| 题名 | 带扇形窜槽的非轴对称固井声场研究 |
| 作者 | 林伟军 |
| 学位类别 | 博士 |
| 答辩日期 | 2005 |
| 授予单位 | 中国科学院声学研究所 |
| 授予地点 | 中国科学院声学研究所 |
| 关键词 | 声场 套管井 窜槽 有限差分 |
| 其他题名 | Acoustic field in a cased well with a sectorial crossing channel |
| 中文摘要 | 非轴对称井孔声场研究是近年来声波测井领域的热点之一，本文着重于带窜槽的套管井声场研究。所谓窜槽是指在固井过程中由于水泥粘结缺失而在套管和地层中形成的一个柱状充液间隙。窜槽的存在对油井生产危害极大，国内外研究者试图通过各种方法检测窜槽，但尚无明显成果。为研究通过常用声波测井仪器检测窜槽并进一步定量其大小的可能性，本文首次研究了带各种角度窜槽的非轴对称套管井声场。而在以往的研究中，一般都假定粘结缺陷是全方位的（相当于一个360度的窜槽），这和实际情况相差很大。我们编制并运用2．5维有限差分程序来计算带各种角度窜槽及多个窜槽的套管井声场，通过傅立叶变换在波数域进行差分计算，从而在通用计算机上实现了需要大量内存和计算量的三维井孔声场计算。通过和实轴积分结果的比较，验证了我们编制的有限差分程序。论文显示了单极子声源在带各种角度窜槽的套管井中激发的声场展开图和不同源距的接收波列。同时，本文还通过二维谱方法计算分析了窜槽对声场的影响。研究显示，加大源距和采用15KHz左右较低中心频率的声源均有利于鉴别窜槽的存在和大小。对于声源和接收探头均位于中心井轴上的情况，只有窜槽的角度大于30度，才能明显地改变接收波列，但是无法判别窜槽的位置。本文还通过非轴对称井孔声场实验，和数值计算的结果进行对比，进一步验证了用2．5维有限差分方法计算非轴对称井孔声场的可靠性。 |
| 英文摘要 | The crossing channel in a cased well is a column filled with fluid in the cement layer between the steel pipe and formation. It is formed during well cementing sometimes and is very harmful to the well. People have been trying to detect crossing channels by various methods. Some new types of tools were developed as well. In order to study the possibility of detecting and sizing the crossing channel by using a traditional logging tool, the acoustic field in a cased well with a crossing channel of various degree is studied for the first time in this paper. To authors' knowledge only situations of well bonded and 360° crossing channels were considered, much different from the practical situations. 2.5-D finite difference method developed by Leslie and Randall are used which transform all Finite Difference(FD) equations into axial wave-number domain and, after the FD iteration in this domain, the result is transformed back to the time-spatial domain by Fourier transform. The most advantage of this 2.5-D method lies in that it solves some kinds of 3-dimensional acoustic field problems with small computer memory. The results of the 2.5-D finite difference method for the cases of 0° and 360° are compared and consistent with that of the well known real axis integration method. Snapshots of normal stress and synthetic time-domain waveforms are displayed. The two-dimensional spectrum in wave-number and frequency domains is also calculated, where the influence of the channel is clearer than that in the waveforms. Numerical study demonstrated that a crossing channel can be detected and sized if its angle is larger than 30 degree, and larger offset and lower frequency source are favorable to detect and size the crossing channel. The acoustic field in an asymmetric borehole was also investigated experimentally and compared with the result of numeric simulation with 2.5-D finite difference method, and a consistent result was obtained. This work provides an accuracy check of our investigation of asymmetric borehole with 2,5-D finite difference method. |
| 语种 | 中文 |
| 公开日期 | 2011-05-07 |
| 页码 | 62 |
| 内容类型 | 学位论文 |
| 源URL | [http://159.226.59.140/handle/311008/1026]  |
| 专题 | 声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文 |
| 推荐引用方式 GB/T 7714 | 林伟军. 带扇形窜槽的非轴对称固井声场研究[D]. 中国科学院声学研究所. 中国科学院声学研究所. 2005. |
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