Natural rubber latex as a potential additive for water-based drilling fluids

The environmental hazards and"carbon footprint"of oil and gas drilling can be significantly reduced by replacing traditional petroleum-based chemical additives with natural materials derived from plants and animals.This paper explored for the first time the interaction mechanism between natural rubber latex(NRL)and bentonite suspensions(BTs)through a series of characterization experiments,as well as the potential applications in water-based drilling fluids(WBDF).The gel viscoelasticity experiments showed that NRL could decrease the consistency coefficient(k)and flow index(n)of BTs,and enhance the shear thinning performance of BTs as pseudo-plastic fluids.In addition,0.5 w/v%NRL not only increased the critical yield stress and strengthened the structural strength between the bentonite particles,but also facilitated the compatibility of pressure loss and flow efficiency.The evaluation of colloidal stability and WBDF performance indicated that NRL particles could promote the hydration and charge stability on the surface of BTs particles,and optimize the particle size distribution and flow resistance of WBDF under the"intercalation-exfoliation-encapsulation"synergistic interaction.Moreover,NRL can improve the rheological properties of WBDF at high temperatures(<150.C),and form a dense blocking layer by bridging and sealing the pores and cracks of the filter cake,which ultimately reduces the permeability of the cake and the filtration loss of WBDF.

Main technical innovations of Songke Well No.2 Drilling Project

Songke Well No.2,one of the main part of the scientific drilling project in Songliao Basin,which was drilled 7018 m and acquired the part of cores continuously from the Low Cretaceous to the Carboniferous and the Permian from the 2843 m deep,can be considered as the deepest continental drilling project in Asia.Aiming at the features of longer well sections,larger diameters and multiple spud-ins for coring of Songke Well No.2,this project broke through the "coring in small diameter and reaming in large diameter"spud-in drilling-completion procedures which are always used in large-diameter-well coring for continental scientific drilling projects in domestic and overseas and the drilling method of short-singlecylinder roundtrip footage.At the same time,"coring in the same diameter and completing drilling at one single diameter"was achieved at all φ311 mm and φ216 mm coring sections of more than one thousand meters long,high-efficient operation with "drilling long footage with drill tools combined in multicylinders"was achieved at deep coring section.Four world drilling records were created which include more than a thousand meters continuous coring at φ311 mm,and the footage per roundtrip footage at φ311 mm,φ216 mm and φ152 mm is all more than 30 m,all of these breakthroughs reduced at least 300 days for this project;moreover,considering the characteristics of formations that the geothermal gradient is high in the drilled sections and the inside-well temperature is over 240℃ after drilling completion,a formate-polymer water-based mud system was developed by compounding attapulgite and sodium bentonite and by adding independently developed high-temperature stabilizer,which can provide critical technical support for successful well completion at 7018 m in the super-high-temperature environment It is the first time that the water-based mud is operated at the working temperature higher than 240℃ in China;Besides,considering the high-quality requirement on cores imposed by the project,the method "mechanical cored is charge"to discharge core nondestructively on the ground was worked out,and more than 4000 m scatheless cores were discharged out of the drill pipes while maintaining original stratum structures.

Drilling Operation and Formation Damage

Transport of particle suspensions in oil reservoirs is an essential phenomenon in many oil industry processes. Solid and liquid particles dispersed in the drilling fluid (mud) are trapped by the rock (porous medium) and permeability decline takes place during drilling fluid invasion into reservoir resulting in formation damage. The formation damage due to mud filtration is explained by erosion of external filter cake. Nevertheless, the stabilization is observed in core floods, which demonstrates internal erosion. A new mathematical model for detachment of particles is based on mechanical equilibrium of a particle positioned on the internal cake or matrix surface in the pore space. In the current work the analytical solution obtained to mud filtration with one particle capture mechanism with damage stabilization. The particle torque equilibrium is determined by the dimensionless ratio between the drag and normal forces acting on the particle. The maximum retention function of the dimensionless ratio closes system of governing equations for colloid transport through porous medium.

Minimizing the filtration loss of water-based drilling fluid with sustainable basil seed powder

Filtration control is important to ensure safe and high efficient drilling.The aim of the current research is to explore the feasibility of using basil seed powders(BSPs)to reduce filtration loss in water-based drilling fluid.The effect of BSP concentration,thermal aging temperature,inorganic salts(NaCl and CaCl_(2))on the filtration properties of bentonite/basil suspensions was investigated.The filtration control mechanism of BSP was probed via water absorbency test,zeta potential measurement,particle size distribution measurement,and filter cake morphologies observation by scanning electron microscope.The incorporation of BSPs into the bentonite suspension generated acceptable rheology below 1.0 w/v%.The BSPs exhibited effective filtration control after thermal aging at 120C,but less efficiency at 150C.After thermal aging at 120℃,the bentonite suspension containing 1.0 w/v%BSPs could resist NaCl and CaCl_(2) pollution of 5.0 w/v%and 0.3 w/v%respectively.Besides general filtration control behaviors,the exceptional water retaining capability formed by numerous nanoscale 3D networks in the basil seed gum and considerable insoluble small particles in BSPs might further contribute to the filtration control.The excellent filtration properties bring basil seed a suitable and green candidate for the establishment of high-performance drilling fluids.

The behaviors of gas-liquid two-phase flow under gas kick during horizontal drilling with oil-based muds

Natural gas is easily soluble in oil-based muds(OBM),leading to complex flow behavior in wellbores,especially in horizontal wells.In this study,a new transient flow model considering wellbore-formation coupling and gas solubility on flow behavior is developed to simulate gas kicks during horizontal drilling with OBM.Furthermore,the effect of gas solubility on parameters such as bottom-hole pressure(BHP),gas void fraction and mixture velocity in the flow behavior is analyzed.Finally,several critical factors affecting flow behavior are investigated and compared to gas kicks in water-based muds(WBM)where the effect of solubility is neglected.The results show that the invading gas exists as dissolved gas in the OBM and as free gas in the WBM.Before the gas escapes from the OBM,the pit gain is zero and there is barely any change in the BHP,annulus return flow rate and mixture velocity,which means that detecting gas kicks through these warning signs can be challenging until they get very close to the surface and develop rapidly.However,in WBM drilling,these parameters change quickly with the increasing gas kick time.Additionally,for both cases,the longer the horizontal length and the greater reservoir permeability,the greater the decrease in BHP,and the shorter the time for gas to migrate from the bottom-hole to the wellhead.A larger flow rate contributes to a greater initial BHP and a lesser BHP reduction.This research is of value in characterizing gas kick behavior and identifying novel ways for early gas kick detection during horizontal drilling with OBM.

北部湾深层深井油基钻井液研究及现场应用

为了缩短钻井周期以及提高井壁稳定,油基钻井液的护壁防塌性能可通过加入封堵剂来优化。本文以纳米SiO_(2)、N-氨乙基-3-氨丙基三乙氧基硅烷和全氟辛基三甲氧基硅烷为原料制备一种纳米封堵剂,其粒径主要分布在10~200nm之间,其粒径较为集中,应用于钻井液中可降低泥饼渗透率,显著提高油基钻井液的封堵性能,降低滤失量,对储层渗透率影响较小。纳米封堵剂与油基钻井液具有良好的配伍性,提高油基钻井液的稳定性。本文研究的高性能油基钻井液成功应用于现场钻井,钻井过程中,纳米封堵剂的加入显著提高了起钻速度,缩短了现场钻井周期,封堵性能的提高使钻井液泥饼在裂缝和孔隙中进行有效封堵,井壁未出现掉块及剥落片。

On the prediction of filtration volume of drilling fluids containing different types of nanoparticles by ELM and PSO-LSSVM based models

There is a direct link between the extent of formation damage and the filtration volume of the drilling fluids in hydrocarbon reservoirs.The filtration volume can be diminished by adding different additives to the drilling fluids.Recently,nanoparticles have been extensively used for enhancing the filtration characteristics of the drilling fluids.However,there is no reliable model for investigating the influence of this class of additives on the performance of drilling fluids.Hence in this study,two powerful tools ELM(extreme learning machine)and PSO-LSSVM(particle swarm optimization-least square support vector machine)are applied to determine the effect of various nanoparticles on the filtration volume.The assessment of the models is carried out by computing the statistical parameters,and it is found that ELM has a greater ability to predict the filtration volumes,while PSO-LSSVM performs satisfactorily too.The model predictions and experimental results are in excellent agreement as suggested by the values of root mean squared error(RMSE=0.2459),coefficient of determination(R^(2)=0.999),and mean relative error(MRE=2.028%)for the dataset.The statistical analysis shows that the suggested model can predict the filtration volume with great accuracy.Moreover,through sensitivity analysis of the input parameters,it is found that for a specified nanoparticle,the filtration volume is highly influenced by nanoparticle concentration and it is the essential variable for the optimization process.

生化—电催化氧化—炭吸附工艺处理水基泥浆压滤液

采用生化—电催化氧化—炭吸附组合工艺处理钻井水基泥浆压滤液。以COD为主要指标、其他污染物为辅助指标,考察去除效果,采用GC-MS和FTIR分析有机物的去除历程,XRF分析元素变化。表征结果显示,组合工艺可去除大部分有机物,顺-7-十四碳乙酸酯、3-氨基-6-甲基吡啶-2(1H)-酮和2-癸基噻吩是本工艺难去除的有机物。实验结果表明:水基泥浆压滤液经组合工艺处理后,出水COD小于50 mg/L,各项指标均可达到辽宁省《污水综合排放标准》(DB 21/1627—2008);经组合工艺处理后,压滤液中Ca、C、Cl、S、O元素含量降低。

超低渗透处理剂的研制与应用

基于近年来国外学者提出的超低渗透钻井液技术理论，由可溶、部分可溶及不溶的聚合物等材料，经过严格加工、准确计算和配比，开发出了一种新型超低渗透处理剂DLS-06。室内实验对其性能进行了评价，结果表明，加入少量该处理剂就可将各种体系转化为超低渗透钻井液，且不影响原钻井液流变参数。介绍了该处理剂在华北油田束3井1402～2300m井段的砾岩、角砾岩裂缝性漏失地层的试验应用情况。应用结果表明，用DLS-06配制的超低渗透钻井液具有良好的防漏堵漏效果，保证了钻井的正常进行；

耐温抗盐降滤失剂AMPS/AM/IA共聚物泥浆性能的研究

以 2 丙烯酰胺基 2 甲基丙磺酸 (AMPS) /丙烯酰胺 (AM ) /衣康酸 (IA)三元共聚物作为降滤失剂 ,研究了2 2 0℃老化前后淡水泥浆和盐水泥浆的中压滤失量和流变性能 ,考察了高温老化前后淡水泥浆粒度分布的变化 ,并与其它几种聚合物的泥浆性能进行了对照 。

抗高温油基钻井液封堵剂PF-MOSHIELD的研制与应用

针对层理和微裂缝发育的高温高压复杂井,从提高多尺度封堵效果和高温稳定性出发,研制了一种由独特的化学改性剂和磺化沥青、油溶性碳酸钙、纳米二氧化硅以及苯乙烯丙烯酸酯共聚物等组成的抗高温油基钻井液封堵剂PF-MOSHIELD。该封堵剂粒径分布在1～189.02μm之间,热稳定性好,分解温度高达378℃,软化点为260℃,且能在油相中稳定分散。与传统的油基封堵剂相比,该封堵剂在压差的作用下挤入微裂缝,同时参与了"内滤饼"和"外滤饼"的形成,在高温下能对不同孔隙度的裂缝进行封堵,有效降低渗透滤失量和滤失速率。在南海海域WZ6-9、WZ12-1等区块井的应用表明,添加PF-MOSHIELD的钻井液体系流变稳定,电稳定性提高,减少页岩中孔隙压力传递效应,能够满足层理和微裂缝发育的硬脆性和破碎性地层井壁稳定要求。

加盐超浓反相乳液的合成、表征及性能研究

采用超浓反相乳液聚合法对AA/AM/AMPS三元单体共聚合,合成出了钻井液用降滤失剂,研究了加盐对产物降滤失性能和稳定性的影响,并通过热重分析法和差示扫描量热法对合成聚合物进行了表征。结果表明,盐的存在一定程度上提高了聚合物乳液的降滤失性能及稳定性,但对聚合物的耐热性能没有显著的影响。

随钻电磁波电阻率测井仪器响应影响因素数值模拟

介绍了随钻电磁波电阻率测井仪器的响应原理及计算模型。通过数值模拟不同地层模型仪器响应,分析了随钻电阻率测井中仪器精度、井眼、井斜与层厚、各向异性、介电常数以及泥浆侵入等因素对电阻率的影响。对于目前数据处理和解释中地层模型不够准确、应用软件都无法同时处理各种影响因素、同时考虑到各种环境因素进行资料的反演几乎不可能、对地层反演结果的不确定性等问题提出建议。为正确利用随钻电磁波测井资料提供理论依据。

高温抗盐降滤失剂SPX树脂

深井和超深井越来越多。对钻井液抗温抗污染能力的要求也越来越高,这样就需要抗高温抗污染的降滤失剂。根据降滤失剂在使用过程中存在的高温增粘和遇到金属离子污染增粘的问题,从研究降滤失剂的分子结构出发,通过苯氧(基)乙酸与苯酚、甲醛发生缩聚反应同时磺化,合成出磺化苯酚/苯氧(基)乙酸/甲醛树脂(简称SPX树脂)。室内实验以在180℃下老化16h后的8％二级钠膨润土钻井液为研究对象,评价了SPX树脂的抗盐性、抗温性、复配性能、高温高压滤失性能及其对表观粘度的影响等。结果表明,SPX树脂单独使用就具有抗饱和盐、抗高温、非增粘降滤失的作用,而且降滤失效果良好;与SMC和SMK有良好的复配效果。SPX树脂已成功地在中原油田得到应用。

新型磺化腐植酸钻井液添加剂的研究

采用一种新型磺化剂——对羟基苯磺酸钠通过一种新工艺一步合成了纳米级磺化腐植酸,其粒径为27.66nm。对其制备工艺、降黏与降滤失性、抗高温性和配伍性进行了优选和考察。优选出了最佳磺化工艺:风化煤与对羟基苯磺酸钠的质量比为1∶1,反应温度为100℃,反应时间为1h。该新型磺化腐植酸降黏率可达53.5%,抗温可达150℃,并具有良好的降滤失性和配伍性,当其加量为1%时,与0.15%四甲基溴化胺的复配效果最好。采用XRD、IR、TG、TEM等测试手段对产品的结构性能进行了表征,与其它方法获得的磺化腐植酸的比较结果表明,该新型磺化腐植酸得到了更深度的磺化,其晶格化程度高,并且有磺化的特征峰出现,其综合性能更优。理论分析了该新型磺化腐植酸的降黏和降滤失机理,通过TEM表征做了进一步论证。

纳米改性CMC的制备、结构表征和性能评价

选用锌类纳米材料ZZ作为纳米复合处理剂的制备原料,采用溶液共混法与乳液共混法为主、机械共混法为辅的共混方法制得了纳米改性材料CMC-ZZ。红外光谱谱图测试结果表明,CMC与ZZ表面通过氢键结合形成吸附层;应用扫描电镜对纳米改性材料进行结构分析表明,纳米材料ZZ与CMC并非简单地混合在一起,而是发生了物理/化学作用;性能评价结果表明,纳米改性材料CMC-ZZ能改善钻井液的护胶性能,降低常温及高温高压滤失量,同时也能提高塑性黏度和动切力,所以CMC-ZZ能明显提高钻井液老化后的表观黏度。因此当需要提高钻井液高温(大于180℃)下的动切力时,可选用纳米改性材料CMC-ZZ。

聚铝胺盐防塌钻井液研究与应用

为解决吉林油田伊通、大安等区块软泥岩和硬脆性泥岩地层坍塌的问题,从聚胺盐与聚铝盐的抑制防塌机理出发,将两者复配,以发挥两者的协同效应提高钻井液的抑制防塌性能,结合吉林油田软泥岩和硬脆性泥岩地层钻井工程实际情况,通过试验优选其他添加剂及加量,优选出了具有强抑制性的聚铝胺盐防塌钻井液配方,其配方为2.0%钠基膨润土+2.0%封堵剂聚铝盐PAC-1+3.0%抑制剂聚胺盐HPA+1.0%降滤失剂SMP-1+1.5%降滤失剂APC-026+2.0%抑制剂磺化沥青+pH值调节剂NaOH。性能评价结果表明:强水敏泥岩在聚铝胺盐防塌钻井液中的一次回收率为75%、膨胀率为17.4%;聚铝胺盐防塌钻井液能抗15%NaCl和1%CaCl2污染,耐150℃高温。14口井的现场应用表明:聚铝胺盐防塌钻井液的抑制性和封堵能力强,能有效防止泥岩坍塌,解决了吉林油田伊通、大安等区块泥岩地层钻井过程中因井壁坍塌和缩径造成的掉块、起下钻遇阻等问题。

高取代度羧甲基淀粉醚合成条件的优化

以淀粉、氯乙酸为原料 ,异丙醇为溶剂合成羧甲基淀粉醚 ( CMS)。通过正交实验对影响羧甲基淀粉醚取代度 ( DS)的各反应因素进行了考察。考察了反应时间、反应温度、溶剂用量、水的用量对取代度的影响 ,并进行了优化。在所优化的合成条件下能制备取代度 DS>1 .5的羧甲基淀粉醚。

一种消除裂缝性储层钻井液滤饼的新方法

介绍了强氧化剂二氧化氯的基本性质、制备方法及其与有机聚合物的作用机理 ,利用组合裂缝储层保护评价实验新技术 ,对不同类型的解堵剂进行了解堵效果评价。试验结果表明 ,酸化和氧化相结合的二元复合滤饼消除法的解堵效果较好 。

钻井液滤失规律及其回归方程

由于钻井液在不同滤失介质和不同条件下的滤失性能有较大差异,按照API标准进行的滤失量测定不能全面地反映钻井液滤失性能。因此,根据Ostwarld方程,对实验条件下测定的滤失数据进行处理并得出滤失回归方程。实验证明,钻井液滤失方程既是钻井液自身滤失特性的规律性概括,又反映了钻井液与所接触地层的匹配程度,可以此为依据设计和优选钻井液、判断钻井液滤液损害深度。实验研究了滤饼渗透率的变化规律及测定方法,认为用恒定滤失速率表示滤饼渗透性是较好的方法。