【摘要】：海洋單道地震勘探以其配置靈活、簡(jiǎn)便高效的優(yōu)勢(shì),在海洋區(qū)域地質(zhì)調(diào)查、近海工程物探等領(lǐng)域得到了廣泛的應(yīng)用。數(shù)據(jù)采集時(shí),激發(fā)震源和接收電纜拖曳于船后一定深度的海水中,調(diào)查船以一定速度沿設(shè)計(jì)的測(cè)線航行,震源按一定時(shí)間間隔激發(fā),一次激發(fā)形成一個(gè)地震道,震源與檢波器組中心點(diǎn)距離較短,得到的地震記錄通常能夠較為直觀地反映地下地層結(jié)構(gòu)。但由于海上單道地震記錄存在著各種各樣的干擾波,如多次波、虛反射、環(huán)境噪聲等,這些干擾波都會(huì)或多或少地影響資料解釋,因此必須了解干擾波的來(lái)源、形成機(jī)制及傳播規(guī)律,研究單道地震資料處理方法,提高資料處理技術(shù)。本文對(duì)海洋地震勘探方法、海上單道地震勘探常用的電火花震源與接收電纜、海上單道地震記錄中常見(jiàn)干擾波的形成機(jī)制進(jìn)行了闡述,以平潭海域的實(shí)際調(diào)查資料為數(shù)據(jù)基礎(chǔ),首先利用地震記錄中背景噪聲與震源子波的頻率特征差異進(jìn)行濾波,然后利用直達(dá)波提取地震子波并進(jìn)行相關(guān)濾波,通過(guò)對(duì)單道地震資料的分析、處理,提高地震剖面的信噪比和分辨率,最后利用鉆孔沉積物分析結(jié)果對(duì)地震層序進(jìn)行了劃分,得到了以下幾點(diǎn)認(rèn)識(shí):1)海洋地震勘探以調(diào)查船為載體,船舶及船載設(shè)備產(chǎn)生的噪聲貫穿著整個(gè)地震勘探工作,不同船型、船速以及不同海域引起的背景噪聲對(duì)地震記錄的影響也有所不同。通過(guò)“只記錄不激發(fā)”的采集方式獲得地震勘探的背景噪聲資料,并對(duì)其進(jìn)行頻譜分析,得出該工區(qū)地震記錄背景噪聲的頻率范圍在35~140Hz,而采用的電火花震源的有效頻率范圍在180~2000Hz,二者可在頻域分開(kāi),故可以利用背景噪聲與震源子波的頻率特性差異來(lái)選擇頻域?yàn)V波參數(shù),最大限度地保留有效信號(hào)。2)由于水體對(duì)地震波的吸收作用相對(duì)較弱,且直達(dá)波的傳播距離相對(duì)較短、傳播穩(wěn)定、受污染少,原始地震記錄中的直達(dá)波能量較強(qiáng),波形形變較小,因此可以利用直達(dá)波提取地震子波。而由于海洋勘探環(huán)境的復(fù)雜多變性,利用直達(dá)波提取地震子波時(shí)首先需要消除隨機(jī)因素的影響,可先利用相關(guān)法拾取各道的直達(dá)波,將各道提取的直達(dá)波進(jìn)行疊加再平均,通過(guò)平均的手段消除隨機(jī)因素的影響,最后以平均的結(jié)果作為提取的地震子波。3)提取的地震子波與反射波的相關(guān)性強(qiáng),而與其它干擾波的相關(guān)性弱,因此可以利用提取的地震子波進(jìn)行相關(guān)濾波,提高地震記錄的信噪比。進(jìn)行相關(guān)濾波時(shí),相關(guān)子波長(zhǎng)度不宜超過(guò)地震子波的延時(shí)。而相關(guān)濾波前對(duì)地震記錄先進(jìn)行帶通濾波能夠有效地克服低頻水波干擾對(duì)相關(guān)處理的影響。地震資料解釋通常需要結(jié)合地質(zhì)鉆孔、地球物理測(cè)井等資料。利用測(cè)線附近取得的鉆孔沉積物樣品的分析測(cè)試結(jié)果,對(duì)沉積層序進(jìn)行劃分,根據(jù)以往經(jīng)驗(yàn),沉積物聲速設(shè)為1600m/s,將柱狀樣長(zhǎng)度轉(zhuǎn)換為地震波旅行時(shí),與處理后的時(shí)間剖面進(jìn)行對(duì)比,并結(jié)合反射同相軸的接觸關(guān)系,識(shí)別出4個(gè)主要反射界面。
[Abstract]:The marine single-channel seismic exploration has the advantages of flexible, simple and effective configuration, and has been widely used in the fields of marine area geology survey, offshore engineering geophysical exploration and so on. When the data is collected, the excitation source and the receiving cable are towed in seawater at a certain depth after the ship is towed, the survey ship is sailing along the designed test line at a certain speed, the seismic source is excited at a certain time interval, a seismic channel is excited at one time, the distance between the seismic source and the center point of the detector group is shorter, The resulting seismic records can generally reflect the subsurface formations more visually. However, due to the existence of various kinds of interference waves, such as multiple wave, virtual reflection, environmental noise, etc., these interference waves will influence the interpretation of data more or less, so it is necessary to understand the source, formation mechanism and propagation law of the interference wave. To study the method of seismic data processing in single channel and to improve the data processing technology. In this paper, the formation mechanism of common interference waves in marine seismic exploration method, marine single channel seismic exploration, electric spark source and receiving cable, sea single channel seismic record is expounded, and the actual survey data in Pingtan sea area is the data base. firstly, filtering the difference between the background noise and the frequency characteristic of the seismic source sub-wave in the earthquake record, extracting the seismic sub-wave by using the direct wave and carrying out relevant filtering, analyzing and processing the single-channel seismic data, improving the signal-to-noise ratio and the resolution of the seismic section, Finally, the seismic layer sequence is divided by using borehole sediment analysis results, and the following points are obtained: 1) the noise generated by ship and ship loading equipment is penetrated through the whole seismic exploration work, different ship types, The influence of ship velocity and background noise caused by different sea areas on seismic records is also different. acquiring the background noise data of seismic exploration through the acquisition mode of the 鈥淩ecord non-excitation only鈥，

本文編號(hào)：2294864