發(fā)布時(shí)間：2018-07-05 01:15

  本文選題：微地震 + 低信噪比�。� 參考：《長(zhǎng)江大學(xué)》2015年碩士論文

【摘要】：隨著油氣勘探開(kāi)發(fā)的進(jìn)展,傳統(tǒng)油氣田中后期開(kāi)發(fā)、新興非常規(guī)油氣田開(kāi)采中大量使用水力壓裂及微地震監(jiān)測(cè)技術(shù)。油氣開(kāi)發(fā)中注水、注氣、熱驅(qū)或壓裂時(shí),地下巖層產(chǎn)生裂縫或斷裂,產(chǎn)生地震波。該項(xiàng)技術(shù)通過(guò)在鄰井中的檢波器來(lái)監(jiān)測(cè)壓裂井在壓裂過(guò)程中誘發(fā)的微地震波來(lái)描述壓裂過(guò)程中裂縫生長(zhǎng)的幾何形狀和空間展布。它能實(shí)時(shí)提供壓裂施工產(chǎn)生裂隙的高度、長(zhǎng)度和方位角,利用這些信息可以優(yōu)化壓裂設(shè)計(jì)、優(yōu)化井網(wǎng)或其他油田開(kāi)發(fā)措施,從而提高采收率。與天然地震和常規(guī)地震勘探相比,微地震具有地震強(qiáng)度低、頻率高、持續(xù)時(shí)間短等特點(diǎn)。本文首先闡述微地震形成機(jī)理及其特征,并對(duì)微地震監(jiān)測(cè)采集、處理、解釋等技術(shù)進(jìn)行描述。微地震監(jiān)測(cè)技術(shù)中,壓裂和采集方案設(shè)計(jì)、信號(hào)處理、波場(chǎng)分離、極化分析、初至拾取、正反演分析等都是重要步驟。在微地震監(jiān)測(cè)中,受儀器設(shè)備制約以及強(qiáng)噪音的影響,接收到的微地震信號(hào)經(jīng)常是低信噪比信號(hào),所以微地震信號(hào)的處理、微地震事件的識(shí)別和初至拾取就成為整個(gè)流程中最關(guān)鍵的環(huán)節(jié)。微地震監(jiān)測(cè)的資料處理和解釋方法來(lái)源于天然地震和常規(guī)地震勘探。本文針對(duì)地震記錄中噪音產(chǎn)生的原因、類型、特點(diǎn)進(jìn)行了分析,介紹了常用的地震信號(hào)去噪方法。本文對(duì)K-L變換處理微地震資料的方法進(jìn)行了探討,并從傅里葉變換出發(fā),對(duì)傳統(tǒng)的時(shí)頻分析方法進(jìn)行綜述,分別從從短時(shí)傅里葉變換和小波變換推導(dǎo)S變換,總結(jié)其特性：與傅里葉變換直接聯(lián)系,其過(guò)程無(wú)損可逆；介于小波變換和短時(shí)傅里葉變換之間,是線性時(shí)頻表示方法,沒(méi)有交叉項(xiàng)的干擾；分辨率與信號(hào)頻率直接相關(guān)；基本小波不用考慮容許性條件限制。本文對(duì)這些時(shí)頻分析方法進(jìn)行綜合比較,S變換的時(shí)頻分辨率在線性變換中有明顯的優(yōu)勢(shì),相對(duì)于二次型變換,沒(méi)有交叉項(xiàng)干擾。結(jié)合微地震信號(hào)的特性,本文選擇S變換進(jìn)行微地震識(shí)別和信號(hào)重構(gòu)。隨機(jī)噪聲的不可預(yù)測(cè)性以及與有效波之間的頻譜重疊是微地震信號(hào)處理中的一個(gè)難點(diǎn),低信噪比微地震信號(hào)的去噪處理中,容易出現(xiàn)信號(hào)處理的失真。在信號(hào)處理的過(guò)程中,信噪比的提高和信號(hào)的保真在算法的實(shí)現(xiàn)過(guò)程中是一個(gè)重要的平衡。傳統(tǒng)的地震相拾取方法包括能量比法、AIC法、分形分維法、神經(jīng)網(wǎng)絡(luò)等。本文詳細(xì)論述能量比法、AIC法等傳統(tǒng)微地震信號(hào)初至拾取方法的算法,總結(jié)借鑒眾多算法的優(yōu)勢(shì)和缺陷：能量比法拾取初至簡(jiǎn)單、有效,但是受時(shí)窗長(zhǎng)度影響較大；AIC法能精確拾取初至,但是不能對(duì)信號(hào)中是否包含微地震事件進(jìn)行有效識(shí)別�；赟變換對(duì)微地震信號(hào)重構(gòu)獲得較高信噪比信號(hào)的基礎(chǔ)上, 本文設(shè)計(jì)先用能量比法識(shí)別微地震事件、再用AIC法進(jìn)行精確拾取的兩步法對(duì)微地震事件進(jìn)行初至拾取。此方法不受時(shí)窗變化影響,能夠?qū)崿F(xiàn)重構(gòu)后信號(hào)的有效和精確拾取。本文針對(duì)低信噪比微地震信號(hào),利用S變換進(jìn)行時(shí)頻分析重構(gòu),能量比-AIC兩步法進(jìn)行拾取,獲得更準(zhǔn)確的初至信息,對(duì)壓裂效果進(jìn)行反演和解釋,進(jìn)而實(shí)現(xiàn)對(duì)壓裂方案的優(yōu)化。
[Abstract]:With the development of oil and gas exploration and development, in the middle and late development of traditional oil and gas fields, hydraulic fracturing and microseismic monitoring are widely used in the exploitation of new unconventional oil and gas fields. In the course of oil and gas development, water injection, gas injection, thermal flooding or fracturing, the underground rock produces crack or fracture and produces seismic waves. This technology is monitored by the geophone in adjacent wells. Microseismic waves induced by fracturing during fracturing describe the geometry and space distribution of fracture growth during fracturing. It can provide the height, length and azimuth of fractured construction in real time, using these information to optimize the fracturing design, optimize the well network or other oil field development measures, so as to improve the recovery and natural recovery. Compared with conventional seismic exploration, microseismic has the characteristics of low seismic intensity, high frequency and short duration. This paper first describes the mechanism and characteristics of microseismic formation, and describes the techniques of microseismic monitoring collection, processing and interpretation. In microseismic monitoring, the design of fracturing and acquisition schemes, signal processing, wave field separation, and extreme seismic detection are used in microseismic monitoring. In microseismic monitoring, the microseismic signals are often low signal to noise ratio signals, so the processing of microseismic signals, the recognition of microseismic events and the initial pick-up are the most critical links in the whole process. The methods of data processing and interpretation of seismic monitoring are derived from natural earthquakes and conventional seismic exploration. This paper analyzes the causes, types and characteristics of noise produced in seismic records, introduces common seismic signal denoising methods. This paper discusses the method of K-L transformation for processing microseismic data, and starts from Fu Liye transform, The traditional time-frequency analysis methods are summarized. The S transform is derived from the short time Fu Liye transform and the wavelet transform, and their characteristics are summarized. The process is directly connected with Fu Liye transform. The process is nondestructive and reversible; between the wavelet transform and the short-time Fu Liye transform, it is a linear time frequency representation method, without the interference of the cross term; resolution and letter. The frequency of the basic wavelet is directly related; the basic wavelet does not consider the admissibility conditions. This paper makes a comprehensive comparison of these time frequency analysis methods. The time frequency resolution of the S transform has obvious advantages in the linear transformation. Compared with the two type transformation, there is no cross term interference. In combination with the characteristics of the microseismic signal, this paper chooses the S transform to carry out the microseismic recognition. The unpredictability of the signal and the signal reconstruction. The unpredictability of random noise and the overlapping of the spectrum with the effective wave are a difficult point in the processing of the microseismic signal. In the denoising processing of the low signal to noise ratio microseismic signal, it is easy to appear the distortion of signal processing. In the process of signal processing, the enhancement of signal to noise ratio and the fidelity of signal in the process of signal processing are the realization of the algorithm. The traditional method of picking up seismic phase includes energy ratio method, AIC method, fractal fractal dimension method and neural network. This paper discusses the algorithm of the first arrival method of traditional microseismic signal, such as energy ratio method and AIC method, and summarizes the advantages and the deficiency of many algorithms: the energy ratio method is simple and effective, but it is effective, but subject to the energy ratio method. The length of the time window has great influence; the AIC method can pick up the first arrival accurately, but can not effectively identify the micro seismic events in the signal. Based on the S transform to obtain the signal to the high signal to noise ratio for the reconstruction of the microseismic signal, this paper first uses the energy ratio method to identify the microseismic events and then the two step method of picking up accurately with the method of AIC. This method is not affected by the change of the time window and can realize the effective and accurate pick-up of the reconstructed signal. In this paper, the S transform is used to reconstruct the time frequency analysis of the low signal to noise ratio microseismic signal, and the energy is picked up by the -AIC two step method, and the accurate initial information is obtained, and the fracturing effect is retrieved and the results are retrieved. In addition, the optimization of the fracturing scheme is realized.
【學(xué)位授予單位】：長(zhǎng)江大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P631.4

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本文編號(hào)：2098280