多传感器下基于遗传算法的钻头与套管间距离研究

为确保海上丛式井组钻井作业的安全,在造斜前必须实时监测钻头与邻井套管的距离。基于钻头振动波的特征,提出了一种基于多传感器计算钻头与套管间距离的理论模型;该模型将四个传感器布置在邻井风险段的环空套管内壁,同步接收钻进时的振动信号,通过分析钻头与传感器组的空间位置关系,推导得到钻头距邻井套管距离的计算公式,且确定了振动波的衰减系数;设计开展了模型验证试验,采集到振动波在弱胶结地层中传播的振动信号,基于遗传算法对信号数据进行处理,优化采集数据,增加模型的容错率。试验结果表明,该模型可以有效预测钻头与邻井套管的距离,提高防碰监测中井间距离的预测精度。     

采用等效介质模型研究地应力场中套管井周波速的空间分布

在以往的工作中,利用弹性力学理论获得了地应力场中套管—水泥环—地层系统应力分布的解析表达式。在此基础之上,应用等效介质模型的速度—应力关系式,研究了地应力场中套管井周弹性波速的空间分布规律。分析结果表明,相对裸眼井,套管井应力集中的程度更加明显,由于套管和水泥环的存在,地层应力集中的范围明显缩小到井眼附近。应力集中将导致套管井周波速空间分布的各向异性,对应不同方位径向偏振的横波速度的交叉点明显向井孔附近移动,这意味着垂直偏振的两种弯曲波频散曲线的交点会向高频移动。这一结果表明,在高频情况下,在套管井中应用正交偶极子声测井检测应力导致的各向异性是可行的。     

YD705井套管失效原因分析

YD705井在钻水泥塞过程中套管失效,依据测井资料和钻塞现象对套管失效的原因进行了分析。结果表明:在钻井过程中,采用动力钳高速引扣使得套管粘扣或错扣,其接箍处承受异常环向拉伸应力,套管在此处脱扣,最终套管失效。     

声波水泥胶结测井中岩性对地层波影响研究及资料应用

针对砂泥岩地层,数值研究了套管井中高密度和低密度水泥完全胶结时短源距声波测井全波波形特性,通过地层孔隙度和泥质含量的变化,分析了水泥特性和地层岩性对地层波幅度的影响。结果表明水泥特性对地层波幅度影响很小,但地层孔隙度和泥质含量对地层波幅度影响很大,并给出了地层波岩性影响的校正图版。根据理论结果结合实际测井记录的波形特点,研究了波形信息提取方法,得到了第一、第二界面胶结指数等参数,用以评价固井质量。这种方法在西北油田固井质量评价中获得了较好的结果。     

过套管地层电阻率测井仪的水泥环影响分析

过套管电阻率测井是在金属套管井中测量地层电阻率较新的一种测井方法。在实际进行测量的过程中,仪器测量得到的地层视电阻率受到套管,水泥环、围岩、测量仪器多种因素的影响。这些影响因素会使测量结果与实际地层电阻率存在偏差,从而影响到测量的准确性。本文改进对以往用公式推导来推算水泥环对过套管电阻率的影响的方法,采用修正的传输线方法,通过数值模拟对过套管电阻率测井水泥环影响因素进行分析,得到水泥环影响规律,并对实际井的校正方法进行了研究。     

完整岩体对测井频率应力波的滤波特性

不同频率范围内的应力波在岩体的传播过程中,衰减系数对频率的依赖性具有显著差异。通过现场试验研究完整岩体对测井频率范围内应力波的滤波特性,针对常用黏弹性模型在描述衰减系数与频率关系存在不足,在频域上对黏性系数进行非定常处理,建立黏性系数非定常Maxwell模型,采用波形相关系数评价改进模型的滤波效果。研究结果表明,完整岩体总体上表现为低通滤波,在低通滤波范围内具有非等间距带通滤波特性,随传播距离增加,带通数逐渐减小;在吸收频率过渡带,应力波衰减系数随频率变化非常快,黏性系数非定常Maxwell模型能够有效描述应力波在完整岩体中的衰减系数变化规律;吸收频率过渡带的边界频率与传播距离成负指数关系,吸收频率过渡带的陡度参数可以近似认为是常数;随传播距离增加,黏性系数非定常Maxwell模型描述完整岩体的滤波效果明显提高,当传播距离为4.75m时,波形相关系数达到0.89,表明采用改进模型描述完整岩体是有效的。     

重塑黄土内球面应力波粒子速度测量波形的拉格朗日分析

选用密度为1.8 g/cm3、饱和度为22%的重塑黄土作为应力波传播介质,在其中心处安装0.125 g TNT当量微型炸药球,建立起了尺度为Ф1370 mm×1200 mm的球面波发生装置。在重塑黄土样品中心圆形环面上布设多根圆环形电磁粒子速度计,测量了一系列粒子速度波形。为研究重塑黄土样品粘弹性区域的本构关系,为有限元数值模拟提供可靠的数据支持,以实测粒子速度波形为基础,使用Lagrange分析方法对该区域的应力-应变关系展开了研究。该文详细介绍了一维球对称条件下Lagrange分析方法的理论推导及求解过程,对实测粒子速度波形运用Lagrange分析方法计算了对应的应变、应力及应变率波形,得到了各量计安装位置处,重塑黄土完整的压缩、拉伸全过程应力-应变滞回曲线。并对Lagrange分析方法使用中遇到的问题提出了几点认识。     

小井眼固井测井质量影响因素分析

伴随小井眼套管困井,有可篱存在水泥环薄等特征,同时源距不同、水泥环厚度也对波形有重大影响,这为固井质量评价带来相当大的困难。本文根据大量测井资料和实验研究详绷分析套管井中影响声波信号的一些因素以及对井眼固井质量评价产生的影响,指出在利用声波信号评价固井质量时,必须充分考虑这些影响因素,才能得习有效评价结果。     

全波列声波测井评价低比重水泥固井质量向题探讨

本文通过模拟计算套管井中理论波型,分别讨论了钢—水泥—地层胶结好坏三种情况,认为全波列声波测井不仅能评价低比重水泥固结质量,而且还能解决水泥胶结第二界面问题。这对石油工业勘探开发过程中,提高固井质量、防止油层污染,油水窜流等现象有着十分重要意义。     

套管井中泄漏弯曲型Lamb波声场的模拟与分析

基于套管中传播的最低阶泄漏弯曲型Lamb波(以下简称弯曲型Lamb波)对套管后介质尤其是低阻抗慢速水泥声学参数的敏感性,通过建立多层介质模型并利用实轴积分方法,数值模拟了有限尺寸定向辐射探头激发的声场和定点接收的全波波列。结果表明,在声源辐射到套管内壁上的入射角度约为33°时,在套管中主要激发弯曲型Lamb波。声场快照显示弯曲型Lamb波在沿着套管传播时,还会向与套管耦合的泥浆或水泥中泄漏比它速度低的波。若套管后介质是纵横波速度均低于弯曲型Lamb波相速度的慢速水泥,则套管中弯曲型Lamb波的衰减较大。利用弯曲型Lamb波对套管后耦合不同参数介质时的敏感性,可以有效地区分声阻抗接近的固体和液体,提高低阻抗水泥固井质量评价的效果。     

Experimental study the collapse failure mechanism of cemented casing under non-uniform load

Under non-uniform in-situ stress, the casing collapse failure often happens easily, and especially in soft rock the problem is more serious. In addition, only the few scholars do some studies about failure mechanism of cemented casing under non-uniform in-situ stress which has a strong effect on collapse properties of cemented casing, especially testing investigation. Hence, the collapsing test was performed for cemented casing under non-uniform load (NFL) by adopting self-developed testing equipment, by which the radial deformation of cemented casing and damage rules of cement sheath have been measured and the stress-strain laws of cemented casing are obtained during the testing process by the electrical method. The initial yield load and plastic limit load of cemented casing as well as the subsequent yield load have been obtained. By analyzing testing data, the stress-hardening rate and strain-hardening rate after hardening have been determined. The effects of cement sheath on collapse properties of P110SS casing and strain and deformation laws of P110SS casing after hardening have been obtained. The hardening character and failure mechanism of cemented casing have been figured out under NFL.     

钢纤维增强水泥砂浆压剪联合冲击下动态剪切性能

基于唐志平等提出的剪切波跟踪技术(SWT),对钢纤维增强水泥砂浆进行了冲击速度40m/s~270m/s倾斜角为0~20°的斜撞击试验。研究结果表明,在此冲击速度下,材料处于损伤状态和由损伤状态向孔洞崩塌过渡阶段。此结果与聚丙烯纤维增强水泥砂浆的实验结果进行对比,发现钢纤维体积含量为0.5%时,对压缩性能的增强效果并不明显,但相应的剪切波速明显增加;当钢纤维体积含量为1%时对压缩性能和剪切波速均有较大的提高。由于钢纤维与水泥砂浆基体的强度相差太大,剪切强度有一定的改善,但数据较离散。同时通过对剪切结果分析表明,采用剪切波,尤其是卸载剪切波来探测脆性材料内部动态损伤非常有效。     

Elasticity solution for the casing under linear crustal stress

The integrity of the casing is crucial for oil and gas well. Based on stress function method, a three-dimensional model of the casing-cement sheath-formation system subjected to linear crustal stress is proposed. And then an analytical solution of the model was obtained. In the process of calculation, the casing and cement sheath are simplified as the perfect cylinder. The cement sheath is closely bonded with the casing and formation. The formation is considered to be an isotropic material without the layer-block structure. And the crustal stress is assumed to be linearly increasing with the depth of the well. The analytical solution strictly meets the stress and displacement continuity condition and boundary condition, and exhibits good agreement with finite element method. The results imply that an analytical method to capture the stress and displacement field of the casing under linear crustal stress along the axis is presented. Next, a benchmark for numerical and approximate solutions is provided. In addition, a new idea about solving the casing under the non-linear loads along the axis in some special stratum (such as heterogeneity stratum, salt rock) is proposed. Finally, our understanding for the casing under complex loads will be deepened.     

刚-柔耦合支护巷道围岩应力波传播和衰减规律及试验分析

支护巷道围岩冲击破坏及防治一直是采矿工程中难以解决的问题。对冲击应力波在支护巷道中的传播和衰减过程进行分析,分别得到了冲击应力波作用巷道围岩、刚性支护巷道和刚-柔耦合支护巷道发生破坏的应力判据和能量条件。采用低能爆炸加载方式,利用高速数据采集方法(数字散斑观测),对炮孔距离巷道顶部为200mm,硝铵炸药量为6.0g条件下裸巷和刚-柔耦合支护巷道冲击破坏过程进行监测,得到了裸巷和刚-柔耦合支护巷道表面散斑场变形破坏特征。试验结果说明了刚-柔耦合支护可有效缓冲动态载荷、吸收冲击能量,也为防治巷道冲击破坏提供了一种新方法。     

Material response at hypervelocity impact conditions using laser induced shock waves

Dynamic fracture at hypervelocity impact conditions was investigated in different materials using short pulsed laser induced shock waves. All stages of damage evolution were identified for one dimensional or spherical shock wave impact geometry. A new experimental method is presented to estimate the shock pressure decay in materials. In the theoretical section we obtain the damage induced in the target, as follows: The shock wave is modeled by an expanding stress front, which creates micro-damage in the laser impacted layer and extrudes a bulge at the far surface. The calculated bulge geometry compares well with that observed by us for metal-adhesive-metal sandwiches. The micro-defects coalesce into macro- damage or fracture by a mechanism which is described by percolation theory.     

注汽井套管的三轴预应力设计

以暴露于热蒸汽中的目的层套管为研究对象,根据弹性力学理论,首先给出了套管在热应力和非均匀地应力作用下的三轴应力表达式,然后利用对套管施加预应力来降低套管的轴向热应力,以使得套管的有效应力控制在相应温度下套管的最小屈服极限内为原则,得到了热采井套管三轴预应力设计方法,并对辽河油田常用的N80钢级套管进行了预应力设计分析,给出了该套管在不同注汽温度和井深条件下所应使用的径厚比及相应的预应力值。研究表明,在实际注汽过程中适当增加注汽压力可以提高套管的安全性,传统的单轴预应力设计及只考虑热应力的三轴预应力设计结果偏于保守,建议以后注汽井在进行预应力设计时应考虑热应力和实际非均匀地应力的共同作用。     

基于热-流-固耦合的热采井受力数值计算

针对热采井套损十分严重的情况,建立了考虑多场耦合的热采过程井壁受力计算数学模型.借助数值计算软件模拟了热采过程油井周围渗流场和应力场的变化情况,并与辽河油田稠油热采井套损情况对比验证了所建立模型的有效性.通过数值模拟研究分析了热采过程注采参数对套管挤压力的影响规律,研究表明:在开井生产时,随着井底压力的下降,套管承受的...     

Cased Hole Flexural Modes in Anisotropic Formations

Based on the perturbation method, for flexural wave in cased hole in anisotropic formation, the alteration in the phase velocity caused by the differences in elastic constants between anisotropic formation of interest and a reference, or unperturbed isotropic formation is obtained. Assuming the cased hole is well bonded, the Thomson-Haskell transfer matrix method is applied to calculate the dispersion relation of flexural wave in cased hole in unperturbed isotropic formation. Both the cases of a fast and slow formation are considered where the symmetry axis of a transversely isotropic (TI) formation makes an angle with the cased hole axis, the dispersion of the phase velocity of the flexural mode in cased holes is studied. The corresponding dispersion curves of flexural wave in open hole are presented simultaneously for comparison. The computational results indicate that because of the influence of the casing, the flexural wave dispersion curves in cased hole in both fast and slow TI formations all almost tend toward an identical Stoneley wave velocity at higher frequency. The casing and the cement affect the form as well as the cut-off frequency of flexural wave dispersion curves more greatly in slow TI formation than in fast TI formation. At a frequency high enough, the flexural and the Stoneley waves reach the appropriate Scholte wave velocity in both the open hole and cased hole situation.