本文選題：VSP　切入點：數(shù)值模擬　出處：《東北石油大學》2015年碩士論文

【摘要】：為了滿足如今油氣勘探和開發(fā)對高精度處理復雜地下構造的迫切需求,VSP技術以其高信噪比、高分辨率,能夠識別井旁小斷層、微裂隙等精細構造的優(yōu)勢,正在成為目前地震勘探中解決精細成像地下構造和精細描述油氣儲層等問題的一項有力技術。隨著地震設備性能的逐步提升,VSP數(shù)據(jù)的采集也越來越完善,因此有效的VSP數(shù)據(jù)成像方法也逐漸成為地震資料處理中的一個研究熱點。本文簡述了VSP觀測系統(tǒng)及其波場特征,在VSP數(shù)據(jù)的數(shù)值模擬、波場分離以及逆時偏移方面進行了研究探索。本文采用有限差分法數(shù)值模擬VSP數(shù)據(jù),利用泰勒級數(shù)展開式推導了波動方程的時間二階、空間高階有限差分格式,并討論了正演模擬的穩(wěn)定性條件和震源函數(shù)。詳細分析了完全匹配層吸收邊界條件對人工邊界產生的反射干擾進行吸收和衰減的原理及效果。針對有限差分法數(shù)值模擬中的頻散問題,應用通量校正傳輸法對其做有效壓制。VSP資料包含豐富的波場信息,上下行波的能量差異為處理工作帶來了難度。通過分析傳統(tǒng)波場分離方法的缺點和局限性,對f-k濾波法和中值濾波法分別進行優(yōu)化。優(yōu)化f-k濾波法解決了傳統(tǒng)方法輸出波場中的Reiber混合問題,優(yōu)化中值濾波法突破了傳統(tǒng)方法濾波方向和濾波窗長單一的局限,提高了波場分離精度。疊前逆時偏移基于雙程波動方程,被認為是目前精度最高的地震資料偏移算法。本文詳細介紹了逆時偏移的計算過程,針對邊界和存儲問題,在應用PML邊界條件的基礎上提出優(yōu)化存儲方式,實現(xiàn)了在不引入隨機噪音的同時大大節(jié)約存儲的逆時偏移算法,保證了偏移剖面的精度。關于逆時偏移中成像條件的應用,本文分析和比較了互相關成像條件、歸一化成像條件和上下行波振幅比成像條件三種方法的原理和應用。對逆時偏移結果中的低頻噪音干擾,采用拉普拉斯算子噪音壓制法進行處理,提高成像精度。綜合分析表明,高精度的逆時偏移方法可有效成像VSP地震數(shù)據(jù),對精細刻畫井旁小斷層、大傾角、井旁局部構造具有一定優(yōu)勢,作為一項地震勘探新技術具有深遠的研究意義和廣闊的應用前景。
[Abstract]:In order to meet the urgent need of oil and gas exploration and development to deal with complex underground structures with high precision, VSP technology has the advantages of high signal-to-noise ratio (SNR), high resolution, and the ability to identify fine structures such as small faults and micro-fractures near wells. It is becoming a powerful technique in seismic exploration to solve the problems of fine imaging underground structure and fine description of oil and gas reservoir. With the gradual improvement of seismic equipment performance, the acquisition of VSP data is becoming more and more perfect. Therefore, the effective imaging method of VSP data has gradually become a research hotspot in seismic data processing. In this paper, the VSP observation system and its wave field characteristics are briefly described, and the numerical simulation of VSP data is presented. The wave field separation and inverse time migration are studied. In this paper, the finite difference method is used to simulate the VSP data, and the Taylor series expansion is used to derive the second order and high order finite difference schemes of the wave equation. The stability condition and source function of forward modeling are discussed. The principle and effect of absorbing and attenuating the reflection interference caused by artificial boundary by perfectly matched layer absorbing boundary condition are analyzed in detail. The dispersion problem in value simulation, The effective suppression of VSP data by flux correction transmission method contains abundant wave field information, and the energy difference between up-and-down waves brings difficulties to the processing work. This paper analyzes the shortcomings and limitations of traditional wave field separation methods. The f-k filtering method and the median filtering method are optimized respectively. The optimized f-k filtering method solves the Reiber mixing problem in the output wave field of the traditional method, and the optimized median filtering method breaks through the limitation of the traditional filtering direction and the single window length of the filter. The accuracy of wave field separation is improved. Pre-stack inverse time migration is based on two-way wave equation and is considered to be the most accurate migration algorithm for seismic data at present. In this paper, the calculation process of inverse time migration is introduced in detail, aiming at boundary and storage problems. Based on the application of PML boundary condition, an optimized storage method is proposed to realize the inverse time migration algorithm without introducing random noise, which can ensure the accuracy of migration profile. The application of imaging conditions in inverse time migration is discussed. This paper analyzes and compares the principle and application of three imaging methods: cross correlation imaging condition, normalized imaging condition and up / down wave amplitude ratio imaging condition. The Laplace operator noise suppression method is used to improve the imaging accuracy. The comprehensive analysis shows that the high precision inverse time migration method can effectively image VSP seismic data, and can accurately depict small faults near wells with large dip angle. As a new seismic exploration technique, the local structure near the well has some advantages, which has profound research significance and broad application prospect.
【學位授予單位】：東北石油大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P631.4;P618.13

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本文編號：1681822