Hole cleaning evaluation and installation spacing optimization of cuttings bed remover in extended-reach drilling

In extended-reach or long-horizontal drilling,cuttings usually deposit at the bottom of the annulus.Once cuttings accumulate to a certain thickness,complex problems such as excessive torque and drag,tubing buckling,and pipe stuck probably occur,which results in a lot of non-productive time and remedial operations.Cuttings bed remover can efficiently destroy deposited cuttings in time through hydraulic and mechanical stirring effects.This paper aims to build a method for hole cleaning evaluation and installation spacing optimization of cuttings bed remover to improve the wellbore cleaning effect.Firstly,a Computational Fluid Dynamics approach with Eulerian—Eulerian multiphase model was utilized to investigate the mechanism of cuttings transportation,and a new type of cuttings bed remover was designed.Next,an evaluation method of hole cleaning effect of remover was established.After that,the effects of several drilling parameters on hole cleaning including flow rate of drilling fluid,rotational speed of drillpipe,rate of penetration,wellbore size,rheological property of drilling fluid,and remover eccentricity on the performance of cuttings bed remover were investigated.The results demonstrate that the new type of remover with streamline blade performs better than conventional removers.The efficiency of hole cleaning is greatly improved by increasing the rotational speed of drillpipe,flow rate of drilling fluid,remover eccentricity,and 6 rpm Fann dial reading for drilling fluid.While higher rate of penetration and large wellbore size result in worse hole cleaning.These findings can serve as an important guide for the structure optimization design of cuttings bed remover and installation spacing of removers.

Hole Cleaning Prediction in Foam Drilling Using Artificial Neural Network and Multiple Linear Regression

Foam drilling is increasingly used to develop low pressure reservoirs or highly depleted mature reservoirs because of minimizing the formation damage and potential hazardous drilling problems. Prediction of the cuttings concentration in the wellbore annulus as a function of operational drilling parameters such as wellbore geometry, pumping rate, drilling fluid rheology and density and maximum drilling rate is very important for optimizing these parameters. This paper describes a simple and more reliable artificial neural network (ANN) method and multiple linear regression (MLR) to predict cuttings concentration during foam drilling operation. This model is applicable for various borehole conditions using some critical parameters associated with foam velocity, foam quality, hole geometry, subsurface condition (pressure and temperature) and pipe rotation. The average absolute percent relative error (AAPE) between the experimental cuttings concentration and ANN model is less than 6%, and using MLR, AAPE is less than 9%. A comparison of the ANN and mechanistic model was done. The AAPE values for all datasets in this study were 3.2%, 8.5% and 10.3% for ANN model, MLR model and mechanistic model respectively. The results show high ability of ANN in prediction with respect to statistical methods.

Application of Hole-cleaning Simulation for Drilling

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Bridge Plug Drillouts Cleaning Practices—An Overview

Horizontal fracture-simulated completions remain the most reliable method of producing hydrocarbons from shale formations. The vast majority of unconventional wells are completed using the “Plug and Perf” method. This method involves using either a coiled tubing (CT) with a positive displacement motor or a jointed pipe to mill out composite plugs after fracturing operations are completed. An estimated average of 120,000 composite plugs is installed in the US alone each year. Bridge plug drillouts from milling operations tend to accumulate in horizontal wells and can cause stuck pipe incidents and loss of well control. Efficient removal of composite plugs’ debris is crucial in achieving operational efficacies and full production potential. This paper provides an overview of the various bridge plug drillouts cleaning practices adopted in horizontal wells. It discusses several case histories, showcasing how operators solved cleanout challenges. Developed mechanistic models to better understand hole cleaning are also reviewed. As more unconventional wells are being set at more extensive depths, an economical and optimized coiled tubing process becomes increasingly important. This paper focuses on delivering a more conclusive set of recommendations to increase efficiency and improve current composite plug coiled tubing cleaning-milling practices, increase operational efficiency and reduce cost.

智能钻井系统在赵东油田的应用

赵东油田开发后期调整井钻井施工中,需要进行三维防碰绕障,井眼轨道设计复杂,钻进过程中经常出现摩阻扭矩变化大、井眼清洁困难、井壁稳定性差、钻井液漏失等难题。针对精细化井眼轨迹控制和快速识别井下复杂状况等关键技术难点,采取以现场作业人员经验为主、智能钻井系统为辅的作业模式,通过贝克休斯智能钻井系统i-Trak™的量化分析与及时预警,提高了轨迹控制精度及井下复杂状况早发现、早调整的及时性,避免复杂工况的发生,降低非生产作业时间,缩短了建井周期。通过17口井的试验,进一步验证现场“作业人员经验+智能钻井系统”的作业模式能够很好满足安全高效钻井的需求,为海上油田开发后期复杂调整井的钻井施工提供了可借鉴经验。

超浅层大位移水平井“三低”钻井液技术

针对东部超浅层水平井水平段钻井中降摩阻扭矩大、托压严重等问题,分析了该区块的储层特征,构建了“低摩阻、强携砂、防水锁”的思路,优选了低成本的关键处理剂,形成了低摩阻、低成本和低伤害的水基钻井液体系,评价了其主要性能,并进行了现场试验。研究结果及试验表明,羧甲基纤维素(CMC)增黏提切效果好,最优加量为0.3%~0.5%,聚丙烯酸钾(KPAM)降失水明显,最优加量为1.0%~1.5%,复合润滑剂中固体润滑剂(SH-2)和液体润滑剂(RY-838)最佳复配比例为3∶7,防水剂为0.5%F-113。该钻井液体系渗透率恢复平均值为85.38%,中压失水小于5 mL,泥饼粘滞系数为0.0524~0.0612,动塑比为0.52~0.55。现场应用1口井,未出现严重托压,较邻井钻速提高13.5%,钻井液成本降低5.3%,有效解决了超浅层水平井钻井难题。

Synthetic polymers:A review of applications in drilling fluids

With the growth of deep drilling and the complexity of the well profile,the requirements for a more complete and efficient exploitation of productive formations increase,which increases the risk of various complications.Currently,reagents based on modified natural polymers(which are naturally occurring compounds)and synthetic polymers(SPs)which are polymeric compounds created industrially,are widely used to prevent emerging complications in the drilling process.However,compared to modified natural polymers,SPs form a family of high-molecular-weight compounds that are fully synthesized by undergoing chemical polymerization reactions.SPs provide substantial flexibility in their design.Moreover,their size and chemical composition can be adjusted to provide properties for nearly all the functional objectives of drilling fluids.They can be classified based on chemical ingredients,type of reaction,and their responses to heating.However,some of SPs,due to their structural characteristics,have a high cost,a poor temperature and salt resistance in drilling fluids,and degradation begins when the temperature reaches 130℃.These drawbacks prevent SP use in some medium and deep wells.Thus,this review addresses the historical development,the characteristics,manufacturing methods,classification,and the applications of SPs in drilling fluids.The contributions of SPs as additives to drilling fluids to enhance rheology,filtrate generation,carrying of cuttings,fluid lubricity,and clay/shale stability are explained in detail.The mechanisms,impacts,and advances achieved when SPs are added to drilling fluids are also described.The typical challenges encountered by SPs when deployed in drilling fluids and their advantages and drawbacks are also discussed.Economic issues also impact the applications of SPs in drilling fluids.Consequently,the cost of the most relevant SPs,and the monomers used in their synthesis,are assessed.Environmental impacts of SPs when deployed in drilling fluids,and their manufacturing processes are identified,together with advances in SP-treatment methods aimed at reducing those impacts.Recommendations for required future research addressing SP property and performance gaps are provided.

井下双向清洗工具设计与试验研究

针对油气井作业过程中洗井作业存在的返砂困难、冲洗效率低等问题,设计了一种井下双向清洗工具,可以通过正、反循环通道的切换来实现双向循环洗井。正循环洗井过程中,工具底部产生旋转水射流,可对管内、管壁进行冲洗解堵作业,疏通近井地带;反循环洗井过程中,工具侧壁循环孔打开,中心管返出,携砂能力较强。两种循环方式可反复交互进行,提高了冲砂效率,降低了砂卡的风险。通过数值模拟分析,并结合地面测试,验证了工具的可靠性及冲砂效果。研究成果具有一定的现场推广应用前景和价值。

卧式三角型滤筒的脉冲喷吹清灰性能

【目的】为优化卧式三角型滤筒除尘器的清灰性能,探究不同喷吹气流对滤筒内部压力分布的影响,获得不同喷吹孔型式对三角型滤筒的清灰性能的影响规律。【方法】分别采用直管喷吹孔、文氏里管、散射喷嘴、新型曲面诱导引射器共4种喷吹孔型式的诱导引流装置对卧式三角型滤筒开展冷态脉冲实验,以侧壁压强峰值和相对标准偏差作为评价清灰性能的技术指标,分别探讨不同条件下的喷吹射流对滤筒内壁压力分布的影响。【结果】在喷吹压强分别设为0.3、0.4、0.5 MPa的条件下,采用直管、文丘里管、新型曲面诱导引射器时喷吹距离分别设为150、200、250、300、350、400 mm,采用散射喷嘴时喷吹距离分别设为25、50、75、100、125、150、175 mm,则采用直管、文丘里管、散射喷嘴、新型曲面诱导引射器时的平均侧壁压强峰值分别为1037、1758、952、1533 Pa,相对标准偏差分别为0.76、0.58、0.09、0.16;采用新型曲面诱导引射器喷吹孔时,比采用散射喷嘴时的清灰强度高61%,比采用文丘里管时的相对标准偏差小0.47。【结论】新型曲面诱导引射器同时兼顾对侧壁压强峰值和相对标准偏差的要求,在4种喷吹孔型式中清灰性能最佳。

大位移井井筒岩屑运移状态研究现状与展望

井眼清洁不充分是造成60%以上大位移井井下故障的主要原因。自上世纪70年代以来,学者们一直致力于大位移井井筒岩屑运移实验研究和岩屑运移理论研究,以期为准确预测和诊断大位移井全井井眼清洁状态提供可靠的实验数据和理论技术。文章全面回顾并深入分析了国内外岩屑运移实验,包括实验装置、目的、方法和基于实验数据获得的井眼清洁状态。其中,对岩屑运移的理论研究分统计回归模型、颗粒起动力学模型和分层模型等3种类别;认为筹建具备环空堆积岩屑质量准确测量和截面环空岩屑浓度可视化测量功能的311 mm大尺寸岩屑运移实验环路是未来岩屑运移实验研究的重要发展方向;此外,挖掘海量实验数据,建立基于大数据的人工神经网络井眼清洁状态预测方法,可更准确地映射工程因素与井眼清洁状态间的复杂非线性关系,有望取得较传统理论模型更加准确可靠的预测结果。

Simulation study on cuttings transport of the backreaming operation for long horizontal section wells

The backreaming operation plays a significant role in safe drilling for horizontal wellbores, while it may cause severe stuck pipe accidents. To lower the risk of the stuck pipe in backreaming operations, the mechanism of cuttings transport needs to be carefully investigated. In this research, a transient cuttings transport with multiple flow patterns model is developed to predict the evolution of cuttings transported in the annulus while backreaming. The established model can provide predictions of the distribution of cuttings bed along the wellbore considering the bulldozer effect caused by large-size drilling tools(LSDTs). The sensitivity analyses of the size of LSDTs, and backreaming operating parameters are conducted in Section 4. And a new theory is proposed to explain the mechanism of cuttings transport in the backreaming operation, in which both the bit and LSDTs have the “cleaning effect” and “plugging effect”.The results demonstrate that the cuttings bed in annuli is in a state of dynamic equilibrium, but the overall trend and the distribution pattern are obvious. First, larger diameters and longer drilling tools could lead to a higher risk of the stuck pipe. Second, we find that it is not the case that the higher flow rate is always better for hole cleaning, so three flow-rate intervals are discussed separately under the given conditions. When the “dangerous flow rate”(<33 L/s in Case 4) is employed, the cuttings bed completely blocks the borehole near the step surface and causes a stuck pipe directly. If the flow rate increases to the “low flow rate” interval(33-35 L/s in Case 4), a smaller flow rate instead facilitates borehole cleaning. If the flow rate is large enough to be in the “high flow rate” interval(>35 L/s in Case 4),the higher the flow rate, the better the cleaning effect of cuttings beds. Third, an interval of tripping velocity called “dangerous velocity” is proposed, in which the cuttings bed accumulation near the LSDTs is more serious than those of other tripping velocities. As long as the applied tripping velocity is not within the “dangerous velocity”(0.4-0.5 m/s in Case 5) interval in the backreaming operation, the risk of the stuck pipe can be controlled validly. Finally, through the factors analyses of the annular geometry,particle properties, and fluid properties in Section 5, it can be found that the “low flow rate”, “high flow rate” and “dangers flow rate” tend to decrease and the “dangerous velocity” tends to increase with the conditions more favorable for hole cleaning. This study has some guiding significance for risk prediction and parameter setting of the backreaming operation.

一种主螺栓孔清洗装置的研制

提出一种主螺栓孔清洗装置的研制方案和系统构成,对该清洗装置的基本功能及关键技术进行了理论研究。对清洗装置的行走状态,以及清洗组件和定位干燥组件升降模组进行了分析,分析结果表明,该装置可正常行走且不打滑、可完成升降模组的升降操作。提出一种新型自适应定位系统,该清洗装置通过接近开关感应清洗位置实现粗定位,再利用定位干燥筒的导向定位段实现精定位;支架组件始终提供一个径向拉力,车架组件受拉力有向中移动的趋势,但由于侧轮作用将始终与法兰外圆贴紧,从而实现清洗装置的完全定位。对精定位后的误差进行了分析,清洗组件轴线偏差不超过0.3453mm,满足要求。提出利用弹簧片对清洗刷进行限位和复位的方法,并对其设计参数进行仿真优化分析,结果表明,当弹簧片厚度取0.4mm时可有效清洗螺孔。

空穴射流清垢技术在德苏输油管线的应用

因油田产量递减,德苏输油管道采用含水油外输,为减缓苏一联污水站运行压力,采用高温低输量的运行模式,导致管道结垢严重,管道有效通径缩减,严重影响管道安全平稳运行。本次利用空穴射流清垢技术成功实现德苏输油管道全线清管通球,有效清除了管线内结垢,降低了德二联外输压力。清垢过程具有安全、速度快、无环境污染等优点,对海拉尔油田输油管道运行管理具有十分重要意义。

水控多喷孔减压阀的防堵塞设计研究

针对水控多喷孔减压阀在实际应用中容易发生堵塞的问题,文章提出一套完整的防堵塞设计方案。通过选择耐腐蚀、耐磨材料,采用电解抛光和物理气相沉积涂层处理,优化喷孔布置方式和形状,设计流线型流道,以及引入高压冲洗、超声波振动等自清洁装置,有效降低杂质沉积和堵塞风险。最后,通过实验验证该设计方案的有效性。

大直径深孔灌注桩多系统清孔工艺技术研究与应用

论文通过对大直径深孔灌注桩工程施工中的清孔工艺技术进行深入研究,提出了合理的高效清孔工艺的解决办法,通过应用验证后,对大直径深孔灌注桩的能耗效率和质量检测优良等级占比的数据对比,明显优于应用前。论文将成果经验进行分享,以期提高大直径深孔灌注桩基础工程整体施工工艺现状,降低大直径深孔灌注桩施工能耗成本,对改善土木工程领域桩基础工程的技术质量及效益有一定帮助。

苏里格气田长水平段水平井钻井关键技术——以S77-35-H5井为例

为了进一步降低钻井作业成本、提高单井产量、解决长水平段水平井使用“常规动力工具+水基钻井液”替代“旋转导向+油基钻井液”过程中出现的系列问题,采用鄂尔多斯盆地苏里格气田长水平段水平井配套技术实现了低成本开发。研究结果表明:(1)采用“双二维七段制”轨道,可以解决螺杆工具面摆放困难及钻具屈曲的问题;(2)应用数学建模+工程干预技术,能有效提高井筒清洁度;(3)采用井筒压力监测+漂浮下套管综合技术,可以实现顺利下套管;(4)近钻头GR地质导向技术能提高砂层钻遇率;(5)有机盐钻井液体系能有效预防井下坍塌及漏失。现场应用结果表明,起下钻摩阻下降11%,钻进扭矩下降17%,综合钻井速度提高28%,有效降低钻井成本。结论认为,该技术的成功研究为苏里格气田长水平段水平井低成本开发提供了借鉴,也为油气田提质增效开辟了新思路。

南海流花超大位移井井眼净化技术

为适时监测井眼环空净化状况,结合国内外最新研究成果,建立了一套大位移井井眼净化监测和计算方法。该方法可将立管压力转换为循环钻井液当量密度(ECD),做出实测ECD曲线、理论环空无岩屑床ECD曲线和理论环空存在一定厚度岩屑床ECD曲线,通过对比分析,实现对环空井眼清洁程度进行监测,并对环空平均岩屑床厚度进行定量评价。利用该方法对南海L iuhua 11-1-17 B3ERW 4井进行了计算分析,研究结果与实际情况相吻合。计算结果表明,在整个钻进过程中不同井段均有岩屑床形成,其中Φ444.5 mm(特别是井斜角大于45°)的井段,所形成的岩屑床高度均为最高,是大位移井中携岩最困难的井段。该计算方法简单实用,可以对环空岩屑床的形成进行监测,并能给出环空平均岩屑床高度的范围,为现场施工提供指导。

冀东油田水平井钻井液技术

针对水平井钻井要求和冀东油田的地层特点,采用强包被、强抑制、强封堵的技术措施,定向井段和水平井段采用聚磺硅氟乳化原油钻井液。该钻井液中PMHA与JGYJ配合使用进一步提高抑制泥页岩水化分散的能力;GT98、KJ1与NPAN复配使用可以降低高温高压滤失量,改善泥饼质量;QSAMK、YL1与JGWJ复配使用可以提高钻井液的封堵能力;MMH可改善悬浮携带能力,添加了不同粒径的超细碳酸钙和软化点与油层温度相匹配的沥青类材料,对油层孔隙进行快速封堵,避免液相和固相对油层的损害。现场应用表明,该钻井液具有较强的防塌能力、清洁井眼能力和润滑防卡能力,解决了上部地层和水平井段砂岩储层的井塌以及大斜度井段、水平井段的携砂、润滑问题和疏松砂层油层保护问题,完全满足了冀东地区垂深小于3000m水平井的钻井需要。

大斜度井段岩屑运移规律的微观研究

定向井井眼净化是钻井过程中的一大难题 ,与垂直井井眼净化有着本质的区别。井眼净化直接影响着钻井效率、钻井成本、井身质量及钻井安全等重要问题 ,因此一直为钻井工作者所重视。文章从微观的角度出发 ,首先建立了斜井段岩屑微粒运移的物理模型 ,对其受力情况进行简化 ,忽略次要影响因素 ,只考虑重力、钻井液的冲击力、上举力和悬浮力的影响 ,推导得出了斜井段岩屑微粒受力的计算公式。最后 ,以井斜角和钻井液的环空返速为例 ,应用文中所得的计算方法 ,研究了不同因素对岩屑微粒运移规律的影响。文章的计算分析结果满足Boycott效应规律 ,也从理论上探讨了增加钻井液排量对改善井眼净化的有效性。

高效岩屑床清除钻杆作用机理

岩屑携带困难是大斜度、大位移定向井和水平井钻井普遍存在的问题,严重影响钻井安全和钻进效果。设计了高效岩屑床清除钻杆(EHCDP),并利用计算流体动力学(CFD)仿真模拟技术对EHCDP作用下环空流场的流动特性展开研究,从流线图、速度场、压力场等方面对数值模拟结果进行了分析,研究了EHCDP的作用机理,分析了螺旋槽道结构对环空流体流动特性的影响。研究结果表明,在EHCDP作用下,流体在槽道附近形成了涡流结构,改变了偏心环空中流体的流动特性,使流体从小环空往大环空运动,将岩屑输送到大环空,而槽道附近的涡则将岩屑卷入槽道中,并利用钻杆转动所产生的离心力将岩屑"甩入"大环空,达到有效清除井眼低边岩屑床的目的。