS聚有机酸降黏剂分子中引入富含大量邻苯二酚基团的单宁酸,采用自由基聚合法研制了一种抗超高温配位键合型低聚物降黏剂AA-AMPS-TA,并通过正交实验明确了PAAT的最优合成条件。表征并评价了PAAT的降黏性能,结果表明:引入TA后,PAAT的红外光谱出现了源于酚羟基的分子内氢键吸收峰,且因其分子结构中引入了大量苯酚基团,显著提升了热稳定性,分解温度接近500℃;PAAT可降低低浓度膨润土浆和7%膨润土+8%高岭土的高浓度混合黏土浆黏度,在高密度水基钻井液体系中降黏率达26.5%,240℃热滚后降黏率达44.4%。采用Zeta电位与粒径分析验证了PAAT的吸附降黏机理,并在蓬深101井中现场应用,控制了井浆高温下黏度、切力增涨,降黏效果良好。

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。

一种性能优异的水性环氧防腐底漆配方研究

通过双酚A型环氧树脂E-51(EP-51)与聚乙二醇4000(PEG-4000)进行开环反应,合成环氧乳化剂,利用相反转技术制备出了一种水性环氧树脂乳液,研究了环氧/活泼氢当量、固化剂体系、防锈颜料、颜料体积浓度(PVC)对水性环氧涂料性能的影响。

一种抗高温梳型两性离子聚合物降黏剂

针对深井超深井钻井中高密度水基钻井液黏度高、易高温增稠等流变性调控难题,以对苯乙烯磺酸钠盐、2-丙烯酰胺基-2-甲基丙磺酸、2-烯丙基-2-甲基氯化铵、烯丙基聚氧乙烯醚为单体,合成了一种抗高温梳型两性离子聚合物降黏剂ZT-1。采用红外光谱表征了降黏剂的分子结构,验证梳型两性离子聚合物合成的成功,采用热重分析表征了降黏剂的热稳定性,其分解温度达250℃。ZT-1具有良好的抗高温耐盐钙降黏分散性能,抗温240℃,可抗饱和盐,抗2%氯化钙;ZT-1加量为0.3%时,老化温度为200℃,在评价浆中的降黏率可达77.7%,在高密度(2.4 g/cm^(3))水基钻井液体系中表观黏度的降低率达33%,塑性黏度的降低率达14%,动切力降低率达67%。ZT-1性能优于阴离子降黏剂磺化丹宁以及常规线性两性离子聚合物降黏剂XY-27和ADS共聚物,这种梳型两性离子聚合物降黏剂在超高温超高密度钻井液中具有良好的应用前景。

高温下水基钻井液核心组分微观行为分析

水基钻井液在高温下性能调控难度大,主要与核心胶体粒子的分散状态有关,而水基钻井液成分复杂,单一组分与多组分间受高温作用性能变化规律不同,对胶体粒子的分散状态均有影响。针对水基钻井液核心组分,通过高温高压流变性测试获得了膨润土胶体剪切应力-温度曲线,并测试了不同温度下胶体颗粒粒度分布,分析了黏土矿物胶体粒子在室温~220℃范围内的分散、絮凝与聚结状态及形成机制,同时利用SEM测试和黏土矿物晶层结构分析,从微观角度揭示了富含镁多孔纤维状黏土矿物胶体的高温稳定机理,此外,基于对高温热滚前后流变性和滤失量等性能变化的分析,从黏土矿物结构特征和聚合物断链、吸附特性等角度揭示膨润土/复配黏土矿物与聚合物类处理剂在高温下的互相作用机理,结合实验结果,明确了低浓度膨润土与海泡石复配胶体具有明显的高温稳定优势,为超高温水基钻井液的构建提供了理论支撑。

琼东南盆地所在区块系列井钻井液侵入损害综合分析及优化

琼东南盆地属于中孔低渗储层,储层易发生水化、水锁等伤害。当前区块系列井所用深水钻井液侵入损害类型、机理不明,且传统的钻井液伤害评价方法误差大,不能直观地量化损害程度。因此设计了以钻井液污染实验、扫描电子显微镜(scanning electron microscope,SEM)分析、计算机断层扫描(computed tomography,CT)结合的方式分析钻井液固相以及液相侵入损害储层的方法。结果表明,深水钻井液与地层水配伍性良好,储层水锁损害率处于19.8%~31.4%,液相侵入损害主要为水锁损害;岩心SEM扫描结果显示其孔隙连通性差,EDS测试结果中Ba^(2+)、Ca^(2+)含量较高,分析固相侵入损害主要由加重剂引起,且蒸馏水返排后岩心CT扫描结果显示孔隙度微幅上升表明固相堵塞很难通过自然返排的方式清除。于是通过研发降滤失剂和优选加重剂粒径配比的手段优化深水钻井液储层保护性能。根据理想充填理论,确定最佳配比为1000目CaCO_(3)、600目CaCO_(3)和200目CaCO_(3)的比例为5∶11∶9。优化后体系滤失量显著降低,固相颗粒中径在90μm左右,滤饼致密程度明显提高;渗透率恢复值提高12.1%~19.68%,对该区块钻井液储层保护性能优化具有指导意义。

钻井液用新型可酸溶加重剂的制备与应用

以羟基磷灰石为原料,六偏磷酸钠为改性剂,制备了一种可酸溶加重剂。采用FTIR对其化学结构进行表征,对改性后加重剂的酸溶性、Zeta电位以及润湿性进行了评价,并对其配制的钻井液的流变性、滤失性以及储层保护效果进行了评价。实验结果表明,10%盐酸作用下改性加重剂的溶解率可达88.27%;采用该改性加重剂的钻井液具有良好的流变性和降滤失性;采用该改性加重剂的钻井液污染的岩心经10%盐酸浸泡2h后,渗透率恢复值>90%,表明改性加重剂参与形成的泥饼可被酸性工作液有效溶解和清除,从而保护储层。

水平井类油基高性能水基钻井液性能评价

页岩油气水平井钻井难度大,面临着井壁失稳、摩阻大、井眼清洁难度大等问题,常规水基钻井液作业施工困难,通常使用油基钻井液作业,但是油基钻井液成本高,废弃泥浆和钻屑处理环保压力大,研究和开发能够替代油基钻井液的强抑制类油基高性能水基钻井液迫在眉睫。室内根据页岩水平井特征,构建了一套类油基高性能水基钻井液,并开展了全套性能评价,结果表明该体系具有良好的防塌、润滑和携岩性能,在页岩油气具有广阔的应用前景。