흑산분지 내 천연가스 탐지를 위한 3차원 탄성파 탐사자료 AVO 분석

정부흥,이호영 한국자원공학회 2008 한국자원공학회지 Vol.45 No.5

By the results of processing and interpretation of 3-D seismic data acquired in the Heuksan Basin of the Korea continental shelf, an anticlinal structure was identified within the range from 120 to 140 number of inline and around 1000 ms by Two way travel time (TWT). A flat seismic event considered as the typical fluid contact appears in the interior of the anticlinal structure. This anticlinal structure is also found within the range from 900 to 1100 ms on time slice map of 3-D seismic volume. This structure is a nose type of anticline structure which has the 4 km in diameter and extends from northeast to southwest direction. AVO (Amplitude versus Offset) analysis was performed for the whole survey data for detection of free-gas zone. The results of the analysis show that the zone of strong AVO anomaly existed in the vicinity of the anticlinal structure. On the cross plotting of gradient and intercept, AVO anomaly appeared in first and third quadrant. which means a typical natural gas layer.

탄성파 자료를 이용한 시추자료 물리적 특성 예측 기술 자립을 위한 상업용 소프트웨어 활용 사례

정부흥(Chung, Bu-Heung),서영탁(Seo, Young-Tack) 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06

가스 하이드레이트 부존층의 구조 파악을 위한 탄성파 전산처리 및 AVO 분석

정부흥(Chung, Bu-Heung) 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06

Multichannel seismic data acquired in Ulleung Basin of East Sea for gas hydrate exploration. The seismic sections of this area show strong BSR(bottom simulating reflections) associated with methane hydrate occurrence in deep marine sediments. Very limited information is available from deep sea drilling as the risk of heating and destabilizing the initial hydrate conditions during the processing of drilling is considerably high. Not so many advanced status of gas hydrate exploration in Korea, the most of information of gas hydrate characteristics and properties are inferred from seismic reflection data. In this study, The AVO analysis using the long offset seismic data acquired in Ulleung Basin used to explain the characteristics and structure of gas hydrate. It is used primarily P-wave velocity accessible from seismic data. To make a good quality of AVO analysis input data, seismic preprocessing including 'true gain correction', 'source signature deconvolution', twice velocity analysis and some kinds of multiple rejection and enhancing the signal to noise ratio processes is carried out very carefully. The results of AVO analysis, the eight kinds of AVO attributes are estimated basically and some others of AVO attributes are evaluated for interpretation of AVO analysis additionally. The impedance variation at the boundary of gas hydrate and free gas is estimated for investing the BSR characteristics and properties. The complex analysis is performed also to verifying the amplitude variation and phase shift occurrence at BSR. Type III AVO anomaly appearance at saturated free gas area is detected on BSR. It can be an important evidence of gas hydrate deposition upper the BSR.

한국(韓國) 남부지역(南部地域)의 지각구조(地殼構造)

김성균,정부흥,Kim, Sung Kyun,Jung, Bu Hung 대한자원환경지질학회 1985 자원환경지질 Vol.18 No.2

Events detected by the KIER microearthquake network operated in the Southern Part of Korea for 265 days in 1982~1984 were reviewed, and some of them were identified to be a dynamite explosion from several construction sites. The purpose of the present work is to determine the crustal structure of the Southern Korea using the time-destance data obtained from such explosion seismic records. The time·distance data can be well explained by a crustal model composed of four horizontal layers of which thickness, p and s-wave velocity ($V_p$ and $V_s$) are characterized as follows. 1st layer (surface) ; 0~2km, $V_p=5.5km/sec$, $V_s=3.3km/sec$ 2nd layer (upper crust) ; 2~15km, $V_p=6.0km/sec$, $V_s=3.5km/sec$ 3rd layer (lower crust) ; 15~29km, $V_p=6.6km/sec$, $V_s=3.7km/sec$ 4th layer (upper mantle) ; 29km~ , $V_p=7.7km/sec$, $V_s=4.3km/sec$ The relatively shallow crust·mantle boundary and low $P_n$ velocity compared with the mean values for stable intraplate region are noteworthy. Supposedely, it is responsible for the high heat flow in the South-eastern Korea or an anomalous subterranean mantle. The mean $V_p/V_s$ ratio calculated from the relation between p-wave arrival and s-p arrival times appears to be 1.735 which is nearly equivalent to the elastic medium of ${\lambda}={\mu}$. However, the ratio tends to be slightly larger with the depth. The ratio is rather high compared with that of the adjacent Japanese Island, and the fact suggests that the underlying crust and upper mantle in this region are more ductile and hence the earthquake occurrences are apt to be interrupted. As an alternative curstal model, a seismic velocity structure in which velocities are successively increased with the depth is also proposed by the inversion of the time·distance data. With the velocity profile, it is possible to calculate a travel time table which is appropriate to determine the earthquake parameters for the local events.

미소지진(微小地震) 장기관측(長期觀測)을 위한 지진기록계(地震記錄計)의 개발(開發)

김성균,조규장,정부흥,문창배,신인철,성낙훈,Kim, Sung Kyun,Cho, Kyu Jang,Chung, Bu Heung,Moon, Chang Bae,Sin, In Chul,Sung, Rack Hoon 대한자원환경지질학회 1988 자원환경지질 Vol.21 No.2

A two channel seismic recorder suitable for long-term observation of microearthquakes is developed. The direct analogue recording on cassette tape is adopted in the recorder whose circuits of amplifier and mortor units of an audio cassette recorder are modified. The recorder provides contineous record of 10 days with DC 12V battery (100AH) and with standard cassette tape of 60 minute use. The binary coded time signals of date, hour, and minute are generated once a minute by the timing system and absolute time input using radio to measure the time drift is also possible. For the seismic signal processing, the analogue signals from audio cassette player pass A/D converter and digitized data are stored in personal computer. Then visual records can be obtained using computer graphic mode. Basic programs "ADCONVO" and "DRAWO" to accomplish A/D conversions, the creation of data files and visualization of signals were written. Some sample signals reproduced from the recorded tape are presented.

울릉분지 서부 천부퇴적물에서의 가스 하이드레이트 생성과 부존

류병재,이영주,정부흥,M. Riedel,김지훈,R. Hyndman,김일수,박근필,정태진 대한지질학회 2004 대한지질학회 학술대회 Vol.2004 No.

가스 하이드레이트 부존층의 구조파악을 위한 탄성파 AVO 분석 AVO모델링, AVO역산

김건득(Kim, Gun-Duk),정부흥(Chung, Bu-Heung) 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06

The gas hydrate exploration using seismic reflection data, the detection of BSR(Bottom Simulating Reflector) on the seismic section is the most important work flow because the BSR have been interpreted as being formed at the base of a gas hydrate zone. Usually, BSR has some dominant qualitative characteristics on seismic section i.e. Wavelet phase reversal compare to sea bottom signal, Parallel layer with sea bottom, Strong amplitude, Masking phenomenon above the BSR, Cross bedding with other geological layer. Even though a BSR can be selected on seismic section with these guidance, it is not enough to conform as being true BSR. Some other available methods for verifying the BSR with reliable analysis quantitatively i.e. Interval velocity analysis, AVO(Amplitude Variation with Offset)analysis etc. Usually, AVO analysis can be divided by three main parts. The first part is AVO analysis, the second is AVO modeling and the last is AVO inversion. AVO analysis is unique method for detecting the free gas zone on seismic section directly. Therefore it can be a kind of useful analysis method for discriminating true BSR, which might arise from an Possion ratio contrast between high velocity layer, partially hydrated sediment and low velocity layer, water saturated gas sediment. During the AVO interpretation, as the AVO response can be changed depend upon the water saturation ratio, it is confused to discriminate the AVO response of gas layer from dry layer. In that case, the AVO modeling is necessary to generate synthetic seismogram comparing with real data. It can be available to make conclusions from correspondence or lack of correspondence between the two seismograms. AVO inversion process is the method for driving a geological model by iterative operation that the result ing synthetic seismogram matches to real data seismogram wi thin some tolerance level. AVO inversion is a topic of current research and for now there is no general consensus on how the process should be done or even whether is valid for standard seismic data. Unfortunately, there are no well log data acquired from gas hydrate exploration area in Korea. Instead of that data, well log data and seismic data acquired from gas sand area located nearby the gas hydrate exploration area is used to AVO analysis, As the results of AVO modeling, type III AVO anomaly confirmed on the gas sand layer. The Castagna's equation constant value for estimating the S-wave velocity are evaluated as A=0.86190, B=-3845.14431 respectively and water saturation ratio is 50%. To calculate the reflection coefficient of synthetic seismogram, the Zoeppritz equation is used. For AVO inversion process, the dataset provided by Hampson-Rushell CO. is used.

가스 하이드레이트 부존층의 하부 경계면을 규명하기 위한 심도영역 탄성파 구간속도 분석

고승원(Ko, Seung-Won),정부흥(Chung, Bu-Heung) 한국신재생에너지학회 2005 한국신재생에너지학회 학술대회논문집 Vol.2005 No.06

For gas hydrate exploration, long offset multichannel seismic data acquired using by the 4km streamer length in Ulleung basin of the East Sea. The dataset was processed to define the BSRs (Bottom Simulating Reflectors) and to estimate the amount of gas hydrates. Confirmation of the presence of Bottom Simulating reflectors (BSR) and investigation of its physical properties from seismic section are important for gas hydrate detection. Specially, faster interval velocity overlying slower interval velocity indicates the likely presences of gas hydrate above BSR and free gas underneath BSR. In consequence, estimation of correct interval velocities and analysis of their spatial variations are critical processes for gas hydrate detection using seismic reflection data. Using Dix's equation, Root Mean Square (RMS) velocities can be converted into interval velocities. However, it is not a proper way to investigate interval velocities above and below BSR considering the fact that RMS velocities have poor resolution and correctness and the assumption that interval velocities increase along the depth. Therefore, we incorporated Migration Velocity Analysis (MVA) software produced by Landmark CO. to estimate correct interval velocities in detail. MVA is a process to yield velocities of sediments between layers using Common Mid Point (CMP) gathered seismic data. The CMP gathered data for MVA should be produced after basic processing steps to enhance the signal to noise ratio of the first reflections. Prestack depth migrated section is produced using interval velocities and interval velocities are key parameters governing qualities of prestack depth migration section. Correctness of interval velocities can be examined by the presence of Residual Move Out (RMO) on CMP gathered data. If there is no RMO, peaks of primary reflection events are flat in horizontal direction for all offsets of Common Reflection Point (CRP) gathers and it proves that prestack depth migration is done with correct velocity field. Used method in this study, Tomographic inversion needs two initial input data. One is the dataset obtained from the results of preprocessing by removing multiples and noise and stacked partially. The other is the depth domain velocity model build by smoothing and editing the interval velocity converted from RMS velocity. After the three times iteration of tomography inversion, Optimum interval velocity field can be fixed. The conclusion of this study as follow, the final Interval velocity around the BSR decreased to 1400 m/s from 2500 m/s abruptly. BSR is showed about 200m depth under the seabottom

Geobit을 이용한 제 3광구 촉선 1724의 자료처리 기법연구

서상용 ( Sang Yong Suh ),정부흥 ( Bu Heung Chung ),장성형 ( Seong Hyung Jang ) 한국지구물리·물리탐사학회 1998 지구물리와 물리탐사 Vol.1 No.1

반복적 대화식 통합 탄성파 속도분석

서상용 ( Sayng Yong Suh ),정부흥 ( Bu Heung Chung ),장성형 ( Seong Hyung Jang ) 한국지구물리·물리탐사학회 1999 지구물리와 물리탐사 Vol.2 No.1