期刊导航

Totally found 8 items.

  • [会议] A modified expression of Q attribute and its application in hydrocarbon prediction
    Quality factor (Q) is an important parameter to quantify the loss of seismic energy in subsurface. Oil and gas absorb the high frequency components greatly so the low value of Q can be as the symbol of oil or gas. Accurate Q estimation is necessary for seismic data imaging and interpretation. To estimate Q, frequency shift (FS) method is considered to be an effective method. The most commonly used FS methods are centroid frequency shift (CFS) method and peak frequency shift (PFS) method. The centroid frequency has the advantage of stability but the assumption that the seismic spectrum is Gaussian shape, which leads to the errors of CFS method; The PFS method is based on the Ricker shape assumption but the peak frequency is susceptible to noises, which causes instability. Combining the two methods, we modified the expression of Q based on the two methods and applied it to the oil and gas prediction. This modified expression of Q has the advantages of both CFS and PFS, so it has both high precision and strong stability. Validated by models with different signal-to-noise ratios (SNR), it is applied to real hydrocarbon prediction. The results indicate that the modified Q attribute is highly consistent with well data and more suitable for oil and gas prediction.
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  • [会议] Identifying new opportunities in shallow reservoirs using vintage seismic data
    Tertiary reservoirs ranging in depth from around 80 feet to 400 feet have produced hydrocarbons in Northern and North-Eastern part of the State of Kuwait. This paper presents the efforts to identify lead areas to propose locations for exploratory drilling in these shallow reservoirs using vintage 3D seismic data. It was a challenge to utilize the available seismic data acquired and processed for deeper objectives where the imaging of the shallow formations was affected due to unconslidated layers at shallow depths leading to velocity and static related issues. The study integrates the data from surface geology, drilling, well logs, geochemistry, seismic and gravity. The area is affected by NW-SE and NW-SE trending faults, which appear to have acted as conduits for the hydrocarbon migration. The objective was to predict areas having better reservoir properties and their connectivity with the underlying deeper source through faults. The quality of the vintage 3D seismic was enhanced by using limited processing tools on the workstation. The horizon interpretation of the formation tops was done with higher confidence on this enhanced data. The amplitude attributes extracted on this data got calibrated at drilled locations and were used to identify lead areas having better reservoir properties. The wells drilled inside the identified lead areas were hydrocarbon bearing while those drilled outside went dry.
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  • [会议] The identification of subtle strike-slip faults based on fault likelihood attribute in east of Bohai oilfield, Eastern China
    Faults detection plays an important role in reservoir characterization and hydrocarbon detection. There are lots of methods to identify faults in seismic data, including coherence, variance, curvature, etc. These methods can meet the needs of faults identification in the early or relatively simple areas of exploration, and the faults recognition effect is poor in the late exploration and the complex structure areas. The recognition effect of subtle strike-slip faults are relatively poor in the region with inferior seismic data. We propose a novel subtle strike-slip faults identification that combine structure oriented filtering with fault likelihood attribute. Thus, we can achieve some subtle strike-slip faults and micro faults which cannot identified by conventional methods. We use the proposed approach in the east of Penglai 19-3 oilfield, achieved very good results.
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  • [会议] Hydrocarbon accumulation analysis by reconstructing the canyon-fill sequence using seismic stratigraphic interpretation in the central Gulf Coastal Plain of Texas
    The Texas Gulf region has been extensively studied and explored due to its high volume of oil and gas accumulation. One of the most highly productive sequences in the region is the lower Wilcox Group, which was deposited during a gradually sea level rising. The high rate of Tertiary sedimentary source influx and repeatedly transgression and regression resulted in numerous reservoirs and ideal traps. Regression caused the development of incised canyon systems, and later the canyon was filled with marine shales during the transgression. The complex canyon-fill sequence makes petroleum accumulation possible. Both stratigraphic and structural trapping mechanisms are found in the study area. The stratigraphy of the Wilcox Group is divided based on the lithological data and electric logs. In order to investigate the lateral variations of erosional sequences and the distributions of thin-bed sand bodies, we correlate the well logging across the survey. The seismic sequences and related sandstones are identified on the seismic sections after the well-to-seismic tie. Finally, the complex canyon-fill system is rebuilt and the hydrocarbon accumulation pattern is analyzed by conducting seismic stratigraphic interpretation in the study area.
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  • [会议] Gravity and magnetic data applications for hydrocarbon exploration offshore NW Australia
    A recent BHP Petroleum exploration program investigated the frontier Northern Beagle Sub-basin, which is part of the greater Northern Carnarvon Basin and is located approximately 300 km offshore in NW Australia. Onboard gravity and magnetic data were acquired as part of the 22130 km2 Capreolus multi-client 3D seismic survey acquired by Polarcus in the Northern Beagle Sub-basin. These data have recently been purchased by TGS. They were used to investigate the deep structural and stratigraphic architecture over several areas of interest within the basin. Specifically, gravity and magnetic data were used to model the physical properties within the core of a large mid-crustal structure (the Tres Hombres dome). In addition, magnetic data were integrated with 3D seismic data and used to help identify potential volcanic sequences within stratigraphic intervals of interest, in particular over the large upthrown Emu fault block. These case studies illustrate the value of integrating gravity and magnetic data with high quality 3D seismic datasets in hydrocarbon exploration efforts in regional frontier basins.
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  • [会议] Multi-scale strike-slip fault delineation in deep fractured-vuggy carbonate
    The fault-controlled carbonate reservoir in Shunbei Oilfield, Tarim Basin has recently become one of key plays in China. Hydrocarbon is produced from fracture and cave system at middle and lower Ordovician resulting from strike-slip faulting. The major challenge in exploration is to locate different scale of faults and study whether they are connected to deep Cambrian source rock. The steep strike-slip fault system has very complex geometry with flower structure, minus flower structure, or simpler style. Seismic response is typically characterized by beads, faulting, or clutter reflection associated with fractures and caves. Thereby, it is very challenging to use seismic data to delineate these normal or reverse faults based on conventional seismic attribute. In this study, we choose three approaches to delineate fault system of different sales after data conditioning for fault interpretability enhancement. Firstly, we used a directional scheme to delineate large-scale fault by searching the maximum disorder of amplitude gradient in seismic volume assuming the geometric model of a fault is planar in 3D. Secondly, we applied fault enhanced aberrance to delineate middle-scale faults. Finally, we took the multi-spectral coherence and enhancement approach to delineate small-scale fault. The combination of three approaches provide a very promising solution to facilitating fault interpretation in Shunbei Oilfield.
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  • [会议] Applying seismic sedimentology for high-resolution and quantitative imaging of fluvial channel sandstones: An example from Bohai Bay Basin, China
    The complex braided channel sandstones in the Miocene Guantao Formation of Bohai Bay Basin, China, presents a challenge for reservoir prediction in the area with strong effect of the Tanlu strike-slip fault system. Following the principle of frequency fusion by Zeng (2017), we developed a workflow to generate user-controlled linear combination and RGB color blending of RMS frequency panels to quantify the channel sandstones. A linear combination of three frequency panels from -90° data can lead to a reasonable correlation between the width of seismic event and sandstone thickness ranging from 6-28 m. Two different RGB color blending analysis of three selected frequency panels are also conducted here with obviously advantages in illustrating sandstone thickness. Generally, the RGB blending based on -90° phase data has higher resolution on vertical section than the one based on the RMS frequency panels, whereas the later one has higher resolution on the stratal slices. The proposed RGB blending based on the RMS panels can effectively improve the horizontal resolution which may reduce the uncertain impact of manual interfaces interpretation in complicated areas. This would be useful for us to identify potential thick channel sandstones reservoir for future hydrocarbon exploration.
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  • [会议] An Ultra Low-dimensional Inversion of Homogeneous Geobodies in Full Waveform Inversion
    We address the problem of inversion of large, nearly-homogeneous geobodies in a Full Waveform Inversion (FWI) framework. Of particular interest are subsurface salt bodies, as they are known to serve as seals for hydrocarbon reservoirs. Salt bodies offer a sharp contrast of material properties (with respect to their surroundings) to the incident seismic waves, which significantly reduces the transmission of signal through them. Thus, the presence of salt with unknown geometry presents formidable challenges to FWI as a subsurface imaging technique. To this end, we propose a low-dimensional representation of the salt bodies that is grounded on a stochastic view of the subsurface and treats the presence of salt as a spatial random process. In this setting, a salt body can be represented as a linear combination of a set of ordered, orthonormal basis functions with increasingly small marginal utility. Low-dimensionality is then achieved by truncating the number of basis functions to be included in this representation. The truncation can drastically reduce the dimension of the inversion space. When coupled with state-of-the-art optimization algorithms to minimize a loss function of FWI, the proposed representation is shown to recover the complete geometry of salt body, where traditional cell-based representation could only recover the top of it. Additionally, although the proof of concept pertains to the inversion of salt bodies, the methodology applies to any other nearly homogeneous geobody of interest.
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