A Method for Forecasting Failures of Sucker Rod-pumped Wells

An exact forecast of the failures of a sucker rod-pumped well in a production area means much for an oilfield’s operation budget, operational arrangement and production plan. In this paper, according to the characteristics of failed sucker rod-pumped well randomness and strong outburst, with the gray GM (1,1) forecast model and the Markov forecast model combined, gray GM (1,1) forecast model is utilized to handle the primary data of an oilfield, and Markov forecast model is utilized to calculate the state transfer probability of forecast value. Then, the gray Markov forecast model considering the influence of randomness factors is formed. Field results prove that the calculation precision of this method is higher and the practicability is greater.

Using the curve moment and the PSO-SVM method to diagnose downhole conditions of a sucker rod pumping unit

Downhole working conditions of sucker rod pumping wells are automatically identified on a computer from the analysis of dynamometer cards. In this process, extraction of feature parameters and pattern classification are two key steps. The dynamometer card is firstly divided into four parts which include different production information according to the ＂four point method＂ used in actual oilfield production, and then the moment invariants for pattern recognition are extracted. An improved support vector machine （SVM） method is used for pattern classification whose error penalty parameter C and kernel function parameter g are optimally chosen by the particle swarm optimization （PSO） algorithm. The simulation results show the method proposed in this paper has good classification results.

Fault diagnosis for down-hole conditions of sucker rod pumping systems based on the FBH-SC method

Dynamometer cards are commonly used to analyze down-hole working conditions of pumping systems in actual oil production. Nowadays, the traditional supervised learning methods heavily rely on the classification accuracy of the training samples. In order to reduce the errors of manual classification, an automatic clustering algorithm is proposed and applied to diagnose down-hole conditions of pumping systems. The spectral clustering （SC） is a new clustering algorithm, which is suitable for any data distribution. However, it is sensitive to initial cluster centers and scale parameters, and needs to predefine the cluster number. In order to overcome these shortcom- ings, we propose an automatic clustering algorithm, fast black hole-spectral clustering （FBH-SC）. The FBH algo- rithm is used to replace the K-mean method in SC, and a CritC index function is used as the target function to automatically choose the best scale parameter and clus- tering number in the clustering process. Different simulation experiments were designed to define the relationship among scale parameter, clustering number, CritC index value, and clustering accuracy. Finally, an example is given to validate the effectiveness of the proposed algorithm.

Approach to the Design Calculation of Sucker Rod Pumping Systems in Coalbed Methane Wells

The existing design of the pumping systems mainly focuses on the approximate computational formulae and procedures,which are developed based on the analytic approaches of conventional oil/gas fields.The calculation of polished rod loads usually just concerns about the static and inertial loads.And the computation of gearbox torque generally uses empirical formulae and correction factors.The above modeling procedures,if applied to the coalbed methane（CBM） wells,can not give the desired accuracy of the system design and its pertinent analysis.In this paper,based on the kinematic and dynamic analysis of the pumping system,the kinematic relation of polished rod is analyzed,and the variation of the total loads of polished rod is developed with the limits of CBM well conditions along the string.The gearbox torque calculation model is established by combining the counterbalance effect with the calculated dynamometer cards and torque factors.The application characteristics of this model are demonstrated by the example of ZH002-4 well in Qinshui basin.The interpretations of results show that the cranks of beam units should rotate in a counter clockwise direction viewed with the wellhead to the right.Compared with oil？gas fields,the dynamic and friction to polished rod load ratios are relatively high and the computation of polished rod loads should involve the static and inertial loads,as well as vibration and friction loads.And the dynamic load ratio decreases rapidly during the production.Besides,the total deformation of the string is small in CBM wells.As for balanced operation,the gearbox torque load usually has two approximately equal peaks and the magnitudes of instantaneous torque are just within 50% of unbalanced gearbox loadings.The proposed research improves efficiency of the pumping system,loads the pumping unit more uniformly,and provides the reasonable basis for selecting the units.

Multiple fault diagnosis of down-hole conditions of sucker-rod pumping wells based on Freeman chain code and DCA

It is important to achieve continuous, stable and efficient pumping well operation in actual oilfield operation. Down-hole pumping well working conditions can be monitored in real-time and a reasonable production scheme can be designed when computer diagnosis is used. However, it is difficult to make a comprehensive analysis to supply efficient technical guidance for operation of the pumping well with multiple faults of down-hole conditions, which cannot be effectively dealt with by the common methods. To solve this problem, a method based on designated component analysis （DCA） is used in this paper. Freeman chain code is used to represent the down-hole dynamometer card whose important characteristics are extracted to construct a designated mode set. A control chart is used as a basis for fault detection. The upper and lower control lines on the control chart are determined from standard samples in normal working conditions. In an incompletely orthogonal mode, the designated mode set could be divided into some subsets in which the modes are completely orthogonal. The observed data is projected into each designated mode to realize fault detection according to the upper and lower control lines. The examples show that the proposed method can effectively diagnose multiple faults of down-hole conditions.

Adaptive fault diagnosis of sucker rod pump systems based on optimal perceptron and simulation data

A highly precise and timely diagnosis technology can help effectively monitor and adjust the sucker rod production system(SRPS)used in oil wells to ensure a safe and efficient production.The current diagnosis method is pattern recognition of a dynamometer card(DC)based on feature extraction and perceptron.The premise of this method is that the training and target data have the same distribution.However,the training data are collected from a field SRPS with different system parameters designed to adapt to production conditions,which may significantly affect the diagnostic accuracy.To address this issue,in this study,an improved model of the sucker rod string(SRS)is derived by adding faultparameter dimensions,with which DCs under 16 working conditions could be generated.Subsequently an adaptive diagnosis method is proposed by taking simulated DCs generated near the working point of the target SRPS as training data.Meanwhile,to further improve the accuracy of the proposed method,the DC features are improved by relative normalization and using additional features of the DC position to increase the distance between different types of samples.The parameters of the perceptron are optimized to promote its discriminability.Finally,the accuracy and real-time performance of the proposed adaptive diagnosis method are validated using field data.

Novel sucker rod pumping system based on linear motor technology

Obtaining petroleum at the cost of electrical energy is a common problem in almost all oil fields, and it is mainly caused by low duty radio of induction motor used in beam pumping units. Traditional beam-pumping units have many intrinsic disadvantages such as low efficiency, complex transmission devices, poor flexibility, tremendous volume and weight in long stroke, etc.Therefore, a novel direct driven linear electromagnetic pumping unit (EMPU) has been developed by combining oil extraction technology with linear motor technology. The thrust of EMPU matches the changing of suspension center load to improve the system efficiency and cut down the consumption of energy. Based on previous experience, a small-scale prototype was developed and a simulation was conducted with it. Both theoretical analyses and experimental study showed that the problems exiting in beam pumping units can be solved with EMPU system, and this is a new method which can be used to solve high energy waste in oil fields.

注氮气机抽防腐防垢一体化管柱的研制与应用

针对塔河油田注氮气机抽井井筒及井下工具严重腐蚀结垢,易造成抽油泵卡泵、封隔器解封困难等井下故障的问题,在现有技术的基础上,优化改进结构、技术创新,研制了一种注氮气防腐防垢机抽一体化管柱。该管柱包括注气防垢杆式泵、防腐封隔器等关键工具,注气防垢杆式泵优化改进了柱塞和泵筒的结构,泵筒上部设计注气孔、下部设计封堵筒,柱塞下部设计密封堵头,注气时柱塞下部堵头将进油通道密封,能防止高压油液倒灌进入泵腔发生腐蚀结垢,消除柱塞下放失败的风险;防腐封隔器采用新型护肩式的胶筒组件及双“O”型圈、双向支撑密封结构、分级解封机构和分体式双向卡瓦锚定结构,提高封隔器胶筒的耐腐蚀性能、降低上提解封力和保证卡瓦锚定性能。经过理论校核和室内模拟试验均满足现场需求,现场应用表明,该管柱坐封、解封及注气均正常,转采成功率100%,满足开发需求,解决了注气腐蚀结垢卡泵和封隔器解封困难的工程难题,具有很高的推广价值。

多指标排序优选抽油井工作参数软件研发

针对原有抽油机井工作参数软件与采油生产实际结合不够紧密、使用不方便的问题,经过技术攻关研发出多指标排序优选抽油井工作参数软件。首先确立以产液量指标为主、井下效率指标为辅、安全指标可靠的优选抽油井工作参数的设计思路,其次是建立以产液量计算为核心的系统算法。应用工程计算和经验公式相结合的方法,通过抽油泵沉没压力使供液量与排液量建立联系,将与供液量接近的排液量作为产液量,进而计算出井下效率、悬点载荷和抽油杆负载率。对所有“泵径、冲程、冲次”组合的优势产液量和优势井下效率及其对应的指标和下泵深度以列表方式输出,对所有指标与井下效率的关系以曲线方式输出,经过排序对比即可挑选出各项指标均占优势且稳定可靠的抽油井工作参数组合,实现抽油井工作参数优化设计的目标。该软件自2017年应用以来年均指导调参130井次,平均单井增产原油63.54 t,提高井下效率3.2%,取得了显著的应用效果。

抽油杆断裂原因

某油田抽油杆频繁发生断裂现象。采用宏观观察、化学成分分析、力学性能测试、金相检验、扫描电镜及能谱分析等方法分析了抽油杆断裂的原因。结果表明:该抽油杆的断裂性质为腐蚀疲劳断裂;采用深抽工艺后,抽油杆承受较大的拉伸载荷,增大了抽油杆的平均应力,缩短了抽油杆的疲劳寿命;油井中含有硫化氢,对抽油杆外壁产生腐蚀作用,导致抽油杆外壁产生腐蚀坑,腐蚀坑底部应力集中程度较大,在交变载荷作用下,腐蚀坑底部产生微裂纹,微裂纹不断扩展,最终导致抽油杆断裂。

Fluid characteristic of multiphase fluid in annular space between pump barrel and plunger

The pump performance parameters,such as pump pressure,plunger friction and pump valve resistance,are fundamental parameters of optimal design of pump efficiency and sucker rod pumping system (SRPS).In this paper,considering the characteristic of geometrical nonlinear and rheology property of multiphase fluid,the pump performance parameters are studied.Firstly,a dynamics model of annular fluid flow is built.In the detail,a partial differential equation of annular fluid is established and a computing model of fluid pressure gradient is built.Secondly,the simulation models of plunger friction and hydraulic resistance of pump valve are built.Finally,a novel simulation method of fluid pressure in annular space is proposed with software ANSYS.In order to check up the correction of models proposed in this paper,the comparison curves of experiment and simulation results are given.Based on above model,the whole simulation model of plunger pump is simulated with Visual Basic 6.0.The results show that the fluid friction of pump plunger and instantaneous resistance of pump valve are nonlinear.The impact factors of pump performance parameters are analyzed,and their characteristic curves are given,which can help to optimize the pump motion parameters and pump structural.

Dynamic simulation and efficiency analysis of beam pumping system

An improved whole model of beam pumping system was built. In the detail, for surface transmission system(STS), a new mathematical model was established considering the influence of some factors on the STS's torsional vibration, such as the time variation characteristic of equivalent stiffness of belt and equivalent rotational inertia of crank. For the sucker rod string(SRS), an improved mathematical model was built considering the influence of some parameters on the SRS's longitudinal vibration, such as the nonlinear friction of plunger, hydraulic loss of pump and clearance leakage. The dynamic response and system efficiency of whole system were analyzed. The results show that there is a jumping phenomenon in the amplitude frequency curve, and the system efficiency is sensitive to motor power, pump diameter, stroke number, ratio of gas and oil, and submergence depth. The simulation results have important significance for improving the efficiency of beam pumping system.

有杆泵-地面驱动螺杆泵组合举升工艺设计

随着塔里木等深层油气田的开发,能够满足深井大排量深抽的工艺技术逐渐成为现实需要,考虑到机采井的泵挂深度不断加深,单一的举升方式随着举升高度的增加往往表现出一定的局限性和低效性,因此,针对性地提出有杆泵地面驱动螺杆泵组合举升工艺,将螺杆泵和有杆泵安装在同一生产管柱上进行“接力”采油。为论证有杆泵地面驱动螺杆泵组合举升工艺的可行性,在分析有杆泵-地面驱动螺杆泵组合工艺的工作原理、流量匹配及杆柱受力状况的基础上,建立了有杆泵-地面驱动螺杆泵组合举升工艺在油井深抽条件下的悬点载荷计算模型,与单独的有杆泵抽油相比,在保证产量相同的情况下,该组合系统能通过降低抽油机悬点载荷达到增加泵挂深度及排量范围、降低抽油能耗的目的。

新型长冲程举升工艺在低效高耗井应用方案

油田举升方式主要采用游梁式抽油机,部分井存在系统效率低、能耗高、泵效低的问题,尤其在低产低效井和高能耗井更加突出。为探索高效举升新途径,按照“长冲程、低冲次”优化设计理念,某油田应用了超长冲程抽油机和塔架式抽油机等新型长冲程举升工艺,同时研究并应用了碳纤维连续抽油杆和柔性金属泵等配套举升技术,通过调研论证,个性化设计了低产低效井和高能耗井举升工艺应用方案,平均节电率可达30%以上,40口井年节电71.2×10^(4) kWh,年创综合经济效益108.5万元,具备推广应用价值。

抽油机井原油产量计量新方法

产量计量是油田开发生产过程中最重要的基础工作之一,准确的计量结果对于抽油机井工作状态诊断、工作制度调整以及措施方案效果评价都具有重要意义。但传统两相分离式量油和功图量油技术普遍存在投资和维护成本高、自动化程度低、适应性差等问题。为了提高量油效率和精度,利用深度学习技术,以生产大数据样本做支撑,建立电参量油模型,提出了由有功功率数据直接计算产量的新方法。电参量油模型包含特征提取模块和参数融合模块,分别由双层GRU网络和三层全连接网络组成。特征提取模块获取有功功率曲线数据中的生产参数信息,参数融合模块实现了冲程、冲次和泵径特征与有功功率数据挖掘结果的信息融合,提高了电参量油模型的准确性和泛化性。实例井验证结果表明,油井工况越好,实际产量越高,预测产量的精度越高,平均预测精度为94.08%。该研究成果为油井计量开创了新思路,为低成本智能油田建设提供了技术支撑。

螺杆泵采油杆柱受径向力激励的横向振动

杆柱横向振动是螺杆泵采油系统杆管失效的主要原因,研究杆柱匀速自转时液体径向力对杆柱横向振动规律的影响,通过仿真拟合方法得到液体径向力的数学模型并探讨径向力和公转离心力对杆柱作用规律;建立杆柱横向振动的仿真模型,其中液体径向力和由于杆柱偏心旋转离心力为横向激励,研究液体径向力对杆柱横向振动规律的影响;利用数值方法对振动微分方程求解。结果表明:液体径向力的方向变化和偏心率有关且存在使径向力方向转换的临界偏心率,考虑径向力时杆管间碰撞力增大,碰撞次数增多,杆管首次发生碰撞时间缩短,杆柱波动性更大,碰撞力最值出现在杆柱底端和中部附近;杆柱工作时间越长其整体振动越明显,形状越不规则。

电动螺杆泵井下限位杆柱防反转技术的应用

电动螺杆泵作为采油设备目前在各油田应用较广泛,但在生产过程中电动螺杆泵井下杆柱反转易造成设备损坏、人身伤害以及原油产量损失。通过对电动螺杆泵井下生产装置结构、地面防反转措施的分析,提出了电动螺杆泵井下管柱结构技术改进方案,即增加井下限位杆柱防反转机构。井下限位杆柱防反转机构技术改进后,通过现场30口电动螺杆泵井应用,一次成功率100%,减少正憋管柱工序及罐车、泵车的使用费用。电动螺杆泵井停机后反转时间由原10 min~24 h,降低为20 s以内,挽回原油产量损失,提高电动螺杆泵安全运行可靠性,对各油田电动螺杆泵防反转技术改进具有借鉴意义。

基于应力比的延长抽油杆疲劳寿命设计方法

有杆泵采油是目前各油田最常用的采油方式。为研究交变载荷对油井下部抽油杆柱疲劳寿命的影响,模拟抽油杆真实受力环境,开展了不同应力比条件下抽油杆疲劳性能试验。结果表明:1)抽油杆循环拉伸次数随抽油杆应力比增大而增大,当应力比大于0.45时趋于不变,抽油杆寿命与应力比关系进行曲线拟合,具有一元三次方程关系;2)生产井因工作条件不同,最下一级抽油杆柱应力比不同,实测应力比为0.19~0.51,平均值为0.30;3)生产井最下一级抽油杆疲劳寿命拐点应力比为0.37,推荐抽油杆抗疲劳设计应力比大于等于0.37;4)抽油杆柱底端采用加重抽油杆或加粗抽油杆可以提高最下一级抽油杆应力比。该设计方法对于延长抽油杆疲劳寿命具有实际指导意义。

抽油杆柱与油管偏磨机理及偏磨点位置预测

结合油田生产实际,对抽油杆柱与油管系统的磨损介质类型和磨损机理进行了分析,建立了抽油杆三维力学综合分析模型,利用VisualBasic6.0语言和Matlab6.0语言开发了相应的仿真分析软件系统,并进行了三维井眼轨迹对抽油杆柱受力变形的影响研究。利用该软件系统,可以确定抽油杆柱与油管严重偏磨点的位置。使用新型抗摩擦接箍,可使定向井抽油杆柱偏磨的程度大幅度下降,从而节省修井时间并提高油井寿命。

利用低摩阻柱塞抽油泵提高泵效及防偏磨技术的应用

大庆油田杆管偏磨井数逐年增多,严重影响了聚合物驱采油效果和规模应用。对杆柱屈曲的原因、规律和偏磨状态以及偏磨机理进行了分析,研制并应用聚合物驱低摩阻柱塞泵解决了摩阻小、漏失量也小的难题。实施了防偏磨配套技术,研制了3种杆串在线测试仪,解决了杆管偏磨的问题,延长了杆管工作寿命,提高了泵效。