【摘要】：作為電磁場方法在地球物理探測領域中的重要應用,電磁隨鉆測量(Electromagnetic-measurement-while-drilling,EM-MWD)信號無線傳輸技術是比較典型的低頻近場問題。在石油測井以及煤層氣探測等現(xiàn)代測井應用中,隨鉆測量技術擔負著監(jiān)控井下工作,將井下探測數(shù)據(jù)與地面系統(tǒng)交互,是測井控制系統(tǒng)中不可或缺的一部分。由于地層介質(zhì)的復雜性,以及電磁波在井下環(huán)境中的迅速衰減而被迫用極低頻率傳輸使得EM-MWD的理論研究難以建立精確、可靠的模型。如何實現(xiàn)對EM-MWD系統(tǒng)的精確建模,是當前研究工作的一個重要問題。針對EM-MWD系統(tǒng)的精確數(shù)值模型的建立及分析,本文做了以下工作,一共分為6個部分:首先在緒論中介紹了隨鉆測量技術的主要分類,國內(nèi)外EM-MWD技術的發(fā)展歷史與現(xiàn)狀、研究意義以及本文的主要內(nèi)容和組織結(jié)構(gòu)。第二章簡要介紹了體面積分方程以及矩量法求解原理,通過幾何建模,選取基函數(shù),計算阻抗元素,最終求解線性方程組;重點介紹了數(shù)值積分及其奇異性處理和線性方程組迭代求解方法。第三章介紹了多層自適應交叉近似算法的基本原理以及具體流程。MLACA算法有效解決了積分方程矩量法中的大未知量所導致的內(nèi)存以及迭代時長的問題。第四章是本文的重點研究內(nèi)容,在考察了幾種常用的EM-MWD數(shù)值建模方法后,建立了基于體積分方程方法的EM-MWD數(shù)值模型。本文選擇了間隙電壓激勵作為EM-MWD的饋電方式,經(jīng)過理論推導,建立了有限寬度(Finite-Gap)電壓源等效模型,并以此為基礎對EM-MWD模型進行了數(shù)值驗證。第五章為數(shù)值分析部分,對EM-MWD系統(tǒng)的各個參數(shù)進行算例分析,包括地層電導率、鉆桿尺寸及頻率等因素的變化,并對結(jié)果予以解釋。
[Abstract]:As an important application of electromagnetic field method in geophysical detection, electromagnetic while drilling measurement (Electromagnetic-measurement-while-drilling,EM-MWD) signal wireless transmission technology is a typical low-frequency near-field problem. In the modern logging applications such as petroleum logging and coalbed methane detection, while drilling and measuring technology is responsible for monitoring and controlling downhole, and it is an indispensable part of logging control system to interact downhole detection data with surface system. Due to the complexity of formation medium and the rapid attenuation of electromagnetic wave in underground environment, it is forced to transmit at very low frequency, which makes it difficult to establish an accurate and reliable model for the theoretical study of EM-MWD. How to realize accurate modeling of EM-MWD system is an important problem in current research work. Aiming at the establishment and analysis of accurate numerical model of EM-MWD system, this paper has done the following work, which is divided into six parts: firstly, in the introduction, it introduces the main classification of measurement technology while drilling, the development history and present situation of EM-MWD technology at home and abroad. The significance of the study and the main content and organizational structure of this paper. In the second chapter, the decent integral equation and the principle of moment method are introduced briefly. Through geometric modeling, selecting the basis function, calculating the impedance element, and finally solving the linear equation group; The numerical integration and its singularity treatment and iterative solution method for linear equations are introduced in detail. In chapter 3, the basic principle and flow chart of multi-layer adaptive crossover approximation algorithm are introduced. MLACA algorithm effectively solves the problem of memory and iteration time caused by large unknown quantity in the method of moment of integral equation. Chapter 4 is the focus of this paper. After investigating several commonly used EM-MWD numerical modeling methods, a EM-MWD numerical model based on the volume fractional equation method is established. In this paper, gap voltage excitation is chosen as the feed mode of EM-MWD. Through theoretical derivation, the equivalent model of finite width (Finite-Gap) voltage source is established, and the EM-MWD model is verified numerically on the basis of this model. The fifth chapter is the numerical analysis part. The numerical examples of the parameters of EM-MWD system are given, including the variation of formation conductivity, drill pipe size and frequency, and the results are explained.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P631.32

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